title: Prevalence of class 1 integrons in commensal Escherichia coli from pigs and pig farmers in Thailand.
abstract: Escherichia coli isolates (n = 617) from fecal samples of healthy and diarrheal pigs, pig farmers, and nonfarmers were analyzed for class 1 integrons. Three hundred ninety-two isolates (63.5%) were positive for class 1 integrons, based on the presence of intI1, with seventy-one of those isolates (11.5%) harboring all three conserved genes (intI1, qacEdelta1, and sul1) known to be associated with class 1 integrons. The presence of integrons was associated with isolate origin. Integrons were more prevalent in isolates from most pig groups than in isolates from pig farmers and nonfarmers. Selected integron-positive and integron-negative isolates were tested for resistance to 16 antimicrobials. All integron-positive swine isolates were multidrug resistant to at least three antimicrobial agents, demonstrating resistance to 14 different antibiotics that included sulphamethoxazole (100%), tetracycline (97.1%), ampicillin (92.8%), streptomycin (89.9%), trimethoprim-sulphamethoxazole (88.1%), nalidixic acid (60.9%), chloramphenicol (58.0%), kanamycin (55.1%), cephalothin (44.9%), gentamicin (39.1%), ciprofloxacin (33.3%), cefoxitin (8.7%), amoxicillin-clavulanic acid (5.8%), and amikacin (2.9%). All isolates were susceptible to ceftiofur and ceftriaxone. Forty-seven resistance patterns were observed among 69 integron-positive swine and swine farmer isolates. The most frequent pattern was tetracycline-ciprofloxacin-gentamicin-nalidixic acid-sulphamethoxazole-trimethoprim-sulphamethoxazole-kanamycin-ampicillin-streptomycin (10.1%), which was found in diarrheal and healthy pigs. This study shows that integrons and multidrug-resistant commensal bacteria are common and appear to be a significant aspect of microbial communities associated with pigs and humans in southern Thailand.
authors.affiliation: Department of Microbiology, Faculty of Science, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand. souwalak.p@psu.ac.th
authors.forename: Souwalak
authors.initials: S
authors.lastname: Phongpaichit
authors.forename: Sumalee
authors.initials: S
authors.lastname: Liamthong
authors.forename: Alan G
authors.initials: AG
authors.lastname: Mathew
authors.forename: Usa
authors.initials: U
authors.lastname: Chethanond
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002353:Carrier State; D004197:Disease Reservoirs / Q000662:veterinary; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology*; D006801:Humans; D032023:Integrons; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D015995:Prevalence; D013552:Swine / Q000382:microbiology; D013553:Swine Diseases / Q000382:microbiology; D013785:Thailand / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents