Salmonellosis is one of the most important bacterial food borne illnesses
worldwide. Among the many Salmonella serotypes, Typhimurium is the most
commonly implicated serotype in human disease in the United States. A major source of
infection for humans is consumption of chicken or egg products that have been
contaminated with S. Typhimurium. The breadth of knowledge regarding colonization
and persistence factors in the chicken is small when compared to our knowledge of
factors that are important for these processes in other species used in Salmonella
research, such as cattle and mice. Defining the factors important for these processes in
the chick is the first step in decreasing the transmission of Salmonella between animal
and human hosts.
In this work, we developed a chicken model to identify and study intestinal
colonization and persistence factors of Salmonella enterica serovar Typhimurium. We
studied the degree of enteric and systemic colonization of wild type S. Typhimurium
ATCC14028, one of the most widely studied Typhimurium isolates, in White Leghorn chicks and in Salmonella-resistant CBA/J mice during infection. Furthermore, we
determined the distribution of wild type S. Typhimurium and a SPI-1 mutant (invA)
during competitive infection in the cecum of 1-week-old chicks and 8-week-old mice.
Cell associated, intracellular and luminal distributions of these strains in the cecum were
analyzed as total counts in each compartment and also as a competitive index.
Localization of S. Typhimurium ATCC14028 and the role of SPI-1 in colonization are
well studied in murine models of infection, but comparative infection in chicks with the
same strain has not been undertaken previously.
We show that the cecal contents are the major site for recovery of S.
Typhimurium in the cecum of 1-week-old chicks and Salmonella-resistant mice. We
also show that while SPI-1 is important for successful infection in the murine model, it is
important only for cell association in the cecum of 1-week-old chicks. Finally, we found
that in chicks infected at 1 week of age, bacterial counts in the feces do not reflect those
seen in the cecum as they do in mice.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2989 |
| Date | 15 May 2009 |
| Creators | Sivula, Christine Patricia |
| Contributors | Adams, L. Garry, Andrews-Polymenis, Helene L. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, application/pdf, born digital |
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