Azole-resistant Candida albicans from a wild Brazilian porcupine (Coendou prehensilis): a sign of an environmental imbalance?

Abstract

This study aimed at evaluating the in vitro antifungal susceptibility of Candida albicans isolates obtained during necropsy of a wild Brazilian porcupine and the mechanism of azole resistance. Initially, we investigated the in vitro susceptibility of the three isolates to amphotericin B, caspofungin, fluconazole, itraconazole, ketoconazole and voriconazole. Afterwards, three sub-inhibitory concentrations (47, 21 and 12 mg/l) of promethazine, an efflux pump inhibitor, were tested in combination with the antifungal drugs in order to evaluate the role of these pumps in the development of antifungal resistance. In addition, the three isolates were submitted to RAPD-PCR and M13-fingerprinting analyses. The minimum inhibitory concentrations (MICs) obtained with the isolates were 1, 0.03125, 250, 125, 8 and 250 mg/l for amphotericin B, caspofungin, fluconazole, itraconazole, ketoconazole and voriconazole, respectively, and the isolates were found to be resistant to all tested azoles. The addition of the three subinhibitory concentrations of promethazine resulted in statistically significant (P < 0.05) reductions in the MICs for all tested drugs, with decreases to azoles being statistically greater than those for amphotericin B and caspofungin (P < 0.05). The molecular analyses showed a genetic similarity among the three tested isolates, suggesting the occurrence of candidemia in the studied animal. These findings highlight the importance of monitoring antifungal susceptibility of Candida spp. from veterinary sources, especially as they may indicate the occurrence of primary azole resistance even in wild animals.