USMLE Step 1 Microbiology
BACTERIOLOGY OVERVIEW - answer-
Bugs that don't G stain well? - answerThese Rascals May Microscopically Lack Color -
Treponema, Rickettsia, Mycobacteria, Mycoplasma, Legionella, Chlamydia.
Bugs visualized by Giemsa stain? - answerBorrelia, Plasmodium, trypanosomes,
Chlamydia.
Bug visualized by PAS stain? - answerTropheryma whippelii.
Organisms identified by Siehl-Neelsen (carbol fuchsin) stain? - answerAcid-fast
organisms (Mycobacterium > Nocardia).
Bug visualized by India ink? - answerCryptococcus.
Bugs visualized by silver stain? - answerPneumocystis, Legionella, (H. pylori?).
Culture requirement for H flu? - answerChocolate agar w/ factors V and X.
Culture requirement for N. gonorrhea? - answerThayer-Martin media (VPNT -
vancomycin for G+, Polymyxin for G-, Nystatin for fungi; TMP-SMX for Proteus).
Culture requirement for B. pertussis? - answerBordet-Gengou potato agar ("Bordet")
Culture requirement for C. diphtheria? - answerTellurite agar, Loffler's media.
Culture requirement for Mycobacterium TB? - answerLowenstein-Jensen agar.
Culture requirement for Mycoplasma pneumoniae? - answerEaton's agar ("Eatin' the
fried eggs")
Culture requirement for lactose-fermenting enterics? - answerPink colonies on
MacConkey's agar (pink due to acid production) - macConKEE'S - Citraus, Klebsiella,
E. coli, Enterobacter, Serratia.
, Culture requirement for E. coli? - answerMacConkey agar or eosin-methylene blue
(EMB) - blue-black colonies w/ green metallic sheen.
Culture requirement for Legionella? - answerCharcoal yeast extract w/ cysteine and iron
(old men with silver hair in the hot tub kept warm by the charcoal fire).
Culture requirement for fungi? - answerSabouraud's agar.
Obligate anaerobes? - answer"Can't Breathe Air" - Clostridium, Bacteroides,
Actinomyces. Aminoglycosides require O2 for uptake and won't work on these guys.
(Pasteurella?)
Obligate aerobes? - answer"Nagging Pests Must Breathe" - Nocardia, Pseudomonas,
Mycobacterium, Bacillus.
Obligate intracellular parasites? - answerChlamydia and Rickettsiae (includes Erlichia
and Coxiella) - can't make their own ATP.
Facultative intracellular parasites? - answer"Some Nasty Bugs May Live FacultativeLY"
- Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionalla,
Yersinia pestis.
Encapsulated bacteria? - answerSHiNSKiES - S. pneumoniae, H flu B, N meningitides,
Salmonella, Klebsiella, E. coli, S. Epidermidis, Strep agalactiae. Also Pseudomonas
aeruginosa, Cryptococcus neoformans (latex agglutination). Are also competent and
secrete IgAse.
Catalase-positive organisms? - answer(This is the First Aid list) SSPACE for the cats
and granulomas - S. aureus, Serratia, Pseudomonas, Actinomyces, Candida, E. coli.
Urease-positive bugs? - answerPUNCH-K - Proteus, Ureaplasma, Nocardia,
Cryptococcus, H. pylori, Klebsiella.
Virulence factors of group A strep? - answerM protein - prevents phagocytosis.
Erythrogenic toxin.
Location of genes for exotoxin vs. endotoxin? - answerExotoxins are encoded on
plasmids or bacteriophages. Endotoxins are encoded on the bacterial chromosome.
Vaccine application of exotoxins? - answerToxoids used to stimulate T-cells to make
attached capsules antigenic.
2 toxins and bugs that inhibit elongation factor 2? - answerDiphtheria toxin and exotoxin
A (Pseudomonas).
BACTERIOLOGY OVERVIEW - answer-
Bugs that don't G stain well? - answerThese Rascals May Microscopically Lack Color -
Treponema, Rickettsia, Mycobacteria, Mycoplasma, Legionella, Chlamydia.
Bugs visualized by Giemsa stain? - answerBorrelia, Plasmodium, trypanosomes,
Chlamydia.
Bug visualized by PAS stain? - answerTropheryma whippelii.
Organisms identified by Siehl-Neelsen (carbol fuchsin) stain? - answerAcid-fast
organisms (Mycobacterium > Nocardia).
Bug visualized by India ink? - answerCryptococcus.
Bugs visualized by silver stain? - answerPneumocystis, Legionella, (H. pylori?).
Culture requirement for H flu? - answerChocolate agar w/ factors V and X.
Culture requirement for N. gonorrhea? - answerThayer-Martin media (VPNT -
vancomycin for G+, Polymyxin for G-, Nystatin for fungi; TMP-SMX for Proteus).
Culture requirement for B. pertussis? - answerBordet-Gengou potato agar ("Bordet")
Culture requirement for C. diphtheria? - answerTellurite agar, Loffler's media.
Culture requirement for Mycobacterium TB? - answerLowenstein-Jensen agar.
Culture requirement for Mycoplasma pneumoniae? - answerEaton's agar ("Eatin' the
fried eggs")
Culture requirement for lactose-fermenting enterics? - answerPink colonies on
MacConkey's agar (pink due to acid production) - macConKEE'S - Citraus, Klebsiella,
E. coli, Enterobacter, Serratia.
, Culture requirement for E. coli? - answerMacConkey agar or eosin-methylene blue
(EMB) - blue-black colonies w/ green metallic sheen.
Culture requirement for Legionella? - answerCharcoal yeast extract w/ cysteine and iron
(old men with silver hair in the hot tub kept warm by the charcoal fire).
Culture requirement for fungi? - answerSabouraud's agar.
Obligate anaerobes? - answer"Can't Breathe Air" - Clostridium, Bacteroides,
Actinomyces. Aminoglycosides require O2 for uptake and won't work on these guys.
(Pasteurella?)
Obligate aerobes? - answer"Nagging Pests Must Breathe" - Nocardia, Pseudomonas,
Mycobacterium, Bacillus.
Obligate intracellular parasites? - answerChlamydia and Rickettsiae (includes Erlichia
and Coxiella) - can't make their own ATP.
Facultative intracellular parasites? - answer"Some Nasty Bugs May Live FacultativeLY"
- Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionalla,
Yersinia pestis.
Encapsulated bacteria? - answerSHiNSKiES - S. pneumoniae, H flu B, N meningitides,
Salmonella, Klebsiella, E. coli, S. Epidermidis, Strep agalactiae. Also Pseudomonas
aeruginosa, Cryptococcus neoformans (latex agglutination). Are also competent and
secrete IgAse.
Catalase-positive organisms? - answer(This is the First Aid list) SSPACE for the cats
and granulomas - S. aureus, Serratia, Pseudomonas, Actinomyces, Candida, E. coli.
Urease-positive bugs? - answerPUNCH-K - Proteus, Ureaplasma, Nocardia,
Cryptococcus, H. pylori, Klebsiella.
Virulence factors of group A strep? - answerM protein - prevents phagocytosis.
Erythrogenic toxin.
Location of genes for exotoxin vs. endotoxin? - answerExotoxins are encoded on
plasmids or bacteriophages. Endotoxins are encoded on the bacterial chromosome.
Vaccine application of exotoxins? - answerToxoids used to stimulate T-cells to make
attached capsules antigenic.
2 toxins and bugs that inhibit elongation factor 2? - answerDiphtheria toxin and exotoxin
A (Pseudomonas).
