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This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- Caused by Mycobacterium tuberculosis — airborne droplet transmission; notifiable disease
- Active pulmonary TB: chronic cough >3 weeks, haemoptysis, night sweats, weight loss, fever
- Diagnosis: 3× sputum samples (including early morning) for AFB smear and culture; CXR showing upper lobe cavitation
- Standard treatment (NICE NG33): 6-month RIPE regimen — Rifampicin + Isoniazid (6 months) + Pyrazinamide + Ethambutol (first 2 months)
- Latent TB: screen high-risk groups with Mantoux (tuberculin skin test) or IGRA; treat with 3 months isoniazid + rifampicin or 6 months isoniazid
Overview
Tuberculosis (TB) is caused by Mycobacterium tuberculosis, an aerobic, acid-fast bacillus transmitted via airborne droplets from patients with active pulmonary disease. After inhalation, the bacteria reach the alveoli and trigger a granulomatous immune response (Ghon focus + draining lymph node = Ghon complex). In most immunocompetent individuals, the infection is contained (latent TB — positive skin test/IGRA but asymptomatic and non-infectious). Approximately 5–10% of latently infected individuals develop active TB in their lifetime, with risk highest in the first 2 years and in immunosuppressed patients (HIV, anti-TNF therapy, corticosteroids).
Epidemiology
Approximately 4,500 cases of active TB are notified annually in England. Incidence is highest in London and in people born outside the UK (particularly South Asia, sub-Saharan Africa). TB is strongly associated with deprivation, homelessness, substance misuse, and prison populations. HIV co-infection dramatically increases the risk of progression from latent to active TB (5–15% per year vs 5–10% lifetime). Multi-drug resistant TB (MDR-TB — resistant to isoniazid and rifampicin) is increasing globally and requires specialist management.
Clinical Features
Symptoms
Chronic productive cough >3 weeks — often with haemoptysis
Night sweats — drenching, requiring change of clothes/bedsheets
Unexplained weight loss and anorexia
Low-grade fever, particularly evening pyrexia
Fatigue and malaise
Chest pain (pleuritic or from cavitation)
Extrapulmonary symptoms: lymphadenopathy (cervical — scrofula), bone/joint pain (Pott spine), headache (TB meningitis), abdominal symptoms
Signs
May be clinically normal in early disease
Crackles or bronchial breathing over the apex (upper lobe predilection)
Cervical lymphadenopathy (matted, non-tender — "cold abscess")
Cachexia in advanced disease
Signs of pleural effusion (exudative, lymphocytic)
Erythema nodosum (painful red nodules on shins)
Investigations
First-line
Chest X-rayUpper lobe consolidation/cavitation (reactivation TB); hilar lymphadenopathy (primary TB); miliary pattern (disseminated TB)
Sputum for AFB smear and culture (×3)Three samples including early morning sputum. ZN stain or auramine for AFB smear (rapid). Culture on Löwenstein-Jensen medium (takes 6–8 weeks) or liquid culture (MGIT — faster)
Nucleic acid amplification test (NAAT/GeneXpert)Rapid detection of M. tuberculosis DNA and rifampicin resistance — results within hours
Second-line
Mantoux test (tuberculin skin test)Intradermal injection of purified protein derivative (PPD) — read at 48–72 hours. ≥15 mm induration = strongly positive. Does NOT distinguish latent from active TB. False positive with BCG vaccination
IGRA (interferon-gamma release assay)QuantiFERON-TB Gold or T-SPOT — more specific than Mantoux, NOT affected by prior BCG vaccination. Used for latent TB screening
HIV testOffer to ALL patients with active or latent TB — co-infection changes management and prognosis
Specialist
CT thoraxIf CXR abnormal — better delineation of cavitation, lymphadenopathy, miliary pattern
Bronchoscopy with BALIf sputum smear-negative but clinical suspicion high — bronchoalveolar lavage for AFB/culture
Tissue biopsyFor extrapulmonary TB (lymph node, pleural, bone) — caseating granulomata on histology
Management
NICE NG33 (Tuberculosis), 20161
Notification and infection control
- TB is a NOTIFIABLE disease — notify local Health Protection Team immediately
- Respiratory isolation until non-infectious (smear-negative or 2 weeks of effective treatment)
- Contact tracing for all close contacts
2
Active pulmonary TB — standard 6-month regimen (RIPE)
- Initial phase (2 months): Rifampicin + Isoniazid + Pyrazinamide + Ethambutol (RIPE)
- Continuation phase (4 months): Rifampicin + Isoniazid (RI)
- Pyridoxine (vitamin B6) co-prescribed with isoniazid to prevent peripheral neuropathy
- Directly observed therapy (DOT) for patients at risk of non-adherence
3
Drug side effects to monitor
- Rifampicin: orange discolouration of bodily fluids, hepatotoxicity, enzyme inducer (reduces efficacy of OCP, warfarin)
- Isoniazid: peripheral neuropathy (prevented by pyridoxine), hepatotoxicity
- Pyrazinamide: hepatotoxicity (most hepatotoxic of the four), hyperuricaemia/gout
- Ethambutol: optic neuritis (visual acuity and colour vision — test before and during treatment)
- Baseline and regular LFTs for all patients
4
Latent TB treatment
- 3 months isoniazid + rifampicin (3HR) — preferred regimen
- OR 6 months isoniazid alone (6H)
- Screen high-risk groups: recent contacts, new entrants from high-incidence countries, immunosuppressed, healthcare workers
Complications
- Miliary TB: Haematogenous dissemination — widespread small nodules on CXR ("millet seeds"), multi-organ involvement
- TB meningitis: Headache, cranial nerve palsies, confusion — high mortality, requires extended treatment (12 months) + dexamethasone
- Pott disease: Spinal TB causing vertebral body destruction, kyphosis, paravertebral abscess
- Drug-resistant TB: MDR-TB (resistant to isoniazid + rifampicin) requires specialist regimens for 18–24 months
- Hepatotoxicity: From all first-line drugs — monitor LFTs, stop offending drug if ALT >5× ULN
UKMLA Exam Tips
- 1TB is a NOTIFIABLE disease — always mention this in exams
- 2Upper lobe cavitation on CXR + chronic cough + night sweats + weight loss in a high-risk patient = TB until proven otherwise
- 3RIPE for 2 months, then RI for 4 months = standard 6-month regimen — know this cold
- 4Ethambutol → optic neuritis (colour vision). Isoniazid → peripheral neuropathy (give pyridoxine). Rifampicin → orange urine + enzyme inducer
- 5IGRA is more specific than Mantoux because it is NOT affected by prior BCG vaccination
- 6Erythema nodosum + bilateral hilar lymphadenopathy = primary TB or sarcoidosis (key differential)
- 7HIV test should be offered to ALL patients with TB
practicetest your knowledge on tuberculosisApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — respiratory and beyond.
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