淋病奈瑟菌对环丙沙星耐药性的基因研究

摘要

Objective To investigate the occurrence of ciprofloxacin(cip)-resistance among Neisseria gonorrhoeae strains in Linfen region in 2006 and determine the frequency and patterns of mutations in gyrA gene in the ciprofloxacin resistance isolates. Methods A total of 33 gonococcal isolates were collected in Linfen region for Neisseria gonorrhoeae. In vitro, susceptibility tests of ciprofloxacin were performed in 33 isolates, gyrA gene were amplified by polymerase chain reaction(PCR)assay and the PCR products were directly sequenced in order to see if there were mutations in gyrA gene. Results The 33 clinical isolates demonstrated 100% resistance to ciprofloxacin. The gyrA gene containing quinolone resistance-determining region (QRDR)were amplified by PCR in all clinical isolates. The mutations had amino acid substitutions of Ser to Phe at codon 91(33 strains),and Asp to Gly,Asn,Ala at codon 95 of gyrA respectively. The most common gyrA alteration at codon 95, Asp-95 to Gly was found in 19 strains (63.3 %). Conclusions The resistant strains of Neisseria gonorrhoeae to ciprofloxacin in Linfen region are serious. The results from this study suggested that mutations in gyrA gene play an important role in the development of fluoroquinolone resistance of Neisseria gonorrhoeae.%目的 探讨临汾地区淋病奈瑟菌对环丙沙星的耐药性及其与gyrA基因喹诺酮类耐药决定区(QRDR)之间的关系.方法 采集33例淋球菌感染标本,通过药敏试验筛选出对环丙沙星耐药菌株,设计对应于淋球菌gyrA上QRDR区基因片段的引物,经过聚合酶链式反应(PCR)扩增其目的 基因片段,并对扩增产物进行DNA序列测定.结果 33株淋病奈瑟菌临床分离株对环丙沙星全部耐药;所有耐药菌株均经PCR扩增出大小为225 bp(对应于QRDR)的基因片段;测序结果显示耐药菌株都发生了91位点突变(Ser-91→Phe),其中单独91位点突变的有3株,发生91和95双位点突变的有30株,95位点突变类型有三种:Asp-95→Gly, Asp-95→Asn, Asp-95→Ala,以Asp-95→Gly最为常见,有19株,占gyrA 95位点突变株的63.3%.结论 临汾地区淋病奈瑟菌对环丙沙星的耐药情况很严重;gyrA基因突变在淋病奈瑟菌对环丙沙星耐药中起着重要作用.