Tuberculosis — Viva

Q1: Microbiology and transmission (2 min)

• Mycobacterium tuberculosis complex; acid-fast bacilli (Ziehl–Neelsen/fluorochrome)
• Airborne droplet nuclei; only active pulmonary TB is contagious^[2]
• Primary infection vs reactivation (post-primary) patterns

Q2: Diagnosis algorithm (3 min)

• Suggestive: chronic cough, fever, night sweats, weight loss, upper lobe cavitation
• Xpert MTB/RIF: Boehme — 98.2% smear-positive / 72.5% smear-negative culture-positive on one direct test; less than 2 hours; also detects rifampicin resistance
• Smear microscopy, liquid culture + DST; HIV test all patients^[9]

Q3: Drug-susceptible regimen with doses (3 min)

• WHO 2HRZE/4HR for new pulmonary TB^[22]
• ATS: 2 months INH+RIF+PZA+EMB then 4 months INH+RIF; INH 5 mg/kg typically 300 mg, RIF 10 mg/kg typically 600 mg; pyridoxine 25–50 mg/day if neuropathy-risk^[9]
• Stop hepatotoxic drugs if ALT ≥3× ULN with symptoms or ≥5× without^[9]

Q4: Extrapulmonary and TBM (3 min)

• Lymph node, pleural, bone/joint, genitourinary, miliary, pericardial, CNS
• TBM: lymphocytic CSF, high protein, low glucose; ATS 2 + 7–10 months (optimal duration not defined) + dexamethasone/prednisolone 6–8 weeks; Thwaites RR death 0.69^[9][5]
• Miliary: haematogenous; choroidal tubercles; high mortality if delayed

Q5: Drug resistance (2 min)

• pre-XDR = MDR/RR + any fluoroquinolone; XDR = MDR/RR + any FQ + at least one additional Group A drug (LFX, MFX, bedaquiline, linezolid) — WHO 2021^[23]
• Never add one drug to a failing regimen
• WHO 6-month BPaLM (linezolid 600 mg) for eligible MDR/RR ≥14 years; BPaL if FQ-resistant^[22]

Q6: HIV co-infection and LTBI (2 min)

• Always test HIV; atypical CXR and disseminated disease more common
• ART timing: balance IRIS vs mortality benefit — follow current HIV-TB tables (do not invent a DTG milligram from ATS 2016)
• LTBI preferred: 3HP, 4R, or 3HR (NTCA/CDC 2020)^[12]

Q7: Prevention, burden, India programme pearls (2 min)

• WHO GTB 2025: 10.7 million incident / 1.23 million deaths in 2024; India 25%; DS success 88%; among top 10 causes of death and leading infectious-agent killer (2021 ranking: 10th overall, second after COVID-19)^[21]
• NTEP notification, free drugs, contact tracing, airborne precautions
• BCG: mainly life-threatening TB in infants and young children (Pai)^[2]

References7ShowHide

1. [2]Pai M, Behr MA, Dowdy D, et al. Tuberculosis Nat Rev Dis Primers, 2016.PMID 27784885
2. [5]Thwaites GE, Nguyen DB, Nguyen HD, et al. Dexamethasone for the treatment of tuberculous meningitis in adolescents and adults N Engl J Med, 2004.PMID 15496623
3. [9]Nahid P, Dorman SE, Alipanah N, et al. Official American Thoracic Society/Centers for Disease Control and Prevention/Infectious Diseases Society of America Clinical Practice Guidelines: Treatment of Drug-Susceptible Tuberculosis Clin Infect Dis, 2016.PMID 27516382
4. [12]Sterling TR, Njie G, Zenner D, et al. Guidelines for the Treatment of Latent Tuberculosis Infection: NTCA and CDC, 2020 MMWR Recomm Rep, 2020.PMID 32053584
5. [21]World Health Organization Global tuberculosis report 2025 World Health Organization, 2025.Source
6. [22]World Health Organization WHO consolidated guidelines on tuberculosis. Module 4: treatment and care World Health Organization, 2025.Source
7. [23]World Health Organization WHO announces updated definitions of extensively drug-resistant tuberculosis World Health Organization, 2021.Source