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

FEMS Microbiol Lett. 2010 Dec;313(1):10-9. doi: 10.1111/j.1574-6968.2010.02119.x. Epub 2010 Sep 30.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Proteins / genetics
  • Biomarkers / analysis
  • Colombia
  • Drug Resistance, Bacterial / genetics*
  • Food Microbiology*
  • Microbial Sensitivity Tests
  • Molecular Sequence Data
  • Mutation
  • Salmonella enterica / drug effects*
  • Salmonella enterica / isolation & purification


  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Biomarkers

Associated data

  • GENBANK/HM070379
  • GENBANK/HM070380