Emerging Pathogen: Candida kefyr (Kluvyeromyces marxianus)

In the central microbiology laboratory of Gazi University Hospital Candida kefyr was isolated from different clinical samples as 5.3% in 2016 and in 2017 this rate increased to 9.3% which was nearly twofold and this has drawn our attention. The aim of this study was to evaluate the special characteristics, antifungal susceptibility and virulence properties of C. keyfr species. Germ tube, corn meal-tween 80 agar morphology and carbohydrate assimilation profiles on ID32C yeast identification system were used for the diagnosis of Candida species. In this study, DNA sequencing was performed using ITS1 and ITS4 primers amplifying fungal gene between 5.8S and 18S regions of rRNA. Antifungal susceptibility was performed using M27A microdilution method recommended by Clinical and Laboratory Standards Institute (CLSI). Minimum inhibitory concentration (MIC) values for amphotericin B, fluconazole, voriconazole and itraconazole were determined. MIC distribution, MIC50 and MIC90 values and geometric mean (GM) were detected. The existence of virulence factors caseinase, secreted aspartyl proteinase, esterase and phospholipase were investigated in vitro. A total of 865 Candida species were isolated from different clinical samples in the central microbiology laboratory of Gazi University Hospital in 2016. Among them, 46 (5.3%) were C. kefyr. In the first four months of 2017, 30 (9.3%) C. kefyr were identified among 320 Candida isolates. Ten isolates which have shown atypical morphology on corn meal agar were selected. Among these 10 isolates, nine of them were identified as C. kefyr by using ID32C system and DNA sequencing method. Amphotericin B MIC value was 2 mu g/ml for one isolate, and fluconazole MIC value was 8 mu g/ml for another isolate among 46 isolates. Among the 30 isolates of the year 2017, one of them presented MIC value for fluconazole as 8 mu g/ml. No marked antifungal resistance was detected in our isolate group. Caseinase was positive in one C. kefyr isolate, and phospholipase were positive in eight of nine isolates. As a result, the reason of increase in the incidence of this Candida species, which does not show significant resistance and presents mostly phospholipase activity as a virulence factor, should be investigated in more detail.