大肠埃希菌耐药性水平传播实验研究

Experimental study of multidrug-resistant genes transferred horizontally in Escherichia coli

目的研究重症监护病房(ICU)患者标本中分离的大肠埃希菌的耐药情况以及耐药性水平传播的实验研究。方法采取双纸片法(K-B)检测细菌的耐药性;产超广谱β-内酰胺酶(ESBLs)大肠埃希菌为供体菌,耐利福平大肠埃希菌(对其他抗生素敏感)作为受体菌进行接合实验;采用聚合酶链反应(PCR)技术扩增整合子和耐药基因。结果30株大肠埃希菌中产ESBLs菌株检出率为46.7%;接合培养后,接合菌携带23kb和25kb大质粒,而无供体菌中一系列小质粒;供体菌和接合菌均携带Ⅰ型整合子。结论大肠埃希菌耐药性严重,且呈多重耐药性;产ESBLs菌株可通过质粒和整合子将耐药基因转移给敏感菌,导致耐药性传播。

Objective To investigate antibiotic resistance of Escherichia coli in ICU, and the mechanism of mtdti- drug-resistant genes transferred horizontally between clinical Escherichia coli and Rifampicin-resistant Escherichia coli. Methods Antibiotic resistance test was used by method of K-B. Extended-spectrum β-1actamase （ESBLs）-producing strains among clinical isolates of ICU Escherichia coli, and antibiotic resistance transferability were analyzed by conjugation experiments. Donator strains were ESBLs positive strains of Escherichia coli, Rifampicin-resistant Escherichia coli were receptors. The presence of class Ⅰ integron and TEM gene among bacterium examined by PCR. Results The positive rate of ESBLs-producing isolates in Escherichia coli was 46.7%. All conjugation strains could be obtained large plasmids （23 kb or 25 kb） after mixed culturing,but no small plasmids. Class Ⅰ integrons were distributed in donator strains and conjugation strains. Condusions Escherichia coli had high drug resistance to several antibiotics and had multi-resistance. Drug resistance gene transfer by conjugation experiments to sensitive bacteria.