Microbiology remains one of the most important yet often underestimated subjects in NEET PG. With its mix of factual memory and clinical relevance, mastering Microbiology can significantly boost students’ overall scores. In this blog, we bring you the NEET PG Microbiology recall questions, their correct answers and clear explanations. We also highlight microbiology high-yield NEET PG topics you must focus on. 

NEET PG Microbiology Previous Year Questions: Memory-Based Recall Questions 

The following MCQs are based on student recall and expert discussions after the NEET PG last 5-year exam. These questions reflect the exam’s focus on clinical applications, diagnostic techniques and basic organism knowledge. 

Q1 . Nocardia shows which type of staining? 

1. Gram-negative
2. Gram-positive and acid-fast 
3. Gram-variable
4. Non-staining

Answer: B. Gram-positive and acid-fast 

Nocardia is a Gram-positive, weakly acid-fast, branching filamentous bacterium. It retains some carbol fuchsin due to mycolic acids, thus appearing weakly acid-fast. 

Q2. After a positive ELISA for HIV, what is the next confirmatory test?

1. PCR
2. CD4 count
3. Western blot 
4. Antigen detection

Answer: C. Western blot 

Western blot was the standard confirmatory test after a positive HIV ELISA. Nowadays, fourth-generation assays and nucleic acid tests are preferred; however, traditionally, the ELISA-Western blot workflow was used. 

Q3. A 3-week-old neonate presents with fever, lethargy and seizures. Blood culture is taken and grown on sheep blood agar. The lab report notes enhanced hemolysis in an arrowhead pattern when streaked perpendicular to Staphylococcus aureus. Which diagnostic test does this represent, and what is the most likely organism?

1. Coagulase test – Staphylococcus aureus
2. CAMP test – Streptococcus agalactiae 
3. Elek test – Corynebacterium diphtheriae
4. Nagler reaction – Clostridium perfringens

Answer: B. CAMP test – Streptococcus agalactiae 

The CAMP test is used to detect Streptococcus agalactiae (Group B Strep), which shows enhanced β-hemolysis when grown perpendicular to Staph. aureus on blood agar. This organism is a common cause of neonatal sepsis and meningitis. 

Q4. A 34-year-old HIV positive man presents with painless, beefy-red genital ulcers that bleed on touch. There is no lymphadenopathy. A Giemsa-stained smear from the ulcer shows intercellular organisms with a safety pin appearance. What is the most likely causative organism?

1. Chlamydia trachomatis
2. Klebsiella (Calymmatobacterium) granulomatis 
3. Haemophilus ducreyi
4. Treponema pallidum

Answer: B. Klebsiella (Calymmatobacterium) granulomatis 

Donovanosis (granuloma inguinale) is caused by Klebsiella granulomatis. It presents as painless genital ulcers with characteristics of Donovan bodies (intracellular safety-pin-shaped organisms). It is differentiated from syphilis and chancroid based on ulcer characteristics and microscopic findings. 

Q5. A patient undergoing pre-employment screening tests positive for HBsAg and HBeAg. ALT is mildly elevated, and the patient is asymptomatic. What does the presence of HBeAg indicate? 

1. Past resolved infection
2. Immunity due to vaccination
3. High infectivity 
4. Window period of infection

Answer: C. High infectivity 

HBeAg is a marker of active replication of the hepatitis B virus. Its presence implies high infectivity. HBsAg indicates current infection, and anti-HBs suggests immunity. 

Q6. A 45-year-old farmer from eastern India presents with chronic cough, weight loss and mediastinal lymphadenopathy. Chest X-ray shows calcified hair nodes. A fungal culture at 25 degrees shows mould, while at 37 degrees it shows yeast. Which fungus is most likely? 

1. Candida albicans
2. Histoplasma capsulatum 
3. Cryptococcus neoformans
4. Aspergillus fumigatus

Answer: B. Histoplasma capsulatum 

Histoplasma capsulatum is a dimorphic fungus endemic to areas like eastern India and the Ohio River Valley. It mimics TB clinically and radiologically but is identified via fungal cultures showing dimorphism (mould at 25°C and yeast at 37°C).

Q7. A 28-year-old man presents with fever, headache and neck stiffness. Lumbar puncture reveals clear CSF, elevated lymphocytes, normal glucose and slightly elevated protein. What is the most probable diagnosis? 

1. Bacterial meningitis
2. Viral meningitis
3. Tuberculous meningitis
4. Fungal meningitis

Answer: B. Viral meningitis 

Viral meningitis typically presents with lymphocytic predominance, normal glucose and mildly elevated protein. In contrast, bacterial meningitis shows neutrophilic predominance and low glucose levels. 

Q8. A young adult presents with a dry cough, fever and malaise. Chest X-ray shows diffuse infiltrates disproportionate to mild clinical findings. The cold agglutinin test is positive. Which organism is most likely responsible?

1. Klebsiella pneumoniae
2. Mycoplasma pneumoniae 
3. Streptococcus pneumoniae
4. Legionella pneumophila

Answer: B. Mycoplasma pneumoniae 

Mycoplasma pneumoniae causes atypical pneumonia with minimal symptoms but striking radiological findings. It lacks a cell wall, hence is not seen on Gram stain and is resistant to beta-lactams. A positive cold agglutinin test supports the diagnosis. 

Q9. How does tetanospasmin toxin from Clostridium tetani cause symptoms? 

1. Inhibits protein synthesis
2. Blocks acetylcholine release at the NMJ
3. Inhibits inhibitory neurotransmitter release 
4. Causes demyelination

Answer: C. Inhibits inhibitory neurotransmitter release 

Tetanospasmin is a neurotoxin that blocks the release of GABA and glycine from inhibitory interneurons, leading to muscle rigidity and spasms seen in tetanus. 

Q10. The Weil-Felix test is used to detect infections caused by: 

1. Leptospira interrogans
2. Rickettsia 
3. Treponema pallidum
4. Borrelia burgdorferi

Answer: B. Rickettsia 

Weil-Felix test is an older agglutination test used to detect Rickettsial infections. It is based on cross-reaction between Proteus strains (OX2, OX19, OXK) and Rickettsial antigens. 

Microbiology High-Yield NEET PG Topics: Students must revise 

Alongside solving the NEET PG Microbiology previous year paper, you should thoroughly revise the following high-yield areas: 

• Bacterial classification and staining techniques
• Culture media and diagnostic tests (e.g. VDRL, ELISA, PCR)
• Virology markers (HBV, HIV, COVID) 
• Mycology- especially dimorphic fungi 
• Vaccines (types, schedules and cold chain) 
• Hospital-acquired infections and sterilisation 
• Parasitology – malaria, filaria, amoeba 
• Zoonotic diseases and their vectors 

Analysing the NEET PG Microbiology recall questions with answers is a powerful strategy to identify knowledge gaps and focus on microbiology high-yield NEET PG topics. These memory-based questions not only reflect the exam pattern but also help in last-minute revision before exams like NEET PG, FMGE or INICET.