Microbiology Important Questions for NEET PG/FMGE

If you are a NEET PG/FMGE aspirant, you must know how crucial microbiology is when it comes to understanding and diagnosing various infectious diseases. This is what makes it an essential subject for NEET PG/FMGE.

Preparing for microbiology can be pretty daunting considering the vast array of microorganisms, diagnostic techniques, and clinical correlations to cover. However, if you focus on high-yield topics and commonly asked questions, you can easily streamline your preparation.

In this blog, we’ve curated a list of high-yield microbiology questions that frequently appear in NEET PG and FMGE exams. We’ve also included detailed explanations to ensure clarity and deeper understanding.

Read the blog further to ace the exam.

Q1. Match the following sterilisation techniques with their respective control methods. 

Sterilisation technique	Control method
1. Hot air oven	a. Bacillus pumilus
2. Autoclave	b. Serratia marcescens
3. Membrane filtration	c. Bacillus atrophaeus/subtilis spores
4.Ionizing Radiation	d. Geobacillus stearothermophilus spores

1. 1-a, 2-c, 3-b, 4-d
2. 1-c, 2-d, 3-a, 4-b
3. 1-c, 2-d, 3-b, 4-a 
4. 1-d, 2-c, 3-a, 4-b

Answer: 3) 1-c, 2-d, 3-b, 4-a

Explanation:

Sterilisation technique	Control method
1. Hot air oven	c. Bacillus atrophaeus/subtilis spores
2. Autoclave	d. Geobacillus stearothermophilus spores
3. Membrane filtration	b. Serratia marcescens
4. Ionizing Radiation	a. Bacillus pumilus

These control methods are biological indicators used to check the effectiveness of the sterilisation method.

• Spores of Bacillus atrophaeus/subtilis are used as a control method for hot air ovens and ethylene oxide sterilisation (used mainly for heart-lung machines).
• Spores of Geobacillus stearothermophilus are used as a control method for autoclave and plasma sterilisation.
• Bacillus globigi is also used as a control method for ethylene oxide sterilisation.
• Serratia marcescens and Brevundimonas diminuta are used as control methods for membrane filters.

Also read: Pathology Important Questions for NEET PG/FMGE

Q2. A 8-year-old boy presents with a 5-day history of severe sore throat, high fever, hoarseness of voice, and swollen neck. Physical examination reveals a thick greyish pseudomembrane in the throat and significant cervical lymphadenopathy. A throat swab was sent for microbiological analysis and revealed the following: Which staining technique is used to identify the causative organism in this case?

1. Albert stain
2. Gram stain
3. Zeil Neelsen stain
4. Gabbet stain

Answer: 1) Albert stain

Explanation:​​

The above image shows Albert stain of Corynebacterium diphtheria showing metachromatic granules.

Albert Stain

Principle: 

Albert's stain causes the metachromatic granules of Corynebacterium diphtheriae to appear bluish-purple upon staining.

Type	Components	Function
Albert solution 1	- Malachite Green for organism staining - Toluidine Blue for metachromatic staining	- Enhances contrast and specificity in staining.
Albert solution 2	- Iodine	- Specifically targets volutin or Babes-Ernst granules.

Procedure:

• Stain the smear with Albert I stain, then drain and wash it
• Apply Albert II stain to cover the smear, then drain it

Q3. A 19-year-old college student presents to the clinic with a 2-week history of fatigue, sore throat, fever, and swollen lymph nodes. On examination, he has significant posterior cervical lymphadenopathy and hepatosplenomegaly. The physician suspects a viral infection and decides to perform a specific agglutination test. Which of the following statements regarding this test is correct?

1. The test detects heterophile antibodies that agglutinate sheep red blood cells.
2. An agglutination titer of 50 or below is indicative of a positive result.
3. The test requires fresh serum samples without any prior heating.
4. Heterophile antibodies are produced only in response to one type of virus.

Answer: 1) The test detects heterophile antibodies that agglutinate sheep red blood cells.

Also read: NEET PG High-Yield Questions on Parasitology

Q4. Identify the test performed and the organism implicated from the image  given below

1. Germ tube test: Candida albicans
2. Chrom agar   glabrata
3. SDA Culture media test: Candida tropicalis
4. Corn meal agar test: Candida krusei

Answer: 1) Germ tube test: Candida albicans

Explanation:

Laboratory diagnosis of candida
Germ tube test	- The germ tube test is a specific diagnostic test for Candida albicans. - Germ tube also seen in candida dubliniensis - Candida tropicalis: pseudo-germ tube formation Also known as Reynolds Braude Phenomenon Candida + Human serum → Incubation → Big tube-like structure (Pseudohyphae).

Q5. A 32-year-old man presents with fever, jaundice, and dark urine. He is unvaccinated for hepatitis, and liver enzymes are elevated. A healthcare worker uses a detergent-based disinfectant to clean the room. Which of the following viruses is most likely to survive the cleaning process due to its resistance to detergents and solvents?

1. Hepatitis A
2. Hepatitis B
3. Hepatitis C
4. Hepatitis D

Answer: 1) Hepatitis A

Explanation: 

Hepatitis A virus (HAV) is a non-enveloped RNA virus, which makes it more resistant to inactivation by detergents and solvents compared to the enveloped viruses Hepatitis B, C, and D.

Also read: INI-CET High Yield Questions for Microbiology

Q6. A 68 y/o man with a history of diabetes and hypertension presents with fever, shortness of breath, and ground-glass peripheral opacities on chest imaging, as shown in the image below. Which mechanism most likely explains the severe respiratory symptoms he is experiencing?

1. Viral attachment to ACE-2 receptors
2. Increased pulmonary surfactant production
3. Enhanced membrane glycoprotein activity
4. Cytokine storm causing alveolar and endothelial damage

Answer: 4) Cytokine storm causing alveolar and endothelial damage

Explanation:
The diagnosis is likely COVID-19 due to the patient's symptoms and characteristic ground-glass opacities on chest imaging, which are commonly associated with COVID-19 pneumonia. 

Severe COVID-19 can trigger a cytokine storm, which damages alveolar cells and endothelial tissues. This leads to fluid retention, impaired gas exchange, and severe respiratory symptoms, especially in high-risk individuals.

Q7. A 26-year-old sexually active female comes with complaints of burning micturition and haematuria. On investigation, the causative agent is a gram-positive coccus, which is coagulase-negative. What is the most likely organism?

1. Staphylococcus epidermidis
2. Staphylococcus aureus 
3. Staphylococcus saprophyticus
4. Staphylococcus haemolyticus

Answer: 3) Staphylococcus saprophyticus

Explanation:

The causative agent is a gram-positive coccus that is coagulase-negative. In sexually active people, Staphylococcus saprophyticus is the most common cause of a UTI with the above features.

Coagulase-negative staphylococci (CoNS) are part of the human body's normal flora. Significant species include:

• Staphylococcus epidermidis.
• Staphylococcus saprophyticus.
• Staphylococcus haemolyticus.
• Staphylococcus lugdunensis.

Staphylococcus saprophyticus:

• Commonly found on human skin and periurethral area.
• Causes urinary tract infections—second most common cause, especially in sexually active young women.
• Generally susceptible to most antibiotics.
• Resistant to nalidixic acid.
• Identifiable by its novobiotic resistance.

Also read: NEET PG High Yield Questions for Microbiology

Q8. Which statement correctly describes antigenic drift and antigenic shift in influenza viruses?

1. Drift causes pandemics; shift causes minor epidemics.
2. Drift involves minor mutations; shift involves genetic reassortment.
3. Shift occurs in Influenza A and B; drift occurs only in Influenza A.
4. Drift produces a new strain; shift evades immune recognition.

Answer: 2) Drift involves minor mutations; shift involves genetic reassortment.

Explanation:

Antigenic drift involves minor changes due to point mutations, while antigenic shift is an abrupt change due to genetic reassortment.

Q9. A healthcare worker suffers a needle-stick injury from a patient who is HBsAg positive. The healthcare worker's anti-HBs titer is 7 IU/mL. What is the appropriate post-exposure prophylaxis?

1. HBIG only
2. HBV vaccine series only
3. HBIG and start HBV vaccine series
4. No treatment needed

Answer: C) HBIG and start HBV vaccine series

Explanation: 

For individuals with a history of inadequate vaccine response (anti-HBs titer of <10 IU/mL), the recommended treatment is to administer HBIG and start a complete 3-dose vaccine series or a second dose of HBIG after one month.

Alsoo read: Gonorrhea: Causes, Symptoms, Risk Factors, Diagnosis, Treatment

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