NEET PG Microbiology Syllabus

Microbiology syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Microbiology in NEET PG, not a summary of it.

1. 1

   General Microbiology

   5 topics

   • Introduction to Microbiology
     • Historical perspective
     • Scope and significance of microbiology
   • Microbial Classification
     • Bacteria
     • Viruses
     • Fungi
     • Protozoa
     • Helminths
   • Microbial Structure
     • Cell morphology
     • Structure
     • Function
   • Microbial Growth and Nutrition
     • Growth requirements
     • Culture media
     • Methods of microbial cultivation
   • Sterilization and Disinfection
     • Physical methods of microbial control
     • Chemical methods of microbial control
2. 2

   Bacteriology

   6 topics

   • Bacterial morphology
     • Shapes
     • Arrangements
     • Staining characteristics
   • Bacterial genetics
     • Plasmids
     • Transposons
     • Bacterial conjugation
     • Transformation
     • Transduction
   • Bacterial metabolism
     • Aerobic and anaerobic respiration
     • Fermentation
     • Metabolic pathways
   • Bacterial pathogenesis
     • Virulence factors
     • Mechanisms of pathogenicity
     • Host defense mechanisms
   • Clinical microbiology
     • Laboratory diagnosis of bacterial infections
     • Culture techniques
     • Antibiotic susceptibility testing
   • Important bacterial pathogens
     • Gram-positive and gram-negative bacteria causing respiratory infections
     • Gram-positive and gram-negative bacteria causing gastrointestinal infections
     • Gram-positive and gram-negative bacteria causing urinary infections
     • Gram-positive and gram-negative bacteria causing other infections
3. 3

   Viral structure

   1 topic

   • Classification, morphology, and composition of viruses
4. 4

   Fungal morphology

   1 topic

   • Yeasts, molds, and dimorphic fungi
5. 5

   Parasite classification

   1 topic

   • Protozoa and helminths
6. 6

   Immune system components

   1 topic

   • Innate immunity and adaptive immunity

Microbiology flashcards for NEET PG

24 of 51 cards from the Microbiology deck — real questions with worked answers.

1. What is the chemical composition and function of the bacterial peptidoglycan cell wall, and how does it differ between Gram-positive and Gram-negative bacteria?

   Peptidoglycan (murein) is N-acetylglucosamine + N-acetylmuramic acid cross-linked by peptide bridges; it provides shape and resists osmotic lysis. Gram-positive bacteria have a thick multilayered peptidoglycan (retains crystal violet), while Gram-negative have a thin layer plus an outer membrane containing LPS.

2. What is the principle of the Gram stain and the role of each reagent?

   Crystal violet (primary stain) stains all cells; Gram's iodine (mordant) forms a CV-iodine complex; acetone/alcohol (decolorizer) removes the complex from thin-walled Gram-negative cells; safranin (counterstain) makes Gram-negatives appear pink/red while Gram-positives remain purple.

3. What is bacterial endotoxin, where is it located, and what is its active component?

   Endotoxin is lipopolysaccharide (LPS) in the outer membrane of Gram-negative bacteria; its toxic active component is Lipid A, which triggers fever, hypotension, and septic shock via cytokine (TNF, IL-1) release. It is heat-stable and released on cell lysis.

4. Describe the four phases of the bacterial growth curve.

   Lag phase (adaptation, no division), log/exponential phase (maximal division, most susceptible to antibiotics), stationary phase (growth equals death, spore formation, toxin production), and decline/death phase (death exceeds growth due to nutrient depletion and toxic products).

5. What is the difference between sterilization, disinfection, and antisepsis?

   Sterilization = complete destruction of ALL microbial forms including spores; disinfection = destruction of vegetative pathogens (not necessarily spores) on inanimate objects; antisepsis = destruction/inhibition of microbes on living tissue.

6. What are the standard parameters (temperature, pressure, time) for autoclave (moist heat) sterilization?

   121°C at 15 lb/sq inch (1.1 kg/cm²) pressure for 15 minutes; it works by moist heat (steam) causing protein denaturation. The biological indicator used is spores of Geobacillus stearothermophilus.

7. What temperature and time are used for hot air oven (dry heat) sterilization, and what is its mechanism?

   160°C for 1 hour (or 170°C for ~40 min); dry heat sterilizes by oxidation/protein denaturation. It is used for glassware, powders, and oils. The biological indicator is spores of Bacillus atrophaeus (subtilis).

8. List the cells and components of the innate immune system.

   Physical barriers (skin, mucosa), neutrophils, macrophages, dendritic cells, NK cells, complement, and pattern-recognition receptors (e.g., Toll-like receptors). It is non-specific, has no memory, and responds immediately.

9. What are the three pathways of complement activation and their triggers?

   Classical pathway (antigen-antibody complexes, starts at C1), alternative pathway (microbial surfaces, properdin, no antibody needed), and lectin pathway (mannose-binding lectin binding mannose on microbes). All converge on C3 convertase.

10. Which complement components are anaphylatoxins, the major opsonin, and the membrane attack complex?

    Anaphylatoxins: C3a, C4a, C5a (C5a is also chemotactic); major opsonin: C3b; membrane attack complex (MAC): C5b-6-7-8-9 forming a pore that lyses the cell.

11. Differentiate cell-mediated immunity from humoral immunity.

    Cell-mediated immunity is mediated by T lymphocytes (CD4 helper, CD8 cytotoxic) against intracellular pathogens, tumors, and grafts; humoral immunity is mediated by B-cell-derived antibodies against extracellular pathogens and toxins.

12. What are the functions of CD4+ helper T cells versus CD8+ cytotoxic T cells, and which MHC do they recognize?

    CD4+ helper T cells recognize antigen on MHC class II and secrete cytokines to coordinate immunity; CD8+ cytotoxic T cells recognize antigen on MHC class I and directly kill infected/tumor cells.

13. Compare the structure and roles of the five immunoglobulin classes.

    IgG: most abundant, crosses placenta, secondary response, opsonization. IgM: pentamer, first/primary response, best at complement fixation. IgA: dimer in secretions (mucosal immunity). IgE: mediates allergy/anaphylaxis and antiparasitic response. IgD: B-cell surface receptor.

14. Which immunoglobulin appears first in the primary immune response and which dominates the secondary (anamnestic) response?

    IgM appears first in the primary response; IgG dominates the secondary (anamnestic) response, which is faster, higher in titer, and longer-lasting due to memory cells.

15. What is the prozone phenomenon in antigen-antibody reactions?

    Prozone phenomenon is a false-negative result in agglutination/precipitation tests caused by antibody EXCESS, which prevents lattice formation. It is corrected by diluting the serum.

16. Differentiate the direct and indirect Coombs (antiglobulin) tests.

    Direct Coombs test detects antibodies already bound to RBCs in vivo (e.g., hemolytic disease of newborn, autoimmune hemolytic anemia); indirect Coombs test detects free antibodies in serum (e.g., antenatal antibody screening, cross-matching).

17. What is the principle of ELISA and what does each component detect?

    ELISA (Enzyme-Linked Immunosorbent Assay) uses an enzyme-conjugated antibody/antigen; a substrate produces a measurable color change proportional to the antigen/antibody concentration. It is used for HIV screening, hormone assays, and serology.

18. What is the Widal test and which antigens are measured?

    The Widal test is an agglutination test for enteric fever (typhoid) detecting antibodies against Salmonella Typhi O (somatic) and H (flagellar) antigens, and Paratyphi AH/BH. A rising titer in paired sera is more significant than a single value.

19. List the four (Gell and Coombs) types of hypersensitivity with their mechanisms.

    Type I (immediate/anaphylactic): IgE-mediated mast cell degranulation. Type II (cytotoxic): IgG/IgM against cell-surface antigens. Type III (immune complex): antigen-antibody complex deposition. Type IV (delayed): T-cell mediated, peaks at 48-72 hrs.

20. Give a classic clinical example of each of the four types of hypersensitivity.

    Type I: anaphylaxis/atopic asthma. Type II: ABO transfusion reaction, Goodpasture syndrome. Type III: serum sickness, SLE, Arthus reaction. Type IV: tuberculin (Mantoux) test, contact dermatitis, graft rejection.

21. Differentiate Bruton agglobulinemia, DiGeorge syndrome, and SCID as primary immunodeficiencies.

    Bruton X-linked agammaglobulinemia: B-cell defect (BTK gene), absent immunoglobulins. DiGeorge syndrome: thymic aplasia (22q11 deletion), T-cell deficiency with tetany. SCID: combined T and B cell defect (e.g., adenosine deaminase deficiency).

22. What is the difference between hyperacute, acute, and chronic graft rejection?

    Hyperacute rejection: minutes-hours, preformed antibodies (Type II). Acute rejection: days-weeks, T-cell mediated (Type IV), reversible with immunosuppression. Chronic rejection: months-years, fibrosis/vascular damage, irreversible.

23. Differentiate live attenuated, killed (inactivated), and toxoid vaccines with examples.

    Live attenuated (BCG, OPV, MMR, varicella): weakened organism, strong/long immunity, contraindicated in immunocompromised. Killed (IPV, rabies, hepatitis A, pertussis whole cell): inactivated, needs boosters. Toxoid (tetanus, diphtheria): inactivated toxin.

24. At what age is the BCG vaccine given and against what does it protect?

    BCG (Bacille Calmette-Guérin), a live attenuated Mycobacterium bovis vaccine, is given at birth (within the first year). It primarily protects against severe childhood TB (miliary TB and tuberculous meningitis).

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