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215 terms

Micro Exam 3

STUDY
PLAY
How does humoral immunity work?
Uses antibodies (produced by B cells) to help kill invading microbes
What two things must happen in order to activate B cells?
-B cell must bind free antigen
-APC (macrophage) activates helper T cell
Where do B cells get antigens?
-Free antigens circulate in the blood
-When B cells finds matching antigen, it will bind and ingest (endocytosis) antibody-antigen, complex antigen is saved and presented in MHCll
-B cell becomes anigen-presenting cell
What are antigens?
-Generally large molecules found on the surface of cells
-Trigger an immune response in our bodies
-Include LPS and viral capsid proteins
-Are bound to by antibodies
How does humoral immunity help to eliminate pathogens from our bodies?
-By producing antibodies
How do antigen-presenting macrophages activate B cells?
Indirectly through helper T cells which recognize antigens bound to MHC
What do T cells have to perform the same functions of antibodies?
Antigen receptors
How can T cells identify antigens?
-T cell receptors bind to antigens presented in the MHC l or MHC ll
What happens when a T cell binds to an antigen presenting cell?
It releases cytokines
What do cytokines do?
-Increase leukocyte activity
-Activate B cells with bound antigen
-Stimulate T cell division
What is produced by clonal selection?
Effector cells and memory cells
Why is humoral immunity not an effective way to combat viral infections?
-Extracellular pathogens or toxins can be coated with antibodies, making them easier to destroy
-Viruses are intracellular parasites, and spend the majority of their time inside a cell
-Viral antigens are not seen by immune system because they are hidden within the cell
What are the two branches of acquired immune response?
-Humoral (antibody mediated) immuntiy
-Cell mediated immunity
Key players in Humoral Immunity
-B cells
-Helper T cells
-APC macrophage
Key players in Cell mediated immunity
-APC macrophage
-Helper T cells
-Cytotoxic T cells
How are viral infections detected by the immune system?
-Cells infected with a virus will present the viral antigen in a MHC-l complex
-Like a secret flag to the immune system
Which cell recognize the MHC-1 complex on viral cells?
Cytotoxic T cells (kill human cells infected by virus or with cancer)
What happens when cytotoxic T cellsare activated?
They secrete a protein called perforin
What does perforin do?
creates holes in cell membrane, killing the cell
What happens when a viral cell is lysed after cytotoxic T cells kill it
-Its viral particles are released into the blood where they are detected by the Humoral immunity, wider immune response
What is required to kill a virus?
Both Humoral and cell mediated immunity
Which branch of the acquired immune system acts against cancer cells?
Cell mediated immunity
How does our immune system recognize cancer cells?
-Cancer cells display unusual proteins that are displayed in MHC 1 complex
-Cancer cells can over-express various cell-surface molecules
-Cancer cells can also cause a down-regulation in MHC 1 so it is no longer present, missing display case all together
How are cancer cells destroyed?
-"Unusual" proteins recognized as antigens and destroyed by Cytotoxic T cells
-Natural Killer Cells
What is a natural Killer cell and what does it do?
-Cells that recognize abnormal cells
-Works independently, doesn't need antigen presentation or cytokine activation to function
-Destroys cells in the same way as Cytotoxic T cells
HIV infects helper T cells, why do people with HIV have weaker immune systems?
-Their B cells and cytotoxic T cells are not activated and can not destroy invading pathogens
What would cancer rates in people with HIV look like compared to healthy people?
They would be higher
Cell Mediated Immunty...
(A) Is responsible for destroying extracellular pathogens
(B) Is responsible for destroying cancerous cells
(C) Includes the inflammatory response
(D) Involves B and T cells
(E) Is triggered by antigens presented in MHC-ll
(B) Is responsible for destroying cancerous cells
When are memory cells created?
During primary immune response
What are vaccines?
A mixture of dead or much less virulent (pathogenic) bacteria or viruses
How do vaccines work?
-They mimic primary immune response to generate memory cells that will be quickly activated in a real encounter with a pathogen
What were the characteristics of early vaccines?
-they were inactivated whole agent vaccines (dead bacteria and viruses)
-Contained surface antigens but were non viable and non infectious
-Not effective against some types of pathogens
What type of pathogen are inactivated (killed) vaccines NOT effective against?
(A) Gram neg bacteria
(B) Gram pos bacteria
(C) Intracellular pathogens (viruses)
(D) Eukaryotic Worms
(E) None of the above
(C) intracellular pathogens (viruses)
- intracelluar pathogens go inside your cells, but if we try to use a dead pathogen as a vaccine it cant make its way into the cell to mimic viral infection
Problems with inactivated (killed) whole agent vaccines
1. only activates humoral immune response (pathogens dont enter cells so not effective against intracellular pathogens)
2. Pathogen does not replicate so fixed amount of antigen (more antigen=more memory cells= longer immunity)
3. Not effective against exotoxins
4. Surface mollecules are only weakly antigenic
Whay are whole agent vaccines not effective against exotoxins?
because when dead pathogens are injected into your body, they cant create exotoxins, so your body would still be unfamiliar with them.
What are the types of vaccines?
-Inactivated (killed) whole-agent vaccines
-Toxoids
-Attenuated (weakened) whole agent vaccines
-Subunit vaccines
What are inactivated whole-agent vaccines and what are some examples?
-Killed completely
-Used for pathogens where live vaccine is too hazardous
-Rabies, Influenza
What is a toxoid vaccine?
-Inactivated toxins
-Tetanus and diptheria
What are attenuated whole agent vaccines?
-weakened but not killed
-Closer mimic to actual infection, confers lifelong immunity
-MMR
What are subunit vaccines?
-use antigens that elicit the strongest immune response
-Hepatitis B (viral protein coat)
Boosters are additional doses of vaccines given after the original dose to help increase immunity against that antigen. What type of vaccines are boosters most commonly required for?
(A) inactivated (killed) whole agent vaccines
(B) Toxoids
(C) Attenuated (weakened) whole agent
(D) Subunit vaccines
(E) All of the above
(A) Inactivated (Killed) whole agent vaccines
-because inactivated or killed vaccines only have a certain number of antigens, you need another dose so that your body can maintain its immunity
What are the types of acquired immunity?
Active imunity and Passive immunity
What is Active Immunity?
-develops when a person is exposed to antigens, becomes ill, and then recovers
-Duration of immunity varies-lifelong for measles, years for intestinal illnesses
-Can be natural (you get sick) or artificial (vaccine)
What is Passive immunity?
-The transfer of antibodies gives temporary immunity (weeks or months)
-Can be natural (mother to infant) or artificial (anti-venom)
What causes the flu?
-The influenza virus (enveloped RNA virus)
-Influenza virus has HA and NA proteins on its viral cell wall
What are the antigens for the influenza virus?
(A) Nucleic acids (RNA)
(B) Capsid proteins
(C) Envelope proteins (NA and HA)
(D) All of the above
(C) Envelope proteins (NA and HA)
How does the influenza virus avoid the effects of vaccines?
-Errors are mad in the replication of influenza RNA (common in RNA viruses because they lack proofreading enzyme)
-The resulting mutations lead to the formation of different surface proteins, which our immune system will not recognize (antigenetic drift)
How are the influenza vaccines different every year?
-each flu vaccine contains 3 different strains of the influenza virus
-chosen based on the strains of influenza that are predicted to be most common in the coming year
What are the types of flu vaccines?
-Flu shot (killed virus)
-Nasal spray such as FluMist (live attenuated virus)
Side effects of the inactivated (killed) influenza vaccine include soreness, redness, or swelling where the shot was given. What branch of our immune system is primarily responsible for these side effects?
(A) innate immune response
(B) Humoral (antibody-mediated) immune response
(C) Cell-mediated immune response
(D) A, B, and C
(E) Impossible to say
(A) Innate immune response
-inflammatory response is part of innate immunity
Why does it take up to to weeks for protection to develop after receiving an inactivated (killed) flu vaccine?
(A) The virus must multiply to high enough levels to trigger an immune response
(B) It takes time for naiive B cells to become activated and produce antibodies
(C) T cells must migrate to the site of infection
(D) Cytokine levels must reach a minimum concentration to activate B cells
(E) It takes time for memory B cells to be formed
(B) It takes time for naiive B cells to become activated and produce antibodies
Streptococci....
-Shape
-Morphological arrangement
-Gram Stain
-Capsule
-Diagnostic Test
-Hardiness
-Coccus, non motile
-Chains
-Gram Positive +
-Capsule In some species
- Catalase -
-Delecate
Staphlococcus....
-Shape
-Morphological arrangement
-Gram Stain
-Capsule
-Diagnostic test
-Hardiness
-Coccus, non motile
-Irregular clusters
-Gram positive+
-In some species
-Catalase + (growth on MSA)
-Tolerate high salt, resistant to drying and many chemical agents
Why is Mannitol Salt Agar (MSA) a selective growth media only allowing Staphylococcus (but not streptococcus) to grow?
(A) Streptococcus can not use mannitol(sugar)
(B) Streptococcus can not tolerate the high salt
(C) Only bacteria that make hemolysins can grow on MSA
(D) Catalase is required to grow on MSA
(E) All of the above
(B) Streptococcus can not tolerate the high salt
What causes hemolysis of red blood cells?
exotoxins called hemolysins
How do hemolysins work?
-They wedge into membranes to make large holes (pores), causing cell lysis
-Complete hemolysin has 7 subunits
Hemolysis.....
Alpha=
Beta=
Gama=
Alpha=Partial hemolysis
Beta= Complete hemolysis
Gama= no hemolysis
What does it mean when we say RBC hemolysis is an in vitro effect
Happens in the lab
What do the hemolysins target in vivo (in the body)?
Many cells, heart, skeletal muscle fibers, leukocytes, and RBC
-RBC produce the most obvious results
Why is Staphylococcus aureus the most medically important Stapphylococcus?
-They are common in nosocomial infections
-They have extreme drug resistance (MRSA & VRSA)
-Ability to colonize or invade wide number of sites
-Have the ability to survive outside the host
What are some Staphylococcus aureus diagnostic tests?
-Coagulase (enzyme that causes blood to coagulate and form clots) produced by S. aureus
-Mannitol Salt Agar
How is staph differentiated in an MSA experiment?
-both Staphylococcus species will grow, but only S. aureus will ferment mannitol and turn media yellow
What makes S. aureus so prevalent in nosocomal infections?
- It is readily transmitted by inanimate objects
-ex: bed dressings, tools, catheters, contaminated needles
-S. aureus is part of our transient microflora, 20-50% of people
How is coagulase beneficial to S. aureus being an effective pathogen?
-Causes blood clots to form around S. aureus effectively helping it hide from the immune system
How does Staphylokinase contribute to the virulence factor of S. aureus?
-Dissolves clot so that S. aureus can sneak away
How do digestive enzymes contribute to the virulence factor of S. aureus?
-Dissolve connective tissue t promote spread of infection
How do hemolysins contribute to the virulence factorof S. aureus?
lyse a variety of cells, including RBC, WBC, heart, and muscle cells
Why is coagulase considered a virulence factor?
(A) It lyses blood cells providing food for S. aureus
(B) It forms blood clots making it harder for immune cells to phagocytize S. aureus
(C) It forms blood clots which hides S. aureus antigens from the immune system
(D) B and C
(E)All of the Above
(D) B and C
-Coagulase forms blood clots making it harder for immune cells to phagocytize S. aureus
-Coagulase forms blood clots which hides S. aureus antigens from the immune system
Why are S. aureus nosocomal infections so much worse than most infections?
-Hospital strains of S. aureus are generally antibiotic-resistant
-cause staph infections after surgery
What are cutaneous infections?
-Localized infections
-infection of hair follicles leads to skin abscesses. Usually resolved without any further problems
Systemic infections have variety
-often result from cutaneous infection with access to bloodstream
-Can infect most organs (aided by virulence factors allowing passage through bloodstream)
What are the sites of infection for systemic infections?
-Meninges
-Blood
-Kidney
-Liver
-Heart Lining
-Lower respiratory tract
What is scalded skin syndrome?
-Systemic S. aureus infection; symptoms caused by toxin that reaches the skin
-Causes skin to peel
-Common in newborns (contracted through umbilical stump)
What is Toxic shock syndrome?
-Vaginal S. aureus that can proliferate in tampons and produce pyrogenic toxin
What are pyrogenic toxins?
-Superantigens
-Bind directly to T cell antigen receptors and MHC-ll, leading to overstimulation of acquired of immune system
-Leads to non-specific activation of T cells, releasing large amounts of cytokines
How is streptococcus differentiated?
-By patterns in blood hemolysis
You are trying to identify a bacterial sample isolated from the respiratory tract of a patient. The bacteria is a gram + cocci, and does not produce catalase. What two additional diagnostic tests do you need to run to determine whether the bacteria is S. pneumonia or S. pyogenes?
(A) Coagulas and hemolysis
(B) Coagulase and antibiotic sensitivity
(C) Hemolysis and antibiotic sensitivity
(D) MSA and hemolysis
(E)MSA and antibiotic sensitivity
(C) Hemolysis and antibiotic sensitivity
What is the main reservoir for S. pyogenes?
-Humans
-10% of the human population are transient carriers of virulent strains of S. pyogenes in their nasopharynx
What is S. pyogenes sensitive to?
-Penacillins
-Cephalosporins
What 3 major diseases are caused by S. pyogenes?
-Streptococcal pharyngitis (strep throat)
-Impetigo
-Scarlet fever
What helps Streptococcus pyogenes attach to cells?
-Its M protein (part of the fimbria)
What helps S. pyogenes resist phagocytosis?
-Its capsule made of hyaluronic acid
-M protein coats the bacteria with self proteins which resists phagocytosis, doesn't allow MAC to enter membrane
What does the Protein G of S. pyogenes do?
-binds to antibodies and confuses immune system
What are the secreted virulence factors of S. pyogenes?
-Hemolysins (streptolysins) lyse WBC, muscle, heart fibers
-Toxins (toxic shock syndrome)
-Enzymes (ex. streptokinase) that degrade tissues or promote invasion
Which of the following statements about the M protein is false?
(A) It is part of hemolysin, and lyses various cells in the body
(B) It is part of fimbriae, allowing attachment to cells in the body
(C) It coats the bacteria with "self" proteins, preventing phagocytosis
(D) It prevents MAC from getting into the cell membrane
(E)All of the above statements are true about the M protein
(A) Is not part of hemolysin and does not lyse various cells in the body
-also is the only antigen on S. pyogenes that elicits and acquired immune response
What does S. pyogenes rely on to infect?
-sufficient number of bacteria
-an opportune portal of entry
Where are S. pyogenes infections most common?
-in adolescents (direct contact, poor hygiene)
-Immunocompromised individuals
How to reduce infection of S. pyogenes?
-activities that reduce the the microbial load (hand washing) will reduce incidence and transmission
Why are there no vaccinations for S. pyogenes?
-Because antibodies to some variants of the M protein bind to our heart valves (results in autoimmunity: Rheumatic fever)
-Antibodies produced to attack the M protein react (bind) to heart, joints, skin and brain cells
S. pyogenes localized diseases: Cutaneous- what is IMPETIGO?
- Yellow, itchy crusts that are puss filled, highly transmittable
-Portal of entry is broken skin (abrasion)
S. pyogenes localized diseases: Pharynx- What is Strep Throat?
-Infections in mucous membranes of tonsils or pharynx
-Causes redness, edema, difficulty swallowing.
-Often accompanied by fever
-Pus-filled tonsils
S. pyogenes: Systemic Diseases
-Causes most invasive or virulent strains
-Can be fatal (septicemia)
What is Septicemia?
pathogens proliferating in the blood (blood infection); usually accompanied by a fever
What is Scarlet Fever
-Systemic infection
-10% of strep throat cases result in scarlet fever
-Caused by strains of S. pyogenes infected by a dormant (lysogenic) virus
-Viral genes cause secretion of super antigen into blood stream
-Symptoms include spotty inflammation (strawberry tongue), and persistent fever
-Historically fatal in 10-20% of cases, but now successfully treated with antibiotics
What is childbirth fever?
-Mothers die shortly after child birth due to systemic infection w/ S. pyogenes
-Transferred by unwashed hands of doctors and midwives
-Easy access to uterus and blood
-Handwashing and sanitization technique reduced mortality dramatically
S. pneumoniae
-Responsible for majority of bacterial pneumonia cases
-Carried by 33% of people in the nasopharynx
-can not live outside of the host for a long time
What is the morphology of S. pneumoniae
-Diplococcus
Who gets infected by S. pneumoniae?
-Weakened immune
-Those constantly exposed to high doses
What is the main virulence factor for S. pneumoniae?
-capsule that evades phagocytosis
Why can 30% of the population carry S. pneumoniae in their nasopharynx but not have pneumonia?
(A) They carry less pathogenic strains of S. pneumoniae
(B) Their immune system is functioning normally and keeps S. pneumonaie from invading the body
(C) They carry low abundances of S. pneumonaie
(D) They carry strains of S. pneumoniae that lack a capsule
(E) All of the above
(B) Their immune system is functioning normally and keeps S. pneumoniae from invading the body
S. pneumoniae lower respiratory tract infections
-Immune system prevent our own microflora from entering the lower respiratory tract
-Immunocompromised could contract large amounts of S. pneumonaie and develop pneumonia
What is lobular pneumoniae?
-S. pneumoniae that colonizes and infects the alveoli
What is bronchial pneumoniae?
-S. pneumoniae that colonizes in the bronchioles
S. pneumoniae Upper respiratory tract infections
-Middle ear infections (esp in children) and other upper respiratory tract infections
S. pneumoniae Secondary infections
-Migrates from site of primary infection to the blood or meninges
-Most common cause of bacterial meningitis in adults (can be fatal)
Why do mothers in third trimester undergo group B strep testing?
-If it is positive, the mother is given antibiotics to prevent transmission during delivery
Group B Streptococcus
-Newborns (vaginal birth) at risk of infectionby group B streptococcus, which resides in vaginal tract
-Causes fatal pneumonia, septicemia, and meningitis
-Leads to 5000 deaths a year
What us the upper respiratoy system?
-Bronchii up
What is the lower respiratory system?
-Bronchioles and alveoli
How is our respiratory system defended against invaiders?
-Air eddies in nasal cavity slow movement of particles into respiratory tract
-Competitive inhibition from resident microflora
-Cilia in nasal cavity, pharynx, larynx, trachea, bronchi (mucociliary escalator)
-Microbes in alveoli are engulfed by resident (alveolar macrophages)
What is the result of our bodys protection against invaders in the respiratory tract?
-Oral cavity and nasopharynx are colonized by harmless microflora (aid in preventing pathogen colonization)
-Lower respiratory system is generally sterile (no resident microflora)
What are the sites of infectionin the upper respiratory system?
-Pharynx
-Larynx
-Sinus infections
-Ear infections
-Bronchitis
Infection of the pharynx (pharyngitis)
-Sore throat that may be accompanied by a fever
infection of the larynx (laryngitis)
-Sore throat and often loss of voice
Sinus infections
-usually bacterial infection in the hollow sinuses of the skull
-blocks drainage and causes mucous accumulation
-swelling results in pressure induced pain
Ear infections
-Caused by Streptococcus, S. aureus, and P. aeruginosa
-Usually middle ear infections caused by migrating microbes from the pharynx up the Eustachian tube
-More common in young children because eustachian tubes are short and more horizontal
-Inflammation and pus development behind tympanic membrane
-Deafening, painful to swallow
Bronchitis
-infected and inflamed bronchi
Which statement(s) about the microbes that cause sinus infections are true?
(A) The pain associated with sinus infections results from inflammation
(B) Some bacteria that cause sinus infections can have antibiotic resistance, making treatment challenging
(C) Sinus infections are caused by opportunistic pathogens such as S. pneumoniae or S. aureus
(D) Most bacteria that cause sinus infections are part of our transient microflora
(E) All of the above
(E) All of the above
Studies have shown that babies who are breastfed have fewer ear infections. Why does this occur?
(A) Breastfed babies are not exposed to as many bacteria
(B) Breastfed babies have been exposed to more bacteria, and therefore have more immunity
(C) Breastfed babies get antibodies from the breast milk
(D) Breastfed babies get leukocytes from the breast milk
(E) Breastfed babies have longer Eustachian tubes
(C) Breastfed babies get antibodies from the breast milk
Lower respiratory tract infections
-Less common but more serious
-pathogen must overcome host defenses (mucociliary escalator, alveolar macrophages)
-Infections are more common in immunocompromised and chronic smokers (smoke paralyzes ciliary escalator)
Which of the following statements is FALSE?
(A) Lower respiratory tract infections are more common than upper respiratory tract infections because once bacteria reach the alveoli there are few defenses
(B) Lower respiratory tract infections are more severe than upper respiratory tract infections because the lower respiratory tract is generally sterile
(C) Lower respiratory tract infections are more common in chronic smokers
(A) Lower respiratory tract infections are more common than upper respiratory tract infections because once bacteria reach the alveoli there are few defenses
-Lower respiratory tract infections are not more common
Pneumonia
-Leading cause from infectious disease in the US (common in AIDS patients and elderly)
-Mortality ranges from 30% (no treatment) to 5% (prompt treatment)
-Produces bloody sputum
-Can migrate from site of infection to blood or meninges
What are the types of pneumonia viruses?
-Klebsiella pneumonia
-Pseudomonas aeruginosa
-Mycoplasma pneumoniae
Klebsiella pneumonia
-More destructive form of pneumonia, higher mortality rate
-Causes extensive destruction of lung tissue
Pseudomonas aeruginosa
-opportunistic pathogen that causes pneumonia in immunocompromised patients
-Produces attachment pili, commonly found on non-living surfaces
Mycoplasma Pneumonia
-Milder form of pneumonia
-Mycoplasma has no cell walls and lacks much cellular macinery
-relies on host, cannot live outside humans
Legionnaire's Disease
-Discovery
-Bacterial cause
-where it replicates
-Symptoms
-death
-how its transmitted
-Discovered in 1976 after an Americans Legion convention resulted in several deaths
-Caused by Legionella pneumophila
-Replicate inside alveolar macrophages and eventually rupture cell
-Symptoms: Impaired respiration, fevers, diarrhea, vomiting, and pain in abdomen and chest
-death results from systemic shock and kidney failure (5-30%)
-Transmitted by water (can withstand chlorine)
What branch of the immune system will be activated if you are infected with Legionella pneumophila?
(A) Passive immunity
(B) Humoral immunity
(C) Cell-mediated immune system
(D) all of the above
(C) cell mediated immunity
What bacteria causes Tuberculosis (TB)?
-Caused by Mycobacterium tuberculosis
What is the course of infection for a primary infection of TB?
-10-100 cells for a minimum dose
-Bacteria are inhaled and phagocytized by alveolar macrophages
-Bacteria reproduce inside the macrophages (slowly) until they eventually lyse the cell
-3 to 4 weeks after infection, tubercules form (accumulation of infected macrophages and other immune cells)
-In 95% of the cases the immune system surpresses bacteria at the primary infection stage
What are the two things that can happen after the primary infection of TB?
-Become nonsymptomatic latent TB (not infectious)
-Progress to secondary infection (active TB infection)
What happens during the secondary infection of TB?
1) Bacteria escape tubercles and infect new areas
2) Growth of tubercles leads to necrosis and rupture of lung tissue (allows M. tuberculosis to spread to other parts of the lung)
-Symptoms: violent cough, malaise, extreme fatigue, blood in sputum, wasting away (in advanced state)
3)Disease waxes and wanes in severity (bouts of illness followed by bouts of recovery)
-fatality rate 60% within 5-10 years if left untreted
How is TB transmitted?
Transmitted by respiratory droplets from infected individuals (which are resistant to drying)
-transmission is high in crowded, poortly ventalated households
What is the generation time like for Myobacterium (TB)
-Very long, 15-20 hours, grows very slowly
-has long incubation time, 6-8 weeks
-Hard to culture and identify pathogen via diagnostic tests
What makes Myobacterium (TB) so resistant to drying?
-Cell wall contains large amounts of lipids, creating a waxy coat
-Viable in dried sputum for up to 6 months
Why was TB originally called the white plague?
-Name created by Robert Koch
- When TB first came about it affected the poor in europe in the 1800's and had a mortality rate of almost 25% before antibiotics
What did Koch do after he found that TB was transmitted in droplets from the mouth?
-He led efforts to improve sanitation and encourage people to cover their cough
What was the first cure for TB?
Streptomyocin (1946)
Why did TB make a resurgence in the 1980's?
-Latent TB more likely to become active TB in immunocompromised
-The emergence of drug resistant strains of TB
-Increasing world population and travel
What is the current treatment for TB?
-6 months of an antibiotic drug cocktail
What are the current effects of TB?
Causes 3 million deaths a year (mostly in Asia and Africa)
-incidence is on the rise, especially in AIDS patients with antibiotic resistant strains
How much of the worlds population is infected with TB?
-1/3 of the worlds population
(lowest rates are in the US)
What percent of TB cases will progress to active TB?
What percent of active TB infections are fatal without treatment?
- 10% progress to active TB
- 50% are fatal without treatment
Where are infection rates of TB the highest in the US? Why?
-Highest TB rates are in the US
-Because of large immigrant population and rigorous testing program
What is a Manoux test?
-Test to diagnose TB
-Purified TB protein injected just under the skin
-Measures resp. from cell-mediated immune system
-Memory cells will react to proteins and produce hardening around the injection site in 48 hrs
How does someone confirm TB after a positive Manoux test?
-Chest X-ray
-DNA testing
Why has the prevalence of Tuberculosis been on the rise since the 1980s?
(A) Increase in immunocompromised individuals.
(B) The development of antibiotic resistant strains
(C) Increasing world population and travel
(D) AIDS pandemic
(E) all of the above
(E) all of the bove
How is infection prevented in the urogenital tract?
- regular flushing w/acidic urine, valves in kidney prevent backflow
What role does lactobacilli play in the vagina?
-It creates a low pH, which inhibits most other microbes
What is the most common bladder infection?
-Cystis
What is Cystis?
-inflammation of the bladder
-painful urination and pus in urine
-Caused by E. coli and S. saprophyticus
How much more likely are women to get cystis? Why?
-8 times more common in females
-because of short urethra and closer proximity to anal opening
What percentage of Cystis develop into inflammation of kidney and bacteremia?
-25% develop into bacteremia (bacteria in the blood)
Cranberry juice is commonly suggested to help prevent bladder infections. Scientists have now shown that it affects the fimbriae of E. coli. Why would this reduce bladder infections?
(A) Fimbriae are necessary for attachment to epithelial cells, which is a necessary first step for infection
(B) E. coli need fimbriae to overcome resident microflora
(C) Fimbriae are required for E. coli to produce toxins
(D) Fimbriae allow E. coli to evade the immune system
(E) all of the above
(A) Fimbriae are necessary for attachment to epithelial cells, which is a necessary first step for infection
What are the causes of STD's?
-Bacteria that are transferred mainly through sexual intercourse
-Does not mean that these pathogens can only be transmitted through intercourse
-Also does not mean that these pathogens only infect the urogenital system
What are common features of the STD's we discuss?
-All are delicate and need to be transferred directly from mucous membrane to mucous membrane
-All use humans as reservoirs
Which of the following statements about STDs and their modes of infection and transmission are TRUE?
(A) They are delicate bacteria that can't live long outside the host
(B) They can infect many regions of the body, including the reproductive system
(C) They use humans as reservoirs
(D) They are transmitted primarily by sexual intercourse
(E) All of the above are true statements
(E) All of the above are true statements
What is the causative agent of Syphilis?
Treponema pallidum
Syphilis...
-morphology
-reservoir
-hardiness
- Gram- spirochete (difficult to stain)
-Only found in humans, primarily transmitted by sexual encounters
-Very delicate, killed quickly outside of the host
What allows Syphilis to infect the mucous membranes of the body?
-Adhesins, they attach to epithelial cells and corkscrew shape helps penetrate tissue
What happens after Syphilis infects mucous membranes?
-It enters the circulatory system and invades deeper tissues
What are the virulence factors of Syphilis?
-Adhesins allow for the ability to escape opsonization and neutralization
What does syphilis do to the body?
-Causes inflammation around the blood vessels and heavy replication damaging tissues
What can syphilis do in pregnant women?
-Can cross placenta in pregnant women and create stillborns, miscarriages, or congenital syphilis
What happens during the incubation phase of Syphilis? And how long is it?
-bacteria will adhere and replicate, usually at or near site of infection
-Lasts for 3 weeks
What happens in the primary stage of syphilis? and how long does it last?
-it is the development of of chancre sores due to local inflammation at site of infection (internal or external genitalia)
-Lasts 1-2 months)
-When bacteria enter blood stream
What happens during the first latency period? and how does it last?
-Chancres heal
-Bacteria is multiplying in bloodstream and entering target tissues
-Last 2 weeks-2 months
What happens during the secondary stage of syphilis? and how long can it last?
-Systemic
-Variable symptoms (fever, rash, painful lesions on cervix and oral cavity)
-Highly infectious both sexually and orally
-Can reoccur for months or years
What happens during the second latency period of Syphilis? and how long can it last?
-all symptoms disappear
-Difficult to detect
-Bacteria have moved into favorable tissues and are laying low
-Less contagous
-Variable, can be for life
What happens during the tertiary stage of syphilis? and how long can it last?
-infections in particular organs (heart, nerves)
-Soft and swollen tumors in various organs
-Organ damage can lead to death or mental impairment
-can last for life
What stage of syphilis is characterized by having spirochetes spreading from localized infections to all organs to all organs of the body (although there are no symptoms)?
(A) Primary
(B) 1st latency
(C) Secondary
(D) 2nd latency
(E) Tertiary
(B) 1st latency
How can you treat syphilis?
-Penicillin G is the best antibiotic even though its Gram -
What is the causative agent of Gonorrhea?
-Neisseria gonorrhoeae
-Gram - diplococcus
What does Gonorrhea mean?
-Means flow of seed, due to its primary symptom, puss secreting from the penis
Gonorrhea...
-Reservoir
-Hardiness
-Humans are the only reservoir
-They are extremely delicate and can not survive outside host for long, primarily transmitted sexually
Virulence factors of gonorrhea?
-Some strains are resistant to penicillin or tetracycline
-Capsule
-Attachment pili (fimbria)
-Invade mucous membrane cells and neutrophils and replicate inside them
-Mild endotoxin can cause tissue damage
How does Gonorrhea invade the body?
-attaches to epithelial surface by fimbria, and then invades connective tissue
What happens in males affected with gonorrhea?
-infects lower urethra, can migrate up to vas deferens
-Produces characteristic puss that is painful (burns)
-10-20% of males are asymptomatic
What happens in females affected with gonorrhea?
-Infects vaginal wall, cervix, and urethra
-Can migrate to fallopian tubes (scarring leads to sterility)
-50-70% of females are asymptomatic
-Can transfer to newborn babies and cause conjunctivitis and blindness-silver nitrate beings
Other than the genital, what else can gonorrhea affect?
-Pharynx (oral sex)
-Rectal region (anal sex)
What is the second most common STD in the US?
Gonorrhea
Why is there no effective acquired immunity for gonorrea?
-Because gonorrhea produces a protein that binds T cells and prevents activation
Although gonorrhea and syphilis have similar methods of transmission and process of infection, the prevalence of syphilis has remained fairly stable in the US whereas gonorrhea has continued to increase. Which of the following statements best explains this pattern?
(A) Gonorrhea is a harder pathogen which can live outside the host
(B) Syphilis is easily diagnosed, making treatment easier
(C) Infections with syphilis result in immunity (ie formation of memory sales) whereas infections with gonorrhea do not
(D) Syphilis only causes localized infections
(E) Gonorrhea is transmitted by vectors in addition to through sexual intercourse
(C) Infections with syphilis result in immunity (ie formation of memory sales) whereas infections with gonorrhea do not
What is the most common bacterial STD?
Chlamydia, like milder form of gonorrhea
How much of the population is infected with chlamydia at any given time?
-0.5-1% of the population
-10% of sexually active individuals
Chlamydia...
-Causative agent
-gram stain
-reservoir
-Chlamydia trachomatis
-Gram negative, extremely small, spherical, obligate pathogen
-reservoir is humans
How many people with chlamydia are asymptomatic?
-50% of males
-70% of females
How does chlamydia function in the body?
-replicates inside cells and bud off like a virus
How is chlamydia treated?
-drugs that target external cell walls are innefective
-Drugs that target metabolic processes (such as translation) are used
What is pelvic inflammatory disease (PID)?
-general term for any bacterial infection of the female pelvic organs (uterus, cervix, uterine tubes, ovaries)
-is a polymicrobial infection (caused by >1 microorganism)
-Most commonly caused by N. gonorrhoeae and C. trachomatis
-Can lead to sterility
What is a systemic disease?
-relies on lymphatic system and/or cardiovascular system to transport the pathogen or toxins that cause disease
-results in widespread distribution of pathogen or toxins in the body
What is septicemia?
-pathogens proliferating in the blood (blood infection) usually accompanied by fever
-can lead to sepsis
What is sepsis?
-whole body inflammation as a result of pathogen or toxins
-Can lead to Septic shock (severe sepsis) or Toxic shock (hypotension as a result of toxins)
What is gram- sepsis?
shock resulting from the release of LPS from gram- bacteria
How can systemic diseases lead to fatalities?
-Septicemia leads to septic shock
-multiple organ failure, bacteria colonize or invade multiple organs via blood stream
-Lethal toxins can circulate through blood and lead to toxic shock or kill certain tissues or cells
Several weeks ago, we discussed toxic shock syndrome caused by Staphylococcus aureus. How does this disease result in mortality?
(A) It causes septicemia which leads to septic shock
(B) It causes multiple organ failure
(C) Lethal toxins produced by S. aureus result in hypotension
(D) An allergic response to gram + bacteria in the tissues
(E) All of the above
(C) Infections with syphilis result in immunity (ie formation of memory sales) whereas infections with gonorrhea do not
Several weeks ago, we discussed toxic shock syndrome caused by Staphylococcus aureus. How does this disease result in mortality?
(A) It causes septicemia which leads to septic shock
(B) It causes multiple organ failure
(C) Lethal toxins produced by S. aureus result in hypotension
(D) an allergic response to Gram + bacteria in the tissues
(E) All of the above
(C) Lethal toxins produced by S. aureus result in hypotension
What are common features of many systemic pathogens?
-Humans are not reservoirs
-Many transferred by arthropod vectors
What bacteria caused the plague?
-Yersinia pestis (gram- bacillus)
How was the plague transmitted?
Flea bites
What are some virulence factors of the plague?
-Grow intracellularly inside macrophages
-inhibit phagocytosis
-Murine toxin which inhibits respiration by mitochondria
What is the bubonic plague?
-lymph nodes are inflamed and hemorrhage
-Bacteria move into circulatory system and cause necrosis and hemorrhaging of various organs
-Death in seven days (50-75% mortality if untreated)
What is Pneumonic plague?
-infects lungs (inhaled bacteria), and then causes systemic disease
-Mortality is almost 100%
How did scientists confirm that Y. pestis caused the plague so long ago?
-They dug up the bodies of people who died from the plague and tested microbes from their teeth and bones
What factors led to the exceptionally high mortality rates from plague in Europe in the 1300's?
(A) This form of plague was caused by a different species of bacteria
(B) This form of plague had additional virulence factors
(C) poor living conditions and malnutrition led to increased mortality rates
(D) Transmission was entirely human to human
(E) All of the above
(C) poor living conditions and malnutrition led to increased mortality rates
Anthrax
-Bacillus anthracis (endospore-former)
-Reservoir is livestock
-Is opportunistic pathogen that can grow or reproduce in soil
What type of infection is anthrax?
-Cutaneous infections that enter abrasions
-Mortality is 20% without treatment, <1% with antibiotics
hat are pulmonary infections caused by anthrax?
-anthrax is inhaled
-secretes toxins that enter the blood, kill macrophages and cause massive cytokine release leading to shock and death
-Death in 24-36 hrs, mortality 100%
Anthrax can be used as a biological weapon, and letters containing anthrax powder were sent through the US mail system to several prominent targets in 2001, infecting 22 people and killing 5. What feature of Bacillus anthracis makes it a commonly used bioterrorism weapon?
(A) Livestock reservoir
(B) Endospore formation
(C) Intracellular pathogen
(D) gram +
(E) all of the above
(B) Endospore formation
Lyme disease
-bacteria
-reservoir
-transmission
-Borrelia burgdorferi (spirochete)
-Reservoir is Rodents or deer
-Transmitted by adult ticks (humans accidentally infected)
What is the first symptom of Lyme disease?
-localized "bulls eye" rash around site of infection
What happens after initial infection of Lyme disease?
-Spirochete disseminates into blood stream; can enter joints and neural tissue
What can happen if lyme disease goes untreated?
-chronic arthritic conditions and neurological problems (facial paralysis, meningitis, memory loss, etc)
Rickettsia
-transmission
-target
-leads to?
-transmitted by lice and ticks
-Targets endothelial lining of capillaries
-Infections lead to vascular necrosis and hemorrhaging (loss of blood flow to neural tissue can damage CNS)
Would you expect Tick-borne diseases (such as lime disease and rocky mountain fever) to be more common in rural or urban areas?
(A) Rural (country)
(B) Urban (City)
(C) Equally common in both
(A) Rural (country)