Mechanisms of colonization of the swine intestinal tract by Salmonella spp.

In the first part of the paper the bacteriology and epidemiology of Salmonella infections in swine is characterized. The differences from symptomless colonization of the intestinal tract to gastroenteritis and systemic infection with clinical symptoms are mentioned. The degree of pathogenicity of Salmonella organisms is related to the genes. The most frequent is colonization of the intestines, which are the major reservoir of Salmonella organisms as pathogens transmitted to humans on account of pork and pork product consumption. Strains of Salmonella Typhimurium, Salmonella Derby and Salmonella Enteritidis of swine origin play an important role in toxicoinfections of humans worldwide. The second part of the paper deals with genes coding the property of the colonization of the intestines and different degrees of virulence of Salmonella organisms. It is hoped that this knowledge will enable the improvement of methods essential in the prevention of colonization of the intestines of swine, which would minimize the carrier-ship of Salmonella organisms. In particular it may contribute to the improvement of the efficacy of vaccines against colonization. These would be based on the selection for vaccine production of Salmonella strains which are responsible for intestinal colonization. Until now this was not possible since mostly strains originating from systemic infection, after inactivation or attenuation, were used. Probably because of this approach the presently available vaccines did not immunize swine to a sufficient degree against the colonization of the intestines by Salmonella organisms.