The increasing incidence of Haemophilus influenzae with decreased susceptibility to quinolones (quinolone low-susceptible H. influenzae ) in Japan has raised concerns about therapeutic failure. Thus, assessment of effective antimicrobial agents is necessary to establish an effective therapeutic strategy against resulting infections. In this study, in vitro bactericidal effects of quinolones on low-susceptible H. influenzae strains were evaluated using time-kill curve analysis. For tosufloxacin, log reduction values for low-susceptible strains were significantly lower than those for susceptible strains at both Cmax and 1/2 Cmax. Conversely, although the log reduction values were lower for susceptible strains, the Cmax of levofloxacin and β-lactams (amoxicillin and cefditoren) indicated bactericidal effects. In addition, higher concentrations of tosufloxacin at 2×Cmax and 4×Cmax had bactericidal effects on not only susceptible but also low-susceptible strains. These data strongly suggest that we should consider the presence of low-susceptible strains and reconsider the appropriate dosage of tosufloxacin for treatment, especially for paediatric patients.

中文翻译：

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喹诺酮类药物对低感流感嗜血杆菌的杀菌作用比较

在日本，随着对喹诺酮类药物（喹诺酮类低敏感流感嗜血杆菌）的敏感性降低，流感嗜血杆菌的发病率不断增加，这引起了人们对治疗失败的担忧。因此，必须评估有效的抗微生物剂，以建立有效的治疗策略来对抗由此产生的感染。在这项研究中，喹诺酮类药物对低敏感流感嗜血杆菌菌株的体外杀菌效果使用时间-杀灭曲线分析进行评估。对于托舒沙星，在 C max和 1/2 C max 时，低易感菌株的对数减少值显着低于易感菌株的对数减少值 . 相反，尽管敏感菌株的对数减少值较低，但左氧氟沙星和 β-内酰胺类（阿莫西林和头孢托仑）的 C max表明具有杀菌作用。此外，在 2×C max 和 4×C max 下较高浓度的托舒沙星不仅对易感菌株而且对低易感菌株具有杀菌作用。这些数据强烈建议我们应该考虑低敏感菌株的存在，并重新考虑适当的托舒沙星治疗剂量，尤其是对儿科患者。