沙门氏菌耐药株gyrA基因和parC基因突变特征分析

提取沙门氏菌染色体DNA，设计引物扩增gyrA基因和parC基因片段，克隆测序寻找耐药菌株的突变位点，通过系统的比较，分析氟喹诺酮类药物（以环丙沙星为代表）对各沙门氏菌MIC和耐药突变位点之间的关系。通过对耐药突变位点的研究，可以为下一步研究耐药性监测的快速方法提供理论基础。

Characterization of mutations in gyrA and gyrC of clinical and experimental inductive of fluroquinolone-resistant Salmonella strains

Chromosomal DNA were extracted from 68 isolates of Salmonella. The QRDR of the gyrA and parC gene of the Salmonella strains were amplified by PCR. The purified DNA fragment with expected size were cloned into pMD18-T vecter,then transformed into JM109. The positive clones were sequenced. The results showed that the mutation in gyrA at Ser83 or Asp87 and in parC at Ser80 resulted in the resistance to FQs of salmonella. When isolates were low-level resistance to FQs, there was a single mutation in gyrA, but high-level resistance required a combination of the gyrA double mutations and one parC mutation, and mutation in the parC gene were based on double mutations in the gyrA gene. On the other hand, clinical resistant isolates and experimentally induced resistant strains have the same resistant mechanisms.