ABPath Medical Microbiology 2 — Questions and Answers
Question 1: A catalase-positive, coagulase-positive gram-positive cocci in clusters is isolated from a wound. Which organism is most likely?
- Staphylococcus aureus (Correct answer)
- Staphylococcus epidermidis
- Streptococcus pyogenes
- Enterococcus faecalis
Correct answer: Staphylococcus aureus
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?
- Ziehl-Neelsen (acid-fast) (Correct answer)
- Gram stain
- India ink
- Giemsa
Correct answer: Ziehl-Neelsen (acid-fast)
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?
- Neisseria meningitidis (Correct answer)
- Streptococcus pneumoniae
- Listeria monocytogenes
- Haemophilus influenzae
Correct answer: Neisseria meningitidis
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?
- Mucor (Zygomycetes) (Correct answer)
- Aspergillus
- Candida albicans
- Cryptococcus neoformans
Correct answer: Mucor (Zygomycetes)
Mucormycosis shows broad aseptate hyphae branching at wide (~90°) angles.
Question 5: Which test differentiates Streptococcus pneumoniae from viridans streptococci?
- Optochin sensitivity (Correct answer)
- Bacitracin sensitivity
- Coagulase test
- Oxidase test
Correct answer: Optochin sensitivity
S. pneumoniae is optochin-sensitive whereas viridans streptococci are resistant.
Question 6: A febrile patient returning from sub-Saharan Africa has ring forms and banana-shaped gametocytes on blood smear. Diagnosis?
- Plasmodium falciparum (Correct answer)
- Plasmodium vivax
- Babesia microti
- Trypanosoma brucei
Correct answer: Plasmodium falciparum
Crescent/banana-shaped gametocytes are characteristic of P. falciparum.
Question 7: Which virus is most commonly associated with cervical cancer?
- Human papillomavirus (HPV) (Correct answer)
- Herpes simplex virus type 2
- Epstein-Barr virus
- Cytomegalovirus
Correct answer: Human papillomavirus (HPV)
High-risk HPV types 16 and 18 are the primary cause of cervical carcinoma.
ABPath Medical Microbiology 2
A catalase-positive, coagulase-positive gram-positive cocci in clusters is isolated from a wound.
Which organism is most likely?