In vitro Antibacterial Activity of Norfloxacin and Other Agents against Ocular Pathogens

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Abstract
302 clinical isolates representing 16 bacterial species most often implicated in ocular infections were tested in vitro against norfloxacin and a panel of antibacterial agents. On the basis of the 90% minimal inhibitory concentration (MIC90) data, norfloxacin was 4–32 times more active than the next best antimicrobial tested against Citrobac-ter freundii, Escherichia coli, Morganellamorganii, Proteus mirabilis, Proteus vulgaris, Haemophilus influenzae, Neisseria gonorrhoeae and Staphylococcus epidermidis, with overall MlC90 < 1 mg/1. Norfloxacin was equal in activity to polymyxin B against Klebsiella pneumoniae (MIC90 = 1 mg/1), and it ranked second to both polymyxin B against Pseudomonas aeruginosa and cotrimoxazole against Staphylococcus aureus, (MIC90 = 2 mg/1 in each case). Along with neomycin and cotrimoxazole, norfloxacin (MIC90 = 1 mg/1) ranked second to gentamicin and tetracycline against Moraxella species. Compared to erythromycin (MIC90 < 0.125 mg/1), norfloxacin (MIC90 < l6 mg/1) was considerably less active against streptococci. Overall, norfloxacin was the most active agent in both potency and antibacterial spectrum against the test organisms. These results suggest the potential use of norfloxacin in the treatment of superficial bacterial infections of the eye.