肠集聚性大肠埃希菌在健康老年人肠道中的分布及其耐药机制研究

The resistance mechanism and distribution of enteroaggregative Escherichia coli from the intestines of healthy elderly people

目的分析健康老年人肠道中肠集聚性大肠埃希菌(EAEC)的检出率,并探讨其毒力基因及超广谱β-内酰胺酶(ESBL)的携带情况。方法取健康老年人的粪便标本分别接种于血平板、SS平板、麦康凯平板进行细菌培养,用全自动微生物鉴定仪和质谱仪鉴定细菌到种;对分离的大肠埃希菌采用双纸片协同法检测其ESBL的表型,用PCR法扩增其EAEC毒力基因astA和aggR;ESBL表型阳性的EAEC菌株用PCR法检测其ESBL基因型。结果在175例研究对象中,共检出160株大肠埃希菌,ESBL携带率为36.30%(58/160);EAEC检出16株(10.00%),其中astA阳性14株(8.75%),aggR阳性2株(1.25%);EAEC菌株的ESBL携带率为56.25%(9/16),其基因型均为CTX-M型,其中以CTX-M-14最多,占66.70%(6/9)。结论本研究获得了健康老年人肠道中EAEC的检出率及其毒力基因和ESBL的携带情况,提示我们EAEC不仅是腹泻患者的病原菌,还可以在健康老年人群中携带,且具有较高的携带率和耐药性,提醒我们加强防范。

Objective To analyse the detection rate of Enteroaggregative Escherichia coli（EAEC）in healthy elderly intestines,and explore the distribution of ESBL and virulence genes of EAEC.Methods The stool specimens were cultured on blood plate,SS plate and MAC plate.The bacterial strains were identified by using VITEK-2compact and mass spectrometry.The resistance phenotypes were determinated by usng K-B disk diffusion method.The resistance genes and EAEC virulence genes,astA and aggR,were amplified by PCR and compared against GenBank.Results Among the 175 healthy volunteers,there were 160 strains of E.coli,36.30%（58/160）of which carrying ESBLs genes.The detection rate of EAEC was 10.00%（16/160）,among which 14strains（8.75%）were astA positive,and 2strains（1.25%）were aggR positive.ESBLs positive EAEC strains accounted for 56.25%（9/16）,all carrying CTX-M type genes,among which CTX-M-14 was predominant,accounting for 66.70%（6/9）.Conclusion The detection rate of EAEC in healthy elderly intestines and the ESBL and virulence genes of EAEC suggest that EAEC is not only the pathogenic bacteria of diarrhea patients,it can also be carried in healthy people,with high carrying rate and drug resistance.