Distribution, virulence attributes and antifungal susceptibility patterns of Candida parapsilosis complex strains isolated from clinical samples

It was recently proposed that Candida parapsilosis represents a complex composed of three closely related species, i.e., C. parapsilosis sensu stricto, C. orthopsilosis, and C. metapsilosis. The aim of this study was to describe the distribution of C. parapsilosis complex isolates among clinical samples. We also evaluated antifungal susceptibility profiles, in vitro presence of lipase and secreted aspartyl proteinase, as well as their ability to grow in total parenteral nutrition (TPN) solution, and biofilm production. A total of 413 non-C. albicans Candida isolates were obtained from various clinical samples between 2010 and 2011 in a Turkish Tertiary Care Hospital. Of them, 42 were identified as members of the C. parapsilosis complex. Among these, 38 (90.5%) were C. parapsilosis sensu stricto, 3 (7.1%) C. metapsilosis, and 1 (2.4%) C. orthopsilosis. All isolates recovered from blood were found to be C. parapsilosis sensu stricto and C. metapsilosis. In phenotypic tests, all 42 isolates grew in TPN solution and, although 26.2% of C. parapsilosis sensu stricto-isolates were capable of forming biofilms in vitro, neither C. orthopsilosis nor C. metapsilosis isolates were able to do so. Acid proteinase activity was detected in 31% of isolates and lipase activity in 33%. All isolates were sensitive to voriconazole, caspofungin, and anidulafungin, with only a single C. parapsilosis sensu stricto isolate showing dose-dependent susceptible to fluconazole. While the number of C. metapsilosis and C. orthopsilosis isolates remained low, there were no significant differences in antifungal MIC as compared to C. parapsilosis sensu stricto.