多重耐药大肠埃希菌接合性质粒与转座子遗传标记

Genetic markers of conjuagal plasmids and transposons in multidrug-resistant strains of Escherichia coli

目的调查多重耐药大肠埃希菌中接合性质粒与转座子的分布状况。方法从患者尿液标本中分离多重耐药大肠埃希菌60株,采用聚合酶链反应（PCR）法分析接合性质粒遗传标记traAt、rbC和转座子遗传标记ISEcp1I、S26t、np513。结果 5种基因在60株多重耐药大肠埃希菌中均有检出,traAt、rbCI、SEcp1I、S26t、np513阳性率分别为81.7%（49/60）、70.0%（42/60）、76.7%（46/60）、83.3%（50/60）、38.3%（23/60）。有58株菌至少检出1种基因,各菌株基因阳性数1~5种不等,共可分为17种阳性基因模式。其中,15株菌同时检出5种基因,22株菌同时检出4种基因,12株菌同时检出3种基因,5株菌同时检出2种基因,4株菌仅检出1种基因。结论本组大肠埃希菌中接合性质粒与转座子的阳性率高,多重耐药的表型可能与携带接合性质粒和转座子、插入序列导致耐药基因高表达相关。耐药基因水平转移是导致医院感染病原菌耐药性快速传播的常见机制。

Objective To investigate the distribution of conjuagal plasmids and transposons in multidrug-resistant strains of Escherichia coli（E.coli）.Methods Sixty strains of multidrug-resistant E.coli isolated from urine were collected.Two kinds of conjuagal plasmids and three kinds of transposons were analyzed by PCR.Results Five kinds of genes were all detected in 60 strains of E.coli,with the positive rates of 81.7% for traA,70.0% for trbC,76.7% for ISEcp1,83.3% for IS26,and 38.3% for tnp513,respectively.Fifty-eight strains were detected at least to carry one kind of gene.And 17 kinds of positive modes were classified according to the presence of positive genes.Fifteen strains were detected to carry 5 kinds of genes,22 strains were detected to carry 4 kinds of genes,12 strains were detected to carry 3 kinds of genes,5 strains were detected to carry 2 kinds of genes,4 strains were detected to carry one kind of gene.Conclusion The high positive rates exist in conjuagal plasmids and transposons carrying E.coli.And phenotype of multidrug-resistance may be involved in the mechanism of conjuagal plasmids,transposons and insertion sequence resulting in overexpression of resistance genes.Transference of multidrug-resistance gene is a common mechanism for inhospital rapidly spread of resistance of bacterial pathogens.