Characterization of clinical isolates of the Cryptococcus neoformans-Cryptococcus gattii species complex from the...

The differentiation and classification of pathogenic Cryptococcus species provides useful data for epidemiological studies and for the clinical diagnosis and treatment of patients.

The aim of this study was to characterise 40 clinical Cryptococcus isolates obtained from patients at the Tropical Medicine Foundation of Amazonas (FMTAM) from 2006 to 2008.

It was used phenotypic (i.e., enzyme production and antifungal resistance) and molecular biological (URA5-RFLP) experiments.

Patients with HIV/AIDS were most affected with cryptococcosis. Thirty-one (75.5%) of the clinical isolates were classified as Cryptococcus neoformans and 9 (22.5%) as Cryptococcus gattii. High amounts of protease and phospholipase enzymes were produced by most of the isolates. Using the disk diffusion test (CLSI M44-A), 81, 35 and 100% of the C. neoformans isolates were characterized as susceptible to fluconazole, itraconazole and amphotericin B, respectively, whereas 78, 56 and 100% of the C. gattii isolates were susceptible to these antimicrobial agents. The average of Minimal Inhibitory Concentration (MIC) for C. neoformans and C. gattii isolates was 0.26 and 0.58 μg/mL, respectively. The 9 isolates of C. gattii had a fingerprint pattern comparable with the VGII molecular type, while all 31 isolates of C. neoformans presented with a pattern consistent with the VNI type.

This study confirms the importance of HIV/AIDS for the cryptococcosis epidemiology, the susceptibility of the isolates to amphotericin B and the high prevalence of the molecular genotypes VNI and VGII in the north of Brazil.