Diagnostic utility of auramine O smear microscopy for detecting non-tuberculous mycobacteria versus Mycobacterium tuberculosis complex in adult clinical samples: a 5-year retrospective study (2018–2022)

The diagnostic utility of AOSM was limited by poor sensitivity and PPV for NTM, and by poor sensitivity for MTBC. A positive AOSM result was a much more reliable indicator of the presence of MTBC than of NTM. In settings with a higher burden of TB than NTM disease, AOSM-positive patients with a clinical history suggestive of TB disease should be considered for TB treatment initiation while awaiting culture confirmation. In contrast, AOSM-positive patients whose clinical history is not strongly suggestive of TB-or is suggestive of NTM disease-should undergo additional testing using alternative methods, such as rapid molecular assays, that can reliably detect and distinguish between MTBC and NTM while awaiting culture confirmation.