Acute Salmonella infection in swine

Loynachan, Alan
Major Professor
Hank Harris
Committee Member
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Veterinary Microbiology and Preventive Medicine

The objectives of this dissertation are focused on defining acute Salmonella infection in swine, and contains six chapters and two appendices. Acute Salmonella infection is defined as the ability of swine to infect alimentary and non-alimentary tissues within 3 hours following inoculation.;Chapter 1 provides a general overview of Salmonella. It includes a description of swine salmonellosis, the pig's response to Salmonella infection, methods of Salmonella detection, an overview of intervention used for the reduction of Salmonella infections, and describes acute Salmonella infection in swine.;Chapter 2 indicates that the most common swine associated Salmonella serotypes are capable of acutely infecting pigs. Pigs were inoculated with varying Salmonella serotypes, necropsied, and alimentary and non-alimentary tissues were cultured for the presence of Salmonella . In conclusion, Salmonella wildtype isolates were capable of acutely infecting pigs more so than vaccine strains.;Chapter 3 helps elucidate the mechanisms utilized by Salmonella to acutely infect swine. Varying Salmonella wildtype isolates, mutant strains, and vaccine strains were inoculated and evaluated in there abilities to acutely infect pigs. Reduction in acute Salmonella infection was seen in avirulent deletion mutants in which the cya/crp genes had been inactivated or in those strains attenuated by neutrophil passage. This study also indicated that acute infection virulence may be enhanced after continual passage of Salmonella through pigs.;Chapter 4 indicates the minimal number of Salmonella that are required to induce acute Salmonella infection. Pigs were exposed to various levels of Salmonella by either intranasal inoculation, or subjecting them to a contaminated environment. Greater than 1 X 103 Salmonellae were required to induce acute Salmonella infection.;Chapter 5 analyzes acute Salmonella infection in germfree pigs. Germfree pigs were inoculated with probiotic bacteria and subsequently challenged with Salmonella. This study established a germfree probiotic model for the reduction of acute Salmonella infection, and indicates that germfree pigs are susceptible to acute Salmonella infection.;Chapter 6 is a general conclusions chapter. Additionally, it provides suggestions for further work to advance science in the field of acute Salmonella infection in swine.