摘要
目的了解尿液分离大肠埃希菌中Ⅰ类整合子及相关基因盒的分布,分析整合子与细菌耐药性的关系。方法选取108株临床非重复分离自尿液标本中的大肠埃希菌,经全自动细菌分析系统鉴定并检测其对临床常用抗菌药物的耐药性,聚合酶链反应(PCR)检测Ⅰ类整合酶基因,对Ⅰ类整合酶阳性菌株用PCR扩增并测序分析可变区基因盒种类及可变区启动子类型。结果 108株临床非重复分离自尿液大肠埃希菌中有60株占56.0%检测到Ⅰ类整合酶基因;共检测出5种不同长度的可变区片段:8株750bp片段不含基因盒,2株1500bp片段为aadA2,34株2200bp片段为dfrA17-aadA5,4株2500bp片段为dfrA12-orfF-aadA2,2株2800bp片段为aa-cA4-cmlA1,其中1株大肠埃希菌同时扩增出2200、2500bp的可变区片段,有11株Ⅰ类整合酶基因阳性大肠埃希菌未扩增出可变区;可变区启动子大多为相对较弱的启动子PcH1、PcW;Ⅰ类整合子阳性菌株对多种抗菌药物的耐药率高于Ⅰ类整合子阴性菌株。结论Ⅰ类整合子及相关基因盒在尿液分离大肠埃希菌中分布广泛,与细菌耐药性关系密切,所携带的整合子具有较强的捕获外源性耐药基因盒的能力。
OBJECTIVE To investigate the distribution of classⅠintegrons and integrated gene cassettes in Escherichia coli isolated from urine and analyze the correlation between the integrons and antibiotic resistance.METHODS A total of 108 non-repeated isolates of E.coli from urine samples were selected,automatic bacterial analysis system was used to identify the strains,and the antimicrobial susceptibility testing was performed to test the drug resistance to commonly used antibiotics.ClassⅠ integron integrase genes（intI1）were screened by PCR,the inserted gene cassettes of variable regions in intI1 positive isolates were detected by using PCR combined with sequence analysis.RESULTS Among 108 E.coli clinical non-repeated isolates from urine,intⅠ1 were detected in 60 isolates（56.0%）.Five kinds of variable fragments of different lengths were detected in intI1 positive isolates：750bp fragment（8 strains）did not contain the gene cassette,1500 bp fragment（2 strains）contained gene cassette aadA2,2200 bp fragment（34 strains） was gene cassette array dfrA17-aadA5,2500 bp fragment（4 strains） was gene cassette array dfrA12-orfF-aadA2,2800 bp fragment（2 strains） was gene cassette array aacA4-cmlA1.Both 2200 bp and 2500 bp fragment were detected in a strain and the variable regions of class Ⅰintegrons failed to be amplified in 11 strains.Most of the common promoters of variable regions of class Iintegrons were relatively weak promoter PcH1 and PcW.Multiple antimicrobial resistance rates of classⅠ integron-positive strains were higher than the negatives.CONCLUSION ClassⅠintegrons as well as their associated gene cassettes widely distribute in E.coli strains isolated from urine and are closely related to antibiotic resistance.Class Ⅰintegrons detected in these strains with relatively weak common promoters are predicated to have strong capability of capturing exogenous antibiotic resistance gene cassettes.
出处
《中华医院感染学杂志》
CAS
CSCD
北大核心
2013年第8期1759-1761,共3页
Chinese Journal of Nosocomiology
基金
浙江省自然科学基金资助项目(Y2110743)
关键词
整合子
基因盒
耐药性
启动子
Integron
Gene cassette
Antibiotics resistance
Promoter
