[Investigation of antifungal susceptibilities and some virulence factors of Candida strains isolated from blood cultures and genotyping by RAPD-PCR].

Candidemia is a serious clinical picture with a rather high mortality. Early diagnosis and appropriate treatment is crucial in this picture especially in immunocompromised cases. The aims of this retrospective study were to investigate the antifungal susceptibility patterns and to detect the presence of phospholipase, esterase and biofilm production which are excepted as virulence factors of Candida spp. strains and to evaluate the clonal relationships between isolates. A total of 46 Candida spp. Strains isolated from blood cultures of patients of whom eight were newborn and 38 were adults, between the period of February 2005 to July 2010, were included in the study. Of the isolates 17 were identified as C.albicans, 18 were C.parapsilosis, five were C.glabrata, four were C.tropicalis, one was C.guilliermondii and one was C.krusei. Antifungal susceptibility tests were performed by using "Sensititre Yeast One (Trek Diagnostic Systems, USA)" commercial kit. Esterase activity was detected in Tween-80 medium; phospholipase activity in yolk egg agar and biofilm formation was investigated by microplate assay. Strain genotyping was performed by RAPD-PCR (random amplified polymorphic DNA-polymerase chain reaction) by using OPE-03, OPE-18, AP50-1, Cnd-3 and Cnd-4 primers. All strains were found to be susceptible to amphotericin B, voriconazole, posaconazole, and caspofungin. C.krusei strain was defined as resistant (intrinsically) to fluconazole. All strains of C.albicans, C.parapsilosis, C.glabrata, and C.tropicalis were found to be susceptible to fluconazole. Three of five C.glabrata strains were resistant to itraconazole, while the other strains were found to be susceptible. All of the C.albicans strains had phospholipase and esterase activity, however none were biofilm-producing isolates. In contrast all of the C.parapsilosis strains were negative for phospholipase and esterase activity, however all were positive for biofilm formation. Phospholipase activity has not been detected in non-albicans strains; esterase activity were found positive in all of the C.tropicalis strains, while biofilm formation was detected in three C.tropicalis, one C.glabrata and one C.krusei isolates. The results of genotyping demonstrated that C.albicans strains displayed 5-8 different patterns and C. Parapsilosis strains 2-3 patterns with the use of five primers. Among C.parapsilosis strains, 14 were found identical (with the use of all the primers forming a single pattern (pattern A). In conclusion, the Candida spp. İsolated from blood samples were highly susceptible to the tested antifungals, and C.albicans strains had high phospholipase and esterase activity, while C.parapsilosis strains had high rate of positivity for biofilm formation. The predominant pattern amongst C.parapsilosis strains was thought to be related to exogenous dissemination.