Abstract：Using 37 mono-resistant to isoniazid, 10 pan-sensitive Mycobacterium tuberculosis (M. tuberculosis) clinical isolates and H37Rv, the effects of the four efflux pump inhibitors, verapamil (VP), chlorpromazine (CPZ), thioridazine (TZ) and carbonyl cyanide m-chlorophenyl hydrazone (CCCP), to the minimum inhibitory concentration (MIC) of isoniazid for M. tuberculosis were studied by means of microplate Alamar blue assay detecting the changes of isoniazid's MIC. χ2 test of paired comparison of enumeration data was used to compared the levels of isoniazid's MIC changed before and after added VP, CPZ, TZ and CCCP. Of 37 M. tuberculosis isolates mono- resistant to isoniazid, the isoniazid's MICs of 24 (6 4.86%), 18(48.65%), 16(43.24%) and 14(37.84%) strains were decreased by VP, CPZ, TZ and CCCP, respectively, and 2 fold reduction were most common, the isolates of which's MIC of isoniazid reduced by ≥2 fold caused by VP were more than that caused by TZ and CCCP, the P value was all ﹤0.05. And the MICs of 6 of 10 pan-sensitive M. tuberculosis and H37Rv were decreased at least 2 fold by VP. The results show that the four drug efflux pump inhibitors had different influence on the MIC of isoniazid for M. tuberculosis, and VP had the most strongest effect for decreasing the MIC of isoniazid.
2013, Vol. 29 
