title: Comparative evaluation of the Vitek 2 yeast susceptibility test and CLSI broth microdilution reference method for testing antifungal susceptibility of invasive fungal isolates in Italy: the GISIA3 study.
abstract: The newly available AST-YS01 Vitek 2 cards were evaluated, and the results were compared with those obtained by the CLSI M27-A2 microdilution reference method. Clinical fungal isolates, including 614 isolates of Candida spp., 10 Cryptococcus neoformans isolates, 1 Geotrichum capitatum isolate, and 2 quality control strains, were tested for their susceptibilities to amphotericin B, fluconazole, and voriconazole using both methods. The majority of fungal isolates were susceptible to all antifungal agents tested: the MIC(90) values determined by the Vitek 2 and CLSI methods were 0.5 and 1 microg/ml, respectively, for amphotericin B; 8 and 16 microg/ml, respectively, for fluconazole; and <0.12 and 0.25 microg/ml, respectively, for voriconazole. Overall there was excellent categorical agreement (CA) between the methods (99.5% for amphotericin B, 92% for fluconazole, 98.2% for voriconazole), but discrepancies were observed within species. The CAs for fluconazole were low for Candida glabrata and Candida krusei when the results of the CLSI method at 48 h were considered. Moreover, the fully automated commercial system did not detect the susceptibility of Cryptococcus neoformans to voriconazole. The Vitek 2 system can be considered a valid support for antifungal susceptibility testing of fungi, but testing of susceptibility to agents not included in the system (e.g., echinocandins and posaconazole) should be performed with other methods.
authors.affiliation: Department of Public Health-Microbiology-Virology, Università degli Studi di Milano, Milan, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Borghi
authors.forename: Roberta
authors.initials: R
authors.lastname: Iatta
authors.forename: Rita
authors.initials: R
authors.lastname: Sciota
authors.forename: Caterina
authors.initials: C
authors.lastname: Biassoni
authors.forename: Teresa
authors.initials: T
authors.lastname: Cuna
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Montagna
authors.forename: Giulia
authors.initials: G
authors.lastname: Morace
mesh_terms: D000666:Amphotericin B / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology*; D002175:Candida / Q000187:drug effects* / Q000302:isolation & purification; D003455:Cryptococcus neoformans / Q000187:drug effects* / Q000302:isolation & purification; D015725:Fluconazole / Q000494:pharmacology; D005848:Geotrichum / Q000187:drug effects* / Q000302:isolation & purification; D006801:Humans; D007558:Italy; D008826:Microbial Sensitivity Tests / Q000379:methods; D009181:Mycoses / Q000382:microbiology*; D011743:Pyrimidines / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology; D065819:Voriconazole
chemical_list: D000935:Antifungal Agents; D011743:Pyrimidines; D014230:Triazoles; D000666:Amphotericin B; D015725:Fluconazole; D065819:Voriconazole