8 Oct 2026 · Case #033
Pulmonary tuberculosis
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Diagnosis
Pulmonary tuberculosis
First-line treatment
Rifampicin, isoniazid, pyrazinamide and ethambutol (RIPE)
How the diagnosis is reached
A cough of more than three weeks that ignores a standard antibiotic has stopped being ordinary community-acquired pneumonia, and weight loss, drenching night sweats and low-grade fever narrow it to a short list: tuberculosis, lymphoma, malignancy. Each remaining clue chips at that list. Birth in a high-incidence country is the strongest single risk factor in a migrant population, since most adult disease here is reactivation of infection acquired years or decades earlier. The absence of smoking makes bronchial carcinoma much less likely in a 34-year-old, and there is no lymphadenopathy to suggest lymphoma. The blood picture is chronic inflammation rather than acute bacterial sepsis: a normal white cell count with a markedly raised CRP, a normocytic anaemia and a low albumin, all fitting something smouldering for months. A negative HIV test cuts both ways: it makes the diagnosis no less likely, but removes the immunosuppressed differential and predicts the classical radiographic pattern, since HIV-positive disease is often atypical or lower-zone. The radiograph is the giveaway: reactivation tuberculosis has a strong preference for the apical and posterior segments of the upper lobes, where oxygen tension is highest, and cavitation there is close to definitive. Acid-fast bacilli on the smear confirm mycobacteria, and the molecular test names the organism and screens for rifampicin resistance within hours rather than the weeks a culture takes. Treatment therefore starts now rather than in six weeks, since a positive smear with no rifampicin resistance is enough to commit. Four drugs for two months, rifampicin, isoniazid, pyrazinamide and ethambutol, then rifampicin and isoniazid alone for four more: six months for drug-sensitive pulmonary disease. Pyridoxine accompanies the isoniazid against the neuropathy it otherwise causes, and liver function is checked throughout, since three of the four are hepatotoxic. The case is notifiable, and the colleague on his shift with a cough of his own is exactly why.
Key clinical clues
- A cough of more than three weeks that failed to respond to a standard antibiotic
- Weight loss, drenching night sweats and low-grade fever, constitutional symptoms pointing at TB, lymphoma or malignancy
- Birth in a high-incidence country, the dominant risk factor for reactivation disease
- Normal white cell count with high CRP, anaemia and low albumin, chronic inflammation, not acute bacterial infection
- Upper-lobe cavitation on the chest radiograph, with acid-fast bacilli on sputum microscopy
The case in full
Presenting complaint
Patient history
A 34-year-old man has had a cough for about three months. It was dry at first and now brings up small amounts of sputum, occasionally streaked with blood. A week of amoxicillin from his GP six weeks ago made no difference at all.
Systemic symptoms
Symptoms
He has lost 8 kg over the same period without trying, and most nights wakes with his shirt and the sheets soaked through. He feels persistently tired and has had intermittent low-grade fevers. His appetite is poor.
Background and social history
Patient history
He moved to the UK from Ethiopia four years ago and works in a warehouse. He has never smoked and drinks little alcohol. He takes no regular medication and has no history of recurrent infections. A colleague on his shift has also had a prolonged cough this year.
Examination and observations
Vital signs
He is thin. Coarse crackles are heard over the right upper zone; the rest of the chest is clear. There is no lymphadenopathy, no clubbing and no rash.
| Parameter | Value | Reference |
|---|---|---|
| Temperature | 37.8 °CRef 36.1–37.5 | 36.1–37.5 |
| Heart rate | 94 bpmRef 60–100 | 60–100 |
| Respiratory rate | 18 /minRef 12–20 | 12–20 |
| SpO₂ (room air) | 96 %Ref 95–100 | 95–100 |
| BMI | 18.1 kg/m²Ref 18.5–24.9 | 18.5–24.9 |
Blood tests
Laboratory results
Routine bloods and a screening panel are sent.
| Parameter | Value | Reference |
|---|---|---|
| White cell count | 9.1 ×10⁹/LRef 4.0–11.0 | 4.0–11.0 |
| Lymphocytes | 1.1 ×10⁹/LRef 1.0–3.0 | 1.0–3.0 |
| Haemoglobin | 108 g/LRef 130–170 | 130–170 |
| CRP | 62 mg/LRef <5 | <5 |
| Albumin | 31 g/LRef 35–50 | 35–50 |
| HIV antigen/antibody | NegativeRef Negative | Negative |
| Blood cultures | No growth at 48 hRef No growth | No growth |
Chest imaging and sputum
Imaging
The chest radiograph shows patchy right upper lobe consolidation with a thick-walled cavity and volume loss, no effusion and no hilar mass. Sputum Ziehl–Neelsen staining shows acid-fast bacilli, and amplification testing detects M. tuberculosis with no rifampicin resistance.