USMLE Step I Microbiology Flashcards
List 3 bacteria which stains silver
- Legionella
- Fungi (Pneumocystis)
- H. pylori
Which microbe is too thin to be visualized by gram staining?
Treponema
Which microbe stains with India Pink?
Cryptococcus neoformans
Which microbes stain with carbon fuchsin?
Acid-fast bacteria: AKA Ziehl-Neelsen
- Nocardia
- Mycobacterium
Which stain is used to diagnose Whipple Disease?
PAS (periodic acid-schiff):
- Tropheryma whipplei
- Stains glycogen, mucopolysaccharides.
Which 5 microbes are stained with Giemsa?
- Chlamydia
- Borrelia
- Rickettsiae (intracellular parasite)
- Trypanosomes
- Plasmodium
Certain Bugs Really Try my Patience
List 3 obligate aerobes
- M. tuberculosis
- P. aeruginosa (burn wounds, diabetic ulcers, nosocomial pneumonia, cystic fibrosis)
- Nocardia
List 3 obligate anaerobes
- Clostridium
- Bacteriodes
- Actinomyces
- Foul smelling, produce gas in tissue
- Lack superoxide dismutase and catalase. Thus are prone to O2 radicals.
Which antibiotic is ineffective against obligate anaerobes? Why?
Aminoglycosides. Because they require O2 to enter in the bacterial cell.
Individuals without spleens are most susceptible to what 3 microbes?
- S. pneumoniae
- H. influenza
- N. meningitidis
Because such individuals have low opsonizing ability, without spleen clearance.
Which 7 bacteria are encapsulated (anti-phagocytic and hence low opsonization…need spleen clearance!)?
- S. pneumoniae
- H. influenza
- N. meningitidis
- E. coli
- Salmonella
- K. pneumonia
- Group B strep
Antigen in vaccines are from capsule + protein conjugate
Which bacteria have catalase as a virulence factor?
- Pseudomonas
- Listeria
- Aspergillus
- Candida
- E. coli
- S. aureus
- Serratia
- Catalase degrades H2O2.
Which individuals have recurrent infections with catalase bacteria?
chronic granulomatous disease (NADPH oxidase deficiency)
red microbe
Serratia marcescens
yellow sulfur granules microbe
Actinomyces israeli