Study on relationship between efflux pumps and Candida albicans resistance mechanism

Objective To investigate whether efflux mechanism is involved in azole resistant Candida albicans strains isolated in China. Methods We compared rhodamine 6G uptake and glucose induced efflux between azole sensitive and azole resistant strains to elucidate resistance to azole due to efflux pump, then measured mRNA level of efflux gene cdr1 and cdr2 by reverse transcriptase polymerase chain reaction (RT PCR). Results Rhodamine 6G moved from extra into the intracellular compartment in both azole resistant and azole sensitive strains quickly when in glucose free incubation condition. However, efflux of rhodanmine 6G was enhanced significantly in azole resistant strains and decreased in azole sensitive strains while adding glucose in the media. The mRNA level of efflux gene cdr1 and cdr2 was higher in clinical azole resistant strains and fluconazole induced resistant strains than strains reverted from resistance to sensitivity. However, all such strains had higher efflux gene expression than azole sensitive strains. Conclusions Efflux mechanism is associated with the resistance to azole in Candida albicans strains isolated in China. Fluconazole can induce efflux pumps expression leading to resistance to azole but the resistance to azoles can be reversed after withdrawing fluconazole.