In the last decades, the increase of candidiasis has been accompanied
by an intensification of infections caused by Candida tropicalis.Indeed, C.
tropicalis has been described as able to colonize and infect several
anatomically distinct sites, including the skin, gastrointestinal,
genitourinary and respiratory tracts. Adaptation to diverse pH that exists
in each human niche has been shown to be critical for virulence in many
commensal pathogens, but there are no reports concerning C. tropicalis.
Biofilm formation ability is one of the most important virulence factors that
have important clinical repercussions due to its increased resistance to
antifungal therapy. Thus, the aim of the current study was to characterize
the influence of pH on C. tropicalis biofilm formation, structure and
composition. The effect of pH (3, 4, 7 and 8) on C. tropicalis biofilms was
evaluated by enumeration of culturable cells, total biomass quantification
and matrix composition. Biofilm structure and the morphology of its cells
were analysed through scanning electron microscopic and confocal laser
microscopy. The resultsrevealed an intensification of C. tropicalis capacity
to form biofilm at neutral and alkaline conditions, with an increased on
number of culturable cells and total biomass and in its structural
complexity, comparatively to acid conditions. For the first time, we have
demonstrated that C. tropicalis biofilm formation is highly influenced by
the environmental human pH, which has an important clinical impact,
which may partly explain the increase incidence of candidiasis