Comparison of antifungal MICs for yeasts obtained using the EU-CAST method in a reference laboratory and the Etest in nine different hospital laboratories

Abstract

In routine laboratory practice, the determination of MICs of antifungals for yeasts often relies on the Etest, because of a good correlation with reference methods. However, this correlation was established through predesigned studies, rather than prospective testing.The surveillance programme of fungaemia (YEASTS programme), implemented since 2003, facilitated our comparison of the Etest and the EUCAST results, obtained on a routine basis in nine different hospitals and in a reference laboratory, respectively. The analysis included 690 isolates recovered from blood culture (362 Candida albicans, 113 Candida glabrata, 69 Candida parapsilosis, 55 Candida tropicalis, 31 Cryptococcus neoformans, and 60 other yeast species) that were tested for their susceptibility to amphotericin B (n = 655), fluconazole (n = 669), itraconazole (n = 198), voriconazole (n = 588), flucytosine (n = 314), and caspofungin (n = 244). Agreement between the Etest and EUCAST datasets was calculated and categorized on the basis of previously published breakpoints. The level of agreement at ±2 dilutions was 75% for amphotericin B and 90% for flucytosine; for the azoles, it ranged from 71% for itraconazole to 87% for voriconazole. No significant difference was observed among the yeast species, except for Cryptococcus neoformans and flucytosine, with an agreement <40%. Categorical agreement ranged from 60% for itraconazole to 90% for flucytosine. Major and very major discrepancies occurred in <12% and 6%, respectively. The Etest, even when performed on a routine basis, shows a ‡71% agreement with the EUCAST reference method.

Characteristics and risk factors of candidemia in pediatric intensive care unit of a tertiary care children's hospital in Egypt

“…There was considerable agreement between our Etest-MICs results for antifungals including those for amphotericin B, for which clinical breakpoints have not been established yet, and the EUCAST reference method [26,27]. Similarly, Dannaoui et al, found that the level of agreement between Etest and the EUCAST reference method was 75% for amphotericin B and ranged from 71% to 87% for azoles, even when performed on a routine basis [28].…”

Comparison of European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Etest Methods with the CLSI Broth Microdilution Method for Echinocandin Susceptibility Testing of Candida Species

“…All three of the echinocandins are acknowledged as first-line agents for the treatment of invasive candidiasis, including candidemia (29). Despite the broad utilization of these agents (5,19,38,42), longitudinal surveillance studies have documented the excellent and sustained potency of all three echinocandins since the introduction of caspofungin in 2001 (6,10,11,14,15,(30)(31)(32). Although resistance to echinocandins remains uncommon among cases of invasive candidiasis, sporadic examples of clinical failure associated with elevated MICs to one or more of these agents have been reported (1,3,16,26,39).…”

Interlaboratory Reproducibility of Etest Amphotericin B and Caspofungin Yeast Susceptibility Testing and Comparison with the CLSI Method

“…However, this correlation was overall lower for amphotericin B than for caspofungin, in line with data reported previously by Fleck et al (7), who found 89% and 98% EAs for amphotericin B and caspofungin, respectively. With a different study design and comparing the Etest to the EUCAST broth dilution assay, Dannaoui et al (4) previously found a 75% g mE, minor error; ME, major error; VME, very major error.…”