Susceptibility to antifungal agents and genotypes of Brazilian clinical and environmental Cryptococcus gattii strains

Author(s)

Silva, Dayane C. ^[1] ; Martins, Marilena A. ^[1] ; Szeszs, Maria Walderez ^[1] ; Bonfietti, Lucas X. ^[1] ; Matos, Dulcilena ^[1] ; Melhem, Marcia S. C. ^[1]

Affiliation

^[1] Secretary Hlth, Adolfo Lutz Inst, Mycol Unit, Publ Hlth Reference Lab, BR-01246902 Sao Paulo - Brazil

• Document type: Journal article
• Source: DIAGNOSTIC MICROBIOLOGY AND INFECTIOUS DISEASE; v. 72, n. 4, p. 332-339, APR 2012.
• Web of Science Citations: 13

Abstract

There are few reports concerning the in vitro antifungal susceptibility of clinical and environmental Cryptococcus gattii isolates. In this study, we performed polymerase chain reaction-restriction fragment length polymorphism to investigate the molecular subtypes of 50 clinical and 4 environmental Brazilian isolates of C. gattii and assessed their antifungal susceptibility for fluconazole (FLU) and amphotericin B (Amb) according to recent recommendations proposed for antifungal susceptibility testing of nonfermentative yeasts. Time-kill curve studies were performed using RPM1 1640 medium to analyze the fungicidal effect of AmB. We found 47 VGII (94%) molecular types and 3 VGI (6%) types among the clinical isolates. The environmental isolates were VGII (75%) subtype and VGI (25%) subtype. The FLU-MIC ranged from 1 to 64 mg L-1 and MIC50/MIC90 values were, respectively, 8/16 mg For AmB, the MICs were low and homogeneous, ranging from 0.12 to 0.5 mg L-1, for VGI or VGII. The time required to reach the fungicidal end point (99.9% killing) was 6 h for the majority of strains (64%), but viable cells of VGII were still present after 48 h of exposition. We pointed out the occurrence of high FLU-MICs for C. gattii isolates with highest values for VGII. Our data also suggest that the rate of killing of C. gattii by AmB is strain dependent, and viable cells of VGII genotype strains were still observed after an extended incubation time, addressing future studies to determine whether the in vitro fungicidal activity could be clinically relevant. (C) 2012 Elsevier Inc. All rights reserved. (AU)

• FAPESP's process: 10/04508-0 - Phenotypic and genotypic characterization of clinical and environmental isolates of Cryptococcus gattii in the State of São Paulo
• Grantee: Dayane Cristina da Silva Santos
• Support Opportunities: Scholarships in Brazil - Master