中文摘要：

探讨不同禽源大肠埃希菌中喹诺酮类药物的耐药情况及耐药基因gyrA的分布和突变特征。采用K-B药敏纸片法、gyrA基因的PCR扩增,对9株大肠埃希菌进行喹诺酮类药物试验,并将gyrA基因的PCR产物测序,对测序结果采用DNA MAN、DNA Star、MEGA6等软件分析。药敏试验结果表明,C1、C2、C3菌株对左氧沙星、氧氟沙星、环丙沙星、诺氟沙星敏感,D1、D2、D3、B1、B2和B3菌株对左氧沙星、氧氟沙星、环丙沙星、诺氟沙星均表现为耐药和中介;gyrA基因的测序结果表明,除B1菌株有1处核苷酸突变位点和B2菌株有14处核苷酸突变位点;B2菌株gyrA基因的氨基酸突变发生在87位Ile→Val替代、101位Leu→Met替代、102位Ala→Ser替代、129位Lys→Gln替代。9株禽源大肠埃希菌的同源性和进化树分析表明,不同禽源耐氟喹诺酮类药物的大肠埃希菌菌株中B2菌株gyrA基因与其他9株菌株相比,同源性在90%左右,进化树不在一个分支上,研究中的B2菌株将为大肠埃希菌的氟喹诺酮类耐药机制的研究提供候选菌株。

英文摘要：

This paper discussed the distribution and mutation characteristics of gyrA gene and drug resistance of quinolones resistant gene in different avian Escherichia coll. The quinolone resistance test of 9 E. coli were determinded by the K-B method. After PCR amplification of gyrA gene, sequencing, the softwares as DNA MAN,DNA STAR, MEGA6 were used to analyze the results. The result of drug sensitivity test showed that strains of C1, C2 and C3 were sensitive to levofloxacin,ofloxacin, ciprofloxacin and norfloxacin, strains of D1,D2, D3, B1, B2 and B3 were resistant and intermediate to levofloxacin, ofloxacin, ciprofloxacin and norfloxacin. Sequence analysis of gyrA gene showed I mutation in the nucleotide in strain B1 and 14 mutations in stain B2 lgyrA gene showed 4 mutations in the amino acids in strain B2,which resulted in 87 Ile →Val,101 Leu→Met,102 Ala→Ser and 129 Lys→Gln. Homology and phylogenetic tree analysis of 9 strains of avian Escherichia coli showed fluoroquinolone-resistant strains from different avian E. coli, compared with other 9 strains,the homology of gyrA gene of B2 strain was at 90% ,phylogenetic tree was not in a same branch. B2 strain in this resarch provided candidate strain to study the fluoroquinolone-resist- ance mechanism of E. coll.