市售整鸡中环丙沙星耐药大肠埃希氏菌的分布及耐药机制研究

目的 本研究旨在阐明市售整鸡中环丙沙星耐药大肠埃希氏菌的分布和耐药机制特点.方法 对广东省3个不同地区市售整鸡中的环丙沙星耐药大肠埃希氏菌进行分离和鉴定,并对分离株进行种系分群、药敏试验和喹诺酮耐药机制研究.结果与结论 从58份市售整鸡中分离出41株环丙沙星耐药大肠埃希氏菌,其中27株属于A群.分离株耐药谱主要有两种:AMP-CAZ-CIP-CTX-Cl-SXT-TET和AMP-CAZ-CIP-CTX-Cl-GEN-SXT-TET.喹诺酮耐药机制研究显示,拓扑异构酶编码基因gyrA和parC均有点突变出现,其中,26株分离株携带质粒介导的喹诺酮耐药基因,包括oqxAB、qnrS、aac(6')-Ib-cr,而qnrA、qnrB、qnrC、qnrD和qepA基因则均未检出.耐药菌株在市售整鸡中的广泛分布和复杂的喹诺酮耐药机制,应引起相关部门的重视.

Prevalence and Characterization of Ciprofloxacin Resistant Escherichia coli Isolates in Retailed Whole Chickens

Objective To investigate the prevalence of the ciprofloxacin resistant Escherichia coli in retailed whole chickens and the characterization of resistance mechanisms. Methods Retailed whole chickens were collected from 3 different districts of Guangdong province. Ciprofloxacin resistant Escherichia coli isolates were separated and identified; and antimicrobial susceptibility testing, phylogenetic analysis and quinolone resistance mechanism study were carried out. Results and Conclusion Totally, 41 ciprofloxacin resistant Escherichia coli isolates were isolated from 58 samples, and 27 isolates belonged to phylogenetic group A. Two dominant antimicrobial resistant profiles were AMP-CAZ-CIP- CTX-C1-SXT TET and AMP-CAZ-CIP-CTX-CI-GEN-SXT-TET. Point mutations in topoismerase encoded genes gyrA and parC were identified, and 26 isolates were carried with plasmid-mediated quinolone resistance genes, including oqxAB, qnrS and aac（6＇）-Ib-cr, but qnrA, qnrB, qnrC, qnrD and qepA were not detected. The relevant departments should pay attention to the extensive prevalence and complicated quinolone resistance mechanisms of isolates in retailed whole chickens.