Comparative study of a biphasic culture system (Roche MB Check system) with a conventional egg medium for recovery of mycobacteria. Aichi Mycobacteriosis Research Group.

OBJECTIVE

The clinical utility of a new biphasic culture system (Roche MB Check system) for the recovery of mycobacteria was evaluated in comparison with a conventional egg based medium.

DESIGN

A total of 905 clinical specimens (mainly sputum samples) were tested in 9 clinical microbiology laboratories in Aichi Prefecture, Japan. The recovery rate and detection time of mycobacteria from the specimens were compared between the biphasic system and the egg medium.

RESULTS AND CONCLUSION

Of the 905 samples, 311 were positive in the culture of mycobacteria. The recovery rate of the biphasic system was superior to that of the egg medium (99.0% versus 74.0%, P < 0.0001). In addition, the biphasic system showed a considerable decrease in the number of days required for isolation compared with the egg medium (18.8 days vs. 23.1 days for Mycobacterium tuberculosis, P < 0.0001; 13.4 days vs. 19.8 days for M. avium complex, P = 0.007). The biphasic system is therefore proposed as a feasible and practical method for the recovery of mycobacteria from clinical specimens.