A comparison of topical chlorhexidine, ciprofloxacin, and fortified tobramycin/cefazolin in rabbit models of Staphylococcus and Pseudomonas keratitis.
OBJECTIVE
Chlorhexidine was evaluated as a potential topical therapy for experimental bacterial keratitis.


METHODS
Chlorhexidine (0.01%) was compared to ciprofloxacin (0.3%) and tobramycin (1.36%)/cefazolin (5%) both in vitro and in vivo for the treatment of Staphylococcus aureus and Pseudomonas aeruginosa infections. The minimum inhibitory concentration (MIC) was established for each organism for each antibiotic, using a standardized method. One thousand (1000) colony-forming units (CFU) of S. aureus or P. aeruginosa was intrastromally injected into rabbit cornea. A total of 92 corneas were infected and then treated topically with antibiotics. The control eyes were treated with artificial tears. The rabbits were later sacrificed, and the corneal buttons were harvested.


RESULTS
The MIC for chlorhexidine was <or=40 microg/mL for both organisms. In the rabbit model of S. aureus keratitis, following the treatments, the median number of CFU of recoverable bacteria for chlorhexidine (n = 10), ciprofloxacin (n = 12), tobramycin/cefazolin (n = 12), and controls (n = 10) was 1.1 x 10(3), 4.7 x 10(4), 1.9 x 10(5), and 6.7 x 10(4), respectively. For S. aureus, the only treatment that showed a statistically significant reduction in CFU was chlorhexidine. In the P. aeruginosa keratitis group, CFU were significantly reduced with all treatments, compared to the control.


CONCLUSIONS
Chlorhexidine short-term treatment was an effective topical therapy for bacterial keratitis in the rabbit model, when compared with ciprofloxacin and tobramycin/cefazolin, in particular for S. aureus.
Bu
Ping
P
Department of Ophthalmology, Loyola University Medical Center, Maywood, IL 60153, USA.
Riske
Paul S
PS
Zaya
Ninef E
NE
Carey
Roberta
R
Bouchard
Charles S
CS
D000287:Administration, Topical; D000818:Animals; D000891:Anti-Infective Agents, Local / Q000627:therapeutic use*; D002437:Cefazolin / Q000627:therapeutic use; D002710:Chlorhexidine / Q000627:therapeutic use; D002939:Ciprofloxacin / Q000627:therapeutic use; D015169:Colony Count, Microbial; D003315:Cornea / Q000187:drug effects / Q000382:microbiology; D004195:Disease Models, Animal; D004338:Drug Combinations; D015818:Eye Infections, Bacterial / Q000188:drug therapy*; D007634:Keratitis / Q000188:drug therapy*; D008826:Microbial Sensitivity Tests; D009883:Ophthalmic Solutions; D011552:Pseudomonas Infections / Q000188:drug therapy*; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D011817:Rabbits; D013203:Staphylococcal Infections / Q000188:drug therapy*; D013211:Staphylococcus aureus / Q000187:drug effects; D014031:Tobramycin / Q000627:therapeutic use
D000891:Anti-Infective Agents, Local; D004338:Drug Combinations; D009883:Ophthalmic Solutions; D002939:Ciprofloxacin; D002437:Cefazolin; D002710:Chlorhexidine; D014031:Tobramycin