Assessing the molecular basis of transferable quinolone resistance in Escherichia coli and Salmonella spp. from food-producing animals and food products D. Jones-Dias a,b , V. Manageiro a,b , A.P. Francisco a , A.P. Martins c , G. Domingues a , D. Louro a , E. Ferreira a,b , M. Canic ¸a a,b, * a National Reference Laboratory of Antimicrobial Resistances, Department of Infectious Diseases, National Institute of Health Dr Ricardo Jorge, Av. Padre Cruz, 1649-016 Lisbon, Portugal b Centre for the Study of Animal Sciences (ICETA), University of Oporto, Rua D. Manuel II, 4051-401 Oporto, Portugal c Microbiology Laboratory, Controlvet, ZIM II, 3460-070 Tondela, Portugal 1. Introduction Fluoroquinolones are a class of antimicrobials which are effectively used in the treatment of infections in both humans and animals, being also used as prophylactic agents in food-producing animals (EMA, 2012). Bacterial resistance to fluoroquinolones has emerged quickly and has conventionally been attributed to chro- Veterinary Microbiology xxx (2013) xxx–xxx A R T I C L E I N F O Article history: Received 28 December 2012 Received in revised form 8 August 2013 Accepted 10 August 2013 Keywords: Plasmid-mediated quinolone resistance (PMQR) Portugal Quinolone resistance determining region (QRDR) Animals A B S T R A C T 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. b- 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 b-lactam antibiotics which was justified by the presence of b- 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. ß 2013 Elsevier B.V. All rights reserved. * Corresponding author at: Manuela Canic ¸a, National Reference Laboratory of Antimicrobial Resistances, Department of Infectious Diseases, National Institute of Health Dr. Ricardo Jorge, Av. Padre Cruz, 1649-016 Lisbon, Portugal. Tel.: +351 217519246; fax: +351 217519246. E-mail address: manuela.canica@insa.min-saude.pt (M. Canic ¸a). G Model VETMIC-6319; No. of Pages 9 Please cite this article in press as: Jones-Dias, D., et al., Assessing the molecular basis of transferable quinolone resistance in Escherichia coli and Salmonella spp. from food-producing animals and food products. Vet. Microbiol. (2013), http:// dx.doi.org/10.1016/j.vetmic.2013.08.010 Contents lists available at ScienceDirect Veterinary Microbiology jo u rn al ho m epag e: ww w.els evier.c o m/lo cat e/vetmic 0378-1135/$ – see front matter ß 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.vetmic.2013.08.010