In vitro antifungal susceptibility of yeasts and molds isolated from sputum of tuberculosis relapse and retreatment patients.

Abstract

Introduction opportunistic fungal infections due to immunosuppression coupled with antifungal drug resistance are an emerging challenge globally. The present study examined the antifungal susceptibility of yeasts and molds from sputum of tuberculosis retreatment and relapse patients at selected reference facilities in Kenya.

Methods a total of 340 sputa samples from patients who gave written informed consent were examined. Fungal culture was done on sabouraud dextrose agar (SDA). Molds were identified by macroscopic and microscopic features while yeasts were inoculated on CHROMTMagar Candida and confirmed using API 20C AUXTM. Itraconazole (ICZ), voriconazole (VCZ), fluconazole (FCZ) and amphotericin B (AMB) were tested using broth micro-dilution methods according to Clinical and Laboratory Standards Institute (CLSI).

Results out of the 340 samples, 14.4% (n=49) and 15.6% (n=53) were positive for yeasts and molds respectively. Candida albicans and C. krusei were the most predominant isolates constituting 49.0% (n=24) and 20.4% (n=10) of the total yeasts respectively. Aspergillus spp. were the most frequent (22.6%) molds and isolates with MICs ≥4μg/ml on the antifungal agents were noted. All the molds except two (n=2) isolates of Scedosporium aspiopermum exhibited MICs >4μg/ml for fluconazole. Overall, molds were more sensitive to AMB and VCZ. Candida albicans had MIC50 <0.06μg/ml, and MIC90<4μg/ml. There was a statistically significant difference (F=3.7, P=0.004<0.05) in the overall sensitivity pattern of molds for the four antifungal agents while there was no significant difference (F=1.7, P=0.154>0.05) in sensitivity exhibited by the yeasts.

Conclusion the study demonstrates the significance of fungal colonization in presumptive tuberculosis retreatment or relapse with evidence of triazole resistance. There is need to strengthen fungal diagnostic and clinical management capabilities in susceptible populations.