Characterization of antimicrobial resistance in Salmonella enterica food and animal isolates from Colombia: identification of a qnrB19-mediated quinolone resistance marker in two novel serovars

Authors

  • Maria Karczmarczyk,

    1. Centres for Food Safety & Food-borne Zoonomics, UCD Veterinary Sciences Centre, University College Dublin, Belfield, Dublin, Ireland
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  • Marta Martins,

    1. Centres for Food Safety & Food-borne Zoonomics, UCD Veterinary Sciences Centre, University College Dublin, Belfield, Dublin, Ireland
    2. Unit of Mycobacteriology and UPMM, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa (IHMT/UNL), Lisbon, Portugal
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  • Matthew McCusker,

    1. Centres for Food Safety & Food-borne Zoonomics, UCD Veterinary Sciences Centre, University College Dublin, Belfield, Dublin, Ireland
    2. Cost Action BM0701 (ATENS), Monteria, Colombia
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  • Salim Mattar,

    1. Faculty of Veterinary Medicine, Universidad de Cordoba, Monteria, Colombia
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  • Leonard Amaral,

    1. Unit of Mycobacteriology and UPMM, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa (IHMT/UNL), Lisbon, Portugal
    2. Cost Action BM0701 (ATENS), Monteria, Colombia
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  • Nola Leonard,

    1. Centres for Food Safety & Food-borne Zoonomics, UCD Veterinary Sciences Centre, University College Dublin, Belfield, Dublin, Ireland
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  • Frank M. Aarestrup,

    1. Research Group for Antimicrobial Resistance and Molecular Epidemiology, National Food Institute, Technical University of Denmark, Copenhagen V, Denmark
    2. Department for Microbiology and Risk Assessment; National Food Institute, Technical University of Denmark; Copenhagen V, Denmark
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  • Séamus Fanning

    1. Centres for Food Safety & Food-borne Zoonomics, UCD Veterinary Sciences Centre, University College Dublin, Belfield, Dublin, Ireland
    2. Cost Action BM0701 (ATENS), Monteria, Colombia
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  • Editor: Stefan Schwarz

Correspondence: Séamus Fanning, Centres for Food Safety & Food-borne Zoonomics, UCD Veterinary Sciences Centre, University College Dublin, Belfield, Dublin 4, Ireland. Tel.: +353 1 716 6082; fax: +353 1 716 6091; e-mail: sfanning@ucd.ie

Abstract

Ninety-three Salmonella isolates recovered from commercial foods and exotic animals in Colombia were studied. The serotypes, resistance profiles and where applicable the quinolone resistance genes were determined. Salmonella Anatum (n=14), Uganda (19), Braenderup (10) and Newport (10) were the most prevalent serovars, and resistance to tetracycline (18.3%), ampicillin (17.2%) and nalidixic acid (14%) was most common. Nalidixic acid-resistant isolates displayed minimum inhibitory concentrations ranging from 32 to 1024 μg mL−1. A Thr57→Ser substitution in ParC was the most frequent (12 of the 13 isolates). Six isolates possessed an Asp87→Tyr substitution in GyrA. No alterations in GyrA in a further seven nalidixic acid-resistant isolates were observed. Of these, four serovars including two Uganda, one Infantis and a serovar designated 6,7:d:-, all carried qnrB19 genes associated with 2.7 kb plasmids, two of which were completely sequenced. These exhibited 97% (serovar 6,7:d:- isolate) and 100% (serovar Infantis isolate) nucleotide sequence identity with previously identified ColE-like plasmids. This study demonstrates the occurrence of the qnrB19 gene associated with small ColE plasmids hitherto unrecognized in various Salmonella serovars in Colombia. We also report unusual high-level quinolone resistance in the absence of any DNA gyrase mutations in serovars S. Carrau, Muenchen and Uganda.

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