Evaluation of a rapid culture method on liquid Bio FM (BIO-RAD) medium for the isolation of mycobacteria.

The search continues for a simple, rapid culture system for the isolation of Mycobacterium tuberculosis in low-income countries. Bio FM (BIO-RAD) medium is an enriched 7H9 medium optimised for the growth of mycobacteria and contains a chromogenic indicator.To evaluate the detection rate and time to detection of mycobacteria using the Bio FM system in comparison with the Löwenstein-Jensen (LJ) medium method routinely used in our laboratory.A total of 270 pulmonary and 178 extra-pulmonary samples were cultured in parallel on Bio FM and LJ media. The mycobacterial detection rate and time were compared.The mycobacteria detection rate on Bio FM and LJ were not significantly different (respectively 97.9% and 93.15%, P > 0.05). The growth of M. tuberculosis was faster on Bio FM (mean 12.42 days [3-41] vs. 20.7 [10-48] days for LJ, P < 10(-6)).In our study, the culture method on liquid Bio FM medium was faster, but the detection rate was not better than with solid LJ medium.