Evidence of genotypic diversity among Candida auris isolates by multilocus sequence typing, matrix-assisted laser desorption ionization time-of-flight mass spectrometry and amplified fragment length polymorphism

dThe emergence of resistant strains among common and rare Candida species necessitates continuous monitoring of the in vitro susceptibilities of those isolates. We therefore assessed the in vitro activities of micafungin against 1,099 molecularly identified isolates belonging to 5 common and 20 rare Candida species by the EUCAST, CLSI, and Etest methods, assessing both the intralaboratory agreement and the interlaboratory agreement for two centers. The median micafungin EUCAST MICs were as follows, from the lowest to the highest: for Candida albicans, 0.004 mg/liter; for C. glabrata, 0.016 mg/liter; for C. tropicalis, 0.031 mg/liter; for C. krusei, 0.125 mg/liter; for C. parapsilosis, 2 mg/liter. 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 by the CLSI method, whereas resistance rates of 1 to 2% were found by the EUCAST method. Overall, the EUCAST method resulted in MICs 1 to 2 dilutions higher than those found by the CLSI and Etest methods. The intra-and interlaboratory agreement between methods was >92%, except for the interlaboratory agreement between the EUCAST and CLSI methods (81%), where 17 to 31% of the differences were >2 2-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 interlaboratory comparisons, the EUCAST method resulted in higher MICs than the Etest method for all species, but <7% of these differences were >2 2-fold dilutions. Overall, the CLSI method resulted in lower MICs than the Etest method, with 11% of all isolates demonstrating >2 2-fold-dilution differences (6 to 20% for C. albicans, C. tropicalis, and rare Candida species; <5% for C. glabrata, C. krusei, and C. parapsilosis) and smaller differences found after 24 h. Despite these differences, categorical agreement was excellent (>97%), with only 1 to 2% very major errors between the EUCAST method and the other two methods. Micafungin is an echinocandin used for the treatment and prophylaxis of Candida infections in both neutropenic and nonneutropenic patients (1, 2). Although micafungin has a broad spectrum of activity against different Candida species, including azole-resistant isolates, the emergence of resistance in common and rare Candida species necessitates in vitro susceptibility testing of those isolates (3). Methods for the determination of MICs have recently been published by the Clinical and Laboratory Standards Institute (CLSI) (4) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) (5). Both of these methods are broth microdilution methods; they differ in glucose concentration, inoculum size, the shape of microplates, and the mode of reading. In addition, the Etest is often used to determine susceptibility in routine laboratories (6).Although all these methods are reproducible and reliable in testing the in vitro susceptibility of Candida isolates, there are few comparative stu...

Section: Methodsmentioning

confidence: 99%

Intra- and Interlaboratory Agreement in Assessing the In Vitro Activity of Micafungin against Common and Rare Candida Species with the EUCAST, CLSI, and Etest Methods

Meletiadis

Geertsen

Curfs-Breuker

et al. 2016

“…The first documented clinical case of this species occurred in Japan in 2009 (3). Since then, infections due to C. auris have been published from numerous countries throughout the world (1,2,(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17). Unfortunately, antifungal therapeutic failure and mortality have been commonly reported.…”

mentioning

confidence: 99%

Pharmacodynamic Optimization for Treatment of Invasive Candida auris Infection

Lepak

Zhao

Berkow

et al. 2017

Candida auris is an emerging multidrug-resistant threat. The pharmacodynamics of three antifungal classes against nine C. auris strains was explored using a murine invasive candidiasis model. The total drug median pharmacodynamic (PD) target associated with net stasis was a fluconazole AUC/MIC (the area under the concentration-time curve over 24 h in the steady state divided by the MIC) of 26, an amphotericin B C max /MIC (maximum concentration of drug in serum divided by the MIC) of 0.9, and a micafungin AUC/MIC of 54. The micafungin PD targets for C. auris were Ն20-fold lower than those of other Candida species in this animal model. Clinically relevant micafungin exposures produced the most killing among the three classes.

“…Susceptibility data for Candida auris isolates published to date suggest that this yeast is uniformly characterized by high fluconazole MICs (Ͼ16 mg/liter) and variable susceptibility to the other azoles, echinocandins and amphotericin B (13)(14)(15). The majority of studies have included a limited number of isolates for susceptibility testing; however, two studies, one from India and another collaborative study undertaken by the CDC, included 90 and 54 isolates, respectively.…”

mentioning

confidence: 99%

Comparison of EUCAST and CLSI Reference Microdilution MICs of Eight Antifungal Compounds for Candida auris and Associated Tentative Epidemiological Cutoff Values

Arendrup

Prakash

Meletiadis

et al. 2017

200

189

Candida auris is an emerging multidrug-resistant yeast. So far, all but two susceptibility testing studies have examined Յ50 isolates, mostly with the CLSI method. We investigated CLSI and EUCAST MICs for 123 C. auris isolates and eight antifungals and evaluated various methods for epidemiological cutoff (ECOFF) determinations. MICs (in milligrams per liter) were determined using CLSI method M27-A3, and the EUCAST E.Def 7.3. ANOVA analysis of variance with Bonferroni's multiple-comparison test and Pearson analysis were used on log 2 MICs (significance at P values of Ͻ0.05). The percent agreement (within Ϯ0 to Ϯ2 2-fold dilutions) between the methods was calculated. ECOFFs were determined visually, statistically (using the ECOFF Finder program and MicDat1.23 software with 95% to 99% endpoints), and via the derivatization method (dECOFFs). The CLSI and EUCAST MIC distributions were wide, with several peaks for all compounds except amphotericin B, suggesting possible acquired resistance. Modal MIC, geometric MIC, MIC 50 , and MIC 90 values were Յ1 2-fold dilutions apart, and no significant differences were found. The quantitative agreement was best for amphotericin B (80%/97% within Ϯ1/Ϯ2 dilutions) and lowest for isavuconazole and anidulafungin (58%/76% to 75% within Ϯ1/Ϯ2 dilutions). We found that 90.2%/100% of the isolates were amphotericin B susceptible based on CLSI/EUCAST methods, respectively (i.e., with MICs of Յ1 mg/liter), and 100%/ 97.6% were fluconazole nonsusceptible by CLSI/EUCAST (MICs Ͼ 2). The ECOFFs (in milligrams per liter) were similar across the three different methods for itraconazole (ranges for CLSI/EUCAST, 0.25 to 0.5/0.5 to 1), posaconazole (0.125/0.125 to 0.25), amphotericin B (0.25 to 0.5/1 to 2), micafungin (0.25 to 0.5), and anidulafungin (0.25 to 0.5/0.25 to 1). In contrast, the estimated ECOFFs were dependent on the method applied for voriconazole (1 to 32) and isavuconazole (0.125 to 4). CLSI and EUCAST MICs were remarkably similar and confirmed uniform fluconazole resistance and variable acquired resistance to the other agents.