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🎯 MBBS Microbiology - High Yield Topic Map

Vaccination, Prophylaxis & Treatment

Acting as MBBS University Examiner | 30-Year PYQ Analysis

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📊 EXAM PATTERN BREAKDOWN (100 Marks)

Note: Based on Dr. MGR / similar university patterns, 100M papers typically run: 2×10 + 8×5 + 10×2 + 20 MCQ. I've mapped your exact pattern to highest-yield topics accordingly.

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🔴 TIER 1 - MUST KNOW (Repeated Every 2-3 Years)

1. RABIES - #1 Most Repeated Topic

• Post-exposure prophylaxis (PEP) - complete wound management + immunization
• Pre-exposure prophylaxis (PrEP) schedule
• Types of vaccines: HDCV, PCECV, PVRV - schedule (Days 0, 3, 7, 14, 28)
• Rabies immunoglobulin (RIG): Human RIG vs Equine RIG, dose calculation
• WHO animal bite classification (Category I, II, III)
• Negri bodies, diagnosis, Seller's stain

• Category III bite: wound wash + RIG + vaccine (all three)
• RIG dose: 20 IU/kg (HRIG), 40 IU/kg (ERIG)
• No contraindication to PEP even in pregnancy

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2. TUBERCULOSIS (BCG + Treatment)

• BCG vaccine: Mycobacterium bovis (attenuated), given at birth, intradermal
• BCG efficacy: 80% against TB meningitis and miliary TB
• DOTS (Directly Observed Treatment, Short-course)
• RNTCP drug regimens: 2HRZE/4HR (Category I)
• Drugs: Isoniazid (H), Rifampicin (R), Pyrazinamide (Z), Ethambutol (E), Streptomycin (S)
• Latent TB treatment: Isoniazid preventive therapy (IPT) 6 months
• MDR-TB definition and management

• BCG given by: intradermal route
• Mantoux test: positive >10mm induration (5mm in HIV)
• Drug causing optic neuritis: Ethambutol
• Drug causing orange urine: Rifampicin

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3. HIV/AIDS - Prophylaxis & Treatment

• Modes of transmission + pathogenesis
• Lab diagnosis: ELISA (screening) → Western Blot (confirmatory)
• CD4 count interpretation
• Antiretroviral therapy (ART): NRTI + NNRTI + PI combinations
• First-line regimen: TDF + 3TC + EFV (Tenofovir + Lamivudine + Efavirenz)
• Post-exposure prophylaxis (PEP): 28-day course, within 72 hours
• Opportunistic infection prophylaxis: Cotrimoxazole (CD4 <200), Fluconazole
• Prevention of Mother-To-Child Transmission (PMTCT)

• PEP for needlestick injury - drugs and duration
• Cotrimoxazole prophylaxis in HIV - when to start (CD4 <200)

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4. HEPATITIS B - Vaccine + Treatment

• Hepatitis B vaccine: recombinant (yeast-derived), 3 doses (0,1,6 months)
• Schedule: at birth, 6 weeks, 14 weeks (EPI schedule)
• HBsAg, anti-HBs, HBeAg, anti-HBc - serological markers
• Passive immunization: Hepatitis B Immunoglobulin (HBIG) - within 12-24 hrs of exposure
• Treatment: Tenofovir / Entecavir (chronic HBV)
• Lamivudine (older; resistance develops)
• Perinatal exposure management: HBIG + vaccine within 12 hours of birth

• Vaccine type: recombinant subunit
• First serological marker to appear: HBsAg
• Window period marker: anti-HBc IgM
• Vaccine-induced immunity marker: anti-HBs

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5. TETANUS - Prophylaxis & Treatment

• Passive immunization: TIG (Tetanus Immunoglobulin) - 500 IU IM, for unimmunized/unknown
• Active immunization: TT (Tetanus Toxoid) - 3 doses primary + boosters
• Wound management protocol: clean minor wound vs tetanus-prone wound
• Treatment: TIG + sedation (diazepam) + penicillin/metronidazole + wound debridement
• Tetanus toxoid schedule in pregnancy (TT1 + TT2 for neonatal tetanus prevention)

• Management of tetanus-prone wound in an unvaccinated patient

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🟠 TIER 2 - HIGH YIELD (Repeat Every 3-5 Years)

6. POLIO - Vaccine Types

• OPV (Oral Polio Vaccine/Sabin): live attenuated, 3 serotypes, oral, herd immunity
• IPV (Inactivated Polio Vaccine/Salk): killed, injectable, no VAPP risk
• VAPP: Vaccine-Associated Paralytic Poliomyelitis - only with OPV
• Pulse Polio Programme - 0, 2, 4 months + booster
• Contraindication of OPV: immunocompromised patients

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7. CHOLERA - Vaccine + Treatment

• OCV (Oral Cholera Vaccine): Shanchol, Dukoral - 2 doses, 14 days apart
• WHO recommended for endemic areas + outbreak control
• Treatment: ORS (cornerstone), IV Ringer's lactate (severe), Tetracycline/Doxycycline + Azithromycin
• El Tor biotype - classical vs El Tor Rice watery stool

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8. TYPHOID - Vaccine + Treatment

• Vi capsular polysaccharide vaccine (ViCPS): single dose IM, >2 years
• Ty21a (oral live attenuated): 3-4 doses, oral, >6 years
• Typhoid conjugate vaccine (TCV): newest, >6 months
• Treatment: Ceftriaxone (1st line), Azithromycin, Fluoroquinolones (resistance emerging)
• Widal test: O and H agglutinins

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9. DIPHTHERIA - Immunization

• DPT vaccine: Diphtheria + Pertussis + Tetanus toxoid
• DT/Td for adults (reduced antigen)
• Schick test: immunity testing (positive = susceptible, no antitoxin)
• Treatment: Diphtheria Antitoxin (DAT) + Penicillin/Erythromycin
• Loeffler's serum medium, Albert stain (metachromatic granules)

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10. MENINGITIS - Prophylaxis

• Meningococcal vaccine: MenACWY, MenB
• Chemoprophylaxis for contacts: Rifampicin (600mg BD × 2 days) OR Ciprofloxacin single dose
• Haemophilus influenzae b (Hib) vaccine: conjugate, part of EPI
• Pneumococcal vaccine: PCV13 (conjugate) + PPSV23 (polysaccharide for adults)
• Treatment of bacterial meningitis: Ceftriaxone (empiric), Penicillin (after sensitivity)
• Dexamethasone to reduce inflammation + sequelae

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11. MALARIA - Prophylaxis & Treatment

• Chemoprophylaxis: Chloroquine (sensitive areas), Mefloquine/Doxycycline/Atovaquone-Proguanil (resistant areas)
• Treatment: P. vivax/ovale - Chloroquine + Primaquine (radical cure, hypnozoites)
• P. falciparum (uncomplicated): ACT (Artemisinin-based Combination Therapy)
• Severe malaria: IV Artesunate
• Primaquine: G6PD testing before use (risk of hemolysis)
• RTS,S (Mosquirix): first malaria vaccine, approved by WHO 2021

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12. INFLUENZA - Vaccine + Treatment

• Vaccine types: Trivalent (TIV), Quadrivalent (QIV) - annual due to antigenic drift
• Live attenuated influenza vaccine (LAIV/FluMist): contraindicated in immunocompromised
• Treatment: Oseltamivir (Tamiflu) - within 48 hours of onset
• Zanamivir (inhaled), Baloxavir
• Antigenic drift vs Antigenic shift (shift causes pandemics)

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🟡 TIER 3 - IMPORTANT (Every 5-7 Years)

13. MEASLES / MMR Vaccine

• MMR: live attenuated, 2 doses (9 months + 15 months India), SC route
• Vitamin A supplementation with measles treatment
• Complications: subacute sclerosing panencephalitis (SSPE)

14. CHICKENPOX / VZV - Vaccine + Treatment

• Varicella vaccine: live attenuated, 2 doses
• VZIG (Varicella Zoster Immunoglobulin): for immunocompromised + neonates
• Treatment: Acyclovir (antiviral)
• Best sample for lab diagnosis: vesicular fluid (MCQ)

15. TYPHUS (Rickettsial) - Prophylaxis

• No licensed vaccine currently
• Doxycycline: prophylaxis and treatment of choice

16. PLAGUE - Prophylaxis

• Doxycycline/Tetracycline chemoprophylaxis for contacts
• Streptomycin or Gentamicin: treatment

17. ANTHRAX

• Ciprofloxacin prophylaxis for inhalation anthrax exposure
• Anthrax vaccine: pre-exposure for high-risk
• Treatment: Ciprofloxacin or Doxycycline

18. LEPTOSPIROSIS

• Prophylaxis: Doxycycline 200mg weekly
• Treatment: Penicillin G (mild), Ceftriaxone (severe)

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📝 POSSIBLE EXAM QUESTIONS BY FORMAT

✅ Most Likely 10-MARK QUESTION (Choose one):

"A 35-year-old healthcare worker sustained a needlestick injury from a known HIV-positive patient. Discuss: (a) Post-exposure prophylaxis (b) Management protocol (c) Follow-up"

"A patient is bitten by a dog in a rural area. Discuss the management with emphasis on anti-rabies prophylaxis and treatment."

"A 30-year-old male presents with fever, weight loss, diarrhea, and generalized lymphadenopathy. (a) Probable diagnosis (b) Pathogenesis (c) Lab diagnosis (d) Prophylaxis and treatment" ← Confirmed from 2025 PYQ

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✅ Most Likely 5-MARK SHORT ESSAY QUESTIONS (14 questions):

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✅ Most Likely 3-MARK QUESTIONS (5 questions):

1. Cotrimoxazole prophylaxis in HIV - when, dose, indications
2. Window period in Hepatitis B - markers
3. Schick test - principle, interpretation
4. VAPP - definition, prevention
5. Meningococcal contact prophylaxis - Rifampicin dose/duration

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✅ TOP 20 MCQ PREDICTIONS (Vaccination & Prophylaxis):

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🏆 30-YEAR FREQUENCY RANKING (Examiner's Priority List)

RANK 1  ▶ Rabies (PEP, vaccine types, WHO categories)
RANK 2  ▶ HIV/AIDS (ART, PEP, opportunistic prophylaxis)
RANK 3  ▶ Tuberculosis (BCG, DOTS, drug regimens)
RANK 4  ▶ Tetanus (TIG, TT, wound protocol)
RANK 5  ▶ Hepatitis B (vaccine, HBIG, serological markers)
RANK 6  ▶ Polio (OPV vs IPV, VAPP)
RANK 7  ▶ Diphtheria (DPT, Schick test, DAT)
RANK 8  ▶ Malaria (ACT, Primaquine, RTS,S)
RANK 9  ▶ Typhoid (ViCPS, TCV, treatment)
RANK 10 ▶ Meningitis (chemoprophylaxis, Hib, PCV)
RANK 11 ▶ Cholera (OCV, ORS)
RANK 12 ▶ Influenza (antigenic drift/shift, Oseltamivir)
RANK 13 ▶ Measles/MMR
RANK 14 ▶ Varicella/VZV (VZIG, Acyclovir)
RANK 15 ▶ Leptospirosis (Doxycycline)

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⚡ LAST-MINUTE REVISION FLASH TABLE

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