Bacterial biofilm formation on a human cochlear implant.
OBJECTIVE
To report the characteristics of a bacterial biofilm from the surface of a cochlear implant.


BACKGROUND
Bacterial biofilm formation on implanted devices causes intractable infections and device extrusions necessitating device removal, with loss of function. More information is needed about biofilm characteristics and interactions with the implant surface before better treatments can be designed.


METHODS
A retrospective case review was combined with a descriptive histological study of the surface of an otologic device.


METHODS
The receiver/stimulator device removed from a cochlear implant patient because of intractable infection and partial device extrusion was fixed and processed for microscopic examination. Its surface and the material present on its surface were analyzed using light and electron microscopy, focusing on surface texture, cell types, and bacteria species and extracellular polymeric substances present within the biofilm.


RESULTS
Stereomicroscopic examination revealed extracellular polymeric substances, pinkish yellow in color, with spheres of uniform size scattered throughout, indicative of a biofilm containing Staphylococcus aureus. Biofilm density was greatest in depressions on the surface of the implant. Cross-sectional analysis revealed bacteria interspersed with polymorphonuclear leukocytes. Scanning electron microscopic examination demonstrated an amorphous layer of extracellular polymeric substances containing small filaments, bacteria, and inflammatory cells. Only Staphylococcus aureus was detected.


CONCLUSIONS
Cochlear implant material can provide a surface for bacterial biofilm formation. Impressions can provide an environment conducive to biofilm establishment and growth, ultimately necessitating device removal, with loss of implant function. Biofilm characterization should aid in design of cochlear implant devices less susceptible to biofilm formation.
Pawlowski
Karen S
KS
Department of Otolaryngology, Head and Neck Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, USA. karen.pawlowski@utsouthwestern.edu
Wawro
Debra
D
Roland
Peter S
PS
D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D018441:Biofilms / Q000254:growth & development*; D002443:Ceftriaxone / Q000627:therapeutic use; D002675:Child, Preschool; D019929:Cochlear Implantation; D003054:Cochlear Implants / Q000009:adverse effects / Q000382:microbiology*; D003430:Cross-Sectional Studies; D003638:Deafness / Q000534:rehabilitation; D005260:Female; D006801:Humans; D008855:Microscopy, Electron, Scanning; D016459:Prosthesis-Related Infections / Q000188:drug therapy / Q000382:microbiology* / Q000601:surgery; D012086:Reoperation; D012189:Retrospective Studies; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology* / Q000601:surgery; D013211:Staphylococcus aureus / Q000502:physiology* / Q000648:ultrastructure; D016896:Treatment Outcome
D000900:Anti-Bacterial Agents; D002443:Ceftriaxone