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.
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.
Borghi
Elisa
E
Department of Public Health-Microbiology-Virology, Università degli Studi di Milano, Milan, Italy.
Iatta
Roberta
R
Sciota
Rita
R
Biassoni
Caterina
C
Cuna
Teresa
T
Montagna
Maria Teresa
MT
Morace
Giulia
G
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
D000935:Antifungal Agents; D011743:Pyrimidines; D014230:Triazoles; D000666:Amphotericin B; D015725:Fluconazole; D065819:Voriconazole