Salmonella challenges: prevalence in swine and poultry and potential pathogenicity of such isolates.

Salmonellosis is the second leading cause of bacterial foodborne illness in the United States, and the great majority of these infections are associated with the consumption of products such as meat, poultry, eggs, milk, seafood, and fresh produce contaminated with Salmonella. The per capita consumption of meat and poultry in United States has increased significantly over the past century. This increase is especially evident with poultry products, where there has been a nearly 6-fold increase in chicken consumption and 17-fold increase in turkey consumption since 1909. The per capita consumption of pork has also increased over this time from 18.7 to 21.7 kg/yr. With this increase in meat and poultry consumption, the dynamics of animal production and consumer exposure have changed leading to new challenges in limiting salmonellosis. To meet the demands of consumers, more intensive agricultural practices have been adopted, which has likely changed the population characteristics of Salmonella present among poultry flocks and swine populations. In Salmonella isolated from swine in the United States, S. Typhimurium has replaced S. Choleraesuis as the predominant serovar in recent years. Among isolates from turkeys collected in 2004, serovars S. Senftenberg and S. Hadar were most common overall; however, S. Heidelberg was most common from clinical diagnostic sources, potentially indicating increased virulence. Salmonella Heidelberg was also the most commonly detected serovar among chicken isolates from clinically ill birds and Salmonella surveillance samples. Overall among the 10 serovars most commonly associated with human infections, 6 are also found in the top serovars of swine and poultry. These include S. Typhimurium, S. Enteritidis, S. Heidelberg, S. Montevideo, S. Saintpaul, and S. I 4,[5],12:i:-.