摘要
目的监测大肠埃希菌临床分离株的耐药性,了解大肠埃希菌中Ⅰ类整合子的流行情况和分子特性。方法临床分离114株大肠埃希菌经全自动细菌分析系统鉴定并检测耐药性,应用PCR法扩增质粒DNA上Ⅰ类整合子,对PCR产物进行酶切分析和DNA测序。将序列结果在GenBank中搜索,确定Ⅰ类整合子可变区基因盒的种类和排列。结果细菌耐药率〉50%,且大多为多重耐药菌（耐受3种以上抗生素）。在58株细菌的质粒DNA上检测到Ⅰ类整合子序列,大小约600-3 500 bp,各含1-3个Ⅰ类整合子。整合子中最常见的基因盒为dfrl7（甲氧苄啶耐药基因）与aadA5（链霉素、壮观霉素耐药基因）,最主要的基因盒排列为dfrl7-aadA5。绝大多数携带甲氧苄啶耐药基因盒的菌株对复方新诺明耐受,大多数携带链霉素、壮观霉素耐药基因盒的菌株对链霉素不敏感。结论目前临床分离的大肠埃希菌耐药性强,并广泛存在Ⅰ类整合子。菌株携带基因盒和耐药表型之间有较好的对应关系,基因盒介导了细菌耐药性。细菌的多重耐药率与Ⅰ类整合子的阳性率相关。
Objective To investigate the antibiotic resistance of clinical isolates of Escherichia coli and the prevalence and molecular characteristics of Class Ⅰ integrons in Escherichia coli. Methods 114 Escherichia coli isolates were subject to Vitek 2（BioMerieux） testing for antibiotic susceptibility. Class Ⅰ integrons （IntI） were detected by PCR with plasmid DNA. The amplicons of Class Ⅰ integrons with the identical size were analyzed by RFLP and the purified amplicons of Class Ⅰ integrons were sequenced. The content and order of gene cassetes in the integrons were determined by searching the GenBank. Results The rate of bacterial resistance is greater than 50%, mostly for muhiresistant bacteria （resistant to over 3 antibiotics）. Among 114 strains, the sequence of Class Ⅰ integron was detected in the plasmid DNA of 58 bacteria. The size of Class Ⅰ integrons ranged from 600 bp to 3 500 bp. Each isolate had one to three Class Ⅰ integrons. The predominant gene cassetes included dfr17 （encoding resistance to trimethoprim） and aadA5 （encoding resistance to streptomycin and spectinomycin）. The main order of inserted gene cassettes was dfrlT-aadA5. Most isolates carrying dfr were resistant to sulfamethoxazole/trime-thoprima and most isolates carrying aadA were not susceptible to streptomycin. Conclusion The results suggest that the clinical isolates of Escherichia coli show strong antibiotic resistance and that Class Ⅰ integrons might be prevalent in clinical Escherichia coli. As a whole, the gene cassette carried by the isolates corresponds to its resistance phenotype. Integrons mediate antibiotic resistance. tive of horizontal intraspecies transfer of integrons. The multidrug resistance rate with the positive rate of Class Ⅰ integron.
出处
《福建医科大学学报》
2009年第6期463-466,共4页
Journal of Fujian Medical University
关键词
大肠杆菌O157
药物耐受性
整合子类
基因
细菌
抗菌药
Escherichia coli O157
drug tolerance
Genotyping is sugges- of bacteria is correlated integrons
genes, bacterial
anti-bacterial agents
