How can we help?

You can also find more resources in our Help Center.

63 terms

Microbiology

STUDY
PLAY
What is the gram staining process?
1. Crystal violet dye plus iodine stains all bacterial cell walls
2. Alcohol* extracts* blue dye from lipid rich, thin-walled gram-negative bacteria
3. Red dye * counterstains* decolorized gram-negative bacteria
Describe gram-positive bacteria
-Rich in peptidoglycan
-retain violet dye
Describe gram-negative bacteria
-Poor in peptidoglycan
-counterstain with red dye
What is Ziehl Neelson stain used for?
Acid fast bacteria (red)
What is India ink stains used for?
Cryptococcus
What is Geimsa stain used for?
Blood smears
What is PAS used for?
Glycogen, mucopolysaccharides
What is Prussian blue stain used for?
Iron
What is Congo red stain used for?
Amyloid
What is osmic acid stain used for?
Electron microscopy
normal flora of the skin?
Staphylococcus epidermis
Potential skin pathogens?
Staphylococcus aureus
Normal flora of the nasopharynx?
Streptococcus viridans, anaerobes
Potential pathogens of the nasopharynx?
S.pneumoniae
N.meningitidis
H.influenzae
Normal flora of the mouth?
Streptococcus viridans
Potential pathogens of the mouth?
Candida albicans
Normal flora of the colon?
E. coli
Potential pathogens of the colon?
B.fragilis, enterococci
Normal flora of the vagina?
Lactobacillus
streptococci
Potential pathogens of the vagina?
Candida albicans
Composes the inner layer of the cell wall of all bacteria?
Peptidoglycan
-*thick* in gram-positive
-*thin* in gram-negative
-exception = Mycoplasma
Techoic acid forms the outer layer of the cell wall of which type of bacteria?
Gram-positive
Lipopolysaccharide forms the outer layer of the cell wall of what type of bacteria?
Gram-negative
-outer cell membrane = lipid bilayer
-also contains porins
What is special about mycobacteria cell walls?
Contain mycolic acid
What is special about Mycoplasma cell walls?
-It has no cell wall; membrane only
-only bacterium whose membrane contains cholesterol
Does penicillin work against Mycoplasma pneumonia?
No, penicillin attacks peptidoglycan and there are none
How are exotoxin neutralized?
By antibodys
What type of bacteria produce exotoxins?
Both gram-positive and gram-negative bacteria
What type of bacteria produce endotoxins?
gram-negative only
Endotoxins
-lipopolysaccharides
-nonspecific
-TNF, IL-1 → shock, fever
-poor antigen
-heat-stable
exotoxins
-Polypeptides
-specific
-toxoid used as vaccines
-usually* heat labile*
Which toxin is responsible for *blocking the release of lysine* leading to muscle spasms?
Tetanus toxin
Which toxin is responsible for *blocking the release of acetylcholine* leading to muscle paralysis?
Botulinum toxin
Which toxin *inhibits protein synthesis* by ADP ribosylation of EF-2?
Diphtheria toxin
Which toxin causes hemoloysis, necrosis, and cell death?
Alpha toxin → staph aureus
Which bacteria is responsible for toxic shock syndrome toxin?
Staph aureus → induces cytokine that produce anaphylactic shock
Which toxin *stimulates adenylate cyclase activating GS protein*?
Cholera toxin
Which toxin *stimulates adenylate cyclase inhibiting GI protein*?
Pertussis toxin
What does the heat-stable E. coli enterotoxin do?
Stimulates at guanylate cyclase
Obligate aerobes
M tuberculosis
pseudomonas aeruginosa
nocardia
Microaerophilic bacteria
campylobacter jejuni
Brucella abortus
Obligate anaerobic bacteria
Clostridium
actinomyces
most common cause of the common cold?
Rhinovirus
most common cause of pharyngitis and laryngitis?
Viral >bacterial (beta hemolyzing streptococci)
most common cause of tonsillitis?
beta hemolyzing streptococci
most common cause of otitis media?
Streptococcus pneumoniae, Haemophilus influenza
most common cause of sinusitis?
Streptococcus pneumoniae, Staphylococcus aureus
most common cause of pneumonia in infants?
RSV
most common cause of pneumonia in young adults?
Mycoplasma
most common cause of pneumonia in the elderly?
Streptococcus pneumonia
most common causes of bacterial meningitis in neonates?
-E. coli
-strep agalactica (GBS)
-Listeria
most common cause of bacterial meningitis in adults?
Neisseria Meningitidis >strep pneumoniae
most common cause of bacterial meningitis in the elderly?
Streptococcus pneumoniae >Neisseria Meningitidis
most common cause of endocarditis?
S.viridans
most common cause of carbuncle?
S.aureus
most common cause of sepsis In a catheterized patient?
S.aureus, Candida
most common cause of sepsis in a burn patient?
Pseudomonas aeruginosa
most common cause of diarrhea in children?
Rotavirus
most common cause of diarrhea in adults in the US?
Campylobacter
most common cause of diarrhea in travelers?
E. coli, Shigella, Salmonella
most common causes of genital ulcers?
Herpes >syphilis
most common cause of urethritis?
Chlamydia > gonococcus
most common cause of cystitis?
E. coli