Tuberculosis — SAQ

Stem A (pulmonary TB — diagnosis and first-line treatment)

A 34-year-old man presents with 8 weeks of cough, evening fever, night sweats, and 7 kg weight loss. He smokes and works in a crowded hostel. CXR: right upper lobe cavitation. Sputum GeneXpert MTB/RIF: M. tuberculosis detected, rifampicin resistance not detected. HIV test negative. Weight 55 kg. Baseline LFTs normal, visual acuity normal. ^[22]

Stem B (CNS TB — for part d)

Separately, a 28-year-old woman has 2 weeks of fever, headache, and increasing drowsiness. CSF: lymphocytic pleocytosis, high protein, low glucose. GeneXpert positive on CSF. CT: basal meningeal enhancement, no large hydrocephalus yet. ^[5]

Questions

a) Stem A — state the diagnosis category and the four first-line drugs with adult doses for the intensive phase. (4 marks)

Drug-susceptible pulmonary tuberculosis (bacteriologically confirmed; rifampicin-susceptible on Xpert).^[22]

WHO: 2HRZE/4HR (6 months of rifampicin-containing therapy).^[22] ATS/CDC/IDSA 2016: intensive 2 months INH + RIF + PZA + EMB, then 4 months INH + RIF.^[9]

Adult daily doses (ATS): isoniazid 5 mg/kg (typically 300 mg); rifampin 10 mg/kg (typically 600 mg); pyrazinamide and ethambutol weight-banded. Pyridoxine 25–50 mg/day if neuropathy-risk.^[9]

b) List four essential baseline checks and the key adverse effects to counsel for each major drug. (4 marks)

Baseline: weight, HIV test, LFTs, visual acuity/colour vision (ethambutol), pregnancy test if relevant, sputum for follow-up, contact tracing.^[9]

Toxicities (ATS teaching):

• Rifampicin — orange body fluids, hepatitis, CYP450 induction (OCP/warfarin/PIs)
• Isoniazid — hepatitis, peripheral neuropathy (pyridoxine 25–50 mg/day)
• Pyrazinamide — hepatitis, hyperuricaemia/gout
• Ethambutol — optic neuritis — stop and urgent review if visual change
• Drug-induced liver injury — suspect when ALT ≥3× ULN with hepatitis symptoms, or ≥5× ULN without symptoms; stop hepatotoxic drugs.^[9]

c) Outline public-health actions and when treatment is extended or modified. (3 marks)

• Notify under the national programme (NTEP/Ni-kshay in India); adherence support / DOT
• Contact screening; LTBI treatment in high-risk contacts (NTCA/CDC preferred: 3HP, 4R, or 3HR)^[12]
• Airborne precautions until non-infectious
• Extend/modify for: TBM (ATS 2 + 7–10 months, optimal duration not defined + steroids 6–8 weeks), CNS/bone/joint (WHO: some experts longer than 6 months), rifampicin resistance (BPaLM), severe hepatitis, HIV co-treatment
• Do not add a single drug to a failing regimen — investigate adherence and resistance^[22][9]

d) Stem B — immediate management priorities including steroid evidence. (4 marks)

Tuberculous meningitis — start anti-TB therapy urgently. ATS: 2 months INH+RIF+PZA+EMB then additional 7–10 months INH+RIF (optimal duration not defined) plus adjunctive dexamethasone or prednisolone tapered over 6–8 weeks.^[9]

Thwaites (NEJM 2004): adjunctive dexamethasone reduced the risk of death (RR 0.69, 95% CI 0.52–0.92) but did not significantly reduce severe disability among survivors. The trial milligram schedule is not in the abstract — do not invent 0.15 mg/kg as “the Thwaites dose”.^[5]

Supportive: ABC, seizures, hydrocephalus, HIV test.^[5][9]

Additional teaching points

LTBI: PREVENT TB — weekly rifapentine 900 mg + isoniazid 900 mg for 12 weeks, completion 82.1 vs 69.0%, hepatotoxicity 0.4 vs 2.7% vs 9 months isoniazid. CDC: INH 15 mg/kg, 900 mg maximum; rifapentine weight-banded to 900 mg.^[10][12]

MDR/RR-TB: WHO 6-month BPaLM (bedaquiline, pretomanid, linezolid 600 mg, moxifloxacin) for eligible people ≥14 years; BPaL if fluoroquinolone-resistant. TB-PRACTECAL: mITT unfavorable 11 vs 48% vs 9–20-month standard care.^[22][16]

BCG: mainly prevents life-threatening TB in infants and young children; has not controlled the global epidemic (Pai).^[2]

References8ShowHide

1. [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
2. [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
3. [10]Sterling TR, Villarino ME, Borisov AS, et al. Three months of rifapentine and isoniazid for latent tuberculosis infection N Engl J Med, 2011.PMID 22150035
4. [12]Sterling TR, Njie G, Zenner D, et al. Guidelines for the Treatment of Latent Tuberculosis Infection: Recommendations from the NTCA and CDC, 2020 MMWR Recomm Rep, 2020.PMID 32053584
5. [16]Nyang'wa BT, Berry C, Kazounis E, et al. A 24-Week, All-Oral Regimen for Rifampin-Resistant Tuberculosis N Engl J Med, 2022.PMID 36546625
6. [21]World Health Organization Global tuberculosis report 2025 World Health Organization, 2025.Source
7. [22]World Health Organization WHO consolidated guidelines on tuberculosis. Module 4: treatment and care World Health Organization, 2025.Source
8. [2]Pai M, Behr MA, Dowdy D, et al. Tuberculosis Nat Rev Dis Primers, 2016.PMID 27784885