Sivula, Christine Patricia (2008-08). Comparison of cecal colonization of Salmonella enterica serotype Typhimurium in white leghorn chicks and Salmonella-resistant mice. Master's Thesis. Thesis uri icon


  • 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.

publication date

  • August 2008