Submitted to: American Society of Animal Science Southern Section Meeting
Publication Type: Abstract Only
Publication Acceptance Date: January 5, 1999
Publication Date: N/A
Technical Abstract: Competitive exclusion (CE), which facilitates colonization of the gut by normal, healthy microbes, has been shown to enhance resistance of young pigs to gut colonization by Salmonella. Because of the enhanced resistance of CE treated piglets to S. Choleraesuis (SC), we hypothesized that treatment may provide a way to interrupt horizontal transmission of this pathogen. To test this hypothesis, we orally challenged pigs of 6 different litters at 15 days of age (1 day post weaning) with 10**7 colony forming units (CFU) of SC and then commingled these (designated as seeders) 1 to 2 days later with an equal number of pigs having no known exposure to the pathogen. These latter pigs were designated as contacts. Some seeders and contacts were treated at birth with a porcine derived CE culture derived from cecal contents of a healthy adult pig and cultured in steady-state via continuous flow culture. All seeder pigs were found to be infected by SC at 23 to 26 days of age, as determined by culture of ileocolic lymph nodes and gut contents collected at necropsy. However, SC colonization in gut contents of the CE treated seeders was markedly reduced compared to that in the untreated seeders. Shedding as determined by daily culture of rectal swabs, was less for the CE treated seeders (46%) than for the untreated seeders (52%). Horizontal transmission occurred readily between untreated seeders and untreated contacts, with 11 of the 13 contacts becoming infected. In contrast, only 3 of the 13 CE treated contacts became infected when commingled with the CE treated seeders, thus demonstrating a significant benefit (P<0.01, Chi square test) of CE treatment in stemming the spread of SC.