Detection of qnr genes among Escherichia coli isolates of animal origin and complete sequence of the conjugative qnrB19-carrying plasmid pQNR2078
Detection of qnr genes among Escherichia coli isolates of animal origin and complete sequence of the conjugative qnrB19-carrying plasmid pQNR2078
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DOI：
10.1093/jac/dks024
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发表时间：
2012-05-01
影响因子：
5.2
通讯作者：
Schwarz, Stefan
中科院分区：
文献类型：
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作者：
Schink, Anne-Kathrin;Kadlec, Kristina;Schwarz, Stefan
本研究的目的是确定喹诺酮类耐药大肠杆菌分离株中的qnr基因，从伴侣动物和农场动物在BfT-GermVet研究中获得的定义的疾病条件，并了解其定位和组织的qnr基因区域。qnr基因通过PCR检测和测序确认。qnr阳性分离株通过PCR和喹诺酮耐药决定区测序检查DNA旋转酶和拓扑异构酶IV基因突变。对qnr阳性的E.大肠杆菌分离株。将含有qnr基因的质粒通过接合转移到E.对417株大肠杆菌受体进行了PCR复制子分型和质粒MLST分析，并对其中1株携带qnrB 19的质粒进行了全序列测定。所研究的大肠杆菌分离株携带qnr基因。这两个分离株均来源于马，并显示MLST型ST 86。它们携带接合性qnrB 19质粒，经限制性内切酶分析证明是不可区分的，属于不亲和组IncN，显示质粒MLST型ST 8，并且不携带其他抗性基因。qnrB 19基因的侧翼是插入序列IS 26的拷贝。对其中一个质粒pQNR 2078进行了完全测序，其大小为42379 bp。质粒pQNR 2078与大肠杆菌携带bla（CTX-M-65）的质粒pKC 396相似，但抗性基因区不同。qnr基因在大肠杆菌中很少检出。BfT-GermVet研究中动物的大肠杆菌。在接合质粒上检测到qnrB 19基因，IS 26可能参与qnrB 19的迁移。
The aims of this study were to identify qnr genes among quinolone-resistant Escherichia coli isolates from defined disease conditions of companion and farm animals obtained in the BfT-GermVet study, and to gain insight into their localization and the organization of the qnr gene regions.The qnr genes were detected by PCR and confirmed by sequencing. qnr-positive isolates were checked for mutations in DNA gyrase and topoisomerase IV genes by PCR and sequencing of the quinolone resistance-determining regions. Multilocus sequence typing (MLST) was performed for the qnr-positive E. coli isolates. Plasmids harbouring qnr genes were transferred by conjugation into E. coli recipients, subjected to PCR-based replicon typing and plasmid-MLST, and one qnrB19-carrying plasmid was sequenced completely.Only 2 of 417 E. coli isolates investigated carried qnr genes. Both isolates originated from horses and showed MLST type ST86. They harboured conjugative qnrB19-carrying plasmids, which proved to be indistinguishable by restriction analysis, belonged to incompatibility group IncN, showed plasmid-MLST type ST8 and did not carry other resistance genes. The qnrB19 gene was flanked by copies of the insertion sequence IS26. One of these plasmids, pQNR2078, was sequenced completely and had a size of 42379 bp. Except for the resistance gene region, plasmid pQNR2078 closely resembled the bla(CTX-M-65)-carrying plasmid pKC396 from E. coli.qnr genes were rarely detected among E. coli from animals in the BfT-GermVet study. The qnrB19 gene was detected on conjugative plasmids, with IS26 being likely involved in the mobility of qnrB19.