A laboratory evaluation of antibiotic therapy for ciprofloxacin-reitant peudomona aeruginoa

Purpoe The emergence of ciprofloxacin-reitant Peudomona aeruginoa (CRPA) ha created a new therapeutic challenge in ophthalmology. We evaluated ophthalmic antibiotic in vitro and in a rabbit keratiti model to determine effective therapy. Deign Experimental laboratory invetigation. Method The uceptibilitie of 12 CRPA iolate were determined in vitro for amikacin, ceftazidime, tobramycin, polymyxin B, gentamicin, ticarcillin, and the fluoroquinolone (that i, ciprofloxacin, ofloxacin, levofloxacin, gatifloxacin, and moxifloxacin) uing E-tet and National Committee of Clinical Laboratory tandard. A rabbit keratiti model wa ued to determine the reduction in colony count of CRPA and ciprofloxacin-uceptible P. aeruginoa (CPA) iolate following topical treatment with polymyxin B/trimethoprim, tobramycin (14 mg/ml), ceftazidime (50 mg/ml), and ciprofloxacin (3 mg/ml). Reult For 12 CRPA iolate, the uceptibilitie and median minimum inhibitory concentration ([MIC]μg/ml) were a follow: amikacin (92%, 14.0), ceftazidime (75%, 4.0), tobramycin (67%, 1.75), polymyxin B (42%, 7.0), gentamicin (17%, 7.0), ticarcillin (0%, >32.0), and all fluoroquinolone (0%, >32.0). While no antibiotic regimen reduced colony count in the time frame of the animal model for CRPA, ciprofloxacin alone demontrated a ignificant decreae in colony count for CPA. Comparing CRPA with CPA, both tobramycin and ciprofloxacin demontrated a ignificant decreae in colony count for CPA. Concluion Our laboratory tudie ugget that current antibiotic may be uboptimal in treating CRPA keratiti. Until new antibiotic are available, combination therapy uch a fortified tobramycin and ticarcillin, and other may prove effective in aggreive topical long-term therapy.