Urine and sputum tuberculosis tests: defining the trade-offs in endemic HIV and tuberculosis settings

Clinicians need improved tests to diagnose tuberculosis, especially in people living with HIV. Sputum-based molecular tests (eg, the Xpert MTB/RIF and Xpert Ultra assays, Cepheid, Sunnyvale, CA, USA) perform well in adults with presumptive tuberculosis who are HIV-positive (ie, sensitivity ≥75% and specificity ≥93%),1 but many patients are unable to produce a quality sputum sample. An alternative biomarker is lipoarabinomannan, a glycolipid from the cell wall of replicating Mycobacterium tuberculosis that enters the bloodstream, is filtered by the kidney, and concentrates in urine.