Pulmonary tuberculosis

Definition and natural history

Pulmonary tuberculosis is infection of the lungs caused by Mycobacterium tuberculosis. It spreads from person to person through inhalation of infected respiratory droplets.

After infection, the organism multiplies slowly in the lungs and may be eliminated, become dormant, or progress to active tuberculosis.

Only a minority of infected people develop active TB, but the risk is much higher in immunocompromised patients. HIV co-infection is common in some settings and must be actively considered.

Clinical features and differential diagnosis

• Typical features include cough lasting more than 2 weeks, with or without sputum production or haemoptysis.
• Other symptoms include prolonged fever, night sweats, anorexia, weight loss, chest pain, and fatigue.
• Consider TB in endemic settings in any patient with respiratory symptoms for more than 2 weeks who does not respond to non-specific antibacterial treatment.
• Children may present less specifically with cough, fever, poor weight gain, fatigue, or close contact with a TB case.
• Differential diagnoses include pneumonia, chronic obstructive pulmonary disease, lung cancer, pulmonary distomatosis, and melioidosis in Southeast Asia.

Laboratory investigation

• In the general population, use Xpert MTB/RIF on sputum where available because it detects Mycobacterium tuberculosis and rifampicin resistance at the same time.
• If Xpert MTB/RIF is unavailable, use sputum smear microscopy according to the local TB diagnostic algorithm.
• When HIV co-infection is suspected or diagnosed, use Xpert MTB/RIF and point-of-care urine LF-LAM where available.
• Assess HIV status, nutrition, pregnancy status, diabetes risk, previous TB treatment, TB contact history, drug-resistance risk, and baseline clinical severity.
• Use local or national TB programme guidance for sample collection, infection control, reporting, treatment initiation, and contact management.

Treatment principles

Pulmonary TB treatment is a multi-drug regimen, not a short antibiotic course. Standard drug-susceptible pulmonary TB treatment combines isoniazid, rifampicin, pyrazinamide, and ethambutol in an initial phase followed by a continuation phase, usually totalling 6 months.

Drug-resistant TB requires longer treatment with different medicine combinations under specialised TB programme guidance.

• Successful treatment requires uninterrupted therapy, adherence support, adverse-effect monitoring, and access to care until completion.
• Explain to the patient why stopping or taking medicines irregularly can cause treatment failure, relapse, transmission, and drug resistance.
• Check for drug interactions, especially with rifampicin, antiretrovirals, hormonal contraception, warfarin, some antidiabetics, anticonvulsants, and corticosteroids.
• Monitor for hepatotoxicity, rash, gastrointestinal intolerance, neuropathy, visual symptoms from ethambutol, and clinical non-response.
• Use pyridoxine prevention or treatment for isoniazid-associated neuropathy in patients at risk according to local protocol.

Infection control and public health

• Apply standard precautions and airborne precautions for suspected or confirmed infectious pulmonary TB in healthcare settings.
• Reduce close indoor exposure while infectious TB is being assessed and treatment started, especially around young children and immunocompromised people.
• Notify and manage through local TB/public-health systems. Contact tracing is essential.
• Screen close contacts for symptoms and risk factors. Provide preventive therapy when indicated through the TB programme.

Prevention, complications, and handover

• BCG vaccination in neonates provides partial protection against pulmonary TB and strong protection against severe childhood forms according to local immunisation policy.
• Close contacts may receive isoniazid preventive therapy for 6 months according to local protocol and after active TB has been excluded.
• Complications include haemoptysis, respiratory failure, pleural disease, dissemination, severe weight loss, chronic lung damage, treatment failure, relapse, and drug-resistant TB.
• Handover should include symptom duration, sputum status, Xpert or smear results, rifampicin-resistance result, HIV status, pregnancy status, nutrition, previous TB treatment, contact history, infection-control measures, treatment regimen, adherence plan, adverse-effect risks, and public-health notification.