1. Evaluation of the influence of different antifungal clinical breapkpoints to susceptibility testing of candidemia isolates from 7 Belgian hospitals C. Van Laer 1*,2, K. Lagrou 2, P. Vandecandelaere 3*, AM. Van den Abeele 4*, J. Frans 5*, R. Cartuyvels 6*, E. Oris 7*, H. De Beenhouwer 1*, K. Van Vaerenbergh 1*, A. Boel 1* 1 OLV Hospital, Aalst, 2 University Hospitals Leuven, Leuven, 3 Jan Yperman Hospital, Ieper, 4 Sint-Lucas Hospital, Ghent, 5 Imelda Hospital, Bonheiden, 6 Jessa Hospital, Hasselt, 7 Hospital Zuid-Oost Limburg, Genk; Belgium. *On behalf of the BILULU study group. Evaluation of the influence of different antifungal clinical breapkpoints to susceptibility testing of candidemia isolates from 7 Belgian hospitals C. Van Laer 1*,2, K. Lagrou 2, P. Vandecandelaere 3*, AM. Van den Abeele 4*, J. Frans 5*, R. Cartuyvels 6*, E. Oris 7*, H. De Beenhouwer 1*, K. Van Vaerenbergh 1*, A. Boel 1* 1 OLV Hospital, Aalst, 2 University Hospitals Leuven, Leuven, 3 Jan Yperman Hospital, Ieper, 4 Sint-Lucas Hospital, Ghent, 5 Imelda Hospital, Bonheiden, 6 Jessa Hospital, Hasselt, 7 Hospital Zuid-Oost Limburg, Genk; Belgium. *On behalf of the BILULU study group. EUCAST V3.0, CLSI M27-S3 and revised CLSI 2011 define different clinical breakpoints (CBPs) for antifungals. This study evaluates the influence of using these three different CBPs on the susceptibility reporting of Candida isolates from blood cultures from 7 Belgian hospitals. From December 2010 till August 2011, 104 Candida spp. isolated from blood cultures (no duplicates) were collected in 7 Belgian hospitals: Onze Lieve Vrouw Hospital, Aalst (n=10); University Hospitals Leuven, Leuven (n=55); Jan Yperman Hospital, Ieper (n=8); Sint-Lucas Hospital, Ghent (n=5); Imelda Hospital, Bonheiden (n=6); Jessa Hospital, Hasselt (n=10); Hospital Zuid-Oost Limburg, Genk (n=10). All isolates were identified to species level by ITS2 fragment length analysis. Susceptibility testing was performed in one centre on RPMI agar (AES Chemunex Laboratoire, Bruz Cedex, France) with E-test (Etest® BioMérieux, Marcy-l’Etoile, France) for fluconazole, voriconazole, anidulafungin, caspofungin and amphotericin B. As QC ATCC 22019 C. parapsilosis and ATCC 6258 C. krusei were used. Susceptibility results were interpreted according to 3 different breakpoint guidelines (EUCAST V3.0, CLSI M27-S3 and revised CLSI 2011) for a total of 99 strains from spp. with more than 2 isolates: C. albicans (n=56), C. glabrata (n=35) and C. parapsilosis (n=8). All C. albicans isolates were susceptible for fluconazole, voriconazole, caspofungin and anidulafungin when using the 3 different guidelines, except one strain with a MIC of 0,38 µg/mL for caspofungin (CLSI: S, revised CLSI: S-DD). For C. glabrata EUCAST discourages use of fluconazole and voriconazole, indicating that there is insufficient evidence. For fluconazole, 21 strains interpreted as S when using CLSI, became S-DD when using revised CLSI. Two isolates were R with both CLSI CBPs. The same strains were also voriconazole R according CLSI M27-S3, while all other strains were S. In the absence of CBPs for voriconazole, revised CLSI recommends to use the epidemiologic cutoff value (ECV), 0,50 µg/mL (3). Three strains had a MIC >0,5 µg/mL (non wild-type strains). Revised CLSI lowered CBPs for echinocandins: using CLSI all C. glabrata strains were S for caspofungin, but with revised CLSI 16 isolates were S-DD. For anidulafungin all isolates were S according the 3 CBPs. The MICs should be interpreted with caution, because E-test was used instead of the reference method. Lower MICs for anidulafungin than for caspofungin when using E-test has been described by M. Arendrup (2). Despite higher CBPs for anidulafungin in comparison with other species, half of the C. parapsilosis strains (4/8) were R using CLSI, and S-DD using revised CLSI. In contrast all strains were S for caspofungin. For amphotericin B, only EUCAST CBPs are available. One C. albicans, 1 C. glabrata and 4 C. parapsilosis were S-DD. The other isolates were S for amphotericin B. Introduction Materials and methods Results Table 1: Clinical breakpoints (in µg/mL) of EUCAST, CLSI M27-S3 and CLSI revised for C. albicans, C. glabrata, C. parapsilosis and interpretation of tested strains according the different CBPs (ECV: epidemiologic cutoff value, IE: insufficient evidence, -: no CBP) (1)CLSI Reference Method for Broth Dilution Antifungal Susceptibility Testing of Yeasts; 3th Informational Supplement, M27-S3, vol 28 n°15 (2)M. Arendrup, Susceptibility testing of Fungi, Antwerp 2011, Fungal infections and frustrations across the border (3)Pfaller et al, Triazole and Echinocandin MIC Distributions with Epidemiological Cutoff Values for Differentiation of Wild-Type Strains from Non-Wild-Type Strains of Six Uncommon Species of Candida, J Clin Microbiol 2011; 49(2): 630–637 Acknowledgement: The authors thank Pfizer for the supply of materials for susceptibility testing: E-test and RPMI agars References The changes in CBPs in the newer guidelines affect especially C. glabrata. Conclusions contact: christine.1.vanlaer@uzleuven.be