Micafungin susceptibility of the most common Candida species in 16 French university hospitals : comparison between the Etest® and the EUCAST methods (MICACAND study)

Objectives : Micafungin is currently used in France. The aim of this study is to determine its activity against a recent (2014) French collection of Candida isolates. Although EUCAST is the reference method for in vitro antifungal susceptibility testing, it is not commonly used in routine clinical microbiology laboratories. Thus, it is important to evaluate alternative methods. We compared EUCAST and Etest for micafungin susceptibility testing of Candida spp. and we monitored the emergence of resistance. [br/] Methods: Sixteen centers (6 in Paris area and 10 across France) participated in a two-months prospective study. Clinical isolates of various Candida species (mainly C. albicans, C. glabrata, C. tropicalis, C. parapsilosis, C. kefyr and C. krusei, about 10 isolates of each species per center) were tested by Etest, according to manufacturer’s instructions. All isolates were subsequently centralized in one center for MIC determination by EUCAST method. For comparison purposes, Etest MICs were raised to the next higher EUCAST concentration. Resistance was defined based on EUCAST clinical breakpoints or on epidemiological cut-off values when clinical breakpoints were not available. [br/] Results : A total number of 933 Candida isolates were tested. The overall agreement (+/- 2 log2 dilutions) between EUCAST and Etest was 97.9%. Species n E-Test EUCAST MIC range MIC range % agreement with Etest % resistance C. albicans 159 ≤ 0.015 - 0.06 ≤ 0.015 - 0.06 100 1.3 C. tropicalis 152 ≤ 0.015 - 0.5 ≤ 0.015 - 1 98.7 0.7 C. parapsilosis 152 ≤ 0.015 - 4 ≤ 0.125 - 4 96.1 1.3 C. glabrata 152 ≤ 0.015 - 0.125 ≤ 0.015 - 1 98.7 3.9 C. kefyr 136 ≤ 0.015 - 0.25 ≤ 0.015 - 0.125 97.8 ND C. krusei 127 ≤ 0.015 - 1 ≤ 0.015 - 0.25 96.9 0 Other Candida species* 55 ≤ 0.015 - 1 ≤ 0.015 - 1 94.5 ND Total 933 ≤ 0.015 - 4 ≤ 0.015 - 4 97.9 ND *: C. lusitaniae, C. guilliermondii, C. norvegensis, C. inconspicua, C. famata, C. pelliculosa, C. lambica, C. sphaerica, C. ciferii, C. catenulata, C. utilis, C. colliculosa, C. nivariensis[br/] Conclusions : This study demonstrated a very good agreement between Etest, performed on a routine basis, and EUCAST for micafungin MIC determination. Micafungin resistance among the main Candida species was uncommon