ABPath Medical Microbiology 2

Question 1

A catalase-positive, coagulase-positive gram-positive cocci in clusters is isolated from a wound. Which organism is most likely?

Accepted Answer

Staphylococcus aureus

Answer

S. aureus is catalase-positive and coagulase-positive, distinguishing it from other staphylococci.

Question 2

Which stain is used to identify Mycobacterium tuberculosis in sputum?

Accepted Answer

Ziehl-Neelsen (acid-fast)

Answer

Acid-fast staining detects mycolic acid in the mycobacterial cell wall.

Question 3

A patient with meningitis has CSF showing gram-negative diplococci. Which organism is most likely?

Accepted Answer

Neisseria meningitidis

Answer

N. meningitidis appears as gram-negative diplococci and is a leading cause of bacterial meningitis.

Question 4

Which fungus is identified by broad, ribbon-like, aseptate hyphae with wide-angle branching?

Accepted Answer

Mucor (Zygomycetes)

Answer

Mucormycosis shows broad aseptate hyphae branching at wide (~90°) angles.

Question 5

Which test differentiates Streptococcus pneumoniae from viridans streptococci?

Accepted Answer

Optochin sensitivity

Answer

S. pneumoniae is optochin-sensitive whereas viridans streptococci are resistant.

American Board of Pathology (ABPath) Practice Test