In vitro and in vivo effectiveness evaluation of balofloxacin in experimental Staphylococcus aureus keratitis.
PURPOSE
To evaluate the effectiveness of balofloxacin for treatment of experimental Staphylococcus aureus keratitis.


METHODS
In vitro testing compared the cellular toxicity of and bacterial susceptibility to balofloxacin and levofloxacin in human corneal epithelial cells (HCECs). For in vivo testing, experimental bacterial keratitis was induced and treated with balofloxacin eye drops (0.5%) and levofloxacin eye drops (0.5%).


RESULTS
In vitro toxicity examinations showed that balofloxacin, as well as levofloxacin, had low cytotoxicity in HCECs. Balofloxacin eye drops (0.5%) also showed a similar relative cytotoxicity to levofloxacin eye drops (0.5%). In bacterial susceptibility examinations, both balofloxacin and levofloxacin significantly reduced S. aureus compared with the untreated control (P<0.001 for both balofloxacin and levofloxacin). Balofloxacin was more effective than levofloxacin in the treatment of S. aureus bacterial keratitis (P<0.05). In experimental bacterial keratitis treatment testing, balofloxacin was also more effective than levofloxacin with respect to the parameters of physiological score, histological observation, and bacterial quantitation (P<0.05).


CONCLUSIONS
Balofloxacin was safe in the treatment of S. aureus bacterial keratitis, and more effective than levofloxacin. Therefore, balofloxacin was shown to have potential clinical value in ophthalmic local application.