Candida tropicalis biofilm and human epithelium invasion is highly influenced by environmental pH.

OBJECTIVE: The main goal of this study was to investigate the role of pH on Candida tropicalis virulence determinants, namely the ability to form biofilms and to colonize/invade reconstituted human vaginal epithelia.

METHODS: Biofilm formation was evaluated by enumeration of cultivable cells, total biomass quantification and structural analysis by scanning electron microscopy and confocal laser scanning microscopy. Candida tropicalis human vaginal epithelium colonization and invasiveness were examined qualitatively by epifluorescence microscopy and quantitatively by a novel quantitative real-time PCR protocol for Candida quantification in tissues.

RESULTS: The results revealed that environmental pH influences C. tropicalis biofilm formation as well as the colonization and potential to invade human epithelium with intensification at neutral and alkaline conditions compared to acidic conditions.

CONCLUSIONS: For the first time, we have demonstrated that C. tropicalis biofilm formation and invasion is highly influenced by environmental pH.