title: Antimicrobial susceptibility phenotypes, resistance determinants and DNA fingerprints of Salmonella enterica serotype Typhimurium isolated from bovine in Southern Japan.
abstract: A longitudinal study was conducted in cattle to determine the antimicrobial resistance phenotypes, integron elements, resistance genes and pulsed-field gel electrophoresis fingerprints among Salmonella enterica serotype Typhimurium isolates. A total of 33 strains were isolated and categorised into Groups A, B and C during the period 1989-2004. Thirty-one strains (93.9%) showed resistance to ampicillin (A) encoded by bla(OXA-1), bla(TEM) and bla(PSE-1) genes; 84.8% showed resistance to chloramphenicol (C) encoded by floR and catA1; 97.0% were resistant both to streptomycin (S) and sulfamethoxazole (Su), the former encoded by aadA1 and aadA2; 100% were resistant to oxytetracycline (T) encoded by tetA, tetB and tetG; and 42.4% were resistant to kanamycin (Km) encoded by aphA1-Iab. Multidrug resistance types observed were ACSSuT-Km (n=13), ACSSuT (n=15), ASSuT (n=3) and SSuT (n=2). Class 1 integrons ranging from 1.0 kb to 1.9 kb were detected from 54.5% of isolates (18/33). Integrons were not detected initially (1989-1992), then during the 1993-1996 interval a high frequency of 1.0 kb and 1.2kb amplicons were detected and during 2000-2004 the amplicon size increased to 1.7 kb and 1.9 kb. We report evidence of additional integration of resistance gene cassettes as shown by integrons with increased size. Finally, group B strains showed banding patterns indistinguishable from S. Typhimurium DT104 reference strain, indicating that the DT104 lineage existed on the island since 1993.
authors.affiliation: Laboratory of Veterinary Public Health, Department of Veterinary Medicine, Faculty of Agriculture, Kagoshima University, 1 21-24 Korimoto, Kagoshima 890-0065, Japan.
authors.forename: Francis
authors.initials: F
authors.lastname: Shahada
authors.forename: Asako
authors.initials: A
authors.lastname: Amamoto
authors.forename: Takehisa
authors.initials: T
authors.lastname: Chuma
authors.forename: Akito
authors.initials: A
authors.lastname: Shirai
authors.forename: Karoku
authors.initials: K
authors.lastname: Okamoto
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002417:Cattle; D016172:DNA Fingerprinting; D024901:Drug Resistance, Multiple, Bacterial; D032023:Integrons / Q000235:genetics; D007564:Japan / Q000453:epidemiology; D008137:Longitudinal Studies; D008826:Microbial Sensitivity Tests; D012481:Salmonella Infections, Animal / Q000453:epidemiology / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D000900:Anti-Bacterial Agents