大肠埃希菌临床分离菌株喹诺酮类抗生素耐药机制研究

目的探讨我院临床分离的大肠埃希菌株耐药基因的分布及其在耐药中的作用机制。方法选择我院临床分离的大肠埃希菌菌株,采用纸片扩散法进行喹诺酮类药物药敏试验,筛选耐药菌株并测定环丙沙星MIC,对喹诺酮耐药菌株进行qnrA、qnrB、aac-（6’）-Ib-cr、GyrA及ParC检测,并进行基因扩增测序。结果 84株临床分离的大肠埃希菌菌株中有24株对喹诺酮类药物耐药,耐药率为28.4%。其中对2种药物耐药4株,对3种药物耐药6株,对5种药物耐药14株。耐药菌株MIC值为对照菌株148～596倍,24株耐药菌中检出qnrA质粒基因12株、qnrB质粒基因4株、aac-（6’）-Ib-cr基因4株、GyrA基因喹诺酮决定区突变11株、ParC基因决定区突变4株。结论我院存在大肠埃希菌喹诺酮耐药菌株,且耐药菌株耐药机制复杂,耐药基因的产生及酶类耐药突变是主要原因,临床要加强对耐药菌株的检测。

Study on drug resistance mechanism for carbostyril in escherichia coli from clinical isolates

Objective To investigate the mechanism of action for drug resistance gene in carbostyril resistance es cherichia coli from clinical isolates in our hospital.Methods That escherichia coli strain separated from clinic were selected,susceptibility test for carbostyril were detected with disk diffusion method,drug-resistance bacteria were sieve and minimum inhibitory concentration（MIC） were detected.The qnrA,qnrB,aac-（6 ’）-IB-cr,GyrA and ParC gene were detected and taken gene sequencing in drug-resistance bacteria.Results 24 of 84 strains of escherichia coli from clinical isolates was drug fast for carbostyril,drug fast rate was 28.4%,including 2 strains of escherichia coli drug fast for a type antibiotic,6 strain of drug fast escherichia coli for three type antibiotic,14 strains of escherichia coli drug fast for five type antibiotic,in 24 strains of drug-resistance bacteria,MIC of drug-resistance bacteria in crease 148~596 to control strain,there were 12 strain that found qnrA plasmid gene,4strain that found qnrB plasmid gene,4strain that found aac-（6’）-IB-cr plasmid gene,11 strain that found GyrA gene mutation and 4 strain that de tected ParC gene mutation.Conclusion There are some drug-resistance bacteria strain in our hospital,and mechanism of drug resistance was complicate,drug resistance gene and gene enzyme mutation was major reason,detecting for drug-resistance bacteria strain will be strengthen in clinic.