IM27.1-18 | Tuberculosis — Practice Quiz

Correct. The NTEP 2020 definition of presumptive TB is any person with one or more of the four symptoms: cough ≥2 weeks, fever ≥2 weeks, significant weight loss, or drenching night sweats. A high-risk setting (crowded labour camp) and occupational exposure further support the designation. This patient meets multiple criteria.

The NTEP four-symptom screen (cough ≥2 weeks, fever ≥2 weeks, weight loss, night sweats) should be applied to every patient in a high-burden setting, especially those from crowded living or occupational environments.

The NTEP defines presumptive TB as presence of ANY ONE of four cardinal symptoms: cough ≥2 weeks, fever ≥2 weeks, significant weight loss, or drenching night sweats — not all four combined, and not blood-stained sputum alone. This patient satisfies multiple criteria.

Correct. Pleural effusion produces stony dullness on percussion (fluid is denser than lung), reduced breath sounds (fluid separates the lung from the chest wall), and reduced vocal fremitus (fluid attenuates transmitted vibrations). Bronchial breathing and increased fremitus indicate consolidation, not effusion.

Distinguish pleural effusion (stony dull, reduced BS, reduced fremitus) from consolidation (dull, bronchial breathing, increased fremitus) and pneumothorax (hyper-resonant, absent BS, reduced fremitus) — all can complicate pulmonary TB.

Pleural effusion is characterised by stony dullness (not resonance), reduced breath sounds, and reduced vocal fremitus. Bronchial breathing with increased fremitus indicates consolidation. Hyper-resonance with reduced sounds suggests pneumothorax.

Correct. The TST cut-offs are stratified by risk: ≥5 mm in HIV-positive individuals and other immunocompromised patients; ≥10 mm in high-risk groups (healthcare workers, recent contacts, migrants, prisoners, diabetes); ≥15 mm in low-risk populations. An 8 mm induration in an HIV-positive patient is positive. Note that a negative TST does not exclude TB in HIV-positive patients — anergy is common.

TST cut-offs: ≥5 mm (immunocompromised, HIV); ≥10 mm (high-risk groups, healthcare workers); ≥15 mm (low-risk population). False negatives occur in advanced HIV, severe malnutrition, and recent TB itself — a negative TST never excludes TB.

The Mantoux cut-off for HIV-positive patients is ≥5 mm (not 15 mm, not 10 mm) because immunosuppression reduces the inflammatory response even in sensitised individuals. 8 mm in this context is a positive result.

Correct. A CBNAAT result of MTB detected with RIF resistance detected defines presumptive RR-TB (rifampicin-resistant TB). The immediate steps under NTEP are: (1) mandatory Ni-kshay notification, (2) referral to a DR-TB centre, and (3) additional drug sensitivity testing — line probe assay (LPA) for isoniazid resistance and culture/DST for full second-line sensitivity profiling. Empirical kanamycin-based regimens are now avoided due to the BPaL (bedaquiline, pretomanid, linezolid) shift.

CBNAAT (Xpert MTB/RIF) is the NTEP first-line test for all presumptive TB. RIF resistance detected = presumptive RR-TB → mandatory Ni-kshay notification + DR-TB referral + LPA/culture DST. Never start DS-TB regimen when RIF resistance is confirmed.

A single CBNAAT RIF-resistance result is sufficient to define presumptive RR-TB under NTEP — it does not need three repetitions. Starting standard DS-TB treatment ignores confirmed resistance. The correct pathway is Ni-kshay notification, DR-TB centre referral, and second-line DST.

Correct. The NTEP (National Tuberculosis Elimination Programme) regimen for drug-sensitive TB is 2HRZE + 4HRE — all medications given DAILY (not thrice-weekly) using weight-band-based fixed-dose combinations (FDC). The RNTCP-era thrice-weekly intermittent regimen has been completely replaced. Ethambutol is maintained throughout the continuation phase under NTEP (unlike the older 2HRZE/4HR).

NTEP DS-TB regimen: 2HRZE + 4HRE, DAILY, weight-band FDC. Never cite thrice-weekly dosing. Ethambutol continues into the continuation phase (HRE not HR). This is one of the most frequently tested and most frequently mistaken points in Indian TB medicine.

The RNTCP thrice-weekly intermittent regimen is obsolete. NTEP mandates daily FDC dosing: 2 months intensive (HRZE) + 4 months continuation (HRE). The continuation phase includes ethambutol — it is NOT 4HR alone.

Correct. Diabetes mellitus is a major risk factor for active TB, conferring a 2–3 fold increased risk. The hyperglycaemic milieu impairs macrophage phagocytosis, neutrophil killing, and T-cell function. TB-DM patients have slower sputum conversion, higher relapse rates, and worse treatment outcomes. Rifampicin induces hepatic CYP450 enzymes and reduces levels of sulfonylureas and other oral antidiabetics, often requiring dose adjustment.

Diabetes-TB bidirectional interaction: DM → 2–3 fold TB risk, slower conversion, more relapses. TB-associated stress hyperglycaemia can unmask DM. Rifampicin lowers sulfonylurea/insulin levels via CYP induction. Screen all TB patients for DM and vice versa (bi-directional screening mandate under NTEP).

Diabetes significantly worsens TB outcomes: 2–3 fold increased risk, impaired macrophage function, slower sputum conversion, higher relapse rates. Rifampicin's CYP450 induction reduces sulfonylurea levels — a pharmacokinetic interaction that must be monitored.

Correct. CNS TB (TB meningitis, tuberculoma) requires an extended treatment duration: 2HRZE + 10HRE (total 12 months) under NTEP guidelines. Adjunctive corticosteroids (dexamethasone or prednisolone) are indicated to reduce meningeal inflammation and improve survival. Ethambutol is retained; streptomycin addition is not standard. CSF penetration of rifampicin and isoniazid is adequate.

Extended NTEP regimens: CNS TB = 2HRZE + 10HRE (12 months total) + adjunctive corticosteroids; Bone/joint TB = 2HRZE + 10HRE (12 months). Standard pulmonary = 2HRZE + 4HRE (6 months). Miliary TB = 6 months standard unless CNS involvement.

CNS TB requires total 12 months of treatment (2HRZE + 10HRE, not the standard 6 months) plus adjunctive corticosteroids. The standard 6-month regimen is reserved for pulmonary and most extrapulmonary TB; CNS and bone/joint TB are the two key extensions.

Correct. Rifampicin is one of the most potent inducers of hepatic cytochrome P450 enzymes (CYP3A4, CYP2C9, CYP2C19) and P-glycoprotein. This accelerates the metabolism of many co-administered drugs including antiretroviral agents, oral contraceptives, sulfonylureas, warfarin, and corticosteroids, leading to subtherapeutic plasma levels. For HIV-TB co-infection, efavirenz dose is often increased to 800 mg/day in heavier patients, and PI-based regimens are avoided.

Rifampicin = potent CYP450 inducer → reduces levels of: efavirenz (increase dose or use dolutegravir instead), warfarin (increase dose, monitor INR), oral contraceptives (use barrier method), sulfonylureas, corticosteroids, phenytoin. Always review all co-medications when starting rifampicin.

Rifampicin INDUCES CYP450 (does not inhibit it) — this accelerates drug metabolism and causes subtherapeutic levels of co-administered drugs like efavirenz, warfarin, oral contraceptives, and sulfonylureas. This is one of the most important pharmacokinetic interactions in clinical medicine.

Correct. NTEP recommends isoniazid preventive therapy (IPT) for child contacts of smear-positive TB patients under 6 years of age who have a positive Mantoux test but no evidence of active TB disease. The regimen is isoniazid 10 mg/kg/day (maximum 300 mg) for 6 months. This child fits all three criteria: age <6, Mantoux-positive, active disease excluded. BCG vaccination does not replace chemoprophylaxis once Mantoux positivity is established.

NTEP IPT criteria: child <6 years, household contact of smear-positive TB, Mantoux ≥10 mm (or ≥5 mm if immunocompromised), active TB excluded. Regimen: isoniazid 10 mg/kg/day for 6 months. Also indicated for HIV-positive individuals at any age regardless of Mantoux result.

NTEP recommends isoniazid preventive therapy (IPT) — NOT full ATT — for child contacts under 6 who are Mantoux-positive with no active disease. IPT: isoniazid 10 mg/kg/day for 6 months. Full ATT is for confirmed active disease only.

Correct. Under NTEP, notification of ALL TB cases (both drug-sensitive and drug-resistant, from both public and private healthcare facilities) on the Ni-kshay web portal is mandatory within 24 hours of diagnosis. This is a legal obligation under the Gazette notification of 2012 (TB as a notifiable disease) and reinforced under NTEP. The portal captures patient demographics, disease classification, treatment site, and contact details for follow-up.

Ni-kshay = national TB notification portal; mandatory for every confirmed TB case within 24 hours regardless of drug sensitivity, healthcare sector, or disease site. Failure to notify by private practitioners is a legal offence. The system also triggers contact tracing and Ni-kshay Poshan Yojana (nutritional support) for notified patients.

Ni-kshay notification is mandatory for ALL TB cases (not just DR-TB) within 24 hours of diagnosis, from ALL healthcare facilities — public and private. Verbal notification to the DTO is insufficient. Ni-kshay is the national web-based surveillance platform.