从大肠艾希菌和肺炎克雷伯菌中检测超广谱β内酰胺酶和AmpC酶

Detection of extended spectrum β lactamases and ampC β lactamases from Escherichia coli and Klebsiella pneumoniae

目的 :了解对头孢类抗生素耐药的大肠艾希菌和肺炎克雷伯菌中ESBLs和AmpC酶的分布及其对抗生素的敏感性。方法 :利用双纸片协同试验及纸片法确认试验检测ESBLs ,三相试验检测AmpC酶 ,并用K B法纸片扩散试验和微量稀释法测定细菌对抗生素的敏感性。结果 :从对头孢噻肟耐药的大肠艾希菌和肺炎克雷伯菌中检出产ESBLs分别为 91 4 %和 96 7% ;产AmpC酶分别为 17 1%和 10 % ;ESBLs和AmpC酶共同存在者分别为 8 6 %和 6 7%。产酶菌株对三代头孢类抗生素高度耐药 ,对环丙沙星、庆大霉素及复方增效磺胺耐药率较高 ,对亚胺培南敏感 ,产AmpC酶细菌对含酶抑制剂的复合抗生素高度耐药。结论 :产生ESBLs和AmpC酶是大肠艾希菌和肺炎克雷伯菌对头孢类抗生素耐药的重要机制 ,实验室应对其检测和监测给予足够重视 。

Objective:To know the distribution and anti microbial susceptibility of extended spectrum βLactamase and AmpCβLactamase producing Escherichia coli and Klebsiella pneumoniae which are resistant to cephalosporins Methods: AmpC βLactamase and extended spectrum βLactamases were detected by three dimensional test, double disk synergy test and disk confirmatory test recommended by National Committee for Clinical Laboratory Standards Disk diffusion test was used for anti microbial susceptibility test, the MIC values of AmpC βLactamase producing strains were examined by micro dilution test Results:From Escherichia coli and Klebsiella pneumoniae resistant to cefotaxime, extended spectrum βLactamase producers were 91 4% and 96 7%, AmpC βLactamase producers accounted for 17 1% and 10% , extended spectrum βLactamase plus AmpCβLactamase producers were 8 6% and 6 7%, respectively These strains were highly resistant to the third general cephalosporins, but susceptible to imipenem Their resistance ratio to ciprofloxacin, gentamicin amd trimethoprim/sulfamethoxazole were higher than that of nonproducers AmpC βLactamase producers possessed high resistanceto antibiotics combined with inhibitors Conclusion:Extended spectrum βLactamases and AmpC βLactamases are the most important resistance mechanisms of Escherichia coli and Klebsiella pneumoniae to cephalosporins,much attention should be paid to their detection and surveillance, their resistance to anti microbial agents should be known by clinicians