禽源大肠埃希菌质粒介导的喹诺酮类药物耐药基因的检测

Detection of Plasmid-mediated Quinolone Resistance among Escherchia coli from Avian in China

从我国部分地区病、死家禽中分离到大肠埃希菌403株。按照CLSI(clinical and laboratory standards institute)推荐的K-B药敏纸片法对其中的344株分离株进行药敏纸片试验;根据GenBank上发表的序列,设计并合成了五对引物,对所有分离细菌进行质粒介导的喹诺酮类药物耐药基因的扩增:qnrA、qnrB、qnrS、aac(6′)-ib-cr和qepA。1993年-1996年禽源大肠埃希菌分离株仅对萘啶酸的耐药率超过60%;2001年-2008年禽源大肠埃希菌分离株对1-3代7种喹诺酮类药物的耐药率均超过58%。在403株禽源大肠埃希菌中共检出3(0.7%)株qnrB阳性菌株,2(0.5%)株qnrS阳性菌株,5(1.2%)株aac(6′)-ib-cr阳性菌株以及5(1.2%)株qepA阳性菌株,未检测到qnrA阳性菌株。结果显示,近20年来,我国禽源大肠埃希菌对喹诺酮类药物的耐药性不断上升,同时,质粒介导的喹诺酮类药物耐药基因在禽源大肠埃希菌中呈不断上升的流行趋势。

A total of 403 E.coli field isolates were derived from clinically affected chickens in 18 provinces of China between 1993 and 2009.Of which 344 E.coli isolates from 1990s were carried out to 8 quinolone antimicrobial sensitivity test by using the Kirby-Bauer method recommended by CLSI(clinical and laboratory standards institute).All of the isolates were detected for the presence of qnrA,qnrB,qnrS,aac(6′)-ib-cr and qepA by PCR and sequencing.E.coli isolates from 1993-1996 had a resistance more than 60% only to Nalicixic acid(61.6%),whereas isolates from 2001-2008 had a resistance more than 58% to 7 antibiotics.Among the 403 E.coli isolates from China,qnrB,qnrS,aac(6′)-ib-cr and qepA were detected in 3(0.7%),2(0.5%),5(1.2%),and 5(1.2%) isolates,respectively,no qnrA positive isolate was detected in this study.The results showed that the resistance of E.coli to quinolone agents had been increasing in the past twenty years and there was a rising prevalence of E.coli isolates harboring plasmid-mediated quinolone resistance genes in China.