Candida parapsilosis Sensu Stricto: A Pathobiont in Conditions of Oral Dysbiosis?

Recent publications have reported high prevalence of C. parapsilosis sensu stricto in oral cavity niches. Our research group performed a pilot study in 2017 which showed that of the psilosis complex, C. parapsilosis sensu stricto is the species most frequently isolated from oral cavity niches. Under inflammatory conditions, the probability of recovering it is almost four times higher, and it displays higher biofilm-forming capacity in-vitro, differing significantly from isolates of the same species obtained in conditions of eubiosis. This led us to hypothesize that an oral environment in dysbiosis overregulates virulent genes, promoting a more pathogenic phenotype. Accordingly, we decided to reevaluate the in-vitro biofilm formation assay using a larger sample, under two nutritional conditions, using colorimetric methods for quantification. In addition, the results obtained were validated by imaging techniques. For both clinical conditions (eubiosis and dysbiosis), high biofilm forming phenotype predominated with both reading methods, and for both nutritional conditions tested. XTT showed significant difference between absorbance values for isolates from buccal dysbiosis and eubiosis (p=0.0025). C. parapsilosis sensu stricto cells that colonize oral cavity niches are basically strong biofilm formers, regardless of in vitro growing conditions. However, the oral cavity in dysbiosis probably promotes virulence in this species due to inheritable epigenetic modifications.