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FCPS Part 1 Microbiology MCQs
Microbiology questions test bacterial, viral, fungal and parasitic organisms by their identifying features, virulence factors, the diseases they cause and the drugs used against them.
Below are 5 free single-best-answer questions drawn from the most frequently examined microbiology concepts, each with the answer and a rationale for every option. The full bank has 115 microbiology concepts, each asked several different ways.
Free microbiology questions
Question 1
Itchy crops of vesicles in different stages on an erythematous base. Causative virus:
- A. Rubella virus
- B. Measles virus
- C. Variola major
- D. Varicella-zoster virus
- E. Coxsackievirus A
Show answer
Answer: D. Varicella-zoster virus
VZV (HHV-3) causes chickenpox with vesicles appearing in successive crops, then lies latent in sensory ganglia. Pneumonia is a serious complication in adults, especially in pregnancy.
Why not the others: Measles: maculopapular rash, Koplik spots. Rubella: pink rash, lymphadenopathy. Coxsackie A: hand, foot and mouth. Smallpox: uniform vesicles. Influenza A: no vesicular rash.
High-yield: Vesicles in different stages = chickenpox; adult/pregnant pneumonia = VZV.
Question 2
Gram-positive lancet-shaped diplococci in a sputum smear indicate which organism?
- A. Streptococcus pneumoniae
- B. Klebsiella pneumoniae
- C. Haemophilus influenzae
- D. Neisseria meningitidis
- E. Staphylococcus aureus
Show answer
Answer: A. Streptococcus pneumoniae
Pneumococcus is an encapsulated, alpha-haemolytic Gram-positive diplococcus; the capsule resists phagocytosis, and the spleen clears it. It is the commonest cause of lobar community-acquired pneumonia.
Why not the others: Neisseria meningitidis: Gram-negative diplococcus. Haemophilus influenzae: Gram-negative coccobacillus. Klebsiella pneumoniae: Gram-negative with currant-jelly sputum. Legionella pneumophila: needs special media, atypical pneumonia. Staphylococcus aureus: clusters, not diplococci.
High-yield: Gram-positive lancet diplococci, optochin sensitive, bile soluble = pneumococcus; give vaccine before splenectomy.
Question 3
Vomiting a few hours after reheated fried rice. Organism:
- A. Bacillus cereus
- B. Clostridium perfringens
- C. Escherichia coli
- D. Salmonella typhimurium
- E. Staphylococcus aureus
Show answer
Answer: A. Bacillus cereus
B. cereus spores survive boiling and germinate in rice left warm; they form the heat-stable emetic toxin cereulide, so vomiting starts within 1–6 h.
Why not the others: C. perfringens: watery diarrhoea 8–16 h after reheated meat. Salmonella and Campylobacter: invasive, febrile, after 12–72 h. Vibrio parahaemolyticus: seafood.
High-yield: Rice + vomiting within hours = B. cereus emetic toxin.
Question 4
Tetanospasm toxin of Clostridium tetani is classified as a:
- A. Enterotoxin
- B. Endotoxin
- C. Neurotoxin
- D. Cytotoxin
- E. Erythrogenic toxin
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Answer: C. Neurotoxin
Tetanospasmin travels by retrograde axonal transport to the spinal cord and blocks release of inhibitory GABA and glycine, causing spastic paralysis. Botulinum toxin blocks acetylcholine release; both cleave SNARE proteins.
Why not the others: Endotoxin: lipopolysaccharide of Gram-negative cell walls. Erythrogenic toxin: scarlet fever rash. Enterotoxin: acts on gut. Cytotoxin: kills cells. Haemotoxin: lyses red cells.
High-yield: Tetanus = neurotoxin blocking inhibitory release, spastic; botulinum = flaccid.
Question 5
HIV-positive patient, CD4 under 200, dry cough, hypoxia, bilateral ground-glass shadowing: organism?
- A. Cryptococcus neoformans
- B. Pneumocystis jirovecii
- C. Candida albicans
- D. Streptococcus pneumoniae
- E. Mycobacterium tuberculosis
Show answer
Answer: B. Pneumocystis jirovecii
Pneumocystis jirovecii is a fungus that causes diffuse interstitial pneumonia when CD4 falls below 200 cells/mm3. Patients have dry cough, dyspnoea and desaturation, and lavage silver stain shows disc-shaped cysts.
Why not the others: Mycobacterium tuberculosis: cavitation or miliary spread at any CD4. Streptococcus pneumoniae: lobar consolidation with productive cough. Cryptococcus neoformans: meningitis. Candida albicans: oropharyngeal thrush, not interstitial pneumonia.
High-yield: HIV + dry cough + hypoxia + bilateral infiltrates = Pneumocystis; treat with co-trimoxazole.
Keep going with microbiology
Anaesgen brings every concept back on a spaced-repetition schedule timed to your exam date, as a different question each time, with full mock papers for Paper 1 and 2.
Get full access Try the 5 sample questionsHigh-yield microbiology one-liners
The most-tested microbiology concepts, as a clue and the answer it points to:
- Dew drops on rose petal, crops of vesicles, shingles, varicella pneumonia → VZV.
- Lancet diplococci, rusty sputum, asplenia, commonest CAP → Streptococcus pneumoniae.
- Rice + vomiting within hours → B. cereus (cereulide).
- Tetanospasmin, botulinum toxin, blocks GABA/glycine or ACh release → neurotoxin.
- HIV, CD4 <200, dry cough, silver-stain cysts → Pneumocystis.
- Lichen planus, cryoglobulinaemia, porphyria cutanea tarda → hepatitis C.
- AIDS, purple skin plaques, Kaposi sarcoma → HHV-8.
- Diabetes/DKA, black eschar, broad aseptate right-angle hyphae → Mucor.
- Furuncle to cavernous sinus, pneumatoceles, osteomyelitis, coagulase+ → Staphylococcus aureus.
- Sulphur granules, lumpy jaw, sinuses → Actinomyces (anaerobic, not acid-fast).
- White plaques + pseudohyphae → Candida.
- Penile warts, cervical cancer, koilocytes → HPV (6/11 warts; 16/18 cancer).
- DKA, black nasal eschar, broad non-septate hyphae at right angles → mucormycosis.
- Strawberry cervix, frothy discharge, motile trophozoites → Trichomonas.
- Hand-foot-and-mouth, Coxsackie A16, enterovirus → naked positive-sense RNA.
- Pharyngitis, mimicry, Aschoff bodies, carditis → Group A Streptococcus.
- Non-septate right-angle hyphae, vascular invasion, DKA, rhino-orbital → Mucor.
- Trismus, spasms, dirty wound → benzylpenicillin + immunoglobulin + debridement.
- Germ tube, curdy discharge, chlamydospores → Candida albicans.
- Persistent urethritis after gonococcal cure, obligate intracellular, NAAT → Chlamydia trachomatis.
Other FCPS Part 1 subjects
AnatomyPharmacologyPathologyBiochemistry & GeneticsCardiovascularNeurophysiologyHaematologyGeneral PhysiologyImmunologyEndocrineRespiratoryEmbryologyObstetrics & GynaeRenal & Acid-BaseHistologyGI & LiverPhysicsBiostatistics
New to the exam? Read the FCPS Part 1 exam guide: dates, format and a 12-week study plan.