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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #126440
Title: COMPARISON OF EARLY ILEAL INVASION BY SALMONELLA ENTERICA SEROVARS CHOLERAESUIS AND TYPHIMURIUM

Author
item MEYERHOLZ, DAVID - IOWA STATE UNIVERSITY
item STABEL, THOMAS

Submitted to: Veterinary Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2003
Publication Date: 7/20/2003
Citation: MEYERHOLZ, D.K., STABEL, T.J. COMPARISON OF EARLY ILEAL INVASION BY SALMONELLA ENTERICA SEROVARS CHOLERAESUIS AND TYPHIMURIUM. VETERINARY PATHOLOGY. 2003. V. 40. P. 371-375.

Interpretive Summary: Salmonella species of bacteria are a serious worldwide problem causing swine disease estimated to cost $100 million annually in the United States. Salmonella bacteria also are important human pathogens and are of great concern in food safety. This study was performed to define early events associated with Salmonella serovar Choleraesuis invasion of the small intestine of pigs and to examine differences in intestinal invasion between Salmonella serovar Choleraesuis, a salmonella adapted to infection of pigs, and Salmonella serovar Typhimurium, a salmonella not adapted to infection of one specific animal type. Sections of intestine, called loops, were surgically prepared in young pigs and inoculated with Salmonella for 0 to 60 minutes. Loops were harvested and prepared for both scanning and transmission electron microscopy. Both Salmonella serovars exhibited nonspecific cellular invasion as early as 10 minutes post inoculation. Serovars exhibited differences in early invasion of cells lining the intestinal wall. Cells that were in the process of dying were sites for preferential uptake of Salmonella serovar Typhimurium compared to Salmonella serovar Choleraesuis. Information gained from this pig model will be useful in the study of human salmonellosis and other new and emerging foodborne diseases. In addition, our ability to understand specific mechanism(s) involved in the interaction of animals and specific Salmonella serovars will affect our ability to reduce Salmonella transmission in the pig and thus affect the pork industry's ability to maintain a safe national food chain and compete for new international markets.

Technical Abstract: The mechanisms of Salmonella serovar-host specificity are not well defined. Pig ileal-loops were used to define Salmonella serovar Choleraesuis early cellular invasion events and examine for phenotypic differences of early cellular invasion between nonhost- adapted Salmonella serovar Typhimurium and host-adapted Salmonella serovar Choleraesuis. By 10 minutes post inoculation, both serovars invaded M cells, enterocytes, and goblet cells. Salmonella serovar Choleraesuis invaded M cells in microcolonies, whereas Salmonella serovar Typhimurium invaded as single organisms. Internalization of both serovars resulted in vacuoles containing a single bacterium. The follicle-associated epithelium of Salmonella serovar Choleraesuis inoculated loops responded with more filopodia and lamellipodia while exhibiting less cell swelling than Salmonella serovar Typhimurium. Additionally, Salmonella serovar Typhimurium had a noticeable increase of affinity for sites of cell extrusion at 60 minutes compared to the Salmonella serovar Choleraesuis. These results suggest: 1) Salmonella serovars Choleraesuis and Typhimurium exhibit noncell-specific invasion as early as 10 minutes post inoculation; 2) Salmonella serovars exhibit differences in early invasion of follicle-associated epithelium and M cells; and 3) cells undergoing extrusion may provide a site for preferential adherence of Salmonella serovar Typhimurium compared to Salmonella serovar Choleraesuis.