USMLE
Exam*MICROBIOLOGY
Questions and Answers
Latest Updates (2025/2026)
(Complete, Accurate, and
Verified)
USMLE: Microbiology
Organisms known for causing endocarditis
S. aureus, Staph epididermis, viridans strep, VRE, Strep. bovis, HACEK organisms
Four drug regimen used to treat TB
isoniazid, ethambutol, rifampin, pyrazinamide
Used to treat Trichomonas or Gardnerella
metronidazole
Used to treat Plasmodium vivax or ovale
chloroquine + primaquine
Used to treat Pediculosis capitis or pubus
permethrin, pyrethrin
Organisms most commonly responsible for otitis media
Strep pneumoniae
Haemophilus influenzae
Moraxella catarrhalis
, Organism most commonly responsible for otitis externa
Pseudomonas aeruginosa
Fungus that causes San Joaquin Valley fever
Coccidioides
Fungus found in rural Latin America
Paracoccidioides
Fungus associated with plant thorns and cutaneous injury
Sporothrix
Fungus found in states east of the Mississippi River
Blastomycosis
Fungus found in bird and bat droppings
Histoplasmosis
Mold form contains barrel-shaped arthroconidia
Coccidioides
Encapsulated bacteria (8)
E. coli, Strep pneumoniae, N. meningitidis, Klebsiella pneumoniae, Haemophilus influenzae,
Pseudomonas aeruginosa, Salmonella, group B Strep
steeple sign on X-ray
croup, parainfluenza virus
thumb sign on x-ray
epiglottitis, Haemophilus influenza
Treatment of chronic hepatitis B and C
IFN-alpha, ribavirin
Most abundant bacteria in the colon of most individuals
Bacteroides fragilis
Likely organisms in a patient with chronic granulomatous disease
S. aureus, E. coli, K. pneumoniae, Aspergillus, Candida (all are catalase +)
Organisms that cause infections in the mouth of AIDS patients
HSV, C. albicans, EBV, CMV
Three structural genes that code for HIV proteins
gag (p24)
pol (reverse transcriptase, integrase)
env (gp120, gp41)
Dark purple nodules on the skin in an HIV patient
HHV-8, Kaposi sarcoma
Exam*MICROBIOLOGY
Questions and Answers
Latest Updates (2025/2026)
(Complete, Accurate, and
Verified)
USMLE: Microbiology
Organisms known for causing endocarditis
S. aureus, Staph epididermis, viridans strep, VRE, Strep. bovis, HACEK organisms
Four drug regimen used to treat TB
isoniazid, ethambutol, rifampin, pyrazinamide
Used to treat Trichomonas or Gardnerella
metronidazole
Used to treat Plasmodium vivax or ovale
chloroquine + primaquine
Used to treat Pediculosis capitis or pubus
permethrin, pyrethrin
Organisms most commonly responsible for otitis media
Strep pneumoniae
Haemophilus influenzae
Moraxella catarrhalis
, Organism most commonly responsible for otitis externa
Pseudomonas aeruginosa
Fungus that causes San Joaquin Valley fever
Coccidioides
Fungus found in rural Latin America
Paracoccidioides
Fungus associated with plant thorns and cutaneous injury
Sporothrix
Fungus found in states east of the Mississippi River
Blastomycosis
Fungus found in bird and bat droppings
Histoplasmosis
Mold form contains barrel-shaped arthroconidia
Coccidioides
Encapsulated bacteria (8)
E. coli, Strep pneumoniae, N. meningitidis, Klebsiella pneumoniae, Haemophilus influenzae,
Pseudomonas aeruginosa, Salmonella, group B Strep
steeple sign on X-ray
croup, parainfluenza virus
thumb sign on x-ray
epiglottitis, Haemophilus influenza
Treatment of chronic hepatitis B and C
IFN-alpha, ribavirin
Most abundant bacteria in the colon of most individuals
Bacteroides fragilis
Likely organisms in a patient with chronic granulomatous disease
S. aureus, E. coli, K. pneumoniae, Aspergillus, Candida (all are catalase +)
Organisms that cause infections in the mouth of AIDS patients
HSV, C. albicans, EBV, CMV
Three structural genes that code for HIV proteins
gag (p24)
pol (reverse transcriptase, integrase)
env (gp120, gp41)
Dark purple nodules on the skin in an HIV patient
HHV-8, Kaposi sarcoma
