氟喹诺酮体外诱导耐药肺炎克雷伯菌膜孔蛋白表达的变化

目的 探讨氟喹诺酮体外诱导耐药肺炎克雷伯菌(KPn)膜孔蛋白表达变化.方法 取2008年9月至2009年6月本院临床分离对环丙沙星敏感的KPn 20株,分为对照组和实验组,每组10株.对照组直接涂布于含环丙沙星128 mg/L的平板,观察其对环丙沙星的敏感性.实验组应用不同浓度梯度环丙沙星逐级诱导成为高度耐药株,观察应用环丙沙星前后KPn敏感株和耐药株膜孔蛋白表达的差异.结果 对照组10株KPn直接涂布于含环丙沙星128 mg/L的平板培养后无一存活.3对KPn菌株R9、S9、R4、S4、R3、S3环丙沙星诱导前后膜孔蛋白相对表达量分别是3.86±0.11、6.44±0.26、5.46±0.18、9.58±0.34、1.75±0.06和9.78±0.36,诱导耐药的KPn较相应敏感株膜孔蛋白表达明显减少(均P＜0.05).结论 氟喹诺酮体外诱导耐药KPn膜孔蛋白表达减少,可能通过细菌外膜通透性改变在KPn诱导耐药中起重要作用.

Altered expression of porins in fluoroquinolone-induced drug-resistant Klebsiella pneumoniae in vitro

Objective To investigate the altered expression of porins in drug-resistant Klebsiella pneumoniae (KPn) induced by fluoroquinolone (FQL) in vitro. Methods Between September 2008 and June 2009, 20 clinical stains of FQL sensitive KPn isolated in our hospital were allocated into control and experimental groups (n=10 each). In control group, KPn strains were directly innoculated on a cultureplate containing 128 mg/L FQL and observed for their sensitivity to FQL. In experimental group, KPn strains were induced into highly drug-resistant strains by different concentration gradients of FQL. The altered expression of porins was then observed in sensitive and drug- resistant strains of KPn before and after using FQL.Results No KPn strains in the control group survived on the cultureplate with 128 mg/L FQL. The relative expressions of porin in 3 pairs of KPn strains (R9 vs S9, R4 vs S4 and R3 vs S3 ) were 3.86±0.11 vs 6.44±0.26, 5.46±0.18 vs 9.58±0.34 and 1.75±0.06 vs 9.78±0.36 before and after FQL induction, respectively. The porin expression in drug-resistant strains was significantly lowered compared with sensitive strains (all P＜0.05). Conclusion The down-regulated expression of porin in FQL-induced drug-resistant KPn strains in vitro and hence lowered permeability of the bacterial outer membrane may play an important role in development of drug-resistance.