title: Salmonella in healthy pigs: prevalence, serotype diversity and antimicrobial resistance observed during 1998-1999 and 2004-2005 in Japan.
abstract: To determine prevalence, serotype diversity and antimicrobial resistance of Salmonella in healthy pigs, faecal samples from 6771 pigs on 73 farms collected during 1998-1999 and 2004-2005 were examined. Salmonella isolates were serotyped and tested for susceptibility to 22 antimicrobials: benzylpenicillin, ampicillin, amoxicillin, cefazolin, cephaloridine, gentamicin, kanamycin, streptomycin, fradiomycin, colistin, tetracycline, chlortetracycline, oxytetracycline, chloramphenicol, thiamphenicol, sulfadimethoxine, sulfamethoxazole, sulfamethoxypyridazine, trimethoprim, sulfamethoxazole/trimethoprim, norfloxacin and ofloxacin. Farm-level and pig-level Salmonella prevalences were 35.5% and 2.2% in 1998-1999, and 35.7% and 3.3% in 2004-2005. Prevalence by growth stage was 2.4% for sows, 3.3% for weaned pigs, 2.7% for fattening pigs and 3.8% for finishing pigs. The predominant serotypes identified were Agona (28.4%), Typhimurium (17.9%) and Infantis (16.4%) in 1998-1999, and Typhimurium (32.5%), Anatum (24.6%) and Infantis (13.5%) in 2004-2005. Compared with the 1998-1999 isolates, the 2004-2005 isolates showed significantly higher rates of resistance to all the antimicrobials except tetracyclines (P<0.01 to P<0.05) and resistance to 2 antimicrobials [19.4% (13/67) vs. 39.7% (50/126), P<0.01]. This study provides national estimates of Salmonella prevalence in healthy pigs of different growth stages in Japan.
authors.affiliation: Department of Animal Health 2, School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Sagamihara, Kanagawa 229-8501, Japan. saitohk@azabu-u.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Futagawa-Saito
authors.forename: S
authors.initials: S
authors.lastname: Hiratsuka
authors.forename: M
authors.initials: M
authors.lastname: Kamibeppu
authors.forename: T
authors.initials: T
authors.lastname: Hirosawa
authors.forename: K
authors.initials: K
authors.lastname: Oyabu
authors.forename: T
authors.initials: T
authors.lastname: Fukuyasu
mesh_terms: D000818:Animals; D015373:Bacterial Typing Techniques; D016009:Chi-Square Distribution; D015169:Colony Count, Microbial; D004197:Disease Reservoirs / Q000382:microbiology / Q000662:veterinary; D024881:Drug Resistance, Bacterial; D005243:Feces / Q000382:microbiology; D007564:Japan; D008826:Microbial Sensitivity Tests; D015995:Prevalence; D012481:Salmonella Infections, Animal / Q000382:microbiology; D019779:Salmonella enterica / Q000145:classification* / Q000187:drug effects; D012703:Serotyping; D013552:Swine / Q000382:microbiology; D013553:Swine Diseases / Q000382:microbiology