In vitro susceptibility of a large collection of Candida Strains against fluconazole and voriconazole by using the CLSI disk diffusion assay.

We evaluated all Candida spp. isolates obtained from patients admitted to two tertiary care hospitals between 1999 and 2003 in the city of São Paulo, Brazil. The in vitro activities of fluconazole (FCZ) and voriconazole were determined by the agar disk diffusion test using the Clinical and Laboratory Standards Institute M44-A guidelines. The inhibition zone diameters were read and interpreted automatically by the BIOMIC(®) image-analysis plate reader system. We tested a total of 4,625 strains, including 2,393 strains of C. albicans (51.7%), 658 of C. tropicalis (14.2%), 503 of C. glabrata (10.9%), 495 of C. parapsilosis (10.7%), 292 of C. rugosa (6.3%), 195 of C. guilliermondii (4.2%) and 89 of other Candida species (2.0%). Only 2.0% of the strains tested were classified as dose-dependent susceptible (DDS), and 5.8% of them were resistant to FCZ. The resistance or DDS to fluconazole was verified mainly among C. glabrata (7.8%), C. krusei (67.9%) and C. rugosa (65.1%). Voriconazole exhibited better activity in vitro than fluconazole, even in isolates fluconazole resistant. The resistance of fluconazole and voriconazole did not increase in the isolates of Candida spp. during the evaluated period.

Antifungal susceptibility of 1000 Candida bloodstream isolates to 5 antifungal drugs: results of a multicenter study conducted in São Paulo, Brazil, 1995-2003.

We evaluated all Candida sp. bloodstream isolates obtained from patients admitted to 4 tertiary care hospitals between 1995 and 2003 in the city of São Paulo, Brazil. Susceptibility to amphotericin B, 5-fluorocytosine, fluconazole (FCZ), itraconazole (ITZ), and voriconazole (VCZ) was determined using the Clinical Laboratory Standards Institute broth microdilution method. We tested a total of 1000 strains, including 400 strains of Candida albicans (40%), 243 of Candida tropicalis (24.3%), 238 of Candida parapsilosis (23.8%), 44 of C. glabrata (4.4%), 30 of Candida guilliermondii (3%), and 25 of Candida rugosa (2.5%). Only 1.9% of the strains tested were susceptible in a dose-dependent manner, and 0.2% of them were resistant to FCZ. Almost 100% of the strains were susceptible to VCZ. Despite that azole resistance was a rare finding, a trend toward increased resistance among C. rugosa strains to FCZ and ITZ was noted.

Fluconazole susceptibility of Brazilian Candida isolates assessed by a disk diffusion method.

The increasing magnitude of antifungal resistance as well as the advent of new antifungal drugs has generated a renewed interest in fungal susceptibility testing. We used a previously described disk diffusion method to evaluate the susceptibility profile of a large collection of recent clinical Candida spp. isolates against fluconazole. A total of 1,784 yeast isolates were tested, including the following species: Candida albicans (1,036), C. tropicalis (279), C. parapsilosis (202), C. glabrata (119), C. guilliermondii (90), C. krusei (32), C. lusitaniae (7), Candida spp. (14) and other yeasts (5). Susceptibility ranking to fluconazole obtained with all yeasts tested was: C. parapsilosis congruent with C. tropicalis congruent with C. guilliermondii > C. glabrata > C. krusei. The majority (94%) of all yeast isolates tested were susceptible to fluconazole. Isolates of C. glabrata and C. krusei exhibited the highest rate of DDS/resistance among all isolates tested but they represented only 9% of all yeasts routinely sent to our lab. Careful periodical surveillance is needed in order to identify any changes in the susceptibility patterns of fluconazole with the increased use of this antifungal agent in Brazilian tertiary care hospitals.