National Reference Laboratory of Antimicrobial Resistances, Department of Infectious Diseases, National Institute of Health Dr Ricardo Jorge, Av. Padre Cruz, 1649-016 Lisbon, Portugal; Centre for the Study of Animal Sciences (ICETA), University of Oporto, Rua D. Manuel II, 4051-401 Oporto, Portugal.
Vet Microbiol. 2013 Dec 27;167(3-4):523-31. doi: 10.1016/j.vetmic.2013.08.010. Epub 2013 Aug 22.
Enterobacteriaceae resistant to quinolones frequently arise in animals, being easily disseminated through the food-chain. The aim of this study was to investigate the presence of plasmid-mediated quinolone resistance (PMQR) determinants in Salmonella spp. (n=183) and Escherichia coli (n=180) isolates, collected from food-producing animals and food products among swine, poultry, rabbits and cattle. All isolates were subjected to antimicrobial susceptibility testing and molecular screening of PMQR determinants. β-Lactamase-encoding genes, and the quinolone resistance determining region (QRDR) of gyrA, gyrB, parC and parE genes were also investigated in PMQR-positive isolates. Plasmid characterization was performed by conjugation, followed by replicon-typing. Genetic relatedness of PMQR-positive E. coli was examined by Multilocus Sequence Typing, while Salmonella was previously serotyped. The association of mobile genetic elements and PMQR was investigated through PCR mapping assays. Overall, 4.1% (15/363) isolates harbored qnrB2 (n=3), qnrB19 (n=3), and qnrS1 (n=9) genes. All but one isolate presented one to four mutations in QRDR of gyrA or parC genes, which is consistent with the range of MIC values detected (0.19-64 mg/L) for ciprofloxacin; 60% (9/15) of qnr-harboring isolates were non-susceptible to β-lactam antibiotics which was justified by the presence of β-lactamases from TEM (TEM-1, n=8; TEM-135, n=1) and SHV (SHV-108, n=1) families. Analysis of mobile genetic elements revealed that qnr genes were detected nearby relevant genetic elements like intI1, ISEcl2, IS26 and ISCR1 and enclosed in diverse Inc. type plasmids. This study illustrated the existence of Qnr-producing E. coli and Salmonella from food-producing animals, associated to specific mobile elements that might mediate their transference between species and among distinct settings.
肠杆菌科对喹诺酮类药物的耐药性经常在动物中出现，并且很容易通过食物链传播。本研究旨在调查食源性动物和食品中分离的沙门氏菌（n=183）和大肠杆菌（n=180）中存在的质粒介导的喹诺酮类耐药（PMQR）决定因素。所有分离株均进行了抗生素敏感性试验和 PMQR 决定因素的分子筛选。还研究了 PMQR 阳性分离株中的β-内酰胺酶编码基因以及 gyrA、gyrB、parC 和 parE 基因的喹诺酮耐药决定区（QRDR）。通过接合进行质粒表征，然后进行复制子分型。通过多位点序列分型（MLST）检测 PMQR 阳性大肠杆菌的遗传相关性，而沙门氏菌则之前进行血清分型。通过 PCR 图谱分析检测移动遗传元件与 PMQR 的关联。总体而言，363 株分离株中有 4.1%（15/363）携带 qnrB2（n=3）、qnrB19（n=3）和 qnrS1（n=9）基因。除 1 株外，所有分离株的 gyrA 或 parC 基因 QRDR 均存在 1 至 4 个突变，这与检测到的环丙沙星 MIC 值范围（0.19-64mg/L）一致；15 株 qnr 携带株中有 60%（9/15）对β-内酰胺类抗生素不敏感，这是由 TEM（TEM-1，n=8；TEM-135，n=1）和 SHV（SHV-108，n=1）家族的β-内酰胺酶引起的。移动遗传元件分析表明，qnr 基因位于相关遗传元件附近，如 intI1、ISEcl2、IS26 和 ISCR1，并且包含在不同的 Inc. 类型质粒中。本研究表明，食源性动物中存在产生 Qnr 的大肠杆菌和沙门氏菌，与可能介导它们在物种之间以及在不同环境中转移的特定移动元件相关。
