In Vitro Activity of Caspofungin Against Fluconazole-Resistant Candida Species Isolated From Clinical Samples in Iran

BACKGROUND Candida spp. is the most common organisms involved in fungal infections in the high risk patients. It causes the greatest number of invasive candidiasis. Fluconazole is effective in treating mucosal candidiasis. However, resistance to fluconazole and other azoles antifungal drugs is an important clinical problem to treat candidiasis. Caspofungin is more effective against Candida species such as some azoles-resistant isolates. OBJECTIVES The current study aimed to investigate the susceptibilities of clinical fluconazole-resistant and fluconazole - susceptible dose- dependent Candida species to caspofungin. MATERIALS AND METHODS In the Minimum Inhibitory Concentration (MIC) test, 207 Candida species and other yeasts isolated from Iranian patients (each isolated from a high-risk patient) were evaluated. The yeasts were differentiated by standard mycological methods, CHROM agar Candida, and verified by API20C.AUX. In vitro susceptibilities were determined using Broth Micro Dilution (BMD) method described in the Clinical Laboratory Standards Institute M27-A3. MICs were noted after 24 and 48 hours of incubation. RESULTS The most frequently isolated species were Candida albicans (52.2%), C. glabrata (24.6%), followed by C. tropicalis (7.7%) and C. krusei (3.4%). MICs of caspofungin against 87% of C. albicans and 90% of C. glabrata and C. tropicalis isolates were 2 μg/mL and for C. krusei were 4 μg/mL, respectively. The results revealed that only 20 out of 207 isolates (9.7%) were non-sensitive to caspofungin. Caspofungin non-susceptible isolates were isolated from the patients with cancer, diabetes and AIDS; and not in the species isolated from patients with other underlying diseases. CONCLUSIONS Caspofungin appears more effective in vitro against Iranian fluconazole-resistant Candida isolates and some other yeasts.