Phylogenetic diversity and susceptibility of Candida species from women using contraceptive devices in northcentral Nigeria

Abstract

Background: The use of contraceptive devices predisposes women to vulvovaginal candidiasis (VVC) globally. Despite the high incidence of VVC and antifungal resistance to azoles, the genetic diversity and resistance pattern among contraceptive users in Nigeria is poorly investigated. This study therefore sought to characterize and determine the phylogenetic breadth of Candida species as well as their resistance to antifungal agents. Methodology: This study recruited 1,600 women using contraceptive devices who visited selected gynaecology and obstetrics clinics in northcentral Nigeria. Candida species were isolated and characterized using conventional methods and sequencing of the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA). Bayesian phylogenetic analysis was used to characterize the diversity of Candida species and primer-specific PCR was used to detect the presence of resistant genes. Agar well diffusion technique was used for the determination of antifungal susceptibility profiles. Data analysis was done by Kruskal-Wallis Chi-square test on R Console software version 3.2.2, followed by post-hoc Wilcoxon rank sum test with Bonferroni correction for multiple pairwise comparisons of means where there was a significant difference between the antifungal agents. The level of significance was set at p < 0.05. Results: A total of 710 (44.3%) out of the 1,600 women using contraceptive devices had VVC with five species of Candida identified in them. Although Candida albicans was the predominant (43.2%, n=307) species, other non-albicans Candida species include Candida (Nakaseomyces) glabrata (19.0%, n=135), Candida tropicalis (15.8%, n=112), Candida parapsilosis (8.9%, n=63), and Candida akabanensis (13.1%, n=93) which were phenotypically identified as Candida (Nakaseomyces) glabrata. All the Candida species showed varying degrees of susceptibilities to voriconazole, fluconazole and nystatin. However, resistance of C. albicans to fluconazole was 29.0%, C. tropicalis to nystatin (46.0%) and to voriconazole (14.0%), while C. akabanensis was 100.0% resistant to voriconazole and fluconazole. Kruskal-Wallis Chi-square test showed nystatin as the most effective antifungal agent against the Candida species (2=786.03, df=2, p<0.001). Also, resistant gene Erg11 was identified in all the Candida species that were phenotypically resistant to the antifungal agents tested. Conclusion: Women using contraceptive devices in northcentral Nigeria harbor phylogenetically diverse Candida species including C. akabanensis, an uncommon cause of VVC. Of these Candida species, C. albicans, C. tropicalis and C. akabanensis were notable for multidrug drug resistance as well as harboring Erg11 resistance gene.