TOPICAL FLUOROQUINOLONES - ANTIMICROBIAL ACTIVITY AND INVITRO CORNEAL EPITHELIAL TOXICITY

To assess the potential of fluoroquinolones as topical antimicrobial agents, we evaluated in vitro the antimicrobial activity of five fluoroquinolones (ciprofloxacin, norfloxacin, ofloxacin, pefloxacin, and temafloxacin), as well as gentamicin, tobramycin, and cefazolin against 96 isolates of common bacterial corneal pathogens. Ciprofloxacin and temafloxacin were the most active quinolones [minimal inhibitory concentration inhibiting 90% of stains (MIC90) of 1-mu-g/ml], followed by ofloxacin (MIC90 2-mu-g/ml), and norfloxacin and pefloxacin (MIC90s 4-mu-g/ml). In contrast, gentamicin and tobramycin MIC90s were 32 and 64-mu-g/ml, respectively; cefazolin MIC90 was > 2048-mu-g/ml. The corneal epithelial cytotoxicity of the fluoroquinolones also was evaluated utilizing an in vitro assay of H-3-thymidine uptake of rabbit corneal epithelial cell cultures. The least to greatest toxicity of the fluoroquinolones were as follows: ciprofloxacin and temafloxacin < norfloxacin < ofloxacin < pefloxacin. Our study suggests that the fluoroquinolones, especially ciprofloxacin and temafloxacin, possess excellent in vitro activity against common bacterial corneal pathogens and are less toxic to the corneal epithelium than the aminoglycosides.