Air-flow resistances of silicone rubber voice prostheses after formation of bacterial and fungal biofilms

Laryngectomized patients use silicone rubber voice prostheses to rehabilita te their voice. However, biofilm formation limits the lifetime of voice pro stheses by causing leakage or an increased air-flow resistance and the pros thesis has to be replaced. To determine which bacterial or yeast strains, i solated from explanted voice prostheses, contribute most to increases in ai r-flow resistance of silicone rubber voice prostheses, biofilms consisting of either a bacterial or a yeast strain were grown on voice prostheses in t he artificial throat model. The effects of these biofilms on air-flow resis tances were determined by calculating the difference in air-flow resistance of the individual voice prosthesis as covered with a 7-day-old biofilm wit h the situation prior to biofilm formation. Conspicuously, voice prosthetic biofilms formed by the bacterial strains Staphylococcus aureus GB 2/1 and Rothia dentocariosa GBJ 41/25B and their excreted organic matter showed lar ger increases in air-flow resistance (more then 30 cm H2O.s/L) than biofilm s formed by Candida species. This is contrary to the literature, where ther e seems to be agreement that Candida species are mainly responsible for cli nical failure of silicone rubber voice prostheses. (C) 2001 John Wiley & So ns, Inc.