High frequency of Candida fabianii among clinical isolates biochemically identified as Candida pelliculosa and Candida utilis.

Clinical yeast isolates belonging to Candida pelliculosa, Candida utilis and Candida fabianii are difficult to distinguish in a routine mycology laboratory using common biochemical tests. The aims of this study were to determine the prevalence of C. pelliculosa, C. utilis and C. fabianii in clinical samples and to compare their minimum inhibitory concentrations (MICs) to systemic antifungals. Two hundred and forty-eight clinical yeast isolates obtained from eight large hospitals in the Czech Republic were included in this study. Identification was performed biochemically using ID 32C kit and by MALDI-TOF MS. MICs were determined using colorimetric broth dilution Sensititre YeastOne panels. From a total number of 248 isolates, 175 were identified as C. pelliculosa and 73 as C. utilis using the biochemical kit. In contrast, MALDI-TOF MS identified 222 isolates as C. fabianii, 20 as C. pelliculosa and 6 as C. utilis. The highest mean MICs were found in C. fabianii and, regardless of the studied species, in isolates from blood cultures and central venous catheters. MALDI-TOF MS revealed C. fabianii to be most prevalent in clinical samples as compared with the other studied species. Higher MIC values in C. fabianii support the importance of correct identification of this species.