Bacterial growth on cochlear implants as a potential origin of complications

To investigate the presence and spectrum of bacterial colonization in relation to cochlear implant infections by introducing molecular biologic methods.

In a pilot test, a virgin device served as a control to validate the subsequent sampling and analysis process via PCR and SSCP. Subsequently, analysis was performed on specimens of 15 cochlear implants explanted from 15 patients because of device failures, infections, or malinsertions.

Positive SSCP results could be verified on 8 of the 15 explanted CI, in detail, 3 of 4 infected cochlear implants and 5 of 9 cochlear implants explanted because of device failure. The germ spectrum shows common germs such as Staphylococcus aureus, Pseudomonas aeruginosa, and Haemophilus influenzae, as well as germs from the dental cavity, with a peak of P. aeruginosa in infections.

Detection and identification of microbial colonization on cochlear implants can be successfully conducted using the proposed approach of smear test subsequent genetic analysis. The prevalence of P. aeruginosa and germs from the dental cavity may demand an adaption of antibiosis with respect to these germs. Further investigations of the path of infection are needed, and patients might require a prevention by preoperative dental treatment.