Molecular typing and antifungal susceptibility of clinical isolates of Cryptococcus neoformans and Cryptococcus gattii species complexes from the National Invasive Fungal Surveillance Network of Uruguay

Abstract

Cryptococcus neoformans and C. gattii species complexes (phylum: Basidiomycota) are environmental yeasts and are the main cause of human cryptococcosis worldwide. The most recent molecular typing studies in Latin America have focused on the intertropical region. Thus, this study aimed to update the knowledge of human cryptococcosis in the South American temperate region. We obtained and analyzed 116 C. neoformans/C. gattii species complexes isolates from the Public Health Surveillance Laboratory between 2008-2013 and 2017-2021 (C. gattii species complex = 1 and C. neoformans species complex = 115). The average patient age was 45 years, with an overall male:female ratio of 3.1:1. The proportion of HIV-negative patients was significantly higher in the second study period. Restriction fragment length polymorphism typing of URA5 gene revealed that the C. neoformans species complex comprised 75.7% VNI, 2.6% VNII, 0.9% VNIII, 1.7% VNIV, 17.4% VNII/VNIV hybrids, and one C. neoformans isolate (0.9%) misidentified as VGI; the C. gattii species complex isolates comprised one VGII. The overall case fatality rate was 49.5%, with no differences in lethality between VNI and hybrid isolates. Of the four isolates responsible for episodes of reoccurrence, only one had a genotype different from the first episode. Antifungal susceptibility testing revealed that most isolates fell below the local epidemiological cut-off value. This study provides additional information for the analysis of C. neoformans/C. gattii species complexes dynamics in the South American temperate region.

Keywords: Cryptococcus neoformans/gattii species complex; AD hybrids; EUCAST; Uruguay; molecular typing.