产ESBLs的大肠埃希菌耐药性的转移与基因型的研究

Resistant Transfer and Genotyping Extended-spectrum of Escherichia coli Producing β-Lactamases

目的证实临床分离的部分产超广谱β-内酰胺酶（ESBLs）的大肠埃希菌可以把耐药基因转移给敏感的受体菌。方法用PCR及DNA测序方法检测16株产ESBLs的大肠埃希菌的耐药基因类型，通过接合试验了解耐药基因在细菌间的传递，分别对供体菌和转移接合子进行抗生素药敏试验。结果从16株产ESBLs的大肠埃希菌中共检出TEM，SHV，OXA-1群和CXT—M—1群4种β-内酰胺酶基因，检出率分别为100％（16／16），93．75％（15／a6），12．5％（2／16）和37．5％（6／16）。接合试验中得到了4株转移接合子，均携带了blaCTX-M-1基因，经测序分析与供体菌同源性为100％。转移接合子与供体菌具有相似的药敏试验结果。结论临床分离的产ESBLs大肠埃希菌可以把耐药基因传递给敏感的受体菌，有效控制细菌耐药基因的转移对临床具有重要意义。

Objective To verify that E. coli isolated from the clinic which produced extended-spectrum β-lactamase genes （ESBLs） can transfer resistant genes to sensitive recipients. Methods The resistant genotypes of 16 E. coli isolates producing ESBLs were dected by PCR and DNA sequencing. In order to understand the spread of resistant in bacteria,conjugation assays were conducted. In addition,the antimicrobial susceptibility tests were tested between donors and transconjugants. Results Four β-lactamase resistant genes including TEM,SHV,OXA-1 group and CXT-M-1 group existed in 16 isolates of E. coli producing ESBLs. Their rates were 100% （16/16）, 93.75% （15/16）,12.5% （2/16） and 37.5% （6/16）, respectively. 4 transconjugants were successfully in conjugation experiments. All of them carried blaCTX-M-1 genes,and share 100%identity with donors. It was also found that transconjugants had similar susceptibility results with donors. Conclusion The clinical isolates of E. coli producing ESBLs can transfer their resistant genes to sensitive recipients. It is of great significance to effectively control transference of resistant genes.