Serotype, Antimicrobial Susceptibility, and Genotype of Salmonella Isolates from Swine and Pork in Sa Kaew Province, Thailand

In January 2010, we examined the prevalence of Salmonella in the rectal swab of 66 swine on 8 farms and in 25 pork products at 6 meat retailers of Sa Kaew province. Salmonella was isolated from 3%(2/66) of swine rectal swab samples and 96%(24/25) of pork samples. In rectal swab samples, both S. Weltevreden and S. Dumfries were isolated from one sample, and S. Stanley from another sample. In pork, a total of 42 isolates (16 serovars) were found ; 8 strains of S. Rissen, 5 strains of S. Stanley and S. Anatum, 4 strains of S. Give and S. Kedougou, 3 strains of S. Welteverden, 2 strains of S. Hvittingfoss, S. Agona and S. Krefeld, and only 1 strain of 7 serovars were isolated. The resistance of Salmonella isolates was highest for tetracycline (69%), followed by ampicillin (50%), sulfamethoxazoletrimethoprim (36%), streptomycin (31%), chloramphenicol (14%), cefotaxime (5%), and ciprofloxacin (2%). S. Stanley and S. Weltevreden were found in both rectal swab and pork samples; however, pulsed-field gel electrophoresis and resistance profiles revealed no relationship between the rectal swab and pork isolates. In our study, Salmonella was isolated from only 3% of swine rectal swab samples, however, pork at a meat retailer in Sa Kaew province had a high prevalence of Salmonella. The result suggested that cross contamination may occur during slaughter house, transportation, to retail shop.