Long-term antibiofilm activity of carboxymethyl chitosan on mixed biofilm on silicone.

OBJECTIVES/HYPOTHESIS Silicone voice prostheses are most frequently used in voice rehabilitation of laryngectomized patients. However, the functional device lifetimes are limited due to formation of mixed biofilms. Existing in vitro models simulating biofilm formation are restricted to only short-term periods. STUDY DESIGN The goal of this study was to determine the effect of carboxymethyl chitosan on mixed biofilm formation of fungi and bacteria on silicone over a long-term period. METHODS Mixed species biofilms of Candida albicans, Candida tropicalis, Lactobacillus gasseri, Streptococcus salivarius, Rothia dentocariosa, and Staphylococcus epidermidis were cultivated on the surfaces of medical-grade silicone with and without addition of carboxymethyl chitosan. Biofilm kinetics was monitored using specially designed image analysis software to calculate the percentual surface covering of each platelet. Biofilm architecture was investigated by scanning electron microscopy. RESULTS A cover of living mixed biofilm could be generated over 22 days on silicone and the maximum of 22% biofilm surface covering at day 22. However, less than 4% surface coverage was observed on the carboxymethyl chitosan-treated plates in the testing period. Scanning electron microscopy confirms that, on surfaces treated by carboxymethyl chitosan, the biofilm was less dense. In addition, there were fewer layers of cells and profuse cellular debris, together with degrading and morphologically altered yeast cells. CONCLUSION Carboxymethyl chitosan may serve as a possible antibiofilm agent to limit biofilm formation on voice prostheses. LEVEL OF EVIDENCE NA Laryngoscope, 126:E404-E408, 2016.