PROBLEM TO BE SOLVED: To provide levofloxacin eye drops used in a novel method/dosage for healing an eye infection within a shorter period of time than a conventional method/dosage for preventing occurrence of resistant bacteria without increasing an incidence rate of side effects.SOLUTION: In the novel method and dosage of eye drops containing 1.5% (w/v) of levofloxacin, the eye drops are dropped into the eyes thrice a day. In this way, bacterial conjunctivitis can be healed within a shorter period of time, compared with the conventional case where 0.5% (w/v) eye drops are used thrice a day, without increasing the incidence rate of side effects. Healing of an eye infection within a short period of time contributes to shortening of the exposure time of a pathogenic bacterium causing the eye infection to levofloxacin. As a result, it is expected that the novel method and dosage of levofloxacin-containing eye drops inhibit the emergence of a resistant strain caused by the prolonged usage of levofloxacin-containing eye drops in the conventional method/dosage. Moreover, it is confirmed that the novel method and dosage of levofloxacin-containing eye drops directly inhibit tolerization, which is caused by the short-term usage of levofloxacin-containing eye drops in the conventional method/dosage, in pathogenic bacteria causative of eye infections such as Staphylococcus aureus.【課題】耐性菌の出現を阻止するために従来の用法又は用量の点眼液よりも短期間で眼感染症を治癒し、且つ副作用の発現率も増大させない新たな用法又は用量のレボフロキサシン点眼液の提供。【解決手段】１．５％（ｗ／ｖ）レボフロキサシン点眼液の１日３回点眼。これは、従来の用法又は用量である０．５％（ｗ／ｖ）点眼液の１日３回点眼よりも短期間で細菌性結膜炎を治癒し、しかも副作用の発現率も増大させないという特徴を併せもつ。短期間で眼感染症を治癒させることは眼感染症起炎菌のレボフロキサシンへの曝露期間を短縮することになり、結果として、従来の用法または用量のレボフロキサシン点眼液の長期使用を原因とする耐性菌の出現を抑制することが期待される。さらに、従来の用法または用量のレボフロキサシン点眼液の短期使用を原因とする黄色ブドウ球菌等の眼感染症起炎菌の耐性化を直接的に抑制することが確認された。【選択図】図２
