Biofilm formation in an in vitro model of cochlear implants with removable magnets.

BACKGROUND: Cochlear implant (CI) recesses, such as the removable magnet pocket, appear to harbor more biofilm than smooth surfaces. The aim of this study was to examine the impact of removable magnets on biofilm formation in an in vitro model. METHODS: Silastic models were constructed to represent CIs with and without a magnet pocket and with and without a titanium blank in the pocket. CIs were exposed to a culture of a biofilm forming strain of Staphylococcus aureus. Adherence of planktonic bacteria and biofilm formation were assessed with quantitative bacterial counts and scanning electron microscopy. RESULTS: Adherent bacterial counts were significantly higher in CI models with an empty magnet pocket (P = 0.0097). Biofilm formation was significantly lower in CI models without a magnet pocket (P = 0.0121). CONCLUSIONS: CI magnet pockets harbor bacteria that can increase biofilm development in an in vitro model.