耐氟喹诺酮类药物的大肠埃希菌gyr A 基因点突变检测

Detection of Point Mutations in the gyr A Gene of Highly Fluoroquinolone Resistant Escherichia Coli by PCR

目的：研究大肠埃希菌对氟喹诺酮类药物的耐药机制。方法：对大肠埃希菌标准菌４４３０２和临床收集的３株对氟喹诺酮类药物高度耐药的大肠埃希菌及１株敏感菌，用ＰＣＲ方法扩增ＤＮＡ旋转酶ｇｙｒＡ基因的Ｎ末端编码区，并进行克隆和序列测定。结果：对氟喹诺酮类药物高度耐药的大肠埃希菌的ｇｙｒＡ基因的序列分析，发现３个导致氨基酸改变的基因点突变：丝氨酸－８３→亮氨酸；丙氨酸－８４→脯氨酸；天冬氨酸－８７→天冬酰氨。结论：对氟喹诺酮类药物高度耐药的大肠埃希菌的ＤＮＡ旋转酶Ａ亚单位存在着基因点突变。

Objective:To study the mechanism of resistance of Escherichia coli to fluoroquinolones.Methods:Escherichia coli standard strain 44 302,three clinical highly fluoroquinolone resistant isolates and one sensitive isolate were included in the study.The N terminal coding region of gyr A gene was amplified by PCR,then cloned and sequenced.Results:DNA sequence analysis of gyr A gene revealed three mutations that resulted in amino acid changes:Ser 83→Leu,Ala 84→Pro,Asp 87→Asn.Conclusion:Mutations of gyr(ase)A gene subunit existed in fluoroquinolone resistant Escherichia coli.