Treatment of a cochlear implant biofilm infection: a potential role for alternative antimicrobial agents.

Objective: This study aimed to investigate antimicrobial treatment of an infected cochlear implant, undertaken in an attempt to salvage the infected device.

Methods: We used the broth microdilution method to assess the susceptibility of meticillin-sensitive Staphylococcus aureus isolate, cultured from an infected cochlear implant, to common antimicrobial agents as well as to novel agents such as tea tree oil. To better simulate in vivo conditions, where bacteria grow as microcolonies encased in glycocalyx, the bactericidal activity of selected antimicrobial agents against the isolate growing in biofilm were also compared.

Results: When grown planktonically, the S aureus isolate was susceptible to 17 of the 18 antimicrobials tested. However, when grown in biofilm, it was resistant to all conventional antimicrobials. In contrast, 5 per cent tea tree oil completely eradicated the biofilm following exposure for 1 hour.

Conclusion: Treatment of infected cochlear implants with novel agents such as tea tree oil could significantly improve salvage outcome.