Spread of Antimicrobial-Resistant Salmonella from Poultry to Humans in Thailand

Jpn J Infect Dis. 2021 May 24;74(3):220-227. doi: 10.7883/yoken.JJID.2020.548. Epub 2020 Nov 30.


Food animal production is important for every country. Several antibiotic agents are used in poultry farming to reduce the economic losses arising from mostly untested infectious diseases. This continued study was performed to determine the prevalence of antibiotic-resistant Salmonella in broiler chickens, poultry farmers, and Salmonella bacteremia patients. A total of 121 Salmonella isolates were collected from the Thai provinces of Khon Kaen (65 isolates), Ratchaburi (43 isolates), and Phayao (13 isolates). Salmonella from chicken showed a high rate of resistance to nalidixic acid and tetracycline. Sixty-four percent of Salmonella isolates carried class 1 integrons (intI1 gene-positive). Among the 121 Salmonella isolates, there were 15 serotypes, with S. Enteritidis being the most common. A clonal relationship between the chicken and human isolates was demonstrated by 3 molecular typing methods: enterobacterial repetitive intergenic consensus polymerase chain reaction; pulsed-field gel electrophoresis; and high-throughput multilocus sequence typing. A spread of the sequence type 11 clone was found between chickens and humans. This study revealed a large-scale Salmonella outbreak in Thailand, a link between resistant bacteria from poultry farms and vertical transmission through the food chain, and horizontal transmission of resistance genes. These results can be used for future surveillance and monitoring.

Keywords: clonal spread; humans; molecular epidemiology; poultry; resistant bacteria.

MeSH terms

  • Animals
  • Chickens
  • Disease Outbreaks
  • Drug Resistance, Multiple, Bacterial / genetics*
  • Farmers
  • Humans
  • Integrons / genetics
  • Poultry
  • Poultry Diseases / drug therapy
  • Poultry Diseases / epidemiology
  • Poultry Diseases / microbiology*
  • Salmonella Infections / drug therapy
  • Salmonella Infections / epidemiology*
  • Salmonella Infections / genetics
  • Salmonella Infections / microbiology*
  • Salmonella Infections, Animal / drug therapy
  • Salmonella Infections, Animal / epidemiology
  • Salmonella* / drug effects
  • Salmonella* / genetics
  • Salmonella* / isolation & purification
  • Thailand / epidemiology