Biofilm formation on voice prostheses: in vitro influence of probiotics

In order to determine the influence of probiotic bacteria on biofilm formation on Groningen and Provox 2 voice prostheses in an artificial throat, we grew biofilms on both types of voice prostheses and exposed them 3 times daily to a probiotic bacterial suspension. As a control, we perfused an artificial throat with phosphate-buffered saline solution. Perfusion with Lactococcus lactis 53 suspension reduced the percentage numbers of bacteria and yeasts, respectively, on the Groningen prostheses to 17% and 22% and on the Provox 2 prostheses to 19% and 45%, compared to the number of colony-forming units on the control prosthesis, which was set at 100%. A suspension of Streptococcus thermophilus B reduced the percentage numbers of bacteria and yeasts, respectively, on the Groningen prostheses to 53% and 33% and on the Provox 2 prostheses to 14% and 0%, as compared to the control prosthesis. All other probiotic strains tested caused some reduction in the percentages of bacteria or yeasts, but strong differences between the types of prostheses were observed. In conclusion, L. lactis 53 and S. thermophilus B strongly reduce the occurrence of yeasts and bacteria in voice prosthetic biofilms.