Biofilm formation and genetic variability of BCR1 gene in the Candida parapsilosis complex.

BACKGROUND Candida parapsilosis sensu stricto, Candida orthopsilosis, and Candida metapsilosis are cryptic species that belong to the C. parapsilosis complex, which has been increasingly associated to fungemia in various geographic regions, principally due to the capability of these yeasts to form biofilms on indwelling medical devices. BCR1 is one of the most studied genes related to Candida spp. biofilms. AIMS To evaluate the biofilm forming capability of a subset of 65 clinical isolates of the C. parapsilosis complex using two conventional approaches, and to look for an association between the biofilm forming phenotype and genetic variants of a fragment of BCR1. METHODS The biofilm determination was carried out by crystal violet staining and tetrazolium reduction assay. On the other hand, a segment of BCR1 gene was sequenced by Sanger methodology. RESULTS C. parapsilosis sensu stricto was statistically associated with a low biofilm production phenotype, while C. orthopsilosis was significantly associated with both phenotypes (high and low biofilm producers). According to the BCR1 sequence analysis, genetic variability was detected in C. orthopsilosis and C. metapsilosis without a particular biofilm formation phenotype association. CONCLUSIONS Under the adopted experimental design, C. parapsilosis sensu stricto was associated with the low biofilm phenotype and C. orthopsilosis with both phenotypes (high and low biofilm producers). On the other hand, an association between a biofilm forming phenotype and a particular genetic variant of the analyzed BCR1 fragment was not found.