A comparison of the methods used in investigation of clonal relationships between candida parapsilosis insulations from clinical samples

Candida parapsilosis (C. parapsilosis) complex isolates are known to cause clinically serious infections. However, information about colonization, pathogenesis and epidemiology is limited. Molecular typing methods have an important place in the epidemiological evaluation of Candida infections. The aim of our study was to determine the frequency of C. parapsilosis complex isolates isolated in our hospital as a bloodstream infection agent, to determine the antifungal susceptibility of the strains, to determine the subspecies among the isolates and to investigate the clonal relationships between the isolates. For this purpose, 115 C. parapsilosis complex isolates isolated from blood culture samples sent to our laboratory from inpatient clinics of our hospital between 2016-2022 were included in the study. The fluconazole susceptibility of the isolates was determined by the gradient E test method and the minimum inhibitory concentration values were evaluated according to the recommendations of the European Committee on Antimicrobial Susceptibility Testing. Subspecies determination of C. parapsilosis complex isolates was investigated by polymerase chain reaction (PCR)-restriction fragment length polymorphism method. Arbitrarily primed-PCR, pulsed field gel electrophoresis-electrophoretic karyotyping (PFGE-EK), PFGE-restriction enzyme analysis (PFGE-REA) methods were used to determine clonal relationships among isolates. The discriminatory power of the methods was calculated with the formula developed by Hunter and Gaston. In our study, 34 different genotypes of 115 C. parapsilosis complex isolates were differentiated into 15 clusters by AP-PCR method; 39 different genotypes into 20 clusters with PFGE-REA whereas 69 different genotypes were determined to be analysed into 25 clusters with the PFGE-EK method. The discriminatory power of the methods was determined as D=0.9393 for AP-PCR, D=0.9492 for PFGE-REA, and D=0.9875 for PFGE-EK. The separability index of the PFGE-EK method was higher than the other methods and more genotypes were identified with the PFGE-EK. In conlusion, PFGE-EK method can be considered as a suitable and reliable option in epidemic analysis in cases where outbreaks due to C. parapsilosis are suspected.