title: High prevalence and molecular characteristics of multidrug-resistant Salmonella in pigs, pork and humans in Thailand and Laos provinces.
abstract: This study aimed to examine occurrence and antimicrobial resistance characteristics of Salmonella from pigs, pork and humans in Thailand and Laos provinces. The samples were collected from pigs, carcasses and workers in slaughterhouses, retail pork and butchers in fresh markets and patients in hospitals in Thailand (n=729) and Laos (n=458). A total of 295 of 729 samples (34.6 %) collected in Thailand and 253 of 458 (47.4 %) samples collected in Laos were positive for Salmonella. A total of 548 Salmonella isolates from Thailand (n=295) and Laos (n=253) were further analysed. Serovar Typhimurium was the most common serotype in Thai (34 %) and Laos (20.6 %) samples. Approximately 2.4 % of Thai isolates produced extended-spectrum β-lactamase (ESBL). All the ESBL producers possessed blaCTX-M-14, some of which were horizontally transferred. Class 1 integrons were common in Thai (31.9 %) and Laos (39.1 %) isolates, but none were associated with SGI1. The resistance cassette dfrA12-aadA2 was the most common, while the least common was aadA2-linG (n=1). The dfrA12-aadA2 gene cassette in five isolates and aadA2-linG were located on conjugative plasmid. Three pork isolates were fluoroquinolone resistant and carried an amino acid substitute, Ser-83-Tyr, in GyrA. The qnrS gene was found in 7.1 and 5.5 % of the Thai and Laos isolates, respectively, while qnrB was carried in another Laos isolate (1.9 %). All ESBL producers carried qnrS. In conclusion, multidrug-resistant Salmonella was common in pigs, pork and human samples in this region. The bacteria carried mobile genetic elements and resistance genes on conjugative plasmids that could be readily transferred to other bacterial species.
authors.affiliation: Research Unit in Microbial Food Safety and Antimicrobial Resistance, Department of Veterinary Public Health, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Nuananong
authors.initials: N
authors.lastname: Sinwat
authors.affiliation: Research Group for Prevention Technology in Livestock, Faculty of Veterinary Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Sunpetch
authors.initials: S
authors.lastname: Angkittitrakul
authors.affiliation: Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
authors.forename: Kari F
authors.initials: KF
authors.lastname: Coulson
authors.affiliation: Department of Veterinary Paraclinical Science, College of Veterinary Medicine, University of the Philippines, Laguna, Philippines.
authors.forename: Flor Marie Immanuelle R
authors.initials: FMIR
authors.lastname: Pilapil
authors.affiliation: Faculty of Agriculture, National University of Laos, Vientiane, Lao PDR, Laos.
authors.forename: Dethaloun
authors.initials: D
authors.lastname: Meunsene
authors.affiliation: Research Unit in Microbial Food Safety and Antimicrobial Resistance, Department of Veterinary Public Health, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
authors.forename: Rungtip
authors.initials: R
authors.lastname: Chuanchuen
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D024901:Drug Resistance, Multiple, Bacterial; D005506:Food Contamination / Q000032:analysis / Q000706:statistics & numerical data; D006801:Humans; D032023:Integrons; D007812:Laos / Q000453:epidemiology; D008460:Meat / Q000382:microbiology*; D015995:Prevalence; D012475:Salmonella / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D012480:Salmonella Infections / Q000453:epidemiology / Q000382:microbiology*; D012481:Salmonella Infections, Animal / Q000453:epidemiology / Q000382:microbiology*; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000382:microbiology*; D013785:Thailand / Q000453:epidemiology; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001618:beta-Lactamases