Case #033

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.