Salmonella in healthy pigs: prevalence, serotype diversity and antimicrobial resistance observed during 1998-1999 and 2004-2005 in Japan.

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.

Identification and prevalence of an enterotoxin-related gene, se-int, in Staphylococcus intermedius isolates from dogs and pigeons.

AIMS: To determine the prevalence of enterotoxin-producing Staphylococcus intermedius in dogs and pigeons. METHODS AND RESULTS: A total of 106 S. intermedius isolates from 44 dogs and 62 pigeons were tested for the production of enterotoxins A, B, C and D by reverse passive latex agglutination (RPLA) and for sec-canine by PCR. Only one isolate from dog was positive for SEC and sec-canine. Screening of sec-canine-negative strains by nested PCR led to the identification of a novel enterotoxin-related gene, se-int. SE-int showed a significant homology (59-61% identity) with SEC and (56.6% identity) SEB. All 44 isolates from dogs and five isolates (8.1%) from pigeons were se-int positive. CONCLUSIONS: While S. intermedius was isolated more frequently from pigeons than from dogs, se-int was more prevalent among the S. intermedius isolates from dogs, compared with the pigeon isolates. SIGNIFICANCE AND IMPACT OF THE STUDY: Further characterization of the se-int-positive S. intermedius strains should clarify their pathogenic potential including enterotoxigenicity and zoonotic transmissibility to human beings.