摘要
目的为了解耐环丙沙星产超广谱β_内酰胺酶大肠埃希菌的gyrA基因突变状况。方法在大肠埃希菌gyrA基因喹诺酮耐药决定区(QRDR)序列的两侧自行设计引物并建立PCR扩增和产物直接测序体系,对11株耐环丙沙星产超广谱β_内酰胺酶大肠埃希菌和1株环丙沙星敏感的TEM2型大肠埃希菌的QRDR序列进行检测。结果11株耐环丙沙星的大肠埃希菌均存在第83位和87位的氨基酸密码子的错义突变:TCG(丝氨酸)→TTC(亮氨酸);GAC(天冬氨酸)→AAC(天冬酰胺);其中3株菌株还同时存在第85位氨基酸密码子的同义突变:GTC(缬氨酸)→GTT(缬氨酸)。而环丙沙星敏感的TEM2型大肠埃希菌则无突变。结论耐环丙沙星表型的产超广谱β_内酰胺酶大肠埃希菌存在gyrA基因QRDR区的突变。表明ESBLs菌同时耐喹诺酮类药物的表型有其基因改变的基础。
Objects To investigate the mutations in the DNA gyrase A gene for ciprofloxacin resistance Escherichia coli with extended-spectrumβ-lactamases.Methods The primer was designed in the two flanks of the quinolone resistance-determining(QRDR)region.And the PCR expending and production directive sequencing system were established.The determination of QRDR sequence of TEM 2 type Escherichia coli with extended spectrumβ-lactamases(11strains-isolated of ciprofloxacin resistance,1strain-standard ciprofloxacin sensitive)were made with PCR and sequencing determining.Results11strains-isolated had the sense mutation of the amino acid codes-No.83(TGG[Ser]→TTC[Leu])and No.87(GAC[Asp]→AAC[Asn]);whereas3of them had the synonymous mutation of DNA sequences in No.85of the amino acid coden(GTC[Val]→GTT[Val]).With no mutation in TEM 2 type Escherichia coli much more sensitive to the ciprofloxacin.Conclusions The strains of ciprofloxacin resistance Escherichia coli had the phenotype of extended spectrumβ-lactamases with the mutations in QRDR region in the DNA gyrase A gene,indicating that there existed a gene-base for the resistance phenotype.
出处
《临床儿科杂志》
CAS
CSCD
北大核心
2005年第6期368-370,共3页
Journal of Clinical Pediatrics
关键词
大肠埃希菌
耐药
GYRA基因
Escherichia coli drug resistance gyrase A gene
