淋病奈瑟氏菌对环丙沙星耐药性与喹诺酮类耐药决定区突变的关系

Correlation between ciprofloxacin resistance and mutation of quinolone resistance-determining region

目的了解上海地区淋球菌流行株对喹诺酮类抗生素的敏感性,探讨淋球菌耐药株gyrA与parC基因突变与淋球菌耐氟喹诺酮类药物之间的关系。方法采用琼脂扩散法对淋球菌临床分离株对行喹诺酮类抗生素敏感性测定,同时运用PCR技术扩增gyrA基因和parC基因的喹诺酮类耐药决定区,并对典型株的PCR产物直接进行测序分析。结果所分离的80株菌株对环丙沙星MIC为敏感、中介、耐药分别为1株、3株和76株;产物测序结果显示淋球菌敏感株只检出了gyrA基因在Asp95处的单位点突变;中介及耐药株在gyrA基因均检出有Ser-91→Phe突变并伴有Asp95或者Ala92位突变;6株检出有parC基因的86、87、91位点突变及其他位置的一些无义突变。结论gyrA基因突变是淋球菌耐喹诺酮类抗生素的重要机制,其中Ser-91→Phe更是引起对喹诺酮类耐药非常关键的突变,而parC基因的突变只会伴随gyrA基因突变同时出现,可能会对淋球菌耐喹诺酮类抗生素起促进作用。

Objective To investigate the sensitivity of neisseria gonorrhoeae in Shanghai area, and to discuss the correlation between quinolone resistance and mutations in gyrA and parC genes. Methods The agar diffusion method was used to determine the minimum inhibitory concentrations （MICs） of the strains, with QRDRs of gyrA and parC amplified by polymerase chain reaction. Some typical strains were sequenced directly. Results The number of strains sensitive, intermediate and resistance to ciprofloxacin were 1, 3 and 76 respectively. The sensitive strain had only one mutation in gyrA （Asp95）, while the intermediate and resistance strains had been detected two mutation in gyrA （Ser-91 →Phe and Ser92/Asp95 mutation）. Mutations in parC gene were also detected in Asp86, Set87 and Glu91 accompanying with mutation in gyrA gene. Conclusions The mutation in gyrA gene, especially the mutation of Ser-91→Phe was required for quinolone-resistance, and mutation in parC only found in those strains with mutation in gyrA gene, which could also contributed to quinolone resistance.