Molecular epidemiology and antifungal susceptibility profiles of clinical Cryptococcus neoformans/Cryptococcus gattii species complex

Abstract

<b>Introduction.</b> Limited data regarding the epidemiology and susceptibility profiles of cryptococcosis are available in the Middle East.<b>Aim.</b> Our study aimed to evaluate the molecular diversity, mating types and antifungal susceptibility pattern of <i>Cryptococcus</i> species (<i>n</i>=14) isolated from 320 suspected patients with cryptococcosis.<b>Methodology.</b> The <i>URA5</i> gene was subjected to restriction fragment length polymorphism and sequence analysis. In addition, <i>in vitro</i> antifungal susceptibility testing was performed by Clinical and Laboratory Standards Institute (CLSI) M27-A4 and M59 guidelines.<b>Results.</b> Overall, 14 (4.4 %) patients were confirmed as cryptococcosis. Based on molecular type, 85.7 and 14.3 % of the isolates were <i>C. neoformans</i> VN I and VN II, respectively. Phylogenetic analysis of <i>URA5</i> gene sequences revealed clustering of VN I and VN II isolates into two distinct clades with a substantial difference within each molecular type. Voriconazole and 5-fluorocytosine, respectively, had the lowest (0.031 μg ml^-1) and highest (8 µg ml^-1) MICs. The epidemiological cutoff values (ECVs) for amphotericin B, fluconazole, voriconazole and 5-fluorocytosine encompassed ≥97 % of all 14 <i>C</i>. <i>neoformans</i> VN I species. However, according to the CLSI document M59, ECVs for itraconazole (7; 50 % of the isolates) and for posaconazole (1; 7.1 % of the isolate), were one log2 dilution higher than the wild type range. Combinations of amphotericin B with 5-fluorocytosine, amphotericin B with fluconazole and fluconazole with 5-fluorocytosine exhibited synergistic effects against 37, 31 and 12.5 % of the isolates, respectively.<b>Conclusion.</b> Our findings may significantly contribute to the development of management strategies for patients at a higher risk of cryptococcosis, particularly HIV-positive individuals.