Objective—To determine interactions between Oesophagostomum spp and Salmonella ser. Typhimurium in pigs.

Animals—30 healthy 5- to 6-week-old pigs.

Procedure—Pigs were allotted to 3 groups (n = 10 pigs/group) and treated as follows: group A was given Oesophagostomum dentatum and O quadrispinulatum ; group B was given O dentatum, O quadrispinulatum , and S Typhimurium; and group C was given S Typhimurium only. Pigs in groups A and B were trickle infected with Oesophagostomum spp 3 times weekly throughout the study. After 19 days, groups B and C were inoculated once with S Typhimurium. One pig from each group was euthanatized on the day of Salmonella exposure and 2 and 4 days after Salmonella exposure. The remaining pigs were euthanatized on days 16 and 17 after Salmonella exposure.

Results—Pigs with dual infections of nematodes and bacteria (group B) excreted significantly higher amounts of S Typhimurium in feces, compared with nematode-free pigs (group C). In addition, group-B pigs excreted S Typhimurium on more days than pigs in group C. Salmonella Typhimurium was detected in the cecum and colon in the majority of pigs in group B, whereas S Typhimurium was only detected in the colon in pigs in group C. Immunohistochemical examinations detected S Typhimurium in 7 of 9 pigs in group B but only 2 of 9 pigs in group C.

Conclusion and Clinical Relevance—Interactions between intestinal nematodes and bacteria may play an important role in the dynamics of S Typhimurium infections. (Am J Vet Res 2002;63:130–136)