Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 13, 2003
Publication Date: July 20, 2003
Citation: GENOVESE, K.J., ANDERSON, R.C., HARVEY, R.B., CALLAWAY, T.R., POOLE, T.L., EDRINGTON, T.S., CRAY, P.J., NISBET, D.J. COMPETITIVE EXCLUSION OF SALMONELLA FROM THE GUT OF NEONATAL AND WEANED PIGS. JOURNAL OF FOOD PROTECTION. 2003. V. 66(8). P. 1353-1359. Interpretive Summary: The contamination of pork products with Salmonella continues to be a concern for both pork producers and the consuming public. In addition, the emergence of antibiotic resistant bacteria in food animals has become an important problem. Therefore, our laboratory has investigated alternative measures to antibiotics for the control of Salmonella in swine. Previously we have shown that providing baby pigs and weaned pigs a mixed bacterial culture derived from the gut of swine protected them from infection with Salmonella bacteria. The current report demonstrates that this bacterial culture (PCF1) can protect baby and weaned pigs from transmission of Salmonella between littermates. Pigs administered the PCF1 culture just after birth were less likely to become infected with Salmonella carried by their Salmonella infected littermates. In addition, pigs administered the PCF1 culture and subsequently challenged with Salmonella were also less likely to pass Salmonella to littermates. The results of these studies indicate that the PCF1 culture is an effective method of Salmonella control in baby and weaned pigs, and that the culture may be a viable alternative to the use of antibiotics.
Technical Abstract: In this manuscript we document the effects of the CE culture, PCF1, on gut colonization and fecal shedding by S. cholerasuis in neonatal and weaned pigs and the effects on horizontal transmission of this pathogen among weaned penmates. Control and CE-treated pigs in experiments 1 and 2 were farrowed and raised by separate sows and were euthanized and necropsied by day 8 post-farrow. Treated pigs were orally administered the CE culture twice within the first day of life and all pigs were challenged with S. choleraesuis at 48 hours after birth. CE-treated pigs shed Salmonella significantly (P < 0.05) less than control pigs in experiment 1. Significant reductions were also observed in gut contents and tissues (P < 0.05). In experiment 2, piglets in both the control and CE-treated groups did not shed Salmonella often, resulting in no difference between control and treated fecal shedding (P > 0.05). However, gut contents and tissues showed significant reductions in Salmonella isolated from CE-treated pigs (P < 0.05). In experiment 3, Pigs were followed through day 10 post-wean. Significant reductions in shedding were noted in treated groups both pre- and post- wean (P < 0.05). In one treated litter, cecal contents were also found to have significantly reduced numbers of pigs positive for Salmonella as compared to control pigs and in another litter, the log10 determination for Salmonella CFUs was reduced in the CE-treated group by over 2.5 log10 (P < 0.05) compared to control values. Experiments 4 and 5 assessed effects on horizontal transmission of Salmonella between littermates through day 14 post-weaning. Litters were divided among untreated contacts (UC), untreated seeders (US), treated contacts (TC), and treated seeders (TS). TC in experiment 4 shed Salmonella significantly less than did UC and US (P < 0.05). In experiment 5, the transmission of Salmonella was significantly reduced in litters where either TS or TC were present, as evidenced by reduced shedding of Salmonella by both treated and untreated animals within these litters (P < 0.05). TS shed less often than did US, resulting in reduced levels of Salmonella shedding by both treated and untreated contacts (P < 0.05). Litters containing both TC and UC or US also had less Salmonella shedding than litters in which only UC and US were present (P < 0.05). The results of these experiments demonstrate that the swine CE culture is an effective tool when used to prevent and/or reduce the colonization of the swine gut by Salmonella and its associated shedding in feces and subsequent transmission between littermates.