Antimicrobial activity of synthetic salivary peptides against voice prosthetic microorganisms

Objectives: To investigate whether synthetic salivary antimicrobial peptides have an inhibitory effect on the growth of bacteria and yeasts isolated from used silicone rubber voice prostheses. Methods: The antimicrobial activities of six synthetic salivary peptides (histatin 5, dhvar1, dhvar4, dhvar5, lactoferrin b 17-30 [LFb 17-30], and cystatin 51-15) at concentrations of 2 and 4 mg/mL were determined against different oropharyngeal yeast (four) and bacterial (eight) strains and against a "total microflora" isolated from explanted voice prostheses using agar diffusion tests. The spectrum of susceptible microorganisms was determined qualitatively. Results: Histatin 5 and cystatin 51-15 did not show any antimicrobial activity against the microorganisms involved in this study. Dhvar1 was active against some of the oropharyngeal microorganisms tested, including the yeast strains, but not against Rothia dentocariosa, Staphylococcus aureus, Escherichia coli and the total microflora. Dhvar4 was active against all microorganisms tested, including the total microflora, Dhvar5 lacked activity against E coli and the total microflora. LFb 17-30 did not inhibit the growth of any of the yeast strains involved and showed only minor activity against some of the bacterial strains. LFb 17-30 slightly inhibited the growth of the total microflora from an explanted prosthesis. Conclusions: The synthetic salivary peptide dhvar1 has a broad antimicrobial activity against all microorganism that are commonly isolated from explanted voice prostheses, including yeasts. Therewith, it may represent a useful drug, as an alternative for antibiotics and antimycotics employed in various ways to prolong the Lifetime of voice prostheses in laryngectomees.