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Step One: Infection (FA)
Terms in this set (928)
____ are bacterial structures that provide motility and are composed of protein.
A 56-year-old goat herder develops a painless black ulcer on his arm. What is special about the capsule of the causative agent?
Bacillus anthracis is the only bacteria with a capsule containing D-glutamate
Which aerobe is commonly associated with burn wounds, nosocomial pneumonia, and pneumonias in patients with cystic fibrosis?
Pseudomonas aeruginosa (Pseudomonas AERuginosa is an AERobe)
A 16-year-old girl has recurrent S. aureus, Pseudomonas, and Candida infections. What enzyme deficiency is responsible?
NADPH oxidase deficiency (chronic granulomatous disease); these bugs are catalase (+) and they degrade the limited H2O2
Exotoxins are composed of ____ (polypeptides/lipopolysaccharides) whereas endotoxins are made of____ (polypeptides/lipopolysaccharides).
Polypeptides; lipopolysaccharides (structural part of bacteria; released when lysed)
Many guests in a hotel with central air conditioning develop a high fever, pneumonia. What is the gram stain/shape of the causative agent?
Legionella, a gram-negative bacillus
Endotoxin activation of macrophages causes release of three cytokines. Name the cytokines. Do they cause fever, hypotension, or both?
Interleukin-1 (fever); tumor necrosis factor (fever, hypotension); nitric oxide (hypotension)
Endotoxins activate the coagulation cascade via what factor? What pathology can result from excess stimulation of this pathway?
Tissue factor; disseminated intravascular coagulation
A hospitalized 86-year-old has gram-positive pneumonia; roommate: gram-negative UTI. What structures are unique to each of these bacteria?
Gram-positive organisms have lipoteichoic acid, and gram-negative organisms have an outer membrane formed by endotoxin/lipopolysaccharide
Which five organisms can be visualized on Giemsa stain?
Chlamydia, Borrelia, Rickettsiae, Plasmodium, and Trypanosomes
A young woman has excessive white foul-smelling vaginal discharge. You see clue cells on wet mount. Name the gram stain/shape of the cause.
She likely has bacterial vaginosis caused by Gardnerella vaginalis, a gram-negative bacillus
During lysogeny, which is a ____ form of transduction, the genes for a bacterial toxin are encoded in a lysogenic ____.
What characteristic of Mycobacteria makes it visible with an acid-fast stain?
The high lipid content in the cell wall is detected by carbolfuchsin in acid-fast stain ("acid-fat" stain)
Which bacterial toxin (endotoxin or exotoxin) can be used as a vaccine? Against what antigen are antibodies formed?
Exotoxin toxoid is used as a vaccine against exotoxin-producing organisms; antibodies form against antigens called antitoxins
A 16-year-old boy has warm red swelling at the site of a cut on his foot. You suspect S. aureus. What protein promotes its virulence?
Protein A prevents opsonization and phagocytosis of S. aureus by binding the Fc region of immunoglobulins
A man presents with a new heart murmur after recent streptococcal pharyngitis infection. Name his diagnosis and the diagnostic test.
Rheumatic fever; presence of anti-streptolysin O antibodies
A farmer develops fever, weakness, and muscle pain after drinking unpasteurized milk. What is the gram stain/shape of the causative agent?
He likely has brucellosis; Brucella is a gram-negative bacillus
Clostridium, Bacteroides, Actinomyces all lack ____ and/or ____, making them susceptible to oxidative damage.
Catalase; superoxide dismutase (these obligate anaerobes Cannot Breathe Air)
Where are anaerobes part of the normal flora? And where are they pathogenic?
They are normal flora of the gastrointestinal tract but are pathogenic in all other tissues
A febrile patient with septic shock has bacteria with poorly antigenic toxins in his blood. What two mediators caused this pathology?
Fever and shock due to induction of tumor necrosis factor and interleukin-1
Name three ADP-ribosylating A-B toxins whose primary action is overactivation of adenylate cyclase.
Vibrio cholerae, enterotoxigenic E. coli (ETEC), and Bordetella pertussis
What organisms can be visualized with a Ziehl-Neelsen stain?
Acid-fast bacteria (Nocardia, Mycobacterium)
A 25-year-old man with multiple sex partners develops dysuria and purulent penile discharge. How is the causative organism cultured? Why?
N. gonorrhoeae grows on Thayer-Martin (VPN): Vancomycin kills gram (+), Polymyxin kills gram (-) except Neisseria, Nystatin kills fungi
Segments of DNA are transferred between ____ (chromosomes/plasmids/both) within the same cell in a process called ____.
A 56-year-old goat herder develops a painless black ulcer on his arm. What organism is responsible and what is the mechanism of its toxin?
Bacillus anthracis; edema factor toxin mimics adenylate cyclase enzyme (increases cAMP), causes the edematous borders of black eschar
Name three vaccines that have been prepared to protect against encapsulated bacteria.
Pneumovax (polysaccharide vaccine without a conjugated protein), Haemophilus influenzae type B vaccine, meningococcal vaccines
Name three types of spirochetes.
Leptospira, Borrelia, Treponema
In what medium can Mycoplasma pneumoniae grow?
A 56-year-old diabetic man has a foul-smelling foot ulcer with palpable crepitus. Which antibiotic should you not use to treat it? Why?
He has an anaerobic skin infection; aminoglycosides require oxygen to enter a bacterial cell and are therefore ineffective against anaerobes
A 20-year-old man recently had a splenectomy. Explain why he should receive S. pneumoniae, H. influenzae, N. meningitis vaccines.
Encapsulated bacteria are opsonized then cleared by the spleen; asplenics have decreased opsonizing ability and are at risk for infection
What is the periplasm, and what kinds of enzymes does it contain in its space?
Space between the cytoplasmic membrane and the outer membrane in gram negatives; it contains hydrolytic enzymes (e.g., β-lactamases)
Which of the following is not an enteric bacillus: E. coli , Vibrio, Bordetella, Helicobacter, Serratia, Enterobacter?
Bordetella, which is a respiratory gram-negative bacillus
Which organisms are obligate intracellular pathogens? Why?
Rickettsia, Chlamydia are intracellular because they cannot make their own ATP (stay inside [cells] when it is Really Cold)
____ produces yellow "sulfur" granules. What are the granules made of?
Actinomyces israelii (Israel has yellow sand); the granules are composed of filaments of bacteria
Describe generalized transduction.
Lytic phage infects bacterium, cleaves bacterial DNA/makes viral DNA, and repackages bacterial DNA in viral capsids to infect other bacteria
A girl has rice-water diarrhea and is dehydrated. What organism is responsible, and what is its mechanism of action?
Vibrio cholerae; A-B toxin activates Gs protein and stimulates adenylyl cyclase, which increases Cl- (therefore water) secreted in gut
What is a plasmid, and what information does it carry?
A segment of bacterial DNA; it can contain genes for antibiotic resistance, enzymes, or toxin production
Name the two gram-positive, branching, filamentous bacteria. Which one can be identified with acid-fast staining?
Actinomyces and Nocardia; Nocardia is weakly acid-fast
What is the chemical composition of endotoxin and where is it found?
Lipopolysaccharide; cell walls of gram negatives (eNdotoxin is an integral part of the cell wall of gram-Negative bacteria)
A 10-year-old girl is diagnosed with whooping cough. How was the causative organism cultured?
Bordetella pertussis grows on Bordet-Gengou (potato) agar (Bordet for Bordetella)
What is the composition of the bacterial capsule, and what is its main function?
Polysaccharides; protection from phagocytosis
Bartonella is a ____ (gram-positive/gram-negative) ____ (coccus/bacillus).
Periodic acid-Schiff (PAS) staining is used to stain what types of metabolic substances? What disease can be diagnosed with PAS?
Glycogen and mucopolysaccharides (PASs the sugar); Whipple's disease (Tropheryma whippelii)
What is the primary active component of an endotoxin? What components of the immune response does this agent activate?
Lipid A; macrophages, complement (C3a, C5a)
Why does Mycoplasma not gram stain well?
It does not have a cell wall
A man has a catheter for a week and develops sepsis. Bacteria are found on the catheter. Which bacterial structure lets them adhere there?
Glycocalyx, made up of polysaccharide
Endotoxins are found in gram-____ (positive/negative/both) bacteria; exotoxins are found in gram-____ (positive/negative/both) bacteria
Negative (in the outer membrane); both
For vaccine synthesis against encapsulated bacteria, ____ and ____ are conjugated to promote a ____ (T/B)-cell response.
Protein; polysaccharide antigen; T-cell
Name four obligate aerobes.
Nocardia, Pseudomonas aeruginosa, Mycobacterium tuberculosis, Bacillus (Nagging Pests Must Breathe)
Sabouraud's agar is best for growing which pathogens?
What kind of DNA is transferred during transformation: chromosomal, plasmid, or both?
Endotoxins activate complement via C3a and C5a. ____ (C3a/C5a) causes hypotension/edema; ____ (C3a/C5a) triggers neutrophil chemotaxis.
What four bacteria are pigment producing? What color pigment does each of them produce?
Actinomyces israelii: yellow; S. aureus: yellow; P. aeruginosa: blue-green; Serratia marcescens: red
Where is endotoxin (lipopolysaccharide) located in gram-negative bacteria? What component serves as the antigen?
In the outer membrane; O polysaccharide (O antigen)
A man recovering from trauma has a foul-smelling, necrotic skin lesion, crepitus. Explain the mechanism of action of the causative toxin.
Clostridium perfringens alpha toxin is a phospholipase; degrades phospholipid C causing tissue and cell membrane necrosis (myonecrosis)
A 10-year-old girl has two months of coughing fits, after which she fights to catch her breath. What is the mechanism of the offending toxin?
The toxin of B. pertussis disables the Gi protein (overactivates adenylate cyclase), which impairs phagocytosis allowing bacterial survival
At a cookout, a girl becomes ill. Labs show elevated levels of Shiga toxin. What is the pathology, pathogen, and mechanism of action?
Hemolytic-uremic syndrome; Shigella toxin; elevated cytokine release (Shiga-like toxin also causes HUS)
Exotoxin genes are located in a(n) ____ whereas endotoxin genes are located in a(n) ____.
Plasmid or bacteriophage; bacterial chromosome
Silver stain is used to stain what organisms?
Fungi (e.g., Pneumocystis), Legionella, and Helicobacter pylori
A 24-year-old man has headache, cough, fever. Chest x-ray shows diffuse interstitial pneumonia; gram stain is inconclusive. Likely cause?
Atypical pneumonia caused by Mycoplasma; this bacterium has no cell well and does not gram stain
Why does catalase make organisms more pathogenic?
Catalase degrades H2O2 before myeloperoxidase converts it to microbicidal products
Certain bacteria, such as Corynebacterium diphtheriae, have ADP-ribosylating A-B toxins. Name the function of the A and B components.
B component binds host cell surface receptor, enabling endocytosis; A component disrupts host cell proteins by attaching ADP-ribosyl
Unlabeled bacterial colonies with a pink hue are noted to be acidic. What kind of bacteria are they? What medium was used to identify them?
Lactose-fermenting enterics; MacConkey's agar. E. coli is also grown on eosin-methylene blue agar
Exotoxins ____ (are/are not) secreted and ____ (mildly/very) toxic; endotoxins ____ (are/are not) secreted and ____ (mildly/very) toxic.
Exotoxins are secreted and very toxic (1 µg is fatal); endotoxins are not secreted and are mildly toxic (hundreds of µg needed for death)
Identify the chemical composition and the two main functions of the peptidoglycan layer in bacteria.
It has a sugar backbone with cross-linked peptide side chains; it provides rigid support and protection against osmotic damage
A patient has fever and rash and goes into shock. Name the two most likely causative bacteria and their associated toxins.
Staphylococcus aureus (toxic shock syndrome toxin [TSST-1]) and Streptococcus pyogenes (exotoxin A)
List the five gram-positive bacilli.
Clostridium, Corynebacterium, Bacillus, Listeria, and Mycobacterium (acid fast and weakly gram positive)
Immunoglobulin A protease is secreted by which three bacterial species to help them colonize which part of the body? How does it work?
S. pneumoniae, H. influenzae type B, Neisseria (SHiN), which colonize the respiratory mucosa; IgA protease cleaves IgA
A lab tech adds anticapsular antisera to a culture from a patient with chest x-ray suggesting pneumonia. What test is she performing? Why?
Positive quellung reaction confirms S. pneumoniae; anticapsular antisera cause capsular swelling (quellung = capsular "swellung")
A boy with pharyngitis has a pseudomembrane in his throat. What organism is likely responsible, and what is its mechanism of action?
Corynebacterium diphtheriae; its toxin ADP-ribosylates elongation factor 2 to inactivate it
A patient with scarlet fever has erythrogenic toxins in her blood. What is the pathogen and what is the name of the toxin?
Streptococcus pyogenes; exotoxin A, causing toxic shock syndrome (fever, rash, shock)
Both ____ and ____ are highly pleomorphic gram-negative bacteria that are readily identified with ____ stain.
Rickettsia and Chlamydia; Giemsa
Name six organisms that do not stain well with gram stain.
Treponema, Rickettsia, Mycobacteria, Mycoplasma, Legionella pneumophila, Chlamydia (These Rascals May Microscopically Lack Color)
Describe specialized transduction.
Lysogenic phage infects bacterium, inserts viral DNA into chromosomes, viral (and bacterial) DNA excised into capsid infects other bacteria
Which eight bacteria are urease positive?
Cryptococcus,H. pylori, Proteus, Ureaplasma, Nocardia,Klebsiella, S. epidermidis, S. saprophyticus (CHuck Norris hates PUNKSS)
Which bacteria are facultative, intracellular organisms?
Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis (Some Nasty Bugs May Live FacultativeLY)
Chromosomal DNA is not transferred during ____ (transduction/F+ × F- conjugation/Hfr × F- conjugation/transposition).
F+ × F- conjugation
A(n) ____ cell incorporates a F+ plasmid into its own chromosomes. These cells transfer ____ (chromosomes/plasmids/both).
High-frequency recombination; both
What is the chemical composition of the bacterial plasma membrane, and what are its two main functions?
It is made up of a lipoprotein bilayer; it functions as the site of oxidative and transport enzymes
A 30-year-old has a painless penile chancre. Why does the causative organism not gram stain? What two methods can you use to visualize it?
Treponema is too thin to be visualized by gram stain; it can be seen by dark-field microscopy and fluorescent antibody staining
Bacterial ribosomes synthesize ____ and consist of these two subunits.
Proteins; 30S and 50S subunits
Catalase degrades H2O2 before it is converted to microbicidal products by myeloperoxidase (enzyme). Name seven catalase (+) organisms.
Pseudomonas, Listeria, Aspergillus, Candida, E. coli, S. aureus, Serratia (you need PLACESS for your cats [catalase])
Chest x-ray of a patient with reactivated tuberculosis shows apical infiltrates in both lungs. Explain the location of these findings.
Lung apices have highest partial pressure of oxygen; Mycobacterium tuberculosis (and all obligate aerobes) require oxygen to make ATP
A boy with a sweet tooth develops flaccid paralysis, mainly facial. What food did he likely ingest, and what is the disease mechanism?
Clostridium botulinum in honey (also canned foods); inhibits release of stimulatory Ach at neuromuscular junction by cleaving SNARE
A man recovering from trauma has a foul-smelling necrotic skin lesion; crepitus is noted. How does the infecting agent appear on blood agar?
Clostridium perfringens alpha toxin forms a double zone of hemolysis on blood agar
An unimmunized seven-year-old has sore throat and fever. Exam reveals gray pseudomembranes in his throat. What type of culture must be done?
He likely has Corynebacterium diphtheriae, which grows on a Tellurite plate with Löffler's media
A 16-year-old with shock is admitted due to S. aureus. Name the three toxins produced by this bug and the respective associated symptoms.
(1) toxic shock syndrome toxin (TSST-1): fever, rash, and shock (2) exfoliative toxin: scalded skin syndrome (3) enterotoxin: food poisoning
A six-month-old infant accidentally eats honey. What bacterial infection is the pediatrician worried about? How does it survive in honey?
Clostridium botulinum forms spores (dipicolinic acid with a keratin-like coat) that can survive dehydration, heat, and chemicals
In F+ to F- conjugation, ____ (chromosomes/plasmids/both) are transferred ____ (to/from) the F+ cell through a ____.
Plasmids; from; pilus
An unimmunized one-year-old boy is irritable and sluggish and has a fever and stiff neck. How will you culture the causative organism?
He likely has Haemophilus influenzae meningitis, which is cultured on chocolate agar with factors V (NAD+) and X (hematin)
A hospitalized 86-year-old has S. pneumoniae. His roommate has an E. coli UTI. What structures do these bacteria have in common?
Gram positives (S. pneumoniae) and negatives (E. coli) have a flagellum, pilus, capsule, peptidoglycan, and cytoplasmic membrane
Name three intracellular bacteria that do not gram stain well. Which lacks muramic acid in its cell wall? Which is seen with silver stain?
Rickettsia, Legionella, and Chlamydia; Chlamydia lacks muramic acid in its cell wall; Legionella pneumophila is seen by silver stain
The two main gram-positive cocci are ____ and ____; the major gram-negative coccus is ____.
Staphylococcus and Streptococcus; Neisseria
The binding of superantigens to ____ and ____ receptors results in the widespread release of which two factors, ultimately causing what?
Major histocompatibility complex class II molecules and T-cell receptors; interferon-γ and interleukin-2 eventually cause shock
A seven-year-old girl has had a cough with whooping on inspiration for two months. What is the gram stain/shape of the causative agent?
Bordetella pertussis, a gram-negative bacillus
What are the mechanisms of the heat-labile and heat-stable toxins of enterotoxigenic E. coli (ETEC)?
Heat-labile overactivates adenylate cyclase (more Cl-, H2O secretion); heat-stable activates guanylate cyclase (less NaCl, H2O resorption)
Mycobacteria have what two distinguishing components in their outer layer?
Mycolic acid and high lipid content
____ (Endotoxins/Exotoxins) are heat stable; ____ (endotoxins/exotoxins) are not heat stable (except for ____ enterotoxins).
Endotoxins (stable at 100°C for one hour); exotoxins (destroyed rapidly at 60°C); staphylococcal
What protein from group A Streptococcus prevents phagocytosis by the body's immune cells?
Transfer of plasmids from one bacterium to another is called ____; the phage-mediated transfer of DNA between prokaryotes is called ____.
Name six examples of encapsulated bacteria.
Streptococcus pneumoniae, Haemophilus influenzae type B, Neisseria meningitidis, Salmonella, Klebsiella pneumoniae, group B Strep (SHiN SKS)
Name the unique component in the cell membrane of Mycoplasma.
The Mycoplasma cell membrane has sterols
Many guests in a hotel with central air conditioning develop a high fever and pneumonia. How will you culture the causative organism?
Legionella grows on charcoal yeast extract agar buffered with cysteine and iron
Gram-positive ____ (lipid A/teichoic acid) and gram-negative ____ (lipid A/teichoic acid) induce tumor necrosis factor/interleukin-1.
Teichoic acid; lipid A (lipid A in bacteria lacking a positive gram stain)
An unimmunized one-year-old boy has fever and stiff neck and is irritable and sluggish. What is the gram stain/shape of the causative agent?
Likely Haemophilus influenza B meningitis, against which children are routinely immunized; Haemophilus is a gram-negative bacillus
A homeless man is febrile and coughing up blood. A cavitary lesion is seen on chest x-ray. How should you culture the causative organism?
He likely has Mycobacterium tuberculosis, which grows on Löwenstien-Jensen agar
Name five organisms that have ADP-ribosylating A-B toxin.
Corynebacterium diphtheriae, Vibrio cholerae, E. coli, Pseudomonas aeruginosa, and Bordetella pertussis
Shigella and enterohemorrhagic E. coli (EHEC) release toxins causing GI mucosal damage and dysentery. Name the mechanism.
Shigella: Shiga toxin; EHEC (O157:H7 strain): Shiga-like toxin; both cleave host cell rRNA inactivating the 60S ribosomal subunit
Two plates grow the same lactose-fermenting bacteria. One is pink, the other is silvery blue-black. Identify the bacterium and the media.
E. coli turns MacConkey's agar pink; it grows blue-black metallic colonies on eosin-methylene blue agar
A 40-year-old develops pain, redness, swelling at the site of a bite from her cat. What is the gram stain/shape of the causative agent?
She likely has cellulitis caused by Pasteurella multocida, a common pathogen in cats; Pasteurella is a gram-negative bacillus
Francisella is a ____ (gram-positive/gram-negative) ____ (coccus/bacillus).
Summarize each of the four phases of bacterial growth.
Lag phase: metabolic activity without division; exponential phase: rapid division; stationary phase: nutrient depletion slows growth; death
A 30-year-old man recently underwent splenectomy and received a pneumonia vaccine. What is the antigen in the vaccine?
All vaccines against encapsulated bacteria are made by conjugating the capsular antigen with a protein
Which of the following is not an enteric bacillus: Pasteurella, Shigella, Pseudomonas, Yersinia, Proteus, Bacteroides?
Pasteurella, which is a zoonotic gram-negative bacillus
A toddler presents with impetigo. Tests confirm Streptococcus pyogenes. Name the offending toxin and explain its mechanism.
Streptolysin O degrades cell membranes and lyses RBCs, contributing to β-hemolysis
India ink and mucicarmine can be used to visualize what pathogen? What part of the organism does it stain? What color?
Cryptococcus neoformans; mucicarmine stains the thick polysaccharide capsule red
A six-year-old has abdominal pain and intense vomiting. You suspect a gram-negative enteric bacteria. Name the 13 possibilities.
The toxin tetanospasmin (Clostridium tetani) causes what pathologies by decreasing the level of what neurotransmitters? How?
Muscle rigidity, lockjaw; tetanospasmin toxin blocks release of inhibitory neurotransmitters (glycine, GABA) by cleaving SNARE
____, the ability to take up naked DNA from the environment, is a feature of many bacteria, especially which three bacteria?
Transformation (competence); Streptococcus pneumoniae, Haemophilus influenzae, Neisseria (SHiN)
____ (Endotoxin/Exotoxin) causes tetanus, botulism, diphtheria; gram-negative rod ____ (endotoxin/exotoxin) causes sepsis, meningococcemia.
Name five bacterial toxins coded for in a lysogenic phage.
ShigA-like toxin, Botulinum toxin, Cholera toxin, Diphtheria toxin, Erythrogenic toxin of S. pyogenes (ABCDE)
The glycoprotein-derived ____ allows bacterial adherence to host cells. A variant, ____ ____, attaches two bacteria during conjugation.
Fimbria (pilus); sex pilus
Explain why a vaccine against a polysaccharide antigen alone would result in a weaker immune response.
Polysaccharide antigens alone would not be recognized/presented by T cells; only immunoglobulin M antibodies would be produced
The ____ (cell wall/outer membrane) is the main gram-positive surface antigen; the ____ (cell wall/outer membrane) is gram negative.
Cell wall; outer membrane
A 73-year-old woman develops cystitis and pyelonephritis from an E. coli infection. What virulence factor is responsible?
A Streptococcus culture exhibits complete hemolysis. How will you further determine the species?
Both S. pyogenes and S. agalactiae are β-hemolytic; S. pyogenes is bacitracin sensitive and S. agalactiae is resistant
A patient with N. meningitides septicemia develops acute hypotension, petechiae, and bilateral adrenal hemorrhage. Name the complication.
A Streptococcus culture exhibits α-hemolysis. How will you further determine the species?
S. pneumoniae and S. viridans are α-hemolytic; only S. pneumoniae has a capsule (+ quellung) and is optochin sensitive
A patient has pupil constriction with accommodation but no reaction to light. What is this finding and what is it associated with?
Argyll Robertson pupil; tertiary syphilis
What five types of infection can Neisseria gonorrhea cause?
Gonorrhea, pelvic inflammatory disease, septic arthritis, Fitz-Hugh-Curtis syndrome, neonatal conjunctivitis
Most lactose-fermenting enteric bacteria grow ____ (color) colonies on EMB agar, except E. coli, which grows ____ with a ____ sheen.
Purple or black; purple with a green sheen
Differentiate Legionnaires' disease from Pontiac fever.
Legionnaires' disease is a severe pneumonia with fever and GI and CNS symptoms; Pontiac fever is a mild flu-like syndrome
How does enteropathogenic E. coli cause diarrhea?
It adheres to the apical surface and flattens villi, decreasing absorption
What are sources of the pathogen that causes leprosy?
Armadillos and humans with lepromatous leprosy
Name five bacteria that grow pink colonies on MacConkey's agar.
Citrobacter, Klebsiella, E. coli, Enterobacter, Serratia: test with MacConKEE'S agar
You determine that your patient developed a pulmonary infection from working with wool and inhaling which bacterial spores?
Bacillus anthracis; this patient has Woolsorter's disease
What kind of medium is used to grow Legionella pneumophila?
Charcoal yeast extract culture with iron and cysteine
You suspect that a patient has Haemophilus influenzae. What medium should you use to grow the culture?
Chocolate agar with factors V (NAD+) and X (hematin)
A patient develops cellulitis around the site of a dog bite. What is the likely pathogen?
The rash caused by ____ (rickettsia/typhus) starts on hands and feet.
Rickettsia (Rickettsia on the wRists)
What infection is caused by Pasteurella multocida?
Cellulitis and osteomyelitis from cat and dog bites
What are the symptoms of Mycoplasma pneumoniae pneumonia?
Insidious onset, headache, nonproductive cough, diffuse interstitial infiltrates on chest x-ray
How is Neisseria meningitidis transmitted?
Respiratory and oral secretions
What age group is most commonly affected by Mycoplasma pneumoniae infection? Outbreaks are frequents in what settings?
Individuals younger than 30 years of age; outbreaks often occur among military recruits and in prisons
Name two slow lactose-fermenting, gram-negative rods.
Citrobacter and Serratia
Name four diseases that can be caused by Haemophilus influenzae.
Epiglottitis, Meningitis, Otitis media, and Pneumonia (these are caused by HaEMOPhilus
What can be expected in stage 3 of Lyme disease?
Chronic monoarthritis and migratory polyarthritis
The vector of the organism that causes Lyme disease relies on what animal as part of its lifecycle?
Mice, which play a role in the lifecycle of the Ixodes tick
A child with cystic fibrosis has pneumonia and coughs up blue-green sputum. What is the likely causative organism?
Are humans and other primates more likely to be a reservoir for Shigella or Salmonella?
Shigella; animals are a more common reservoir for Salmonella ("salmon = animal")
A woman with PID caused by Neisseria gonorrhea develops severe RUQ pain from liver capsule inflammation. What complication is this?
What is a common source of Pasteurella infections?
Which of the following has flagella: Salmonella or Shigella? What is the pathological significance?
Salmonella ("salmon swim"); flagella enable hematogenous dissemination
A patient has an abscess draining via the sinuses containing fluid with yellow "sulfur granules." What is the causative organism?
A patient with colon cancer develops a Streptococcus bovis infection. What two complications are possible?
Bacteremia and subacute endocarditis
A two-year-old boy unvaccinated against Haemophilus influenzae has the flu. Can H. influenzae be the cause?
No; influenza virus causes the flu
Gram-negative organisms are resistant to penicillin G but may be susceptible to which penicillin derivatives?
Ampicillin and amoxicillin
What enzyme in Helicobacter pylori helps to create an alkaline environment?
A taxidermist presents with black, painless eschar surrounded by an edematous ring. Explain expected culture results and the diagnosis.
Patient likely has cutaneous anthrax caused by Bacillus anthracis infection; culture shows gram-positive, spore-forming rods
What property of Klebsiella gives it the description of "mucoid"?
A patient has a positive purified purine derivative (PPD) test. Name three possible explanations for this result.
Current tuberculosis infection, previous exposure, BCG vaccination
A young woman presents to your outpatient office with a UTI caused by Enterococcus faecalis. This bacterium is resistant to what antibiotic?
You suspect bacterial vaginosis in a patient. What would you expect to see in a wet prep of her vaginal discharge?
Classically, clue cells, or vaginal epithelial cells covered with bacteria
A surfer is diagnosed with leptospirosis because of the history of present illness and what symptoms?
Flu-like symptoms, jaundice, and photophobia with conjunctivitis suggest leptospirosis
Two smokers in their 60s staying in a hotel develop fever, cough, and dyspnea. What test do you order to evaluate for Legionella?
Urine Legionella antigen
While scrubbing into the OR you explain to your colleagues that it is critical to autoclave surgical equipment for what purpose?
To kill bacterial spores
Tertiary syphilis can present with what neurologic defects?
Tabes dorsalis (broad-based gait, ataxia, positive Romberg sign) and Argyll Robertson pupil
What is the best treatment for cholera?
Prompt oral rehydration
What characterizes brucellosis and what is the vector of the pathogen?
Undulant fever, caused by Brucella spp. in unpasteurized dairy
What happens to patients with primary tuberculosis who develop preallergic lymphatic/hematogenous dissemination?
They develop dormant tubercle bacilli in several organs and are susceptible to reactivation of the disease during their adult life
Streptococcus viridans is optochin ____ (resistant/sensitive); Streptococcus pneumoniae is optochin ____ (resistant/sensitive).
Resistant; sensitive (OVRPS [overpass]. Optochin: Viridans Resistant and Pneumonia Sensitive )
What is a common infection source for Pseudomonas aeruginosa?
Water; such as in swimmer's ear and hot tub folliculitis
Pseudomonas aeruginosa is an ____ (aerobic/anaerobic) gram- ____ (positive/negative) ____ (rod/cocci).
Aerobic gram-negative rod
A newborn shows signs of respiratory distress with a "staccato" cough. What is the treatment?
Azithromycin, for Chlamydia pneumonia (serotypes D-K)
What are the three spirochete species that most commonly infect humans?
Borrelia , Leptospira, Treponema (BLT)
Q fever is caused by what bacterium? How is it contracted?
Coxiella burnetii; transmitted by spores from tick feces and cattle placenta inhaled as aerosols
Name two ways Streptococcus pneumoniae evades the immune system.
Immunoglobulin A protease and encapsulation
The chlamydial cell wall is unique in that it lacks ____ ____.
Why is it not possible to make a vaccine against Neisseria gonorrhea?
Because of the rapid antigenic variation of the pilus proteins
Why are Chlamydia species intracellular organisms?
Because they cannot make their own ATP
What three types of E. coli do not invade the intestinal mucosa?
Enterohemorrhagic, enterotoxigenic, and enteropathogenic; only the enteroinvasive type invades intestinal mucosa
What is the treatment of choice for all rickettsial infections?
An immunocompromised man develops a lung infection with a bacterium with long-branching filaments. What is the organism?
A patient contracts tularemia from Francisella tularensis. How is this pathogen transmitted?
Tick bite, rabbit, deer fly
____ is an aerobic, gram-positive, acid-fast branching filament; ____ is anaerobic and not acid-fast stainable.
What mode of propulsion do Salmonella use to disseminate?
A patient receives intramuscular penicillin for syphilis and later feels like he has the flu. What causes this phenomenon?
Jarisch-Herxheimer reaction, a flu-like syndrome following administration of antibiotics; due to killed bacteria releasing pyrogens
What differentiates the disease caused by enteroinvasive and enterohemorrhagic E. coli?
Enteroinvasive: both toxin and microbe cause necrosis/inflammation; enterohemorrhagic: only the toxin does
A four-year-old boy with recent pharyngitis has tea-colored urine. Name the illness and causative agent. What other illness is a risk?
Acute glomerulonephritis; Streptococcus pyogenes; rheumatic fever (pharyngitis can result in rheumatic "phever" and glomerulonephritis)
What two mycobacteria species are often resistant to multiple drugs?
Mycobacterium tuberculosis and Mycobacterium avium-intracellulare
A camper has a rash ascending the arms and legs, headache, fever, and a very ill appearance. What is the diagnosis and causative organism?
Rocky Mountain spotted fever, caused by Rickettsia rickettsii
A young boy with primary tuberculosis develops severe bacteremia. What subsequent type of tuberculosis might he develop?
Miliary tuberculosis, characterized by small granulomas in multiple organs
A 25-year-old pregnant woman presents at week 36 of gestation. What bacteria should you screen for at this time?
Streptococcus agalactiae, which colonizes the vagina and can be transmitted to the neonate during delivery; screen at 35-37 weeks
What is the treatment for Neisseria gonorrhea and Neisseria meningitidis?
N. gonorrhea: ceftriaxone (+ azithromycin or doxycycline for possible chlamydia); N. meningitidis: ceftriaxone or penicillin G
Which two bacteria are gram-positive rods that form long, branching filaments resembling fungi?
Actinomyces israelii and Nocardia asteroides
A burn victim develops black lesions on his skin. You order treatment with aminoglycosides and piperacillin to eradicate what bacteria?
Pseudomonas aeruginosa; black lesions on skin are a sign of sepsis
What protein is altered in MRSA resulting in resistance to β-lactams?
The skin changes seen in cutaneous anthrax are caused by which two toxins?
Lethal factor and edema factor; both cause a black eschar (painless ulcer) surrounded by an edematous ring
Group A streptococci are bacitracin ____ (resistant/sensitive); group B streptococci are bacitracin ____ (resistant/sensitive).
Sensitive; resistant (B-BRAS. Bacitracin: group B are Resistant, group A are Sensitive)
What are the usual modes of transmission of Yersinia enterocolitica?
Pet feces (e.g., from puppies) and contaminated milk or pork
What are the differences between dysentery caused by enterohemorrhagic E. coli (EHEC) vs enteroinvasive E. coli (EIEC)?
EHEC produces Shiga-like toxin, which causes necrosis and inflammation; EIEC directly invades the mucosa to cause necrosis and inflammation
Toxic shock syndrome, scalded skin syndrome, and rapid-onset food poisoning are all diseases caused by what?
Toxins released by Staphylococcus aureus (TSST-1, exfoliative toxin, enterotoxin)
Adults contract botulism by ingesting ____ (preformed toxin/spores); infants develop botulism by ingesting ____ (preformed toxin/spores).
Preformed toxin; spores, often in honey (botulism is from bad bottles of food and honey [causes floppy baby syndrome])
Which Clostridium difficile toxin binds to the brush border of the gut?
Toxin A enterotoxin
What is the cause of azotemia and jaundice in patients with Weil's disease?
Renal and liver failure
What is the mechanism of action of Staphylococcus aureus protein A?
t binds the Fc region of immunoglobulin G (Fc-IgG), inhibiting complement fixation and phagocytosis
In a culture of S. viridans the agar is ____ (color). Why? Bonus: name another agent with similar culture.
Green; in β-hemolysis, coloration is caused by bacteria-produced H2O2, which oxidizes hemoglobin to green methemoglobin; S. pneumoniae
During their lifecycle, what form of chlamydia replicates by fission?
The Reticulate (initial) body Replicates in the cell by fission
Exotoxins produced by Streptococcus pyogenes can cause what two conditions?
Scarlet fever (erythrogenic/pyogenic toxin); toxic shock-like syndrome (toxic shock syndrome toxin)
Listeria monocytogenes uses what method of bacterial transport from cell to cell?
Induction of "actin rockets" to move into new cells
Name the enzyme produced by E. coli that breaks down lactose into glucose and galactose.
A five-year-old boy eats raw beef and develops bloody diarrhea. Two weeks later he cannot move his legs. What is the likely infection?
In culturing Campylobacter jejuni, what observations help to identify it as a cause of infection?
It is comma or S-shaped, oxidase positive, and grows at 42°C
Name three inflammatory diseases that can result from infection with Staphylococcus aureus.
Skin infections, organ abscesses, and pneumonia
What bacteria causes Lyme disease?
Why are Mycoplasma pneumoniae not seen on gram stain?
They have no cell walls
What type of toxin causes fever and hypotension in Pseudomonas sepsis?
Does enteropathogenic E. coli (EPEC) directly cause damage or act via a toxin?
EPEC does not produce a toxin; it is directly pathogenic
Name two clinical syndromes caused by Legionella pneumophila.
Legionnaires' disease and Pontiac fever
A 75-year-old smoker has mild flu-like symptoms. Labs show hyponatremia. Antigen is detected in the urine. Diagnosis and treatment?
The patient likely has Pontiac fever caused by Legionella pneumophila; treat with macrolides or quinolone
How does the toxin produced by Clostridium botulinum cause flaccid paralysis?
It inhibits acetylcholine release
Name three spore formers that are not found in soil
Bacillus cereus, Clostridium botulinum, Coxiella burnetii
What is the vector for the pathogen that causes Rocky Mountain spotted fever?
Dermacentor tick bite
A hiker in Rhode Island discovers a red rash with a central clearing on his flank. What is the likely infection?
Lyme disease, caused by Borrelia burgdorferi
Streptococcus pyogenes is bacitracin ____ (sensitive/resistant); S. agalactiae is bacitracin ____ (sensitive/resistant).
Your culture of gram-positive, catalase-negative cocci exhibits no hemolysis. How will you further determine the species?
Nonenterococci species (e.g., Streptococcus bovis) will grow in bile but not in 6% NaCl; enterococci are the opposite
Name three types of infections caused by nontypeable strains of Haemophilus influenzae.
Otitis media, conjunctivitis, and bronchitis (all mucosal infections)
By what mechanism does E. coli O157:H7 induce thrombocytopenia, anemia, and acute renal failure in a child?
Endothelial swelling/damage causes hemolysis, low renal blood flow, and platelet consumption
A patient develops bacteremia, and culture confirms an agent that produces biofilms that adhere to prosthetics. Name the most likely agent.
A patient had recent S. pyogenes infection. You ask the lab to test for antibodies to M protein to access risk of what condition?
Rheumatic fever; antibodies to M protein enhance host defense against S. pyogenes but can result in rheumatic fever
Enterococci (E. faecalis, E. facecium) cause urinary tract infections, subacute endocarditis, and ____.
Biliary tract infections
Persons with diabetes are particularly susceptible to which types of pseudomonal infections?
Osteomyelitis and malignant otitis externa
Which three soil-dwelling, gram-positive rods form spores?
Bacillus anthracis, Clostridium perfringens, Clostridium tetani
How is Pasteurella multocida transmitted?
Animal bite (cats, dogs)
An immunocompromised man gets a Bartonella infection. What complication do you mistake for Kaposi sarcoma?
What toxins of enterotoxic E. coli are responsible for traveler's diarrhea?
Labile toxin/stable toxin
Gram-negative rods are differentiated by their ability to ferment what substance?
A patient contracts a UTI while hospitalized, and the culture grows enterococci. This infection is likely to be resistant to what drug?
A patient is suffering from destruction of the vasa vasorum and you determine that it is due to an infection. What is the likely agent?
Treponema pallidum, which causes syphilis
Which β-hemolytic organism has tumbling motility, causes meningitis in newborns, and is found in unpasteurized milk?
A patient has an intact T-cell response and only a few hypoesthetic nodules on his skin. What form of Hansen's disease is this?
A patient has this form of severe leptospirosis, which includes elevated bilirubin and creatinine, fever, hemorrhage, and low hemoglobin.
Rickettsiae are ____ (obligate/facultative) intracellular parasites because they require which two cofactors?
Obligate; coenzyme A and nicotinamide adenine dinucleotide
What disease is caused by Listeria monocytogenes in healthy adults?
In a partially immune, hypersensitized host, what kind of tuberculosis occurs after reinfection with Mycobacterium tuberculosis?
A bird trader who develops fever and dyspnea is diagnosed with an atypical pneumonia, most likely caused by what pathogen?
Chlamydia psittaci, which is carried by birds
A man with a chronic peptic ulcer has a positive urease breath test. What is the first-line treatment?
Triple therapy for H. pylori: 1. proton pump inhibitor; 2. clarithromycin; 3. amoxicillin or metronidazole
A pregnant woman at 37 weeks has a (+) Hippurate test. Cultures show bacitracin-resistant, β-hemolytic bacteria. You give ____ prophylaxis.
Intrapartum penicillin prophylaxis for Streptococcus agalactiae infection to prevent neonatal meningitis, pneumonia, and sepsis
A patient develops flaccid paralysis after eating food from a poorly sealed can. What is the likely causative organism?
Salmonella infection should be treated with which antibiotics?
Salmonellosis should not be treated with antibiotics, since doing so can prolong symptoms
What bacterium found in normal skin flora commonly contaminates blood cultures and infects prosthetics and catheters?
Streptococcus agalactiae is bacitracin ____ (sensitive/resistant) and ____ (α/β/γ) -hemolytic.
A colleague tells you a patient in the ER meets the JONES criteria. Explain the criteria and name the diagnosis.
JONES criteria for rheumatic fever: Joints (arthritis), O (carditis), Nodules (subcutaneous), Erythema marginatum, Sydenham's chorea
How is Legionnaires' disease transmitted?
Aerosol transmission from an environmental water source; no person-to-person transmission
How is ehrlichiosis acquired?
Bite of the Lone Star tick, carrying Ehrlichia chaffeensis
What vector transmits the organisms that cause Lyme disease and babesiosis?
The Ixodes tick
On agar, partial (green) hemolysis is ____-hemolysis, clear hemolysis is ____-hemolysis, and the absence of hemolysis is ____-hemolysis.
α-hemolysis; β-hemolysis; γ-hemolysis
Some bacteria can form spores at the end of the stationary phase. Explain how spore formation is beneficial for bacterial survival.
Spores are highly resistant to heat/chemicals; spores are not metabolically active and thus enable survival in nutrient-poor settings
Explain how reheating rice increases the risk of Bacillus cereus food poisoning.
Spores survive cooking, and keeping rice warm afterward facilitates spore germination and enterotoxin formation ("reheated rice syndrome")
A patient has a biliary tract infection due to Lancefield group D cocci. What lab test can differentiate enterococci from nonenterococci?
Enterococci grow in 6.5% sodium chloride and bile; nonenterococci can only grow in bile
A patient complains of fever, headache, and diarrhea. Physical exam reveals rose spots on his abdomen. What is the likeliest infection?
Typhoid fever, caused by Salmonella typhi
In a nonimmune host (e.g., a child), what kind of tuberculosis occurs after infection with Mycobacterium tuberculosis?
What hematologic finding may help confirm Mycoplasma pneumoniae infection?
High titer of cold agglutinins (IgM), which can agglutinate or lyse RBCs
In what population does group B strep (Streptococcus agalactiae) cause pneumonia, meningitis, and sepsis?
Babies aged younger than three months (group B for Babies)
Name two streptococci that are γ-hemolytic.
Enterococcus and nonenterococcus species (e.g., S. bovis)
Name four gram-positive rods. Which one of the four is anaerobic?
Clostridium, Listeria, Bacillus, and Corynebacterium; Clostridium is anaerobic
Francisella tularensis causes what disease and what are its vectors?
Tularemia; vectors are ticks, rabbits, and deer flies
One of your patients has an Actinomyces infection; another has a pulmonary infection caused by Nocardia. How do you treat each patient?
Actinomyces: penicillin; Nocardia: sulfonamides
Adding Streptococcus agalactiae to a culture of S. aureus results in an enlarged area of hemolysis. Name the causative factor.
CAMP factor made by Streptococcus agalactiae (Note: CAMP stands for the authors of the test, not cyclic AMP)
The rash caused by (rickettsia/typhus) ____ starts in the trunk, moving outward and not involving the palms or soles.
Typhus (Typhus on the Trunk)
A child has pseudomembranous pharyngitis and diffuse lymphadenopathy. What should be used to culture the infectious agent?
Tellurite agar, on which Corynebacterium diphtheriae grows
A patient has a rickettsial infection. He has pneumonia and no evidence of insect bites. What species is responsible?
Which Chlamydia trachomatis serotypes cause lymphogranuloma venereum?
Types L1, L2, and L3
A patient with E. coli infection develops a severe complication due to lipopolysaccharide endotoxin exposure. What is it?
Name three fast lactose-fermenting, gram-negative rods.
Klebsiella, E. coli, Enterobacter
In what region of the United States is Lyme disease common?
The northeastern United States
A traveler who becomes ill with typhoid fever can transmit it to others because the pathogen can remain in what organ?
A man is bitten by a tick and has no rash, but on a blood smear you see granulocytes with "berry cluster" organisms. Diagnosis?
A 15-year-old girl presents with a strawberry tongue, sore throat, fever, and a red rash sparing the face. Name the causative agent.
Streptococcus pyogenes causing scarlet fever (scarlet tongue, scarlet rash, scarlet throat)
Rickettsiae are transmitted by what type of vector?
Arthropods (except Coxiella, which is transmitted by aerosol)
How does enteroinvasive E. coli (EIEC) cause dysentery?
EIEC invades the intestinal mucosa and causes necrosis and inflammation but does not release a toxin
Listeria monocytogenes infection can lead to meningitis in what two populations?
Neonates and the immunocompromised
A patient is bitten by a louse and develops a recurrent fever. What bacteria are likely responsible?
The two main α-hemolytic bacteria are catalase ____ (positive/negative). ____ is/are optochin sensitive; ____ is/are optochin resistant.
Negative; Streptococcus pneumoniae; viridans streptococci
Name the animal reservoir for Mycobacterium leprae in the United States.
Your differential for a man includes Crohn's and appendicitis, but the real problem is caused by Yersinia enterocolitica. What is it?
A month after a child develops bloody diarrhea from contaminated chicken, he complains of sore knees. What other sequelae is possible?
Guillain-Barré syndrome, characterized by ascending weakness and possible respiratory paralysis, sometimes after Campylobacter infection
Which test distinguishes α-hemolytic Streptococcus pneumoniae from Streptococcus viridans?
Optochin sensitivity test (S. viridans live in the mouth because they are not afraid of-the-chin [op-to-chin resistant])
Actinomyces is found in ____ (normal oral flora/soil) and Nocardia is found in ____ (normal oral flora/soil).
Normal oral flora; soil
A teen presents with fever, vomiting, rash, desquamation, and shock. Explain the pathogenesis of the causative toxin.
This teen likely has toxic shock syndrome due to TSST-1, a superantigen that binds MHC II and TCR resulting in polyclonal T-cell activation
You can diagnose Bacillus anthracis on the basis of what unique characteristic?
Cell wall having a polypeptide capsule (contains D-glutamate)
What type of lesion is seen on x-ray of the lung fields of a patient with secondary tuberculosis?
A cavitary lesion in the upper lobe
How do you diagnose Clostridium difficile?
By the presence of toxin A enterotoxin and/or toxin B cytotoxin in stool
By culturing Campylobacter jejuni and Vibrio cholerae, how can one distinguish the two as a cause of infection?
Campylobacter jejuni grows at 42°C, and Vibrio cholerae grows in alkaline media
The mnemonic ABCDEFG is useful for remembering key information about Corynebacterium diphtheriae. State this mnemonic.
ADP-ribosylation; Beta-prophage; Corynebacterium Diphtheriae; Elongation Factor 2; Granules
A swimmer in a cove develops fever, headache, stomach pain, photophobia, and conjunctivitis. What is the water contaminated with?
Animal urine with Leptospira interrogans, which causes leptospirosis
What distinctive color and odor does Pseudomonas aeruginosa exhibit?
Blue-green color (due to pyocyanin) with a grape-like odor
Name five common sites of extrapulmonary tuberculosis. Infection at which site causes Pott's disease?
Central nervous, lymphatic, renal, and gastrointestinal systems and vertebral bodies; infection in vertebral bodies causes Pott's disease
Staphylococcus saprophyticus is novobiocin ____ (resistant/sensitive); S. epidermidis is novobiocin ____ (resistant/sensitive).
Resistant; sensitive (on the office staph retreat, there was NO StRES)
Which is a weakly acid-fast aerobe in soil: Actinomyces israelii or Nocardia asteroides?
Secondary syphilis presents with what type of skin manifestations?
A maculopapular rash on palms and soles and condylomata lata on the genitals
A patient has pseudomembranous pharyngitis. Culture shows metachromatic (blue and red) granules and positive Elek's test. Name the organism.
What are the two forms of Hansen's disease?
Lepromatous and tuberculoid
A patient diagnosed with Lyme disease is given the first-line treatment and advised that the medicine may increase what type of sensitivity?
Photosensitivity, a side effect of doxycycline
A nine-year-old boy has progressively ascending weakness. If this is related to an infection, what did he most likely eat two weeks ago?
Poultry, meat, and unpasteurized milk can harbor Campylobacter jejuni, which can cause Guillain-Barré syndrome
The Haemophilus influenzae vaccine is given to which age group?
Infants 2-18 months of age
What kind of discharge is produced in vaginosis caused by Gardnerella vaginalis?
Gray vaginal discharge with a fishy odor
A four-year-old boy is febrile, lethargic, stridorous, and drooling. Likely diagnosis? What vaccine could have prevented it?
The patient likely has epiglottitis, which can be prevented with Haemophilus influenzae type B vaccine
What population tends to get diarrhea following enteropathogenic E. coli infection?
Children (EPEC = Pediatric)
What is the vector for the pathogen that causes Lyme disease?
Ixodes tick, carrying Borrelia burgdorferi
A man has disseminated Mycobacterium avium-intracellulare infection. What drug likely could have prevented this?
Azithromycin, which is used for prophylaxis, particularly in patients with AIDS
Exotoxin A produced by Pseudomonas aeruginosa inactivates what human enzyme used in protein synthesis?
Elongation factor 2
Name two examples of α-hemolytic bacteria. How do these bacteria appear on blood agar?
Streptococcus pneumoniae and viridans streptococci; they form green rings around colonies
Streptococcus bovis infection is associated with what type of cancer?
Colon cancer (bovis in the blood = cancer in the colon)
What classes of antibiotics are the best treatment for Mycoplasma pneumoniae infection and why?
Macrolides or fluoroquinolones; the organisms are resistant to penicillin since they have no cell walls
What is the treatment of choice for Pseudomonas aeruginosa infection?
Aminoglycoside plus an extended-spectrum penicillin (e.g., piperacillin, ticarcillin)
Rocky Mountain spotted fever is endemic to what area?
North Carolina and along the East Coast, despite its name
What are the symptoms of tuberculosis?
Fever, night sweats, weight loss, and hemoptysis
A four-year-old boy presents with a puffy face and tea-colored urine. On exam you see evidence of what recent skin infection?
Impetigo, caused by Streptococcus pyogenes, more commonly precedes glomerulonephritis than pharyngitis
In what stage of syphilis does the disease become disseminated?
Secondary syphilis, with constitutional symptoms and skin manifestations
Helicobacter pylori causes what two pathologies in the gastrointestinal tract?
Duodenal ulcers and gastritis
A neonate develops pneumonia and meningitis due to an E. coli infection. What virulence factor is responsible?
A diabetic woman is hospitalized due to pneumonia with red "currant jelly" sputum. The likely pathogen causes what other type of infection?
The pneumonia pathogen is most likely Klebsiella, which can also cause nosocomial urinary tract infections
A patient has rapidly expanding necrosis on her leg; S. pyogenes is suspected. This particular strain of S. pyogenes has what protein?
M protein, present in some strands of S. pyogenes, can evade phagocytosis and rapidly move through tissue, causing necrosis
What is the method of transmission of Haemophilus influenzae?
What are the two modes of anthrax inoculation?
Cutaneous and pulmonary
You culture a cellulitis sample suspecting a Staphylococcus species. How can you differentiate among the three main species?
S. aureus is coagulase positive; of the coagulase-negative species, S. epidermidis is novobiocin sensitive and S. saprophyticus is resistant
Streptococcus pneumoniae sepsis occurs at a higher rate in what two patient populations?
Sickle cell anemia and asplenic patients
What is another name for leprosy?
What is the treatment for Listeria monocytogenes infection in infants and immunocompromised patients? In otherwise healthy adults?
Ampicillin; gastroenteritis in otherwise healthy adults is usually self-limited and requires no treatment
What bacteria is most commonly implicated in "walking" pneumonia?
What is the pathologic hallmark of ehrlichiosis?
Monocytes exhibit berry-like inclusions called morulae in the cytoplasm
A woman leaves her tampon in for too long and develops an infection leading to shock. What bacterial toxin is likely responsible?
TSST-1 produced by Staphylococcus aureus
A pregnant patient wants to know how to avoid contracting Listeria monocytogenes. How do you counsel her?
Avoid ingestion of unpasteurized milk/cheese and deli meats
A patient presents with severe diarrhea. Exam reveals pseudomembranous colitis. Culture shows gram-positive spore-forming bacilli. Diagnosis?
Clostridium difficile (DIfficile causes DIarrhea)
Name the four possible outcomes of primary tuberculosis.
Fibrous healing, progressive lung disease, severe bacteremia, preallergic lymphatic/hematogenous dissemination
Which is an anaerobe: Actinomyces israelii or Nocardia asteroides?
Inhalation of Bacillus anthracis spores leads to what symptoms?
Flu-like symptoms, which rapidly progress to fever, mediastinitis, pulmonary hemorrhage, and shock
What is the only spirochete that can be visualized by light microscopy with aniline dyes?
Borrelia (Big size)
What kind of virulence factor is produced by Haemophilus influenzae?
Immunoglobulin A protease
A boy is bitten by a human body louse and develops a rash that spreads from his trunk to his arms, but not palms. What has he contracted?
Epidemic typhus, from Rickettsia prowazekii
A man has a painless sore on his penis and rash developing on his palms. What is the treatment of choice?
Penicillin G, for syphilis
Chest x-ray of a 70-year-old man with a cough shows left lower lobe pneumonia. What hemolysis pattern does the most likely pathogen exhibit?
Streptococcus pneumoniae is the most common cause of pneumonia; it exhibits green partial (α) hemolysis
Name four β-hemolytic bacteria and describe how they appear on blood agar.
Staphylococcus aureus, Streptococcus pyogenes, Streptococcus agalactiae, Listeria monocytogenes; they form clear areas of hemolysis on agar
Which β-hemolytic organism is both catalase and coagulase positive?
A dairy farmer presents with one week of fever that waxes and wanes. Diagnosis?
Brucella spp. from dairy products, causes an undulant fever
Name two gram-negative cocci and how to differentiate them.
Neisseria meningitidis, which ferments maltose, and Neisseria gonorrhoeae, which does not ferment maltose
Streptococcus pyogenes (group ____ strep) and S. agalactiae (group ____ strep) are both catalase ____ (positive/negative).
A; B; negative
Your patient develops gas gangrene and hemolysis due to the effects of the α-toxin produced by what infectious organism?
Clostridium perfringens (PERFringens PERForates a gangrenous leg)
What three clinical syndromes can Neisseria meningitides cause?
Septicemia, meningitis, and Waterhouse-Friderichsen syndrome
A colleague tells you your next patient has confirmed tetanus toxin in his blood/CNS. What symptoms do you expect this patient to exhibit?
Spastic paralysis, trismus (lock jaw), and risus sardonicus (sustained spasm of facial muscles resulting in a "permanent grin")
What disease does Rickettsia prowazekii cause and what is its vector?
Epidemic typhus; vector is lice
Describe the lesions caused by Actinomyces israelii.
Oral/facial abscesses that may drain through sinus tracts; forms yellow "sulfur granules"
Which conditions give biologic false-positive results on the Venereal Disease Research Laboratory (VDRL) test? What does it screen for?
VDRL = Viruses (mono, hepatitis), Drugs, Rheumatic fever, Lupus, and Leprosy; it is supposed to screen for syphilis
A young man gets food poisoning soon after eating food contaminated with Staphylococcus aureus. Name the toxin causing his illness.
Name four clinically important mycobacteria.
M. tuberculosis, M. kansasii, M. avium-intracellulare, M. leprae
A patient presents with lesions over the skin that are diffuse and communicable. What form of Hansen's disease is this?
A patient has pulmonary TB-like symptoms but no Mycobacterium tuberculosis infection. What is the likely causative organism?
Which of the following is first-line treatment for Lyme disease: ceftriaxone, doxycycline, or ampicillin?
Doxycycline; second-line is ceftriaxone
Clinically, how do Salmonella and Shigella infections differ?
Salmonella can sometimes cause bloody diarrhea, but Shigella almost always produces bloody diarrhea
Name four clostridia species that produce exotoxins.
Clostridium perfringens, Clostridium botulinum, Clostridium tetani, Clostridium difficile
Among lactose nonfermenters, which gram-negative rods are oxidase negative?
Shigella, Salmonella, Proteus
A patient with sarcoidosis has a negative purified protein derivative (PPD) test, but you still suspect tuberculosis. Justify your thinking.
This patient may be anergic; anergy can result from steroids, malnutrition, immunocompromised states, or sarcoidosis, causing a negative PPD
You suspect Mycobacterium leprae infection in your patient. What unique characteristic of M. leprae alters your diagnostic testing?
Mycobacterium leprae cannot be grown in vitro
How does Helicobacter pylori thrive as a pathogen in the stomach and cause peptic ulcers?
It produces an alkaline environment
A patient develops cat scratch fever after being clawed by her kitten. What is the causative pathogen?
How can you distinguish enterohemorrhagic E. coli (EHEC) from other types using a culture dish?
EHEC does not ferment sorbitol
Which bacteria are gram-positive, spore-forming, obligate anaerobic bacilli?
What is responsible for the recurrent nature of the fever caused by Borrelia recurrentis?
Variable surface antigens on the bacteria
What differentiates Q fever from other rickettsial diseases and what is the causative pathogen?
There is no rash or vector, and Coxiella burnetii, the pathogen, can survive outside in its endospore form
What two conditions can tuberculosis lead to following central nervous system invasion?
Parenchymal tuberculoma and meningitis
Name four organisms that are gram-negative, coccoid rods.
Haemophilus influenzae, Bordetella pertussis, Pasteurella, Brucella
Which Chlamydia trachomatis serotypes cause urethritis, PID, ectopic pregnancy, neonatal pneumonia, and neonatal conjunctivitis?
What nonlactose-fermenting gram-negative rod is commonly associated with wound and burn infections?
A one-year-old presents with several abnormalities that lead you to diagnose congenital syphilis. What could these abnormalities include?
Saber shins, saddle-nose, cranial nerve VIII deafness, Hutchinson's teeth, and mulberry molars
What characterizes Weil's disease (icterohemorrhagic leptospirosis)?
Jaundice and azotemia; fever, hemorrhage, and anemia
The symptoms of diphtheria are caused by what kind of toxin? How does the toxin inhibit protein synthesis?
Exotoxin (encoded on the β-prophage); by the ADP-ribosylation of elongation factor 2
Describe the vaccine used against Haemophilus influenzae
Contains type B capsular polysaccharide (polyribosylribitol phosphate), conjugated to diphtheria toxoid or other proteins
A seven-year-old boy eats an undercooked burger and then develops diarrhea, oliguria, and low ____ and ____ counts.
RBC and platelet counts, as well as acute kidney injury; this is hemolytic-uremic syndrome due to enterohemorrhagic E. coli (EHEC)
Which species of Neisseria has a polysaccharide capsule: meningitides or gonorrhea?
N. meningitides only
Is Pseudomonas aeruginosa oxidase positive or oxidase negative?
A patient is bitten by a flea and develops endemic typhus. What bacteria is responsible for this disease?
What is the classic triad of symptoms caused by a rickettsial infection?
Fever, headache, and rash (vasculitis)
What is the effect of the toxin produced by Clostridium perfringens?
α-toxin (lecithinase) causes myonecrosis, gas gangrene, and hemolysis
Because Mycobacterium leprae likes cool temperatures, it tends to infect what areas of the body?
The skin and the superficial nerves
What cellular changes caused by toxin B cytotoxin do you see in a patient with Clostridium difficile infection?
Destruction of cell cytoskeleton
Which stage of syphilis is characterized by broad-based ataxia, positive Romberg sign, Charcot joints, and stroke-like symptoms?
Neisseria meningitides ____ (does/does not) ferment maltose; Neisseria gonorrhea____ (does/does not) ferment maltose.
Does; does not
Helicobacter pylori is a risk factor for what two cancers?
Gastric adenocarcinoma and lymphoma
A patient presents with nasal collapse, loss of eyebrows, and lumpy skin. Give the treatment plan, including medications and duration.
This patient has the lepromatous form of Hansen's disease/leprosy; treat with dapsone, rifampin, and clofazimine for two to five years
What type of bacteria grow pink colonies on MacConkey's agar?
Lactose-fermenting enteric bacteria (lactose is KEE; test with MacConKEE'S agar: Citrobacter, Klebsiella, E. coli, Enterobacter, Serratia
A patient eats reheated rice and develops nausea and vomiting. What toxin is responsible? How long after eating did the symptoms begin?
Cereulide, a preformed toxin produced by Bacillus cereus; induces nausea/vomiting 1-5 hours after ingestion (emetic type)
Yersinia enterocolitica outbreaks are common in what setting?
An unvaccinated boy gets meningitis. Bacteria grow on chocolate agar with factors V and X. Diagnosis and treatment plan?
Haemophilus influenzae infection; treatment is ceftriaxone or penicillin G; close contacts should receive rifampin prophylaxis
Which type of Haemophilus influenzae causes the most invasive disease?
Capsular type B
A 27-year-old man has spastic paralysis. You suspect Clostridium tetanus infection. Name the toxin and explain its mechanism of action.
Tetanospasmin exotoxin; it inhibits glycine/GABA (inhibitory neurotransmitters) release from Renshaw cells in the spinal cord
You culture two different α-hemolytic species. What is the catalase and optochin status of each?
Streptococcus pneumoniae is optochin sensitive and Streptococcus viridans is resistant; both are catalase negative
What three diseases start with a rash on the palms and soles?
Coxsackievirus A, Rocky Mountain spotted fever, and Syphilis (you drive CARS using your palms and soles)
A patient develops Bell's palsy and atrioventricular nodal block. What stage of Lyme disease is this?
Which two chlamydial species cause atypical pneumonia and how are they transmitted?
C. pneumoniae and C. psittaci; aerosol transmission
Of the oxidase-positive, comma-shaped, gram-negative bacteria, ____ grows in 42°C whereas ____ grows in alkaline media.
Campylobacter jejuni; Vibrio cholera
Where geographically are Chlamydia trachomatis serotypes A, B, and C found? What do they cause?
Africa; they can cause a chronic infection as well as follicular conjunctivitis
You suspect that your patient has had a recent Streptococcus pyogenes infection. What blood test do you order?
Antistreptolysin O titer
Mycoplasma cell membranes are distinct because they contain ____.
Sterols, for stability
A Chlamydia trachomatis infection can cause what systemic sequelae?
Reactive arthritis, conjunctivitis, nongonococcal urethritis, cervicitis, and pelvic inflammatory disease
You counsel your patients that they can prevent diphtheria by receiving what?
Toxoid vaccine; usually coadministered with tetanus vaccine
During its lifecycle, what form of chlamydia is infectious?
The Elementary body (small, dense), which Enters the body via Endocytosis
A traveler to a developing country develops "rice-water" diarrhea due to a pathogen that acts by what mechanism?
Vibrio cholerae releases a toxin that permanently activates Gs and increases cAMP
A pregnant woman is diagnosed with Listeria monocytogenes infection. What complications may result from this infection?
Amnionitis, septicemia, and spontaneous abortion
In the Viridans group streptococci, Streptococcus ____ causes subacute bacterial endocarditis; Streptococcus ____ causes dental caries.
sanguis (= blood; there is a lot of blood in the heart, and S. sanguis sticks to damaged valves); mutans
Where can treponemes be found during primary and secondary syphilis?
In chancres during primary syphilis and in condylomata lata during secondary syphilis
Is Gardnerella vaginalis considered a sexually transmitted disease?
No; however, it is more common in sexually active women
What characterizes stage 1 of Lyme disease?
Erythema chronicum migrans (expanding "bull's eye" red rash with central clearing), flu-like symptoms
What are the characteristics of the toxin produced by Clostridium botulinum?
Preformed, heat-labile toxin
While examining Listeria monocytogenes under the microscope you see what characteristic microscopic finding?
Which of the two forms of leprosy indicates failed cell-mediated immunity and has a worse prognosis?
Lepromatous = Lethal
Neisseria meningitides ____ (does/does not) have a vaccine; Neisseria gonorrhea ____ (does/does not) have a vaccine.
Does; does not
An alcoholic passes out and aspirates on his vomit. A lung abscess that subsequently develops is most likely caused by what pathogen?
Klebsiella infection (Aspiration pneumonia, Abscess in lungs and liver, Alcoholics, DiAbetics)
Your patient developed pseudomembranous colitis caused by Clostridium difficile. Which antibiotic do you prescribe?
Metronidazole or oral vancomycin
How does the pathogenicity of Salmonella differ from that of Shigella?
Both invade mucosa, but Salmonella causes a monocytic response and spreads by blood; Shigella spreads from cell to cell with a PMN response
A sexually active woman has PID. If it is caused by Chlamydia trachomatis, what do you see on microscopy and how do you treat?
Cytoplasmic inclusions on Giemsa or fluorescent antibody staining; treatment is azithromycin or doxycycline
Which spirochete species is visualized by dark-field microscopy?
Treponema, which causes syphilis
What characterizes typhoid fever? What causes it?
Fever, headache, diarrhea, and abdominal rose spots; caused by Salmonella typhi
Name seven syndromes caused by Pseudomonas.
Pneumonia, Sepsis, External otitis, UTI, Drug use, Diabetic Osteomyelitis, hot tub folliculitis
When is neonatal Chlamydia acquired?
As the infant passes through an infected birth canal
Which two antibiotics are you wary of prescribing because they can promote pseudomembranous colitis?
Clindamycin and ampicillin
You culture a sputum sample, suspecting either Staphylococcus or Streptococcus. What two ways can you differentiate them?
Both are gram-positive cocci, but Staph is catalase (+), Strep catalase (-); Strep grows in chains, Staph in clusters
A positive Venereal Disease Research Laboratory (VDRL) test indicates that antibodies have formed against what molecule?
A neonate who develops Chlamydia pneumonia would most likely have earlier shown what problem: conjunctivitis, urethritis, or pharyngitis?
Compare and contrast the emetic type of Bacillus cereus with the diarrheal type in terms of symptoms and time of onset.
Compare and contrast the emetic type of Bacillus cereus with the diarrheal type in terms of symptoms and time of onset.
What are the harbors of the pathogen that causes bubonic plague?
Flea bites, rodents, and prairie dogs harbor Yersinia pestis
Gram-negative organisms can be classified into what four shapes?
Cocci, coccoid rods, rods, and comma-shaped
A patient contracts bubonic plague after being bitten by a flea containing what bacteria?
What part of gram-negative organisms inhibits the entry of penicillin G and vancomycin?
The outer membrane
How is Neisseria gonorrhoeae transmitted?
What three pyogenic infections does Streptococcus pyogenes cause?
Pharyngitis, cellulitis, and impetigo
Why is silver stain normally used to view Legionella pneumophila?
Because it gram stains poorly (considered gram negative)
In what populations does tuberculosis most frequently develop into progressive lung disease?
HIV-positive or malnourished individuals
Among lactose nonfermenters, which gram-negative rods are oxidase positive?
Pseudomonas and Helicobacter pylori
In virulent M. tuberculosis strains, ____ inhibit(s) macrophage maturation and induce(s) TNF-α release; ____ inhibit(s) phagolysosome fusion.
Cord factor; sulfatides (surface glycolipids)
A man is concerned he has syphilis. What tests do you use to screen and then confirm infection?
Screen with Venereal Disease Research Laboratory (VDRL) test and confirm with fluorescent-treponemal antibody absorption (FTA-ABS) test
What are one biochemical similarity and one biochemical difference between Shigella and Salmonella?
Salmonella produces hydrogen sulfide, but Shigella does not; both cannot ferment lactose
Name the four illnesses most commonly caused by Streptococcus pneumoniae infection.
Meningitis, Otitis media (in kids), Pneumonia, Sinusitis (S. pneumoniae MOPS are Most OPtochin Sensitive)
What chest x-ray finding can be seen in patients with primary but not secondary tuberculosis?
Ghon complex (Ghon focus, typically in mid-zone of the lung, with hilar node involvement)
Lancefield grouping is based on differences in what component of the bacteria?
C carbohydrate on the bacterial cell wall
Mycoplasma pneumoniae can be grown on what medium?
An AIDS patient develops Kaposi sarcoma. Which DNA virus is this associated with?
Human herpesvirus type 8 (Kaposi sarcoma-associated herpesvirus)
What are HIV-positive patients specifically at risk for as their CD4+ cell count drops?
Reactivation of past infections (e.g., TB, HSV, Shingles), dissemination of bacterial/fungal infections, non-Hodgkin's lymphoma
How do HIV-positive adults with invasive Aspergillosis fumigatus infection present?
With pleuritic chest pain, hemoptysis, and infiltrates on chest x-ray
Name two RNA viruses that have reverse transcriptase.
HIV (a retrovirus), and human T-lymphotropic virus
What disease does parainfluenza virus cause?
An HIV-positive patient has malignant neoplasms of the superficial vascular endothelial cells. What is the cause?
Human herpesvirus-8 (Kaposi sarcoma)
Which herpesvirus most often causes genital lesions in humans?
Herpes simplex virus type 2
The recombination of human flu A virus with swine flu A virus is an example of what?
Genetic shift, the reassortment of viral genome
An HIV-positive homosexual man contracts human papillomavirus. What malignancy will he likely develop? Where will a woman likely develop it?
Anal squamous cell carcinoma; cervix
You find that a woman is immune to HIV. What homozygous gene mutation does she have? What would happen if she had a heterozygous mutation?
CCR5 (which aids HIV binding on macrophages); heterozygous mutations cause a slower disease course
A man's lab values show an aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio < 1. Is this viral or alcoholic hepatitis?
Viral; in viral hepatitis, ALT > AST, but in alcoholic hepatitis AST > ALT (alcoholics are wASTed)
Which of the hepatitis viruses have short incubation periods? Which have long? Which can have either?
Hepatitis A and E: short incubations (weeks); B and C: long (months); D: short when a superinfection, long when a coinfection
A 35-year-old male is diagnosed with hepatitis C. What are the possible long-term effects of hepatitis C?
Chronic hepatitis C can cause liver cirrhosis and hepatocellular carcinoma (HCV: Chronic, Cirrhosis, Carcinoma, Carriers)
A virus is making a protein that is also replacing the nonfunctional protein of a coinfecting virus. What is this called?
Which three DNA viruses contain nonlinear DNA?
Papilloma, polyoma, and hepadna viruses, which contain circular DNA
Name the viral family that is made up of double-strand RNA viruses with a double icosahedral capsid.
____ is an example of an acquired prion disease; ____ is an example of a sporadic prion disease.
Kuru; Creutzfeldt-Jakob disease
Name four RNA virus families that have segmental genomes.
Reovirus, arenavirus, orthomyxovirus, and bunyavirus
How are the routes of transmission different for herpes simplex virus (HSV) type 1 and type 2?
HSV-1 is spread mainly by respiratory secretions and saliva; HSV-2 is spread via sexual contact and perinatally
Unlike the other picornaviruses, what type of infection does rhinovirus not cause? Why?
Gastrointestinal tract infections; it is acid labile and therefore destroyed by stomach acid
Which hepatitis types are blood borne, have chronic carriers, and cause chronic active hepatitis, cirrhosis, and hepatocellular carcinoma?
Hepatitis B and C
Which viral genetic event is the cause of worldwide influenza pandemics?
Reassortment, which occurs when viruses with segmented genomes exchange segments
Togaviruses cause what three diseases?
Rubella (German measles), Eastern equine encephalitis, and Western equine encephalitis
Viral genome reassortment occurs in viruses with what type of genomic structure?
Which HIV proteins are located in the envelope, matrix, and capsid, respectively?
Envelope: gp120 and gp41; matrix: p17; capsid: p24
What three infections are possible when CD4+ cell count < 50?
Cryptococcus neoformans, cytomegalovirus esophagitis, Mycobacterium avium-intracellulare
Which DNA virus does not replicate in the nucleus?
Poxvirus; it has a DNA-dependent RNA polymerase and can replicate without nuclear enzymes
Cytomegalovirus causes what conditions?
Congenital infection, mononucleosis, and pneumonia
An AIDS patient develops retinitis as a result of coinfection with what herpesvirus?
Cytomegalovirus (human herpesvirus type 5) (sightomegalovirus)
A man presents to the ER with a high fever, black vomitus, and jaundice. How is this virus transmitted? What is its reservoir?
Yellow fever is transmitted by the Aedes mosquito; the virus can have a monkey or human reservoir
Which viruses are both negative stranded and segmented?
Arenaviruses, bunyaviruses, and orthomyxoviruses
Which herpesvirus is the most common cause of sporadic encephalitis in the United States?
Herpes simplex virus type 1
You determine that your patient is infected with a DNA virus that is not icosahedral. What is it?
Poxvirus (it is complex)
All segmented viruses are ____ (RNA/DNA) viruses.
Epstein-Barr virus and cytomegalovirus establish latency in ____ cells and ____ cells, respectively.
B cells; mononuclear cells
Epstein-Barr virus is associated with the development of what three malignancies?
Hodgkin's lymphoma, endemic Burkitt's lymphoma, and nasopharyngeal carcinoma
What type of disease does papillomavirus cause?
Human papillomavirus: warts (types 1, 2, 6, 11), cervical intraepithelial neoplasia, and cervical cancer (types 16, 18)
What diseases are caused by paramyxoviruses? In what age group do these diseases predominate?
Parainfluenza (croup: seal-like barking cough), mumps, measles, and respiratory syncytial virus (bronchiolitis/pneumonia); infants/children
Name the six negative-stranded virus families.
Arenaviruses, Bunyaviruses, Paramyxoviruses, Orthomyxoviruses, Filoviruses, Rhabdoviruses (Always Bring Polymerase Or Fail Replication)
Aseptic meningitis; myocarditis; herpangina; and hand, foot, and mouth disease are caused by which picornavirus?
In viral genetics, what is reassortment?
The exchange of segments among viruses with segmented genomes (e.g., influenza virus)
An HIV-positive patient presents with a stiff neck, headache, and fever. You suspect a fungal infection. How do you diagnose it?
Cryptococcus neoformans is diagnosed on India ink stain, which reveals narrow-based budding yeast with a large capsule
An HIV-positive woman is becoming more and more forgetful. Why?
HIV is directly associated with dementia (although she could also have dementia from other causes)
Name four killed virus vaccines.
Rabies, Influenza, Salk Polio, hepatitis A virus (RIP Always; SalK = Killed)
All DNA viruses contain double-strand DNA, except which family?
Parvovirus, which has single-strand DNA (part-of-a-virus)
What are the symptoms of mumps?
Parotitis, Orchitis, aseptic Meningitis (mumps makes your parotid glands and testes as big as POMpoms)
Hepatitis E infection is transmitted via the same route as what other hepatitis virus? How do the viruses differ?
Hepatitis A (fecal-oral). HAV: usually Asymptomatic, Acute, Alone (no carriers); HEV: high mortality in pregnancy, waterborne epidemics
A two-year-old develops a fatal case of diarrhea. What virus is the primary cause?
A patient is given a viral vaccine and it reverts to virulence (a rare occurrence). What type of vaccine was it?
Describe the progression of symptoms in rabies infection.
Fever and malaise leading to agitation,_x000D_
photophobia, hydrophobia, paralysis, coma, and death
Measles is usually marked by what three symptoms in addition to Koplik spots and descending rash?
Cough, Coryza, and Conjunctivitis (3 C's)
A patient develops Colorado tick fever. Which virus is responsible?
You are trying to develop a drug that targets the HIV envelope proteins. What is the function of these two proteins?
gp120 is the docking protein that helps HIV attach to CD4+ T cell; gp41 is a transmembrane glycoprotein that facilitates HIV fusion, entry
Which two RNA viruses cause the common cold?
Rhinovirus and coronavirus
A bat researcher develops fever, malaise, photophobia, and coma and then dies. Describe the pathophysiology. How long ago was he infected?
Rabies migrates retrograde up nerve axons to the CNS; it has a long incubation period, and infection occurs weeks to months before symptoms
Which serologic marker indicates prior infection (or vaccination) and protects against reinfection with hepatitis A?
Immunoglobulin G anti-hepatitis A virus antibody (anti-HAV IgG)
Name the two major antigens of the influenza virus and the role they play in infection.
Hemagglutinin (promotes viral entry) and neuraminidase (promotes viral release)
All DNA viruses are linear except which three?
Hepadnavirus (circular, incomplete), papillomavirus/polyomavirus (circular, supercoiled)
An HIV-positive man has low fever, cough, hepatosplenomegaly. Macrophages have oval yeast cells. How does this bug affect those without HIV?
Histoplasmosis capsulatum causes only pulmonary symptoms in immunocompetent individuals
Two viruses coinfect a cell. Virus A is coated with virus B proteins. Progeny viruses have type A genome and coat. What is this called?
An HIV-positive patient presents with progressive multifocal leukoencephalopathy. You suspect a coinfection with what virus?
JC virus (Junky Cerebrum)
What animal bites are most likely to result in rabies infection in the United States?
Bat, raccoon, and skunk
What five RNA viruses are picornaviruses?
Poliovirus, Echovirus, Rhinovirus, Coxsackievirus, Hepatitis A virus (PERCH on a "peak" [pico])
Purified nucleic acids from which viruses are considered infectious?
Most double-strand DNA viruses and positive-strand single-strand RNA viruses
Herpes genitalis and neonatal herpes are most commonly caused by which herpes virus?
Herpes simplex virus type 2
Flaviviruses are responsible for what five diseases?
Hepatitis C virus, yellow fever, dengue, St. Louis encephalitis, and West Nile virus
Describe hepatitis B virus replication.
Viral DNA-dependent DNA polymerase makes dsDNA; host RNA polymerase transcribes mRNA from viral DNA, which then makes viral proteins
Rotavirus belongs to which viral family?
Rotavirus belongs to which viral family?
You diagnose a patient as a hepatitis carrier. Which types of hepatitis could he have?
Hepatitis B, C, or D; only these types have a carrier state
All picornaviruses (except rhinovirus and hepatitis A) can cause what condition in humans? All, except rhinovirus, are spread by what route?
Aseptic meningitis; fecal-oral route (they are enteroviruses)
How is hepatitis B virus transmitted? What other virus is transmitted the same way?
Parenteral, sexual, or maternal-fetal routes (hepatitis B: Blood borne); hepatitis D virus
What lab test can be used to diagnose mononucleosis?
Monospot test: heterophile antibodies detected by agglutination of sheep red blood cells
What three infections are possible when CD4+ cell count < 100?
Candida albicans, Histoplasma capsulatum, Toxoplasma gondii
You examine an HIV-positive patient and see "cotton wool" spots on fundoscopic exam. What other symptom might this infection cause?
Cytomegalovirus can cause esophagitis and retinitis
Name the four families of RNA viruses that have no envelope.
Reovirus, picornavirus, hepevirus, and calicivirus
Name the six positive-strand RNA viruses.
Retrovirus, togavirus, flavivirus, coronavirus, calicivirus, picornavirus
Which is the only hepatitis-causing virus that is a DNA virus?
Hepatitis B virus
What is the Tzanck test?
A test to detect multinucleated giant cells in opened skin vesicles in HSV-1, HSV-2, and HHV-3 (remember that PCR is the test of choice)
You determine that a patient is infected with a diploid virus. What is the only family of virus that it could be?
What is the smallest DNA virus?
Which enzyme does hepatitis B virus have in common with retrovirus?
To which viral family does the yellow fever virus belong?
Flavivirus (also an arbovirus; flavi means yellow, jaundice)
What two other rash-causing viruses is measles sometimes confused with?
Rubella and roseola (caused by human herpesvirus-6)
Coronaviruses are the causative agents of what two diseases?
The common cold and severe acute respiratory syndrome (SARS)
Rubella is a relatively benign illness in most cases. When can serious sequelae result?
When it infects fetuses (it is a ToRCHeS infection)
Which oral premalignant lesion is caused by Epstein-Barr virus in HIV-positive individuals?
Oral hairy leukoplakia (found on the lateral tongue)
What signs and symptoms are characteristic of all hepatitis viruses?
All hepatitis viruses have fever, jaundice, and elevated levels of alanine aminotransferase and aspartate aminotransferase
Vaccinia virus causes what condition?
Cowpox ("milkmaid's blisters")
A boy presents with flesh-colored dimpled dome lesions on his legs. What is the diagnosis and what type of virus causes it?
Molluscum contagiosum, caused by a DNA poxvirus
What does the continued presence of hepatitis B surface antigen in serum mean?
Hepatitis B infection (either acute or chronic)
An adult patient receives a viral vaccine and only humoral immunity is induced. What type of vaccine was it?
Killed virus vaccine
Hepatitis B, C, and D cannot spread via the fecal-oral route. Why?
Unlike naked viruses (e.g., hepatitis A and E), enveloped viruses are killed in the gut
There is an outbreak of respiratory syncytial virus and many infants present to the ER. What clinical presentation do they share?
What is the significance of immunoglobulin M (IgM) vs. immunoglobulin G (IgG) hepatitis B core antibodies?
IgM is a marker for acute or recent disease; IgG is a marker for prior exposure of chronic infection
IgM is a marker for acute or recent disease; IgG is a marker for prior exposure of chronic infection
What does the following mnemonic stand for: "Give PAPP smears and CPR to a naked Hippy"?
Naked viruses: Parvovirus, Adenovirus, Papillomavirus, Polyomavirus, Calicivirus, Picornavirus, Reovirus, Hepevirus
A woman gets an injectable flu vaccine but her five-year-old daughter gets a nasal spray. How are these vaccines different?
Injection contains killed virus; nasal spray contains live, temperature-sensitive mutant virus that replicates in the nose (but not lungs)
Injection contains killed virus; nasal spray contains live, temperature-sensitive mutant virus that replicates in the nose (but not lungs)
Epstein-Barr virus causes what conditions?
Infectious mononucleosis, Burkitt's lymphoma, and nasopharyngeal carcinoma
A patient refuses the flu vaccine because he does not think people can die from the flu. What is the most likely fatal effect of the flu?
A fatal bacterial superinfection pneumonia
Name the five clinically important picornaviruses.
PERCH: Poliovirus, Echovirus, Rhinovirus, Coxsackievirus, HAV
Name four medically important paramyxoviruses using the mnemonic PaRaMyxovirus.
Parainfluenza; RSV (treated with Ribavirin); Mumps and Measles
A patient presents with febrile pharyngitis, pneumonia, and conjunctivitis. What DNA virus is likely to be responsible?
Arenaviruses are the causative agents of what two diseases?
Lymphocytic choriomeningitis and Lassa fever encephalitis (spread by mice)
What population is at particularly high risk for rotavirus? In which months? How is infection prevented?
Infants and young children, especially in daycare centers and kindergartens; winter months; the CDC recommends vaccination of all infants
A man has a CD4 count of 21 due to a viral infection. Where in the host cell does the causative virus replicate?
The patient has HIV, a retrovirus that replicates in the host nucleus
What type of virus is rhinovirus?
A nonenveloped RNA virus that belongs to the picornavirus family
You suspect a patient has hepatitis A. How would you detect active viral infection?
Test for immunoglobulin M hepatitis A virus antibody (anti-HAV IgM)
An HIV-positive patient gets pneumonia, which you suspect to be from cytomegalovirus. What do you see on chest x-ray? On biopsy?
Cytomegalovirus infection causes an interstitial pneumonia; biopsy reveals cells with intranuclear inclusion bodies (owl's eye)
To what viral family does hepatitis B virus belong?
A preterm infant receives a monoclonal antibody to prevent a common respiratory infection. Name the antibody and infection.
Palivizumab is a monoclonal antibody against the surface F protein; pneumonia caused by respiratory syncytial virus
Describe the translation and post-translation modification of picornaviruses.
The RNA is translated into a single polypeptide, which is then cleaved by proteases into functional viral proteins
All negative-sense RNA viruses have what type of capsid?
What three infections are possible when CD4+ cell count < 200?
Cryptosporidium, JC virus reactivation, Pneumocystis jirovecii
A patient has a spongiform encephalopathy and you discover that it is congenital. Diagnosis?
Herpes simplex virus (HSV) type 1 is latent in the ____ ganglia, and HSV-2 is latent in the ____ ganglia.
How does HIV integrate its genome into host DNA?
Reverse transcriptase converts viral RNA into double-stranded DNA; it is then integrated into the host DNA
Which patients are particularly vulnerable to cytomegalovirus infection?
Those who are immunosuppressed (e.g., transplant recipients) and the fetuses of infected mothers
You design an inhibitor that prevents HIV from binding to T cells. What proteins does it target?
CXCR4, CCR5 and CD4
A patient presents with mononucleosis-like symptoms but the monospot test is negative. What is the likely etiology?
Cytomegalovirus infection (human herpesvirus type 5)
A child develops roseola (exanthem subitum). What is the causative virus?
Human herpesvirus type 6
A hepatitis B patient tests positive for e antigen. Another tests positive for e antigen antibody. How is their transmissibility different?
HBeAg indicates active viral replication (high transmissibility); anti-HBe indicates low transmissibility
Which hepatitis serologic marker is positive during the window period?
Hepatitis B core antibody (anti-HBc)
You determine that a patient is infected with a DNA virus that does not replicate in the nucleus. Which virus is it?
Which medically important RNA virus belongs to the orthomyxovirus family?
Human T-lymphotropic virus causes what disease?
A patient comes into the HIV clinic for follow-up care after starting antiretroviral meds. How do you test his response to treatment?
Test HIV polymerase chain reaction/viral load to determine the amount of viral RNA in plasma (high viral load indicates poor prognosis)
With one exception, all DNA viruses replicate in what part of the host cell?
A patient is diagnosed with herpes encephalitis. Which lobe of the brain is most likely affected?
The temporal lobe
The purified nucleic acids of what two double-strand DNA viruses are not infectious?
Pox and hepatitis B viruses; they require nonhuman enzymes for replication
Chickenpox, zoster, and shingles are caused by what DNA virus?
Varicella zoster virus (human herpesvirus type 3)
Influenza virus is ____ (enveloped/nonenveloped), ____ (single/double stranded), with ____ (segmented/nonsegmented) RNA.
Enveloped; single stranded; segmented (there are eight segments)
A patient has hepatitis D. What other hepatitis virus must he have? How does the timing of the other infection affect his prognosis?
Hepatitis B virus; prognosis is better with coinfection (HBV and HDV) than superinfection (new HDV on chronic HBV infection)
A senior in high school is diagnosed with mononucleosis. Which herpesvirus is the most common cause of his infection?
Epstein-Barr virus (human herpesvirus type 4)
When would you diagnose AIDS in an HIV-positive patient?
When CD4+ count < 200 (normal: 500-1500), when an AIDS-defining illness develops (e.g., PCP), or when the CD4/CD8 ratio < 1.5
Which human papillomavirus (HPV) types does the HPV vaccine protect against?
HPV types 6, 11, 16, and 18; the types most likely to cause cervical cancer and genital warts
What are the modes of cytomegalovirus transmission?
Congenital, transfusion, sexual contact, saliva, urine, and organ transplantation
An HIV-positive patient has chronic cough, night sweats, and a cavitary pulmonary lesion on chest x-ray. What two infections do you worry about?
Mycobacterium tuberculosis and Mycobacterium avium-intracellulare (causes tuberculosis-like disease)
During what phase of HIV infection does the CD4+ cell count drop most steeply? What else happens in this phase?
Acute phase (first 1-2 months); wide dissemination of virus, seeding of lymphoid organs
Kaposi sarcoma lesions have ____ (lymphocytic/neutrophilic) inflammation whereas bacillary angiomatosis has ____ (lymphocytic/neutrophilic).
What type of infection does rhinovirus cause? Why is it so common?
The common cold; there are more than 100 serologic types ("rhino has a runny nose")
An HIV-positive patient with a CD4+ cell count < 200 develops pneumonia. What pathogen do you suspect?
Pneumocystis jiroveci (also known as PCP)
Why do negative-stranded DNA viruses carry RNA-dependent RNA polymerase?
To transcribe the negative strand to a positive strand in the host cell in order to replicate
A recent renal transplant recipient presents with renal dysfunction, and tests show a virus with circular DNA. What is the infection?
BK virus (Bad Kidney)
An HIV-positive patient has bacillary angiomatosis. What is this, and how is it caused? What do you see on biopsy?
A superficial vascular proliferation caused by Bartonella henselae; neutrophilic inflammation
A young boy is bitten by a raccoon while playing outside. How should he be treated to avoid rabies infection?
The wound should be cleaned thoroughly and then he should receive rabies vaccination with or without rabies immune globulin
Structurally, what are the three main classes of viruses?
Naked icosahedral, enveloped icosahedral, enveloped helical
Which viral family is responsible for smallpox, cowpox, and molluscum contagiosum?
What is the only live attenuated vaccine that can be given to HIV-positive individuals who are not exhibiting signs of immunodeficiency?
Measles, mumps, rubella (MMR)
An HIV-positive man has white, fluffy "cottage cheese" oral lesions. What is his maximum CD4+ count? What if the lesions were in the esophagus?
Candida albicans causes oral infection if CD4+ cell count is < 400 and esophagitis if < 100
A child presents with erythema infectiosum (fifth disease or "slapped-cheek rash"). What virus is responsible?
An HIV-positive patient presents with progressive multifocal leukoencephalopathy as a consequence of what infection?
JC virus, which reactivates and causes demyelination
What two DNA virus families were originally categorized together as papovavirus?
Papillomavirus and polyomavirus
Why are negative-strand, single-strand RNA and double-strand RNA viruses not infectious?
They require enzymes found in the complete virion to become infectious
A warehouse worker in Arizona has pneumonia and dyspnea; rodents tested near his worksite were infected with an RNA virus. Diagnosis?
Hantavirus, a rodent-borne bunyavirus that causes a pulmonary syndrome in the United States
A patient has fever, headache, sore throat, and myalgias. Tests confirm a viral infection. Where in the host cell does it replicate?
The patient has influenza, an RNA virus that replicates in the host nucleus
What does the mnemonic for the seven DNA viruses, "DNA viruses are HHAPPPPy viruses," stand for?
Hepadnavirus, Herpesvirus, Adenovirus, Poxvirus, Parvovirus, Papillomavirus, Polyomavirus
What surface protein is common to all paramyxoviruses? What is its role?
Surface F (fusion) protein; it causes respiratory epithelial cells to fuse and become multinucleated
A patient who has received many blood transfusions is diagnosed with hepatitis C. How else is it transmitted?
Hepatitis C is primarily transmitted by blood exposures, but also by intravenous drug use
Name four segmented RNA viruses.
Bunyaviruses, Orthomyxoviruses (influenza), Arenaviruses, Reoviruses (BOAR)
All RNA viruses contain single-strand RNA, except for which family?
Reovirus (all are single-strand RNA except "repeatovirus" [reovirus], which is double-strand RNA)
An unvaccinated boy has had fever, lymphadenopathy, arthralgias, and a fine truncal rash for three days. What is the viral infection?
Rubella (a togavirus; also known as German measles or three-day measles)
Which two RNA viruses replicate in the host cell nucleus?
The influenza virus and retroviruses
You are trying to develop a drug that targets the HIV envelope proteins. How are these proteins formed?
env gene encodes a gp160 precursor that is cleaved into gp120 and gp4; acquired through budding from the host cell plasma membrane
A child is administered the hepatitis B vaccine. Which antigen is present in the vaccine?
Recombinant hepatitis B surface antigen
An HIV-positive patient develops large cell non-Hodgkin's lymphoma. What virus may have caused it? Where is the tumor most likely to be?
Epstein-Barr virus; oropharynx (in Waldeyer's ring)
Name six live attenuated vaccines.
Measles, mumps, rubella (MMR); Sabin polio; varicella zoster virus; yellow fever; smallpox; intranasal influenza
Which two picornaviruses commonly cause aseptic meningitis?
Echovirus and coxsackievirus
A pregnant woman is exposed to parvovirus B19. What complication might be seen in her fetus?
Hydrops fetalis (due to red blood cell destruction)
Picornaviruses are ____ (small/large) ____ (RNA/DNA) viruses.
Small; RNA (picoRNAvirus = RNA virus)
Filoviruses are the causative agents of what two diseases?
Ebola hemorrhagic fever and Marburg hemorrhagic fever; both are frequently fatal
An adult man presents with red blood cell aplasia and rheumatoid arthritis-like symptoms. What viral infection does he have?
What are the three viral families with circular RNA?
Arenavirus, bunyavirus, and deltavirus
An intravenous drug user has a positive HIV screening test. What are the chances it is a false positive? What test do you do next? Why?
ELISA is sensitive with a high false-positive rate; Western blot because it is specific with a high false-negative rate
How is the reovirus genome unique among RNA viruses?
It has double-strand DNA; all other RNA viruses are single strand
What is the largest DNA virus?
Name seven viral families that are single-strand, positive-sense, linear RNA viruses with icosahedral capsids.
Picornavirus, hepevirus, calicivirus, flavivirus, togavirus, retrovirus, and coronavirus
A man recently diagnosed with hepatitis is concerned about risk of hepatocellular carcinoma. Which hepatitis types increase this risk? Why?
Hepatitis B (acts as oncogene after integrating into host genome), C (causes chronic inflammation), D (dependent on hepatitis B)
What is the only positive-sense RNA virus with a helical capsid?
Describe the four stages of HIV infection and how they correlate to symptoms a patient may have.
Flu-like: acute HIV syndrome; Feeling fine: clinical latency; Falling count: constitutional symptoms; Final crisis: opportunistic infections
An infant has diarrhea, and you diagnose him with the most important global cause of infantile gastroenteritis. What type of virus is it?
Rotavirus is a segmented dsRNA virus (a reovirus)
Which antibody is protective against hepatitis B infection?
Hepatitis B surface antibody (anti-HBs)
What causes prion diseases?
Normal prion protein is converted to a β-pleated form (PrPsc), which is transmissible, resists degradation, and converts more prion protein
Describe the HIV genome.
It is diploid, with two RNA molecules
A man has a negative HIV test. When in the infection could this be a false negative? Why? Who is at risk for false-positive tests? Why?
ELISA/Western blot may be falsely negative in the first 1-2 months of infection; babies born to infected moms; anti-gp120 crosses placenta
Do most RNA viruses replicate in the cytoplasm or the nucleus of the host cell?
A young boy is brought in with a maculopapular rash on his chest. How do you distinguish between a measles and rubella rash?
Measles causes a rash that spreads from head to toe, including hands and feet; rubella is a truncal rash that spares hands and feet
A patient presents with oral/genital lesions, spontaneous temporal lobe encephalitis, and keratoconjunctivitis. Diagnosis?
Herpes simplex virus type 1 infection
Name a medically important calicivirus that causes viral gastroenteritis.
Random mutations leading to minor genetic changes in the human flu A virus is an example of what?
Genetic drift (antigenic drift)
HSV-1, EBV, and VZV are transmitted via ____ (respiratory secretions/sex); HSV-2, CMV, and HHV-8 are via ____ (respiratory secretions/sex).
Respiratory secretions; sex
Bunyaviruses are the causative agents of what four diseases?
California encephalitis, Sandfly/Rift Valley fevers, Crimean-Congo hemorrhagic fever, and hantavirus
An HIV-positive patient with tuberculosis-like disease has a CD4+ cell count < 50. Diagnosis?
Mycobacterium avium-intracellulare infection
A biopsy from your patient shows Cowdry A intranuclear inclusions in the cells. What do these indicate?
Herpes simplex virus infection
A boy has roseola with high fevers for days and one seizure. He then develops a diffuse malar rash. What agent caused this?
Human herpesvirus type 6
An HIV-positive patient tests positive for Epstein-Barr virus. What three cancers is he at risk for?
Oral hairy leukoplakia, Non-Hodgkin's large cell lymphoma, and primary central nervous system lymphoma (focal or multiple lesions)
What clinical manifestations does prion accumulation cause?
Spongiform encephalopathy, ataxia, dementia, and death
Genetic shift causes ____ (epidemics/pandemics); genetic drift causes ____ (epidemics/pandemics) .
Pandemics; epidemics (Sudden Shift is more deadly than graDual Drift)
Which proteins do each of these HIV genes code for: env, gag, pol?
env: gp120 and gp41; gag: p24; pol: reverse transcriptase, aspartate protease, integrase
What is viral genetic recombination?
The exchange between two chromosomes by crossing over within regions of significant base sequence homology
____ (Live attenuated/Killed) vaccines induce humoral and cell-mediated immunity.
Shingles, encephalitis, and pneumonia can be caused by which herpesvirus?
Varicella zoster virus (human herpesvirus type 3)
What is a pseudovirion?
The genetic material of one virus coated by the surface proteins of a different virus
A patient with sickle cell disease presents with aplastic crisis. What virus is most likely responsible?
How are arboviruses transmitted?
By arthropods (mosquitoes, ticks)
An HIV-positive man who has a cat presents with fever and headache and has a ring-enhancing brain lesion. Cause?
Toxoplasma gondii infection
Name two recombinant vaccines.
Hepatitis B virus and human papillomavirus
An HIV-positive patient presents with chronic watery diarrhea. What stain should you use to make the diagnosis?
Cryptosporidium presents with acid-fast cysts in stool and requires an acid-fast stain
In what age group do you see the peak incidence of Epstein-Barr virus infection?
15-20 years of age; the peak kissing years ("kissing disease")
Live vaccines are dangerous to give to which populations?
Immunocompromised patients or their contacts
Which diseases are caused by arboviruses (RNA viruses transmitted via arthropods)?
Yellow fever, dengue, St. Louis encephalitis, West Nile virus, EEE and WEE, California encephalitis, Crimean-Congo hemorrhagic fever
Which disease caused by a poxvirus has been eradicated but could possibly be used in germ warfare?
The herpesviruses acquire their envelopes from which component of the host cell?
A neonate develops oral thrush. What is the likely responsible organism and how would you treat?
Candida albicans; treatment is nystatin since it is a superficial lesion
Snails are the host for what helminth?
Through what structure must Mucor and Rhizopus penetrate to invade the brain?
The cribriform plate
What is the treatment of choice for Ancylostoma duodenale and Necator americanus?
The -bendazoles or pyrantel pamoate
Praziquantel is used to treat diseases caused by which helminths?
Most of the cestodes and trematodes: Taenia solium, Diphyllobothrium latum, Schistosoma, Clonorchis sinensis, and Paragonimus westermani
What is the characteristic microscopic appearance of blastomycosis?
Big, broad-based budding
How is Toxocara canis transmitted?
Via food that is contaminated with eggs
What is the treatment of choice for Echinococcus granulosus?
A man has "swiss cheese" lesions in the brain and cysticercosis following exposure to eggs in his food. What is the diagnosis?
Taenia solium infection
Mucor and Rhizopus cause disease in which patient populations?
Diabetic patients with ketoacidosis and patients with leukemia
What are the different modes of transmission of Trichinella spiralis and Trichomonas vaginalis?
Trichinella spiralis is caused by eating undercooked meat; Trichomonas vaginalis is a sexually transmitted disease
How is the diagnosis of Naegleria made?
Amoebas in the cerebrospinal fluid
What is the treatment of choice for Loa loa?
What causes recurring fevers in Trypanosoma infection?
Aside from thrush and vulvovaginitis, what other superficial infections can Candida albicans cause?
Chronic infection with Schistosoma haematobium can lead to what cancer?
Squamous cell carcinoma of the bladder
Tinea pedis, cruris, corporis, and capitis are caused by what organisms?
Dermatophytes (i.e., Microsporum, Trichophyton, Epidermophyton)
Why is ethanol injected into Echinococcus granulosus cysts before removal?
To neutralize echinococcal antigens and prevent anaphylaxis
A malaria patient has fever cycles occurring every other day. What protozoa is likely causing this?
Is Cryptococcus neoformans a mold, a yeast, or dimorphic?
Yeast (not dimorphic)
What is the treatment of choice for blood-borne African sleeping sickness?
Toxoplasma causes disease in what two patient populations?
HIV-positive patients and neonates (congenital toxoplasmosis)
What systemic effects does Schistosoma have upon entering a human?
Inflammation, fibrosis, and granulomas of the liver and spleen
What are the treatments for superficial and systemic Candida albicans infections?
Superficial infection: nystatin, systemic infection: amphotericin B
What is the classic triad of congenital toxoplasmosis?
Chorioretinitis, hydrocephalus, and intracranial calcifications
Vulvovaginitis from Candida albicans commonly occurs in which population of women?
Women with a high vaginal pH, diabetes, and/or recent antibiotic use
What roundworm can cause visceral larva migrans in addition to retinal granulomas?
Is Sporothrix schenckii a mold, a yeast, or dimorphic?
What two diagnostic tests are used for Toxoplasma infection?
Serology and biopsy
What are two colloquial names for disease caused by coccidioidomycosis?
San Joaquin Valley fever and desert valley fever (desert bumps)
What is the mode of transmission of Toxoplasma?
Cysts in meat or cat feces
Name two systemic mycoses that are transmitted by inhalation of asexual spores.
Coccidioidomycosis and histoplasmosis
A diabetic patient has headache, facial pain, black necrotic eschar on face, and cranial nerve injury. What infection do you expect?
What does Naegleria fowleri cause?
Rapidly fatal meningoencephalitis
What is the mode of transmission of Echinococcus granulosus?
The ingestion of eggs in dog feces
Name the helminth that causes vitamin B12 deficiency.
Histoplasmosis is endemic in what area of the United States?
The Mississippi and Ohio River valleys
Many HIV-positive patients who drink tap water in your city present with severe diarrhea, and no treatment is offered. What organism is most likely responsible for this condition and how will you confirm the suspicion?
Cryptosporidium; look for cysts on acid-fast staining
Name the helminth that cause microcytic anemia.
Ancylostoma and Necator
What microscopic appearance distinguishes coccidioidomycosis from all other dimorphic fungi?
Coccidioidomycosis is a spherule in tissue, not a yeast
What do histoplasmosis, paracoccidioidomycosis, and blastomycosis have in common?
They are all systemic mycoses caused by dimorphic fungi (mold in soil, but yeast in tissue (remember: mold = cold; heat = yeast)
What is the treatment of choice for visceral leishmaniasis?
What are two treatments for amebiasis?
Metronidazole and iodoquinol
An athlete presents with hypopigmented macules on her upper back after a summer of exercising. What is your diagnosis and what is the treatment?
Tinea versicolor; treat with topical miconazole and selenium sulfide
A girl presents with rapidly progressing meningoencephalitis after swimming in a lake. What is the diagnosis?
What is the mode of transmission of visceral leishmaniasis?
What is the treatment of choice for sporotrichosis?
Itraconazole or potassium iodide
What are the two laboratory diagnostic tests for amebiasis?
Serologic studies and stool examination for trophozoites or cysts
How is the diagnosis of Trypanosoma cruzi made?
By visualizing the organism on blood smear
What are the symptoms of Dracunculus medinensis infection?
Inflammation and ulceration of the skin, often the feet and ankles
A man is bitten by a female black fly and develops hyperpigmented skin and river blindness. What is the diagnosis?
Onchocerca volvulus infection (remember: blackflies, black skin nodules, "black sight")
An African man is bitten by a tsetse fly and has lymphadenopathy, recurring fever, somnolence, and coma. What is the diagnosis?
African sleeping sickness
What disease is caused by Leishmania donovani?
Visceral leishmaniasis, also known as kala azar
In what population is Candida albicans commonly associated with endocarditis?
Intravenous drug users
What is the treatment of choice for Onchocerca volvulus?
Ivermectin (remember: IVERmectin for rIVER blindness)
A man is bitten by a sandfly and develops spiking fevers, hepatosplenomegaly, and pancytopenia. What is the diagnosis?
What is the mode of transmission of the larval cysts of Taenia solium?
Consumption of undercooked pork
The Scotch tape test is used to diagnose what type of infection?
Enterobius vermicularis (pinworms); tape is touched to the perianal area at night to look for presence of pinworm eggs
Distinguish the cyclic nature of fevers found in Plasmodium falciparum and Plasmodium vivax/ovale.
Plasmodium falciparum is more severe and cycles every day whereas Plasmodium vivax/ovale cycle every other day
What does Naegleria cause?
Rapidly fatal meningoencephalitis
What is the mode of transmission of Cryptosporidium?
Cysts in water
Name the helminth that causes biliary tract disease and is associated with cholangiosarcoma.
In patients with AIDS, what does Cryptosporidium cause?
What is the mode of transmission of Naegleria?
Swimming in freshwater lakes (the organism enters via the cribriform plate)
Where are the abscesses in Mucor and Rhizopus infections found?
Nose and frontal lobe
What parts of the body does Loa loa infect?
The skin and the eyes
Name the transmission of Trichinella spiralis vs. that of Trichomonas vaginalis ?
Trichinella spiralis is transmitted from eating undercooked meat; Trichomonas vaginalis is transmitted sexually
Which nematodes are transmitted cutaneously?
Strongyloides, Ancylostoma, and Necator (remember: these get into your feet from SANd)
Name the helminth that causes portal hypertension.
Why does infection with Ancylostoma duodenale and Necator americanus lead to anemia?
The worms suck blood through walls of the intestine causing iron deficiency
What is the common name for Enterobius vermicularis?
Name two biliary tract pathologies caused by Clonorchis sinensis
Pigmented gallstones secondary to biliary tract inflammation and cholangiosarcoma
What fluke is transmitted via undercooked fish?
Why should pregnant women avoid cats and cat feces?
Toxoplasma gondii cysts are found in cat feces and can cross the placenta, causing birth defects
What are the clinical presentations resulting from ingestion of Taenia solium eggs vs larvae?
The ingestion of tapeworm larvae causes intestinal infection whereas the ingestion of eggs causes neurocysticercosis
Name the helminth that causes liver cysts.
How many nuclei do Entamoeba cysts have?
Which nematodes are transmitted by ingesting contaminated food?
Enterobius, Ascaris, and Trichinella (EAT)
What is the treatment of choice for Paragonimus westermani?
An athlete has hypopigmented and hyperpigmented macules on her back after summer training. What is your diagnosis and how would you treat?
Tinea versicolor; treatment is topical miconazole and selenium sulfide (Selsun)
An HIV-positive patient develops disseminated candidiasis. How would you treat her?
Amphotericin B, since the infection is systemic
What are the three major types of helminths?
Nematodes (roundworms), cestodes (tapeworms), and trematodes (flukes)
Toxoplasmosis causes brain lesions that have what appearance on imaging studies?
What is the treatment of choice for Enterobius vermicularis?
Mebendazole or pyrantel pamoate
What disease is caused by Entamoeba histolytica?
Amebiasis (bloody diarrhea, liver abscess, and right upper quadrant pain)
Infection with which protozoa can lead to flask-shaped ulcers if submucosal abscess of colon ruptures?
Amebiasis (Entamoeba histolytica)
What is the treatment of choice for Schistosoma?
What is the appearance of Pneumocystis jiroveci pneumonia on chest x-ray?
Diffuse, bilateral infiltrates
A patient presents with a foul-smelling, itching, burning vaginitis with greenish discharge, and the responsible organism is diagnosed by trophozoites on wet mount. What organism is most likely responsible for this condition?
What is the treatment of choice for Ascaris lumbricoides?
-bendazoles or pyrantel pamoate
A patient has hemolytic anemia and fever after a tick bite. On blood smear there are "maltese cross" forms. What is the diagnosis?
How do you diagnose Naegleria and how do you treat it?
Amoebas in the cerebrospinal fluid; amphotericin is effective in some survivors
What is the treatment of choice for Dracunculus medinensis?
What three diseases does Aspergillus fumigatus cause?
Allergic bronchopulmonary aspergillosis, lung cavity aspergilloma, invasive aspergillosis
A gardener presents with a pustule on her forearm, with lesions tracing upward toward her axilla. Likely diagnosis?
Sporotrichosis, or "rose gardener"s" disease
What causes hypopigmented patches of tinea versicolor?
Degradation of lipids by Malassezia furfur, producing acids that damage melanocytes
How is Pneumocystis jiroveci pneumonia diagnosed?
Sample obtained by lung biopsy or lavage; stained with methenamine silver
What is the treatment of choice for vaginitis caused by Trichomonas vaginalis?
Metronidazole; both the patient and sexual partners must be treated
What is the treatment of choice for Wuchereria bancrofti?
What is the radiologic appearance of lesions found in the brain in patients with Cryptococcus neoformans?
What is the mode of transmission of sporotrichosis?
Traumatic introduction into the skin (eg, by a thorn; hence the name "rose gardener"s disease")
What is the mode of transmission of Trichomonas vaginalis?
Sexual (cannot exist outside of humans because it is unable to make cysts)
What is the common name for Ascaris lumbricoides?
What is the treatment of choice for Clonorchis sinensis?
You advise your AIDS patient that prophylaxis against Pneumocystis jiroveci is necessary when his CD4 cell count drops below what?
A patient develops granulomas and visceral larva migrans after ingestion of food contaminated with eggs. What is the diagnosis?
Toxocara canis infection
A women who gardens daily presents with a pustule on her forearm, with lesions tracing upward toward her axilla. What is the likely diagnosis?
Sporotrichosis (pustule with ascending lymphangitis)
Granulomas are formed in infections that are caused by which helminths?
Schistosoma and Toxocara canis
What is the common name for Ancylostoma duodenale and Necator americanus?
What is the treatment of choice for vaginitis caused by Trichomonas vaginalis?
Metronidazole for both the patient and sexual partners
What treatment must be used to treat Plasmodium vivax and Plasmodium ovale when it is dormant in the liver?
A man is bitten by a mosquito and develops elephantiasis 9-12 months later from lymphatic blockage. What is the diagnosis?
Wuchereria bancrofti infection
Which helminths infect humans via the direct penetration of the skin?
Schistosoma, Ancylostoma duodenale (hookworm), and Strongyloides stercoralis
A patient develops muscle inflammation and periorbital edema after eating undercooked pork. What is the diagnosis?
Trichinella spiralis infection
In what region of the world is Babesia infection most common?
The northeastern United States
Treponema is a type of _____, whereas Trypanosoma is a type of _____.
Spirochete (bacteria); protozoan
Infection with Pneumocystis jiroveci is asymptomatic except in what group of hosts?
Immunocompromised patients (e.g., AIDS patients)
Describe the sizes of the four dimorphic fungi in relation to the size of a red blood cell.
Histoplasmosis: smaller; blastomycosis: same; coccidioidomycosis and paracoccidioidomycosis: larger
What are the presentations resulting from ingestion of Taenia solium eggs vs. larvae?
Larvae: intestinal infection; eggs: neurocysticercosis
The three types of typhus are caused by what three bacteria?
Epidemic typhus = Rickettsia prowazekii; Endemic typhus = Rickettsia typhi; scrub typhus = Rickettsia tsutsugamushi
What four patient populations commonly contract oral and esophageal thrush as a result of Candida infection?
Neonates, steroid users, patients with diabetes, and patients with AIDS
A woman is bitten by a deer fly and develops skin swelling and you see worms in the conjunctiva. What is the diagnosis?
Loa Loa infection
What is the treatment of choice for Strongyloides stercoralis?
Ivermectin or -bendazoles
A patient eats undercooked freshwater fish and develops vitamin B12 deficiency and anemia. What is the likely diagnosis?
Diphyllobothrium latum infection
What is the mode of transmission of Plasmodium species?
On what medium is Cryptococcus neoformans cultured?
What do Trichomonas vaginalis and Chlamydia trachomatis have in common?
They both cause sexually transmitted diseases
How is Dracunculus medinensis transmitted?
Through drinking water; Dracunculus is also known as Guinea Worm
A patient presents with a spiking fever, hepatosplenomegaly and pancytopenia. He mentions recent travel in Africa. What is the most likely diagnosis?
What is the mode of transmission of Entamoeba histolytica?
Cysts in water
Infection with Trichinella spiralis causes what two symptoms?
Inflammation of the muscles (larvae encyst in muscle) and periorbital edema
What drug regiment should be used to treat malaria?
Chloroquine; if resistant, mefloquine should be tried
What immunodeficiency involves a specific inability to fight Candida albicans infections?
Chronic mucocutaneous candidiasis
How is Enterobius vermicularis transmitted?
Via food that is contaminated with eggs
Name the helminth that causes hemoptysis.
How are Ancylostoma duodenale and Necator americanus transmitted?
Larvae penetrate the skin of the feet
In addition to pneumonia, what other illnesses can coccidioidomycosis cause?
Meningitis with dissemination to skin and bone
HIV-positive patients should be started on Pneumocystis jiroveci prophylaxis when their CD4+ cell count drops below what level?
Below 200 cells/mL; trimethoprim-sulfamethoxazole is used unless the patient is allergic
What are the characteristic skin lesions of tinea pedis, cruris, corporis, and capitis?
Pruritic lesions with central clearing (a "ring")
Histoplasmosis is most commonly transmitted via what substance?
Bird or bat droppings
What fluke is transmitted via undercooked crab meat?
What type of disease does infection with Paragonimus westermani cause?
Inflammation of the lungs with superimposed bacterial infection (leading to hemoptysis)
Pneumocystis jiroveci infection causes what type of disease?
A diffuse, interstitial pneumonia
What are the symptoms of malaria?
Cyclic fever, headache, anemia, and splenomegaly
What conditions are caused by Echinococcus granulosus?
Cysts in liver and anaphylaxis (if echinococcal antigens are released from cysts)
What is the treatment of choice for Trichinella spiralis?
With -bendazole drugs
A man eats raw crab, which causes inflammation and superimposed bacterial infection of the lung, leading to hemoptysis. What is the diagnosis?
Paragonimus westermani infection
Name two helminths that are transmitted via undercooked pork.
Taenia solium and Trichinella spiralis
There is a spike in pneumonia and meningitides following an earthquake in Southern California. What is the likely culprit?
What causes the discolored patches of tinea versicolor?
Degradation of lipids by Malassezia furfur, producing acids that damage melanocytes
What is the treatment of choice for meningoencephalitis caused by Naegleria?
There is none
The diagnosis of babesiosis can be made by seeing what pathognomonic sign on blood smear?
Lack of red blood cell pigment and Maltese cross
How is Onchocerca volvulus transmitted?
Female black flies
What condition is caused by ingestion of Taenia solium larvae?
Trichomonas vaginalis and Chlamydia trachomatis both cause sexually transmitted diseases. How are they different?
Trichomonas vaginalis is a protozoan, whereas Chlamydia trachomatis is a bacterium
Ascaris lumbricoides causes infection of what organ?
What type of roundworm can be seen crawling in the conjunctiva of an infected individual?
How is the diagnosis of Trichomonas vaginalis made?
Mobile trophozoites on wet mount
What is the treatment of choice for Chagas" disease?
What opportunistic fungal infection is a cause of diaper rash and endocarditis in IV drug users?
What disease is caused by Plasmodium species?
Pets infected with Microsporum can be treated with what?
How is the diagnosis of malaria made?
The yeast that causes paracoccidioidomycosis has what appearance on microscopy?
The "captain"s wheel" appearance
What stain can be used to visualize Cryptococcus neoformans?
Which two species of Plasmodium form dormant hypnozites in the liver leading to relapsing malaria?
Plasmodium vivax and Plasmodium ovale
How is the diagnosis of African sleeping sickness made?
What conditions are caused by ingestion of Taenia solium eggs?
Neurocysticercosis (mass lesions in the brain resembling Swiss cheese) and cysticercosis
How is Wuchereria bancrofti transmitted?
Via the female mosquito
Taenia solium, Diphyllobothrium latum, and Echinococcus granulosus are examples of what type of organisms?
A 40-year-old male from the American heartland presents with dyspnea and granulomatous skin nodules. What diagnosis do you expect?
Which two tests can be used to diagnose cryptococcal infection?
India ink stain and latex agglutination test
How is the diagnosis of visceral leishmaniasis made?
Macrophages containing amastigotes (the form that lack flagella)
s Pneumocystis jiroveci a protozoan or a yeast?
A yeast (it was originally classified as a protozoan)
Under the microscope, what would one see in the pus from a lesion caused by Sporothrix schenckii
Cigar-shaped, budding yeast
Name four clinically important Plasmodium species.
Plasmodium vivax, Plasmodium ovale, Plasmodium malariae, and Plasmodium falciparum
Diethylcarbamazine is used to treat diseases caused by which helminths?
Loa loa, Toxocara canis, and Wuchereria bancrofti
Dermatophytes have what microscopic appearance in KOH prep?
Visible mold hyphae
Name the three types of typhus and their causative bacteria?
Epidemic: Rickettsia prowazekii; endemic: Rickettsia typhi; scrub typhus: Rickettsia tsutsugamushi
Paracoccidioidomycosis is endemic in what area?
How are Mucor and Rhizopus species morphologically different from Aspergillus species?
Mucor and Rhizopus have irregular, nonseptate hyphae with wide-angle branching, while Aspergillus have more uniform septate hyphae with acute-angle branching
Trypanosoma species cause what conditions?
Chagas" disease and African sleeping sickness
Babesiosis shares its mode of transmission with what other disease?
Lyme disease; both are transmitted by the Ixodes tick
What four populations contract oral/esophageal thrush as a result of Candida infection?
Neonates, steroid users, diabetics, and AIDS patients
A patient gets cardiomyopathy, megacolon, and megaesophagus. He remembers getting a bug bite in Brazil. What is the diagnosis and culprit?
Chagas" disease; Trypanosoma cruzi
What is the treatment of choice for Diphyllobothrium latum infection?
What drugs are used to treat Pneumocystis jiroveci pneumonia?
Trimethoprim-sulfamethoxazole, pentamidine, and dapsone
What are the sizes of coccidioidomycosis, paracoccidioidomycosis, histoplasmosis, and blastomycosis relative to a red blood cell?
Histoplasmosis is smaller, Blastomycosis is the same size, and paracoccidiomycosis and coccidioidomycosis are much larger than a RBC
Aspergillus fumigatus is a ____ (mold/yeast/dimorphic) with a _____ branching pattern and ____ hyphae.
Mold (not dimorphic); V-shaped (remember: Acute Angles in Aspergillus); septate
Strongyloides stercoralis causes infection of what organ?
What is the treatment of choice for Toxoplasma?
Sulfadiazine with pyrimethamine
What is the treatment of choice for African sleeping sickness that affects the central nervous system?
Asexual fungal spores are also known as what?
Are Mucor and Rhizopus species molds, yeasts, or dimorphic?
What is the mode of transmission of Diphyllobothrium latum?
Ingestion of larvae in uncooked freshwater fish
What disease does Onchocerca volvulus cause?
A 29-year-old hiker presents to the emergency room with 2 weeks of foul-smelling diarrhea and flatulence. He also reports a greasy, fat-like quality to his stool. What is your diagnosis and how will you treat?
Giardiasis (bloating, flatulence, and foul-smelling, fat-rich diarrhea) and metronidazole
What are the treatments of choice for babesiosis?
Quinine and clindamycin
A hiker comes to the ER with foul-smelling diarrhea, flatulence, and a greasy, fat-like quality to his stool. Diagnosis?
Ancylostoma duodenale and Necator americanus can cause infection of what organ?
How is Loa loa transmitted?
Via the deer, horse and mango flies
When there is excess ketone and glucose, as in diabetic ketoacidosis, where do Mucor and Rhizopus proliferate?
In blood vessel walls
What is the mode of transmission of Pneumocystis jiroveci pneumonia?
Blastomycosis is endemic in what areas of the United States?
The states east of the Mississippi River; it is also common in Central America
What three diseases are caused by Aspergillus fumigatus?
Allergic bronchopulmonary aspergillosis, lung cavity aspergilloma ("fungus ball"), and invasive aspergillosis
Systemic mycoses can mimic which other infectious disease with granuloma formation?
What tapeworm can cause anemia secondary to vitamin B12 deficiency?
What three organs are most commonly affected in Chagas" disease?
Heart, colon and esophagus (cardiomyopathy, megacolon, and megaesophagus)
What is the mode of transmission of Trypanosoma cruzi?
Reduviid bug (the "kissing bug"), with a painless bite
How can infection with Toxocara canis lead to blindness?
Granuloma formation in the retina
Most fungal spores are _____ (sexual/asexual).
What systemic effects does Schistosoma have once it enters the human?
It causes inflammation, fibrosis, and granulomas of the liver and spleen
How is Strongyloides stercoralis transmitted?
Via larvae in soil penetrating the skin
What laboratory test is used to diagnose Cryptosporidium?
Cysts on acid-fast stain of stool
Ivermectin is used to treat diseases caused by which helminths?
Strongyloides stercoralis and Onchocerca volvulus
Which patient populations are especially susceptible to Aspergillus infections?
Those who are immunocompromised and those with chronic granulomatous disease
Vulvovaginitis caused by Candida albicans commonly occurs in what types of patients?
Women with a high vaginal pH, diabetes, and/or a recent history of antibiotic use
What are the symptoms of Strongyloides stercoralis infection?
Vomiting, diarrhea, and anemia
What is the typical microscopic appearance of the agent causing tinea versicolor on KOH prep?
"Spaghetti and meatballs" (Malassezia furfur)
What disease is caused by Trypanosoma gambiense and Trypanosoma rhodesiense?
African sleeping sickness
Toxoplasma is what type of organism?
Protozoan (one of the TORCH infections)
Aspergillus fumigatus infection is especially likely in what population of patients?
Patients with immunocompromise or chronic granulomatous disease
Typhoid fever is caused by what bacteria?
Name the parasite that causes brain cysts and seizures.
Enterobius vermicularis causes infection of what organ?
All systemic mycoses can cause what type of illness?
Pneumonia that can disseminate
A previously healthy man develops pneumonia after inhaling bird droppings on a trip to the Ohio River valley. Diagnosis?
Histoplasmosis; endemic to the Ohio and Mississippi river valleys, it is spread by bird or bat droppings
A patient has river blindness from Onchocerca volvulus. He develops anaphylaxis as a result of exposure to what?
Treponema species cause what conditions?
Syphilis (Treponema pallidum) or yaws (Treponema pertenue)
What is the treatment of choice for Cryptosporidium?
Only supportive care is possible; primary prevention by filtering water supply
What is the treatment of choice for neurocysticercosis?
What is the treatment of choice for Taenia solium intestinal infection?
How can systemic mycoses mimic tuberculosis? How can they be differentiated?
Both have granulomas, but only tuberculosis has person-to-person transmission
Name the helminth that causes perianal pruritus.
What is the treatment of choice for local infection with dimorphic fungi?
Fluconazole or ketoconazole
Histoplasmosis has what appearance under microscopy?
Macrophages filled with yeast (remember: Histo Hides in macrophages)
What two pathologies of the biliary tract are caused by Clonorchis?
Pigmented gallstones, secondary to biliary tract inflammation, and cholangiosarcoma
Trypanosoma cruzi infections most frequently occur on what continent?
What disease is caused by Trypanosoma cruzi?
Which helminthic infections are treated with mebendazole or pyrantel pamoate?
Hookworm, giant roundworm, and pinworm
In immunocompetent patients, what does Cryptosporidium cause?
Mild, watery diarrhea
How is Candida albicans diagnosed microscopically?
Yeast with pseudohyphae in culture, germ tubes at body temperature
A patient develops anal pruritus after eating contaminated food. You employ the "Scotch tape" test to confirm what diagnosis?
Name the helminth that causes hematuria and bladder cancer.
Tinea versicolor is caused by what organism?
What do histoplasmosis, paracoccidioidomycosis, and blastomycosis have in common?
They are all systemic mycoses caused by dimorphic fungi
Where can the heavily encapsulated yeast of Cryptococcus neoformans be found in nature?
Soil and pigeon droppings
You suspect that a patient has a cryptococcal infection. What tests could you order to diagnose?
India ink stain and latex agglutination test
How is Trichinella spiralis transmitted?
Via undercooked meat (usually pork)
Parasitized red blood cells with Plasmodium falciparum infection tend to occlude capillaries in what three organs?
Kidney, lungs, and brain (cerebral malaria)
What is the mode of transmission of Giardia lamblia?
Cysts in water
Tinea pedis, tinea cruris, tinea corporis, and tinea capitis are caused by what organisms?
Dermatophytes (ie, Microsporum, Trichophyton, Epidermophyton)
What animals are commonly reservoirs for Microsporum?
An HIV-positive patient presents with brain abscesses that present as ring-enhancing lesions on CT/MRI. Diagnosis?
Toxoplasma gondii infection
A malaria patient has severe daily fever cycles and red blood cells are occluding the brain, kidney, and lungs. What protozoa is causing this?
What is the mode of transmission for African sleeping sickness?
Tsetse fly, with a painful bite
What laboratory test is used to diagnose giardiasis?
Trophozoites or cysts in stool
Describe the infection that is caused by Trichomonas vaginalis.
Vaginitis with foul-smelling greenish discharge that burns and itches
Infection by Enterobius vermicularis is marked by what symptom?
What is the treatment of choice for systemic infection with dimorphic fungi?
Describe the pathogenesis of the disease caused by Wuchereria bancrofti?
Blockage of lymphatic vessels by the worm leads to elephantiasis after 9-12 months
Describe the disease caused by Babesia (babesiosis).
Fever and hemolytic anemia
How is Schistosoma transmitted to humans?
Through cercariae penetration of the skin in freshwater
Cryptococcus neoformans causes what two diseases?
Cryptococcosis and cryptococcal meningitis
Coccidioidomycosis is endemic in what area of the United States?
The southwestern United States, including California
What is the treatment of choice for Toxocara canis?
A patient in an area in which Lyme disease is prevalent presents with malaria-like symptoms of fever and anemia. A blood smear shows red blood cells with a four-sided figure. What organism is most likely involved?
An immunocompromised patient presents with "soap bubble" lesions in the brain. What fungal infection is likely?
How do Cryptococcus species appear on microscopy?
Yeasts with wide capsular halos that exhibit narrow-based budding
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