A comparison of topical chlorhexidine, ciprofloxacin, and fortified tobramycin/cefazolin in rabbit models of Staphylococcus and Pseudomonas keratitis.

ABSTRACT

AIMS: 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 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.