Susceptibility of Candida isolates to Amphotericin B and Imidazole: effect of CCCP on Imidazole activity

Abstract

Nine Candida strains (one C. dublinienses , six Candida albicans, two C. tropicalis, and one C. krusei )  isolated from human genital specimens were characterized based on their susceptibility to amphotericin B and imidazole (done by an adaptation of the National Clinical Laboratory Standards Broth Macrodilution method).  All the nine strains were susceptible to amphotericin B with minimum inhibitory concentrations varying from 0.25 to 1.0 µg/ml, and resistant to imidazole at 64µg/ml drug concentration. Treatment of the strains with an efflux pump uncoupler (CCCP) significantly increased the killing in imidazole-treated cells, suggesting the presence of an efflux pump in imidazole resistance. These results support current evidence that amphotericin B is a more effective drug than imidazole (an azole), and that resistance of Candida strains to imidazole is related to the presence of efflux pump. It is suggested that CCCP effect be investigated in the resistance of Candida strains to other azoles.