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目的分析中国大陆20家三甲医院尿来源大肠埃希菌的耐药特点并调查质粒介导的喹诺酮类耐药基因的分布情况和流行特点。方法收集卫生部全国耐药监测网2007年1月至2008年3月非重复298株尿液分离大肠埃希菌;琼脂稀释法测定其对20种抗菌药物的敏感性,多聚酶链反应和DNA测序分析qn-rA,qnrB,qnrS,aac(6’)-ib和qepA基因的流行性;接合实验分析质粒的转移性;Eric-PCR分析喹诺酮基因阳性菌株之间的遗传相关性;卡方检验用于分析耐药基因与氟喹诺酮耐药之间的相关性。结果 298株大肠埃希菌对20种抗菌药物耐药现象严重,其中对环丙沙星和左氧氟沙星有很高的耐药性,耐药率高达78.5%和74.2%。经基因比对分析,62株(20.8%)细菌携带aac(6’)-Ib基因;45株(15.1%)细菌携带喹诺酮耐药基因,1株(0.3%)检测出qnrA基因,3株(11.4%)检出qnrB基因,5株(1.7%)检出qnrS基因,25株(8.4%)确定为aac(6’)-Ib-cr基因,12株(4.7%)检出qepA基因;此外,有3株细菌分别发现aac(6’)-Ib-cr和qepA1基因aac(6’)-Ib-cr和qnrB1基因,qepA和qnrS1基因共存。45株喹诺酮基因阳性菌株之间具有很大的遗传差异,并且其中有16株细菌携带的基因具有可转移性。aac(6’)-Ib的流行性与细菌的环丙沙星和左氧氟沙星不敏感性相关(P<0.05);喹诺酮耐药基因的流行性与细菌的氟喹诺酮不敏感性相关(P<0.05)。结论尿液分离的大肠埃希菌耐药严重,质粒介导的喹诺酮耐药基因主要以aac(6’)-ib-cr为主,qepA1次之,这些潜在播散的喹诺酮耐药基因对于临床尿路感染的治疗有很大的挑战。
Objective To analyze the drug resistance of urinary Escherichia coli from 20 top three hospitals in mainland China and investigate the distribution and epidemiological characteristics of plasmid-mediated quinolone resistance genes. Methods A total of 298 isolates of Escherichia coli isolated from urine were collected from January 2007 to March 2008 by the National Drug Resistance Surveillance Network of Ministry of Health. The susceptibility to 20 antibiotics, polymerase chain reaction and DNA sequencing were determined by agar dilution method The epidemiology of qn-rA, qnrB, qnrS, aac (6 ’) - ib and qepA genes was analyzed. The conjugation experiments were used to analyze the transfer of plasmids. The genetic correlation between quinolone-positive isolates was analyzed by Eric-PCR. To analyze the relationship between resistance genes and fluoroquinolone resistance. Results 298 strains of Escherichia coli were resistant to 20 kinds of antibacterial drugs. Among them, Ciprofloxacin and Levofloxacin were highly resistant and the resistance rates were as high as 78.5% and 74.2%. Forty-two strains (15.1%) carried quinolone resistance genes and one strain (0.3%) detected qnrA gene and three strains (20.8% QnrS gene was detected in 5 (1.7%), 25 (8.4%) were identified as aac (6 ’) - Ib-cr and 12 Three strains of bacteria found aac (6 ’) - Ib-cr and qepA1 gene aac (6’) - Ib-cr and qnrB1 genes, qepA and qnrS1 genes co-exist. Among the 45 strains of Quinolone-positive isolates, there was a great genetic difference among them, and among them, 16 strains of bacteria carried the gene with transferability. The prevalence of aac (6 ’) - Ib was related to the insensitivity of bacteria to ciprofloxacin and levofloxacin (P <0.05). The prevalence of quinolone resistance gene was correlated with the susceptibility of bacteria to fluoroquinolone (P <0.05) . Conclusion The urinary Escherichia coli isolated from Escherichia coli is highly resistant. The major gene of quinolone - resistant plasmids is aac (6 ’) - ib - cr, followed by qepA1. These potentially dispersible quinolone resistance genes are clinically The treatment of urinary tract infection has great challenges.