Biofilm formation on coated silicone tympanostomy tubes.

OBJECTIVES: Tympanostomy tube (TT) surface modifications have been promoted as a means of reducing biofilm formation, otorrhea, and occlusion. The goal of this study was to determine if biofilm formation on silicone TTs could be prevented by commercially available surface coatings.

METHODS: Silicone TTs with and without polyvinylpyrrolidone (PVP) or/and silver oxide were exposed to human plasma and cultured with Pseudomonas aeruginosa or Staphylococcus aureus (22 TTs per group). After 4 days, antibiotics were added to kill planktonic bacteria. Biofilm formation was assessed by quantitative bacterial counts and scanning electron microscopy.

RESULTS: PVP, silver, and PVP-silver coatings reduced P. aeruginosa biofilm formation relative to silicone by over 1 log (p<0.0001). PVP was superior to silver (p=0.04) and PVP-silver (p<0.0001). PVP and PVP-silver coatings increased S. aureus biofilm formation nominally (p=0.01 & 0.003).

CONCLUSION: PVP and silver coatings reduce P. aeruginosa biofilm formation on silicone TTs. Combining PVP and silver coatings does not further improve biofilm resistance. TT surface coatings warrant further study through clinical trials.