Anti-biofilm activity of low-molecular weight chitosan hydrogel against Candida species

Candida invasive infections have increased in frequency during the last decades. Such infections are often associated to medical indwelling devices like central venous catheter. The recurrent nature and difficulties in the treatment of these infections are often related to biofilm formation. The objective of this study was to investigate the anti-biofilm activity of low-molecular weight chitosan hydrogel (LMWCH), a natural biopolymer obtained from the N-deacylation of crustacean chitin, upon clinical relevant Candida species. The in vitro ability of LMWCH to impair biofilm formation and to disorganize a preformed biofilm was tested in polystyrene microplates and quantified by the semi quantitative XTT assay and by the crystal violet assay. LMWCH in vivo efficacy as a coating for medical indwelling devices was evaluated for the first time for Candida parapsilosis, using a mouse subcutaneous foreign body model using polyurethane catheter segments. Scanning electron microscopy was used to access biofilm architecture after LMWCH treatment. We found that LMWCH efficiently impaired biofilm formation of all Candida species, also promoting biofilm disaggregation. Most importantly, LMWCH was able to significantly inhibit biofilm formation by C. parapsilosis in an in vivo catheter mouse model. SEM images showed biofilm collapsed cells compatible with membrane damage, suggesting that this could be one of the possible mechanisms underlying biofilm impairment. LMWCH revealed to be a promising compound for treatment of candidiasis or its prevention through medical device coating.