CANDIDA ALBICANS HYPHAL DEVELOPMENT AND BIOFILM FORMATION/PERSISTENCE ARE DIFFERENTIALLY AFFECTED BY MOUTHWASHES DEPENDING UPON THEIR COMPOSITION.

Introduction: Oral candidiasis is a frequent opportunistic fungal infection, occurring especially in susceptible individuals. This pathology, mainly associated with Candida albicans species, may be prevented by a good oral hygiene, the daily use of toothbrush and mouthwashes. Among several virulence factors, C. albicans has the ability to switch from yeast-to-hyphal forms and to produce biofilm, thus contrasting antimicrobial agents and host immune defences as well [1-3]. The aim of this study is to investigate the susceptibility of C. albicans, in terms of growth, hyphal formation and biofilm production/persistence, to mouthwashes with different composition. Materials and Methods: Candida albicans SC5314 and 7 commercial mouthwashes have been employed: 3 with 0.2% chlorhexidine digluconate; 1 with 0.06% chlorhexidine digluconate and 250 ppm F- sodium fluoride; 3 with 125-250ppm Fsodium, amino and/or stannous fluoride. The effects of the mouthwashes on C. albicans were assessed by crystal violet, tetrazolium salt reduction assays and morphological analysis by microscopy. By using four different protocols, combining different concentrations and different contact times, the mouthwashes were tested against: 1) C. albicans growth on Muller-Hinton agar, as assessed by disk diffusion assay; 2) hyphal formation and biofilm production by yeast cells, cultured in RPMI + 10% FBS; 3) early pre-formed (24 h-old) Candida biofilm and 4) mature (48 h-old) Candida biofilm. Results: The highest anti-Candida activity was consistently exhibited by the chlorhexidine digluconate- containing mouthwashes, irrespective of the protocols employed. Morphological and functional impairments occurred and fungal survival/ growth were impaired as well; the effects strictly depended on both the dilution employed and the time of contact. Discussion and Conclusions: Both C. albicans hyphal development and biofilm formation/persistence are affected by mouthwashes, provided that they contain chlorhexidine digluconate. Thus, special attention should be used when choosing mouthwashes for prevention and/or treatment of Candida-associated oral pathologies. 1. Ramage G, et al. Eukaryot Cell 2005; 4: 633-8. 2. Orsi CF, et al. Microb Pathog 2014; 69-70: 20-7 3. Orsi CF, et al. J Biol Regul Homeost Agents 2014; 28: 743-52.