Objective To investigate antimicrobial resistance of Escherichia coli (E.coli )isolated from patients with bloodstream infection,and provide evidence for rational use of antimicrobial agents in clinical practice.Methods BacT/A-lert automated blood culture system and VITEK 2 automated identification system were used for bacterial culture and identi-fication.Antimicrobial susceptibility testing and detection of extended-spectrum β-lactamases (ESBLs)-producing strains were performed by Kirby-Bauer method.Results From 2009 to 2011 ,a total of 235 strains of E.coli were isolated from patients with bloodstream infection,90 (38.30%)of which were ESBLs positive strains.The resistant rates of ESBLs-producing strains to ampicillin,cefotaxime and ceftriaxone were all 100%,but susceptibility rate to imi-penem/cilastatin and meropenem were all 100%,to cefmetazole and amikacin were >90%.The resistant rate of non-ESBLs-producing strains to ampicillin was the highest (70.63%),susceptibility rate to imipenem/cilastatin and meropenem were both 100%,to amikacin,cefotaxime,and cefmetazole were all >95%.The resistant rate of ES-BLs-producing strains was significantly higher than that of the non-ESBLs-producing strains.Ofβ-lactamase inhibi-tor,only susceptibility rate of ESBLs-producing E.coli to cefoperazone/sulbactam was>90%,susceptibility rates to piperacillin/tazobactam and ticarcillin/clavulanate were both<80%.Conclusion Antimicrobial resistant rate of ESBLs-producing strains causing bloodstream infection is high,individualized treatment strategies should be made according to antimicrobial resistance of bacteria causing infection in patients.%目的：分析某院血流感染患者标本分离的大肠埃希菌耐药性，为临床合理应用抗菌药物提供依据。方法采用 BacT／Alert 全自动血培养仪、VITEK 2细菌鉴定仪对患者血标本进行培养、鉴定；K-B 药敏纸片测定法进行药敏试验并筛选出产超广谱β-内酰胺酶（ESBLs）细菌。结果2009—2011年共分离血流感染大肠埃希菌235株， ESBLs 阳性90株，阳性率38．30％。产 ESBLs 菌株对氨苄西林、头孢噻肟、头孢曲松100％耐药；对亚胺培南／西司他丁、美罗培南敏感率均为100％，对头孢美唑、阿米卡星敏感率＞90％。非产 ESBLs 菌株耐药率最高的是氨苄西林，达70．63％；对亚胺培南／西司他丁、美 罗 培 南 敏 感 率 均 为100％，对阿米卡星、头孢噻肟、头孢美唑敏感率＞95％。产 ESBLs 菌株的耐药率均明显高于非产 ESBLs 菌株。在含有β-内酰胺酶抑制剂的复合抗菌药物中，只有头孢哌酮／舒巴坦对产 ESBLs 大肠埃希菌的敏感率＞90％，哌拉西林／他唑巴坦和替卡西林／克拉维酸的敏感率均未超过80％。结论血流感染大肠埃希菌产 ESBLs 株的耐药性较高，临床用药应根据患者感染菌的耐药情况制定合理的个体化治疗措施。
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