Molecular characterization of antibiotic-resistant bacteria in contaminated chicken meat sold at supermarkets in Bangkok, Thailand

Jpn J Infect Dis. 2012;65(6):527-34. doi: 10.7883/yoken.65.527.

Abstract

We assessed contamination by antibiotic-resistant bacteria in chicken meat obtained from supermarkets in Bangkok, Thailand. The prevalence of Salmonella enterica and Escherichia coli was 18.7% (14/75) and 53% (106/200), respectively. Most probable number (MPN) analysis showed that 56.7% of the samples (34/60) were in violation of the limit of allowable coliform bacteria in chicken meat, for which the maximum is 46,000 MPN/g. Multidrug-resistant phenotypes of both S. enterica and E. coli were found. The presence of class 1 integrons was demonstrated by polymerase chain reaction (PCR) and dot-blot hybridization. PCR showed that class 1 integrons were present in 42.9% (6/14) and 37.7% (40/106) of S. enterica and E. coli isolates, respectively. Resistance genes identified in this study were aadA2, aadA4, aadA22, and aadA23 (for aminoglycoside resistance); dfrA5 (for trimethoprim resistance), and lnuF (for lincosamide resistance). Four S. enterica isolates underwent multilocus sequence typing and the results were sequence type (ST) 50, ST 96, ST 1543, and ST 1549, which matched well with strains from many countries and reflected an international spread. Our study revealed that class 1 integrons have spread into community sources and might play an important role in horizontal antibiotic resistance gene transfer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Load
  • Chickens
  • DNA, Bacterial / genetics
  • Drug Resistance, Bacterial*
  • Escherichia coli / drug effects*
  • Escherichia coli / genetics*
  • Escherichia coli / isolation & purification
  • Genes, Bacterial
  • Integrons
  • Meat / microbiology*
  • Multilocus Sequence Typing
  • Polymerase Chain Reaction
  • Salmonella enterica / classification
  • Salmonella enterica / drug effects*
  • Salmonella enterica / genetics*
  • Salmonella enterica / isolation & purification
  • Thailand

Substances

  • Anti-Bacterial Agents
  • DNA, Bacterial