Asmar S., Chatellier S., Mirande C., van Belkum A., Canard I., Raoult Didier, Drancourt M. (2015). A novel solid medium for culturing Mycobacterium tuberculosis isolates from clinical specimens. Journal of Clinical Microbiology, 53 (8), p. 2566-2569. ISSN 0095-1137.
Titre du document
A novel solid medium for culturing Mycobacterium tuberculosis isolates from clinical specimens
Asmar S., Chatellier S., Mirande C., van Belkum A., Canard I., Raoult Didier, Drancourt M.
Source
Journal of Clinical Microbiology, 2015,
53 (8), p. 2566-2569 ISSN 0095-1137
The laboratory diagnosis of tuberculosis usually relies on culture-based isolation of the causative Mycobacterium tuberculosis bacteria. We developed and evaluated the performance of MOD9, a new blood-free derivative of the MOD4 solid medium on which we previously reported for the isolation and culture of mycobacteria. First, inoculation of Lowenstein-Jensen medium with 21 M. tuberculosis isolates at 10(5), 10(3), and 10 CFU yielded colonies in 5.7 +/- 1.5 days, 7.6 +/- 0.8 days, and 10.8 +/- 1.7 days versus 1.5 +/- 0.4 days, 3.5 +/- 0.6 days, and 4.9 +/- 1 days in MOD9 (P < 0.05, Student's t test). Further, the time to detectable growth of M. tuberculosis was measured on MOD9 and Lowenstein-Jensen media after duplicate inoculation of 250 clinical specimens decontaminated with 0.7% chlorhexidine. The contamination rate was 1.6% (4/250) on MOD9 versus 4.4% (11/250) on Lowenstein-Jensen medium (P = 0.11, Fisher's exact test). Chlorhexidine-MOD9 yielded 38/250 (15.2%) isolates versus 32/250 (12.8%) isolates for the chlorhexidine-LJ (P = 0.5195, Fisher's exact test). All together, eight M. tuberculosis isolates were cultured solely from chlorhexidine-MOD9, and two M. tuberculosis isolates were cultured solely from chlorhexidine-LJ. The time to detection was 9.8 +/- 3.9 (range, 5 to 18) days for chlorhexidine-MOD9 versus 17.4 +/- 5.9 (range, 10 to 35) days for chlorhexidine-LJ (P < 0.05, Student's t test). These data indicate the superiority of the MOD9 medium over the standard LJ medium following chlorhexidine decontamination for the recovery of M. tuberculosis.
