2005-2007年中国食品中大肠埃希菌O157亚碲酸钾抗性基因簇的分布和抗性水平的研究

目的了解中国2005-2007年食源性疾病监测网分离的大肠埃希菌O157亚碲酸钾抗性基因簇的分布和抗性水平的关系。方法运用PCR方法进行基因检测,使用平皿法检测亚碲酸钾抗性水平。结果在所检测的89株大肠埃希菌O157中,共51株菌携带亚碲酸钾(ter)基因簇:在42株大肠埃希菌O157∶H7中,41株菌具有ter基因簇;6株携带flicH7基因、无动力O157∶NM(non-mobile)都具有ter基因簇;在41株不携带flicH7基因、无动力O157∶NM和O157∶hund(具有动力,无法判定H型别)中仅有4株菌具有ter基因簇。ter基因簇阳性的51株大肠埃希菌O157,其亚碲酸钾抗性水平为64～512μg/ml。ter基因簇阴性菌株共有38株,亚碲酸钾抗性水平大多数介于2～16μg/ml,仅1株为128μg/ml。29株携带志贺毒素基因的大肠埃希菌,共有28株具有该基因簇和较高水平的亚碲酸钾抗性。结论食品来源的大肠埃希菌O157具有不同亚碲酸钾抗性水平,高水平的亚碲酸钾抗性与携带亚碲酸钾基因簇具有很高的相关性。

Variability in tellurite resistance and the ter gene cluster among Escherichia coli O157 isolated in food from 2005 to 2007

Objective To investigate the presence of tellurite resistance(ter) gene cluster and its resistance in Escherichia coli O157 strains collected by national foodborn disease surveillance system from 2005 to 2007.Methods The ter gene cluster was tested by PCR.Tellurite resistance was evaluated by plate dilution method.Results Of the investigated 89 E.coli strains,the presence of ter gene cluster was found in 51 strains.They were separately from 41 of 42 E.coli O157∶H7 strains,all of 6 strains of O157∶NM(non-mobile flicH7 positive) and only 3 of 41 O157∶NM(flicH7 negative)/O157∶hund strains.The 51 strains with ter gene cluster were resistance to the high level of potassium tellurite.The MIC was from 64-512μg/ml.In contrast,the MIC of most of 38 strains without ter gene cluster was from 2-16μg/ml.Only one strain was 128μg/ml.28 of 29 stx-positive E.coli isolates contained the ter gene cluster and had the high levels of tellurite resistance.Conclusion E.coli O157 from food had the diversity levels of tellurite resistance.The presence of the ter gene cluster had significant associated with the high levels of tellurite resistance.