Protective effects of local administration of ciprofloxacin on the risk of pneumococcal meningitis after cochlear implantation.
OBJECTIVE
To determine whether ciprofloxacin retains its antimicrobial activity after storage with Healon at ambient temperature and at 37 degrees C over 5 weeks and then to establish whether the application of ciprofloxacin/Healon onto scala tympani electrode arrays reduces the risk of meningitis in implanted rats inoculated with S. pneumoniae.


METHODS
In vitro laboratory and in vivo animal studies


METHODS
The antibacterial activity of three concentrations of ciprofloxacin/Healon (7.5, 75, and 750 microg/mL) was examined over 5 weeks at both ambient temperature (23 degrees C) and body temperature (37 degrees C). Thirty-six rats (18 implanted with ciprofloxacin [750 mg/mL]/Healon-coated electrode array and 18 without the coating) were infected with S. pneumoniae 4 weeks after implantation by way of three different routes of infection (hematogenous, middle ear, and inner ear) and observed for the development of meningitis.


RESULTS
The antibacterial activity of ciprofloxacin/Healon was maintained over 5 weeks at both 23 degrees C and 37 degrees C. The implanted rats with the ciprofloxacin/Healon-coated electrode array were protected from meningitis when the bacteria were given by way of the hematogenous route (Fisher's exact test, P = .008) but not when the bacteria were inoculated directly into the middle or inner ear. However, the time to develop meningitis was significantly longer in rats implanted with a coated array, irrespective of the route of inoculation (P < .05, log rank test).


CONCLUSIONS
Our animal model demonstrated that a ciprofloxacin-coated electrode array can protect healthy implanted rats from meningitis when the route of infection is hematogenous and can delay the onset of meningitis when bacteria are inoculated directly into the middle or inner ear.
Wei
Benjamin P C
BP
Department of Otolaryngology, Bionic Ear Institute, University of Melbourne, Royal Victorian Eye and Eye Hospiatl, Melbourne, Victoria, Australia. bwei@bionicear.org
Robins-Browne
Roy M
RM
Shepherd
Robert K
RK
Azzopardi
Kristy
K
Clark
Graeme M
GM
O'Leary
Stephen J
SJ
D000276:Adjuvants, Immunologic / Q000627:therapeutic use; D000287:Administration, Topical; D000818:Animals; D000890:Anti-Infective Agents / Q000008:administration & dosage*; D002939:Ciprofloxacin / Q000008:administration & dosage*; D019929:Cochlear Implantation / Q000009:adverse effects*; D004567:Electrodes, Implanted / Q000382:microbiology; D006820:Hyaluronic Acid / Q000627:therapeutic use; D008586:Meningitis, Pneumococcal / Q000209:etiology / Q000517:prevention & control*; D023421:Models, Animal; D051381:Rats; D017208:Rats, Wistar; D013296:Streptococcus pneumoniae / Q000187:drug effects
D000276:Adjuvants, Immunologic; D000890:Anti-Infective Agents; D002939:Ciprofloxacin; D006820:Hyaluronic Acid