Screening of Fluconazole-Resistant Candida Species with Fluconazole-Containing Sabouraud Dextrose Agar Plates

Lee, Mi Kyung; Kim, Tae Hyoung

Abstract

BACKGROUND
Antifungal susceptibility testing methods are relatively expensive and laborious and are not easily applicable for screening purposes in routine laboratories.
OBJECTIVE
We have developed a susceptibility screening method by adding fluconazole to Sabouraud dextrose agar (SDA) plate. In this study, SDA plates screening was compared with the Clinical and Laboratory Standards Institutes (CLSI) broth microdilution method for determining fluconazole susceptibility of Candida spp.
METHODS
A total 186 isolates of Candida spp. (134 C. albicans, 24 C. tropicalis, 15 C. glabrata, 13 C. parapsilosis) were tested with the CLSI document M27-A2 method and fluconazole-containing SDA plate (0, 8, 16 microgram/mL of fluconazole). By this method, colony count and diameter were read after 24 hr of incubation.
RESULTS
Fluconazole-susceptible Candida spp. are significantly smaller (> or =50%) on SDA with fluconazole than on fluconazole-free SDA. On SDA with 8 and 16 microgram of fluconazole per mL, 80.7% (150/186) and 87.1% (162/186) of isolates were correctly predicted, respectively.
CONCLUSIONS
These data suggest that the fluconazole-containing SDA plates can be used as a routine screening procedure for susceptibility of Candida spp. in clinical laboratories.