中文摘要：

采用二倍稀释法测定临床分离的4株鸡毒支原体对常用抗菌药物的敏感性,PCR方法和基因测序法对鸡毒支原体DNA回旋酶编码基因gyrA、gyrB及拓扑异构酶Ⅳ编码基因parC和parE耐药决定区进行分析。敏感性测定结果表明,4株分离鸡毒支原体对泰乐菌素、泰妙林、沃尼妙林和替米考星有很高的敏感性,对四环素和红霉素中度敏感,对林可霉素、氟苯尼考和氟喹诺酮类药物呈现不同程度的耐药性。4株耐氟喹诺酮类药物鸡毒支原体均在GyrA和ParC的喹诺酮类耐药决定区（QRDR）发生氨基酸的改变,GyrA的氨基酸取代模式有两种,分别为Ser81→Gly和Ser83→Ile,ParC仅在80位发生氨基酸取代（Ser80→Leu）,GyrB和ParE均未发生氨基酸改变。

英文摘要：

Susceptibilities of 4 isolated M.gallisepticum to common used antimicrobials were determined by broth dilution method.PCR and sequencing were applied for analysis of quinolone resistance-determining regions of the four target genes encoding DNA gyrase and topoisomerase Ⅳ from 4 isolates.The results showed that 4 isolates presented higher susceptible to tylosin,tiamulin,valnemulin and tilmicosin,moderate susceptible to tetracycline and erythromycin,and resistant to lincomycin,florfenicol and 3 fluroquinolone drugs to a certain extent.Several mutations were found in the two fluoroquinolone targets GyrA and ParC.Double mutations within QRDR of GyrA were found among 4 isolated M.gallisepticum,with the same substitution patterns of Ser81→Gly and Ser83→Ile.There was only one alteration existed within QRDR of ParC（Ser80→Leu） among 4 isolates.No mutations were found within QRDR of GyrB and ParE in 4 isolates.