Antifungal susceptibility and detection of mutant ERG11 gene in vaginal Candida isolates in University of Uyo Teaching Hospital, Uyo, Nigeria

Abstract

Background: Candida vulvovaginitis is an important cause of morbidity among women. Fluconazole and other azoles are among the commonest antifungal agents used for the treatment of this condition. Azole resistance among Candida species is an increasing problem, and mutations in the ERG11 gene is the commonest cause of fluconazole resistance in Candida. The objectives of this study are to determine antifungal susceptibility of vaginal Candida isolates and detect carriage of mutant ERG11 gene by them.

Methods: High vaginal swabs obtained from 260 participants were cultured on Saboraud’s Dextrose agar (SDA) for isolation of Candida, and identified by growth on CHROMagar Candida, germ tube and carbohydrate fermentation tests. Antifungal susceptibility to fluconazole, voriconazole, nystatin and flucytosine was determined by the Kirby Bauer disc diffusion method on supplemented Mueller Hinton agar. ERG11 gene was detected by conventional singleplex polymerase chain reaction (PCR) assay.

Results: Candida was isolated from 126 of 260 (48.5%) participants, and the identified species were Candida albicans, Candida glabrata, Candida tropicalis, Candida parapsilopsis and Candida famata. There were 112 (88.9%) isolates susceptible to fluconazole, 122 (96.8%) to voriconazole, 111 (88.1%) to nystatin, and 16 (6.6%) to flucytosine. The mutant ERG11 gene was detected in all four fluconazole-resistant isolates but not from any of five randomly selected fluconazole susceptible dose dependent (SDD) isolates.

Conclusion: Azole resistance among Candida in this environment is associated with mutant ERG11 gene expression.

Keywords: antifungi, fluconazole, Candida, ERG11, PCR