Impact of the New Clinical Breaking Points Proposed by the Clinical and Laboratory Standards Institute (CLSI) in the Antifungal Susceptibility Profile of Clinical Strains Isolated from Invasive Bloodstream Candida Spp. Infections in Spain

We tested a global collection of Candida spp. strains against fluconazole, voriconazole, caspofungin and anidulafungin using CLSI M27-A3 broth microdilution (BMD) method, in order to to compare if there are any differences between the susceptibility data using the old and new CLSI clinical breakpoints for azoles (fluconazole and voriconazole) and echinocandins (caspofungin and anidulafungin) in a large number of Candida albicans and the non-albicans Candida species emerging in Europe (C. parapsilosis and C. tropicalis) strains isolated from BSIs. During the study period, a total of 919 isolates of Candida spp. (427 C. albicans, 304 C. parapsilosis, 82 C. tropicalis and 106 isolates of other species) were obtained from over 40 Spanish hospitals. The MICs90 (in mg/L) for fluconazole, voriconazole, caspofungin and anidulafungin, respectively, for each considered species were as follows: C. albicans, 2, 0.06, 0.125, 0.125; C. parapsilosis, 2, 0.06, 2, 2; C. tropicalis, 2, 0.125, 0. 125, 0.125. Considering the effects in antifungal susceptibility of the new clinical breakpoints it seems that the new clinical breakpoints are more sensitive in the detection of cross – resistance between different azoles, but contrary to what happened on the susceptibility profile of azoles, the increase in the new clinical breakpoints MIC values decreased the rate of C. parapsilosis echinocandin resistant isolates. Therefore, the new epidemiological clinical breakpoints provided by the CLSI promises to be a more sensitive tool to detect emerging reduced antifungal susceptibility among Candida spp. as well as improve the clinical utility of antifungal in vitro testing.