Salmonella enterica isolated from infections in Australian livestock remain susceptible to critical antimicrobials

Sam Abraham, Mitchell D. Groves, Darren J. Trott, Toni A. Chapman, Bernadette Turner, Michael Hornitzky, David Jordan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)

Abstract

Salmonella enterica is a zoonotic pathogen causing a variety of diseases in humans and animals. Many countries are reporting an increase in the prevalence of multidrug-resistant (MDR) S. enterica in food animals. The aim of this study was to determine whether S. enterica isolated from livestock in New South Wales, Australia, have similar resistance traits to those reported internationally. Salmonella enterica (n= 165) from clinical infections in food animals between 2007 and 2011 were serotyped and tested for susceptibility to 18 antimicrobials. Also, 22 antimicrobial resistance genes (ARGs), 3 integrons and 18 plasmid replicon types were screened for using PCR. Most isolates (66.1%) remained susceptible to all antimicrobials; 8.5% of the isolates were resistant to four or more antimicrobials. Antimicrobials with the highest prevalence of resistance were sulfafurazole (28.5%), ampicillin (17.0%), tetracycline (15.8%) and trimethoprim (8.5%). There was no resistance to fluoroquinolones or third-generation cephalosporins. The most common ARGs were blaum (15.2%), sul2 (10.3%), tetB (9.1%), tetA (5.5%), aphAl (4.8%) and dhfrV (4.8%). Class 1 integrons (7.9%) and IncEIIA (69.7%) were the most commonly detected integron and plasmid replicon types, respectively. Class 1 integrons were positively associated with MDR phenotypes and ARG carriage (P <0.001). Internationally prominent MDR serovars associated with severe disease in humans (e.g. AmpC-positive Salmonella Newport) were not detected. Overall, the comparatively favourable resistance status of S. enterica in Australian livestock represents minimal public health risk associated with MDR strains and supports a conservative approach to the registration of antimicrobial drug classes in food-producing animals.

Original languageEnglish
Pages (from-to)126-130
Number of pages5
JournalInternational Journal of Antimicrobial Agents
Volume43
Issue number2
DOIs
Publication statusPublished - Feb 2014
Externally publishedYes

Keywords

  • Antimicrobial resistance
  • Salmonella
  • Australia
  • Animals
  • Plasmid replicon
  • MULTIPLE ANTIBIOTIC-RESISTANCE
  • TYPHIMURIUM DT104
  • ESCHERICHIA-COLI
  • FLUOROQUINOLONE RESISTANCE
  • SPECTRUM CEPHALOSPORINS
  • SEROTYPE NEWPORT
  • UNITED-STATES
  • POPULATION
  • INTEGRONS
  • ANIMALS

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