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DNB Microbiology Previous Year Questions

These are the DNB Microbiology theory questions asked by NBEMS in the December 2025 and June 2025 exams, listed paper by paper as they appeared. The Prep DNB app has all 20 DNB sessions from December 2014 to December 2025 — 800 questions in total — with repeat-question tracking, examiner keywords and MCQs.

Jump to: December 2025 · June 2025 · Important topics · Older papers

DNB Microbiology December 2025 Question Paper

Paper 1

  1. Discuss the germ theory of disease and Kochs postulates. [10]
  2. What are the different phases of clinical trials and what is the main objective of each? [10]
  3. Discuss diagnostic parameters to evaluate a diagnostic kit. [10]
  4. Discuss the terminal disposal of sharps generated by hospitals. [10]
  5. Explain the role of barcoding and GPS tracking for BMW bags as mandated by CPCB. How does this apply to a hospital-based molecular microbiology lab? [5+5]
  6. Discuss in brief about genetic transformation in bacteria. [10]
  7. Discuss the treatment of carbapenem-resistant enterobacterales. [10]
  8. Write a short note on digital droplet PCR. [10]
  9. Discuss the basic principle and usage of LAMP method for the diagnosis of infections. [10]
  10. What is the basic principle and use of BLAST search in microbiology? [10]

Paper 2

  1. Write in brief about non-typhoidal salmonella infections and emerging antimicrobial resistance among them. [10]
  2. Discuss the diagnosis and treatment of lymphogranuloma venereum. [5+5]
  3. Phaeohyphomycosis. [10]
  4. Discuss the current methods of detection of MDR-TB. [10]
  5. Discuss the current status of cholera in India. [10]
  6. Toxin mediated diarrheal diseases. [10]
  7. Discuss the emerging drug resistance among Aspergillus fumigatus. [10]
  8. Discuss the clades of Candida auris and drug resistance among them. [5+5]
  9. Discuss the laboratory methods for therapeutic drug monitoring (TDM) of antifungal drugs. [10]
  10. Write briefly about mycotoxins and the diseases caused by them. [10]

Paper 3

  1. Discuss various genes and antigens of Hepatitis B virus. What are the different mutations seen in it? [6+4]
  2. Discuss the epidemiology, laboratory diagnosis and prophylaxis of Japanese encephalitis. [4+3+3]
  3. Pathogenesis and laboratory diagnosis of herpes simplex viruses. [10]
  4. HIV diagnosis and treatment in infants. [10]
  5. Nipah virus. [10]
  6. What do you understand by iatrogenic CJD and how to prevent it? [10]
  7. What are the various causes of parasitic diarrhea and how to prevent them? [10]
  8. Discuss the food borne trematodes and their laboratory diagnosis. [10]
  9. Write in brief about National Filaria Eradication Programme (NFEP)'. [10]
  10. Discuss drug resistant amebiasis. [10]

Paper 4

  1. Discuss about CNS device associated HAIs. [10]
  2. Discuss prevention bundles for CLABSI. [10]
  3. Discuss about syndromic approach in STI. [10]
  4. Discuss antimicrobial stewardship and cascade reporting. [6+4]
  5. Discuss edible vaccines. [10]
  6. Discuss role of CRISPR based diagnostics for infections. [10]
  7. Lab-on-chip. [10]
  8. Discuss the various types of operation theatres with purpose of each of them. [10]
  9. What are key microbiological tests performed during commissioning of new or renovated operation theatres and what are the key acceptable limits as per International standards? [10]
  10. Discuss about agents of biological warfare. [10]

DNB Microbiology June 2025 Question Paper

Paper 1

  1. Write briefly on factors influencing efficacy and methods to test efficacy of sterilant/disinfectant. [5+5]
  2. Colistin resistance: a) Mechanism of resistance. [5] b) Laboratory detection. [5]
  3. Define catheter associated blood stream infections. Discuss the surveillance strategies for catheter associated blood stream infections. Describe bundle care. [2+4+4]
  4. Discuss the role of probiotics & prebiotics in human health. [5+5]
  5. Discuss antibiotic interactions. How is in-vitro antibiotic synergy tested in the laboratory? [5+5]
  6. Discuss the non-culture based tests used in microbiology for diagnosis of infectious diseases. Discuss their advantages and disadvantages. [5+5]
  7. a) Define sharp injury and prevention strategies in health care. [5] b) Discuss the management for Hepatitis B infection following needle stick injury in health care worker. [5]
  8. Discuss toll like receptors and their significance. [10]
  9. What is acquired and intrinsic resistance. Briefly discuss the genetic mechanisms of antibiotic resistance in bacteria with examples. [3+7]
  10. Write about the modifications of PCR as diagnostic aid in various diseases. [10]

Paper 2

  1. Discuss the clinical manifestations and laboratory diagnosis of histoplasmosis. [5+5]
  2. Write briefly on oncogenic bacteria? [10]
  3. Write about allergic broncho-pulmonary aspergillosis (ABPA) under the following headings: definition, manifestations, diagnosis. [2+3+5]
  4. Discuss briefly on medically significant non-diphtheria corynebacteria. [10]
  5. Discuss briefly regarding antimicrobial resistance in Neisseria gonorrhoea. Describe briefly regarding mechanism of resistance to beta-lactam antibiotics and fluoroquinolones [5+5]
  6. Lobomycosis. [10]
  7. Halophilic vibrio. [10]
  8. Laboratory diagnosis of non-albicans candida species. [10]
  9. Current status of leprosy in India. [10]
  10. A patient of suspected enteric fever visits the OPD. Describe in detail the laboratory diagnosis and management of the patient. [5+5]

Paper 3

  1. a) Babesiosis. [5] b) Microsporidiosis. [5]
  2. Discuss Epstein Barr virus under pathogenesis and laboratory diagnosis. [5+5]
  3. a) Artemisinin resistance in plasmodium falciparum. [5] b) Advances in malaria vaccines. [5]
  4. Discuss monkeypox under epidemiology, diagnosis and prevention. [4+3+3]
  5. Write briefly about paragonimus westermani. [10]
  6. Write briefly about tropism and its significance in HIV. [10]
  7. Discuss cysticercosis under epidemiology and laboratory diagnosis. [5+5]
  8. Write briefly about chikungunya in India. [10]
  9. Newer staining methods for parasites. [10]
  10. Recent advances in hepatitis E. [10]

Paper 4

  1. Discuss next generation sequencing (NGS) under principles and prospects in microbiology. [5+5]
  2. Machine learning versus artificial intelligence and role in microbiology. [10]
  3. Write briefly about post exposure prophylaxis against blood borne viral infections. [10]
  4. Write briefly about novel alternatives to antibiotics. [10]
  5. Write briefly about reverse vaccinology. [10]
  6. Role of biomarkers in guiding antimicrobial therapy. [10]
  7. Point of care tests for sexually transmitted infections. [10]
  8. Newer recombinant vaccines. [10]
  9. Methods of storage and preservations in bacteria. [10]
  10. Viral oncogenicity. [10]

High-Yield DNB Microbiology Topics

A selection of 26 of the 39 important topics curated in the app from repeated DNB Microbiology questions.

Sterilization and lab basics

  • Sterilization: autoclave (principle, cycle, BI), hot air oven, ETO, plasma; Spaulding classification
  • Disinfection: hypochlorite, glutaraldehyde, alcohol; CSSD setup and quality indicators
  • Staining: Gram, ZN (fluorescent), special stains; culture media (selective, differential, transport)

Antimicrobial resistance — high priority

  • Beta-lactamases: ESBL, AmpC, carbapenemases (MBL, KPC); MRSA, VRE, CRE
  • ESKAPE pathogens and colistin resistance
  • AMR detection: disk diffusion, MIC, E-test, automated systems, molecular methods (PCR, NGS)

Immunology and vaccines

  • Innate immunity: TLRs, complement, NK cells; adaptive immunity: T/B cells, MHC
  • Hypersensitivity types I–IV; primary immunodeficiency (SCID, CGD); IRIS in HIV
  • Vaccines: live, killed, subunit, conjugate, mRNA; adjuvants; cold chain

Gram-positive bacteria

  • Staphylococcus aureus: toxins, MRSA, CoNS, TSST-1, PVL
  • Streptococcus: pyogenes (ASO), pneumoniae (vaccines, resistance), agalactiae (neonatal sepsis)
  • Enterococcus: VRE, HLAR; Clostridia: C. difficile, tetani, botulinum, perfringens (gas gangrene)

Gram-negative bacteria and enteric infections

  • Enterobacteriaceae: E. coli pathotypes, Klebsiella, Salmonella, Shigella
  • Typhoid: Widal limitations, blood culture, carriers, vaccines
  • Non-fermenters: Pseudomonas, Acinetobacter, Burkholderia (SPACE organisms in HAI)

Mycobacteria and anaerobes

  • TB diagnosis: GeneXpert, LPA, MGIT, culture; MDR/XDR/Pre-XDR, BPaL, bedaquiline/delamanid
  • NTM: MAC, M. abscessus; anaerobic culture and identification

Virology

  • HIV: NACO testing strategies, viral load, drug resistance, EID, PEP/PrEP
  • Hepatitis B markers and HCV (genotyping, DAAs); HEV in pregnancy
  • COVID-19: RT-PCR, RAT, variants; influenza (shift/drift); RSV

Parasitology and mycology

  • Malaria: microscopy, RDT, species identification, drug resistance, P. knowlesi
  • Leishmaniasis (rK39), filariasis, toxoplasmosis, neurocysticercosis, hydatid disease
  • Intestinal protozoa: amoebiasis, giardiasis, cryptosporidium

Infection control and diagnostics

  • HAI prevention: VAP/CLABSI/CAUTI/SSI bundles; hand hygiene (WHO 5 moments)
  • Needle-stick injury and PEP; biomedical waste colour coding
  • Molecular diagnostics: PCR types, LAMP, CRISPR, MALDI-TOF, syndromic panels

Older DNB Microbiology Question Papers

The remaining 18 papers are available in the Prep DNB app, organized paper-wise with repeat-question tracking.

Get all 20 papers in the app

Previous Year Questions for Other DNB Subjects