Time to detection of Mycobacterium tuberculosis as an alternative to quantitative cultures

• Published in: Tuberculosis (Edinburgh, Scotland) Vol. 91; no. 3; pp. 257 - 259
• Main Authors: Bark, C.M, Okwera, A, Joloba, M.L, Thiel, B.A, Nakibali, J.G, Debanne, S.M, Boom, W.H, Eisenach, K.D, Johnson, J.L
• Format: Journal Article
• Language: English
• Published: Scotland Elsevier Ltd 01-05-2011
• Subjects: Adolescent; Adult; BACTEC; Clinical Trials, Phase II as Topic; Colony Count, Microbial; Colony forming units; Culture Media - pharmacology; Female; Humans; Infectious Disease; Male; Middle Aged; Mycobacterium tuberculosis; Mycobacterium tuberculosis - isolation & purification; Pulmonary/Respiratory; Retrospective Studies; Sputum - microbiology; Time Factors; Time to detection; Tuberculosis; Tuberculosis, Pulmonary - epidemiology; Tuberculosis, Pulmonary - microbiology; Uganda - epidemiology; Young Adult; Uganda; Colony forming units; Tuberculosis; BACTEC; Time to detection
• ISSN: 1472-9792; 1873-281X
• DOI: 10.1016/j.tube.2011.01.004

Summary Testing new drugs is critical to improving the treatment of tuberculosis. Quantitative cultures of Mycobacterium tuberculosis on solid media have been used in Phase 1 and 2 trials, but are time and resource intensive. Time to detection (TTD) of growth of M. tuberculosis in automated liquid culture systems is an alternative. TTD has been shown to correlate with CFU in quantitative cultures, and is faster and simpler to perform. We compared TTD in the BACTEC 460 liquid culture system with CFU in a clinical trial that included 110 subjects. Comparing all sputum cultures collected between baseline and 2 months we found a strong negative correlation between log10  CFU and TTD (rho = −0.91). In addition, when TTD at baseline was compared with 1 and 2 month sputum culture positivity, subjects whose cultures were negative after 1 and 2 months had a significantly longer median baseline TTD compared with subjects whose cultures were positive at 1 and 2 months (5 vs. 3 days and 3 vs. 2 days, respectively). TTD compares closely with CFU and represents a faster, simpler alternative to quantitative cultures.