Rifampicin induced virulence determinants increase Candida biofilm formation

Increased intravenous catheter use has been paralleled by increased bacterial and yeast bloodstream infection. Biofilm formation, which is associated with the cell surface hydrophobicity (CSH) phenotype, represents a major pathogenicity strategy of , becoming especially important in the colonization Candida albicans of intravascular medical devices. Increasing evidence shows the induction of virulence factors in by diverse substances. Therefore, we C. albicans investigated whether rifampicin, an antibiotic shown to be capable of inducing MDR1 expression in may also promote the formation of a C. albicans pathogenic biofilm. In response to 40 μg/mL rifampicin, an enhanced retention of SC5314 cells on polystyrene culture plates was observed by C. albicans measuring increased metabolic activity by XTT assay, indicating induction of biofilm formation. Rifampicin treatment also induced fibronectin binding, cell hydrophobicity and germ tube formation. Furthermore, increased RNA and protein expression of CSH1p, a major mediator of CSH, was demonstrated. We conclude that exposure to rifampicin may result in upregulation of key Candida virulence determinants, potentially boosting pathogenicity and supporting biofilm formation. This finding gains clinical significance from the increasing popularity of rifampicin-coated catheters, which might provide an advantageous gateway for bloodstream infections. Candida 1* 1,2* 1 1