Micafungin against common and rare Candida species

In vitro activity of micafungin against common and rare Candida species with the EUCAST, CLSI and E-test method: Intra- and inter-laboratory agreement [PublishAheadOfPrint]:

The emergence of resistant strains among common and rare Candida species necessitates continuous monitoring of in vitro susceptibility of those isolates. We therefore assessed the in vitro activity of micafungin against 1099 molecularly identified isolates belonging to 5 common and 20 rare Candida species with the EUCAST, CLSI and E-test methods assessing both the intra- and inter laboratory agreement between 2 centers. The median micafungin EUCAST MICs were from low to high C. albicans (0.004 mg/l), C. glabrata (0.016 mg/l), C. tropicalis (0.031 mg/l), C. krusei (0.125 mg/l) and C. parapsilosis (2 mg/l). Among rare Candida species, high MICs were found for C. guilliermondii, C. lipolytica, C. orthopsilosis, C. metapsilosis and C. fermentati. No resistant isolates were found with CLSI whereas 1-2% resistant rates were found with the EUCAST method. Overall, the EUCAST resulted in 1-2 dilutions higher MICs than the CLSI and the E-test methods. The intra- and inter-laboratory agreement between methods was >92% except the inter-laboratory agreement between EUCAST and CLSI (81%) where 17-31% of the differences were >2 two-fold dilutions for C. albicans, C. glabrata, C. tropicalis and other rare Candida species and <6% for C. parapsilosis and C. krusei. For the other inter-laboratory comparisons, EUCAST resulted in higher MICs than the Etest method for all species but <7% of these differences were >2 two-fold dilutions. Overall, the CLSI resulted in lower MICs than the E-test method with 11% of all isolates demonstrating >2 two-fold dilutions differences (6-20% for C. albicans, C. tropicalis and rare Candida species, <5% for C. glabrata, C. krusei and C. parapsilosis) and smaller differences found after 24h. Despite these differences, categorical agreement was excellent (>97%) with only 1-2% very major errors between EUCAST and the other two methods.



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