Experimental in vitro efficacy study on the interaction of epiroprim plus isoniazid against Mycobacterium tuberculosis

Thirty Mycobacterium tuberculosis strains (8: INHR/INHR, 12: INHR/RIFS, 10: INHS/RIFS) were examined against MICs of epiroprim (EPM) and isoniazid (IN H) separately or in association. EPM alone proved to be insufficiently acti ve against the various mycobacterial isolates (MIC greater than or equal to 256 mug/ml). The observed average sensitivity to the association of EPM pl us INH was, in contrast, considerably increased, as reflected by reduced MI Cs and lower percentages of resistant strains. MICs ranged between 16 and 3 2 mug/ml EPM and 2 and 4 mug/ml INH for INHR strains. All INHS isolates wer e inhibited by a concentration of 0.125 mug/ml EPM and 0.06 mug/ml INH. The fractional inhibitory concentration indices indicated an additive activity on INHR/ RIFR strains and a synergistic activity on INHR/RIFS and INHS/RIF S strains. The synergistic activity of this drug association needs to be co nfirmed in an animal model. Copyright (C) 2001 S. Karger AG, Basel.