Ⅰ类整合子介导大肠埃希菌与肺炎克雷伯菌耐药机制的初步研究

目的了解临床分离的大肠埃希菌、肺炎克雷伯菌中I类整合子的分布情况,探讨整合子与细菌耐药之间的关系。方法琼脂平皿稀释法进行药敏试验;双纸片法筛选出产ESBLs的菌株;运用PCR扩增、DNA测序及DNA序列比对等方法对其携带的I类整合子相关耐药基因进行分析。结果 36株大肠埃希菌与46株肺炎克雷伯菌对头孢克肟、头孢克洛、头孢氨苄、哌拉西林/他唑巴坦、头孢他啶、头孢噻肟钠、阿莫西林纳/舒巴坦钠、氨苄西林钠/舒巴坦钠及头孢哌酮/舒巴坦钠等的耐药率分别为61%、86%、86%、50%、75%、64%、39%、47%、30%与65%、63%、78%、52%、67%、54%、48%、41%、28%;10株细菌检测出产ESBLs,其中大肠埃希菌4株,肺炎克雷伯菌6株,并全部检测出1类整合子,其整合子可变区的耐药基因排列顺序与GenBank登录号为NC010410的菌株达到100%相似,并且皆含有blaVEB-1耐药基因盒。结论Ⅰ类整合子及整合子相关基因盒在大肠埃希菌和肺炎克雷伯菌中分布广泛,整合子在细菌耐药中发挥作用。

Investigation on the mechanism of drug resistance mediated by class I integron in Escherichia coli and Klebsiella pneumoniae

Objective To study the distribution and the characterization of class I integron in clinical isolates of Escherichia coli and Klebsiella pneumoniae and explore the relationship between class I integron and their drug resistance.Methods Agar dilution method and double disk diffusion method were used to analyze the 82 strains of clinical isolates;class I integron and drug resistance gene cassettes integrated by integron I were analyzed by polymerase chain reaction(PCR) screening,DNA sequencing and sequence analysis in 36strains of Escherichia coli and 46 strains of Klebsiella pneumoniae.Results Ten of 82 clinical isolates were were observed in class I integron,and all of them carried the integrated drug resistance gene.Susceptibility test showed the Escherichia coli’s resistance rate were as follows,61% of cefixime,86% of cefaclor,86% of cephalexin,50% of piperacillin-tazobactam,75% of ceftazidime,64% of cefotaxime sodium,39% of amoxicillin/sulbactam,47% of ampicillin sodium/sulbactam sodium,30% of cefoperazone sodium/sulbactam sodiumis,respectively,while the Klebsiella pneumoniae’s resistance rate were 65%,63%,78%,52%,67%,54%,48%,41%,28%.There were 10 strains of ESBLs-producing in them,Escherichia coli 4 strain,Klebsiella pneumoniae 6 strains,and all were detected to haveI integron,the gene cassettes’s marshaling sequence was 100% similar to the strain and its genbank number was NC010410,and all contained blaVEB-1 resistance gene cassettes.Conclusion Class I integron and integrated gene cassettes are prevalent among the ESBLs-producing strains of Escherichia coli and Klebsiella pneumoniae.Integrons are important molecular mechanism in the development of drug resistance.