Biofilm formation in cochlear implants with cochlear drug delivery channels in an in vitro model.

Abstract

Cochlear implant (CI) drug delivery (DD) may improve electrophysiological outcomes, but it may also increase the risk of suppurative complications. The aim of this study was to evaluate the development of bacterial biofilms on DD ports when subjected to varying types of penetration. Silastic models were constructed to represent CIs with a DD channel, with an intact port, a widely opened port, a noncoring needle penetrating the port, and a noncoring needle removed from the port. CIs were exposed to a culture of a biofilm-forming strain of Staphylococcus aureus for 5 days. Biofilm formation was assessed with quantitative bacterial counts (after eliminating planktonic bacteria) and scanning electron microscopy. Bacterial counts were significantly higher in CIs with widely fenestrated ports than all other port conditions (P = 0.0003). Biofilm formation may be minimized on CIs with DD by using fine, noncoring needles and limiting the duration of port penetration.