Isolation time of patients with tuberculosis
One of the difficulties of managing tuberculosis in hospitalized patients is the maintenance of isolation time. The golden standard diagnostic test is culture negative for Mycobacterium tuberculosis. AFB stain can still be positive with non-viable bacteria, leading to more isolation time than necessary. The morphological characteristics of bacilli are useful: broken bacteria with gaps in staining are probable dead bacteria, but this information is rarely used to define the isolation time. The Chaisson LH et al study, done at Zuckerberg San Francisco General Hospital and Trauma Center, included 234 patients . GeneXpert molecular testing was used to define non-contagious state of tubercular disease in isolated patients with tuberculosis. There were no false positive molecular result. Molecular testing showed excellent agreement with culture, and diagnosed accurately all 7-positive patients. Discontinuing isolation has many useful features; patients can be discharged earlier and the psychological implications of isolation are minimized.
Chaisson LH, Duong D, Cattamanchi A, Marguerite Roemer BA, Handley MA, Schillinger D, et al. Association of rapid molecular testing with duration of respiratory isolation for patients with possible tuberculosis in a US Hospital. JAMA Inter Med. 2018;(Suppl E 1-E8). http://doi10.1001/jamainternmed.2018.3638