头孢西丁不敏感大肠埃希菌的耐药性及质粒型AmpC酶基因分析

Analysis of Escherichia Coli of Clinical Isolates with Resistance to Cefoxitin and Its Prevalence of AmpC Encoding Genes

目的 对107株头孢西丁不敏感大肠埃希菌的耐药特点及质粒型AmpC酶基因的流行性进行分析。方法 使用WHONET5.6软件分析2012年4~9月头孢西丁不敏感大肠埃希菌的耐药性,并与同期分离的头孢西丁敏感大肠埃希菌的耐药性进行比对分析;PCR扩增和DNA测序分析blaDHA、blaACT、blaCMY、blaFOX等质粒型AmpC酶基因的流行性。结果 头孢西丁不敏感大肠埃希菌对阿米卡星,第三、四代头孢菌素和氟喹诺酮类等药物均具有较高的耐药性（P〈0.05）。25株（23.3%）细菌携带质粒型ApmC酶基因。其中23株为blaCMY基因（17株为blaCMY-2,6株为blaCMY-42）,2株为blaDHA-1。结论 头孢西丁不敏感大肠埃希菌对多种抗菌药物具有较高的耐药性,且有质粒型AmpC酶基因的广泛流行,应加强监护,预防播散。

Objective To analyze 107 Escherichia coli isolates that were not sensitive to cefoxitin and investigate the prevalence of plasmid mediated AmpC, Methods WHONET 5.6 software was used to analyze the resistance of E. coli isolates to cefoxitin collected from April to September 2012. Plasmid mediated AmpC encoding genes including blaDHA, bIaACT, blaCMY,and blaFOX were explored by PCR and DNA sequencing. Results E. eoli resistant to cefoxitin also displayed high resistance towards multiple antibiotics, including amikacin, and the third/fourth generation of cefalosporins as well as fluoroquinolones （P〈0.05）. Genes encoding plasmid mediated AmpC enzyme were confirmed in 23. 3% （25/ 107）of the strains. Among them,21.5% （23/107） were blaCMY（17 blaCMY-2, 6 blaCMY-42 ）,the other 2 were blaD- HA-1. Conclusion High frequency of E. coli cefoxitin resistantce were found to multiple antibiotics with the high preva lence of plasmid mediated AmpC encoding genes. Consecutive surveillance for those cefoxitin resistant strains will help reduce the nosocornial dissemination.