The oral cavity promotes virulence of Candida parapsilosis sensu stricto via up-regulation of BCR1

Candida parapsilosis sensu stricto behaves as a frequent colonizer of niches of the oral cavity, predominantly in pathological conditions. Studies have suggested the influence of the ecological niche in the virulence of C. parapsilosis. Given this background, we hypothesize that the conditions of the niche affect the virulence of C. parapsilosis sensu stricto due to inheritable epigenetic changes. Measure and compare the virulence, at the phenotype and molecular level, of clinical isolates of C. parapsilosis sensu stricto from different niches and clinical conditions. Biofilm-forming ability was compared in 20 clinical isolates of C. parapsilosis sensu stricto obtained from blood (candidemia), skin (onychomycosis), and oral cavity (eubiosis and dysbiosis); by quantification of biofilm biomass, and metabolic activity. The results were corroborated by optical microscopy and correlated with the basal expression of the global biofilm regulator BCR1 by RT-PCR.  Biofilm production and baseline BCR1 expression were significantly different depending on the ecological niche and the clinical origin of the isolates. The oral cavity exerts a preponderant role in the modulation of the virulence of this yeast via regulation of BCR1. The biofilm-forming ability in C. parapsilosis sensu stricto is dependent on the strain, but can be modulated by environmental conditions or ecological niche via epigenetic regulation of global biofilm regulators such as BCR1.