title: A Novel Solid Medium for Culturing Mycobacterium tuberculosis Isolates from Clinical Specimens.
abstract: 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.
authors.affiliation: Aix Marseille Université, URMITE, UMR CNRS 7278, IRD 198, Inserm 1095, Marseille, France.
authors.forename: S
authors.initials: S
authors.lastname: Asmar
authors.affiliation: bioMérieux SA, Innovation Unit, La Balme Les Grottes, France.
authors.forename: S
authors.initials: S
authors.lastname: Chatellier
authors.affiliation: bioMérieux SA, Innovation Unit, La Balme Les Grottes, France.
authors.forename: C
authors.initials: C
authors.lastname: Mirande
authors.affiliation: bioMérieux SA, R&D Microbiology, La Balme Les Grottes, France.
authors.forename: A
authors.initials: A
authors.lastname: van Belkum
authors.affiliation: bioMérieux SA, Innovation Unit, La Balme Les Grottes, France.
authors.forename: I
authors.initials: I
authors.lastname: Canard
authors.affiliation: Aix Marseille Université, URMITE, UMR CNRS 7278, IRD 198, Inserm 1095, Marseille, France.
authors.forename: D
authors.initials: D
authors.lastname: Raoult
authors.affiliation: Aix Marseille Université, URMITE, UMR CNRS 7278, IRD 198, Inserm 1095, Marseille, France michel.drancourt@univ-amu.fr.
authors.forename: M
authors.initials: M
authors.lastname: Drancourt
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D003470:Culture Media / Q000737:chemistry*; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000254:growth & development* / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D013997:Time Factors; D014376:Tuberculosis / Q000175:diagnosis*
chemical_list: D003470:Culture Media