Hair isoniazid levels predict TB sputum culture conversion.

<sec><title>BACKGROUND</title>Sputum culture is the gold standard for diagnosing TB disease and confirming treatment outcomes. However, the turnaround time is 6-8 weeks, which leads to delays in decision-making regarding the care of TB patients.</sec><sec><title>OBJECTIVE</title>To evaluate isoniazid hair drug levels as a predictor of sputum culture conversion at 8 weeks of TB treatment.</sec><sec><title>METHODS</title>We enrolled 56 TB patients and started them on treatment. We collected sputum and hair samples at baseline and Weeks 4, 8, and 26. Sputum culture was done on solid and liquid media. The hair drug levels assay was done using liquid chromatography-tandem mass spectrometry.</sec><sec><title>RESULTS</title>We excluded 22 participants (8 with contaminated cultures, 10 were unable to produce sputum, and 4 missed the Week 8 visit). Of the remaining 28, about 24 (86%) were TB sputum culture-negative with a median hair drug level of 0.0514 ng/ml (IQR 0.1165-0.0314), and 4 (14.1%) were TB culture-positive, with a median hair drug level of 0.0192 (IQR 0.0267-0.0132).</sec><sec><title>CONCLUSION</title>A median isoniazid hair level of ≥0.05 ng/ml may be predictive of sputum culture conversion by the end of the intensive phase of TB treatment.</sec>.