ASSESSMENT OF A BIPHASIC CULTURE SYSTEM FOR MYCOBACTERIA ISOLATION FROM PATIENTS HIGHLY SUSPECTED OF TUBERCULOSIS

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).