H. Laforest et Ph. Lagrange, ASSESSMENT OF A BIPHASIC CULTURE SYSTEM FOR MYCOBACTERIA ISOLATION FROM PATIENTS HIGHLY SUSPECTED OF TUBERCULOSIS, Pathologie et biologie, 42(2), 1994, pp. 145-149
The efficiency of a biphasic culture medium, MB-Check (MB) for mycobac
terial isolation was assessed versus two egg-based media Loewenstein-J
ansen and Coletsos (LJC). 74 specimens from 30 patients highly suspect
ed of tuberculosis were inoculated on all three media. Smear examinati
on gave 20 positive samples out of 74 (presence of acid-fast bacilli :
AFB). All these specimens gave a positive culture on the MB medium. H
owever, 20 % of the samples did not grow on LJC, mainly due to contami
nants (non-significant difference, p > 0.05). 32 samples out of 74 wer
e found positive for Mycobacterium tuberculosis with MB-Check, and 25
out of 74 with LJC media (NS, p > 0.05). Five atypical mycobacteria we
re isolated in the biphasic medium, 3 of which were also recovered on
the LJC media. Average recovery time (ART) for Mycobacterium tuberculo
sis was 20.2 +/- 8.3 days and 28.4 +/- 10.6 days respectively for MB-C
heck and LJC media. This difference is statistically significant (p =
0.001). When considering only the samples found positive upon smear ex
amination, the difference is more obvious : ART for M. tuberculosis is
16.6 +/- 4.4 days and 25.3 +/- 8.7 days respectively for MB-Check and
LJC media (p < 0.05). Of the 14 specimens found negative upon smear e
xamination, 12 gave a positive culture on the MB medium, vs 9 on the L
JC medium (NS). Of these 12 specimens, 2 were cerebrospinal fluids whi
ch were found negative after culture on LJC media. The difference in A
RT between MB-Check and LJC media was not statistically significant (2
7.8 +/- 8.5 days vs 33.8 +/- 11.4 days) (p > 0.05).