Statistical analyses of correlation between fluconazole MICs for Candida spp. assessed by standard methods set forth by the European Committee on Antimicrobial Susceptibility Testing (E.Dis. 7.1) and CLSI (M27-A2).

The European Committee on Antimicrobial Susceptibility Testing (EUCAST) Subcommittee on Antifungal Susceptibility Testing recently published a standard for determining the susceptibility of fermentative yeasts to antifungals. From the beginning, the EUCAST and its North American counterpart, the CLSI, decided to work together in order to establish common standards. As part of this exercise, the susceptibility of a set of 475 yeast isolates was tested by both standards. The intraclass correlation coefficient and the equations defining the linear regression between both methods were estimated. Both methods produced very similar results, with an intraclass correlation coefficient of 0.954 (0.945 to 0.962), although linear regression analysis shows that the EUCAST standard resulted in slightly lower MICs. There were only eight isolates showing at least four twofold dilution MIC differences between both standards. After 24 h of incubation, the MICs obtained by the CLSI method were equivalent to those obtained by the EUCAST standard. In summary, both methods produce very similar MICs, indicating that methodology does not pose any obstacle to obtaining uniform standards for antifungal susceptibility testing of yeasts.