Factors influencing the fate of Escherichia coli and Salmonella typhimurium in germ-free piglets and rats.

Germ-free (GF) animals are an excellent model for studies of the interactions between intestinal bacteria and the host. Such animals can be easily colonized with various strains of enteric bacteria and this facilitates studies of the fate of microorganisms in various compartments of the host on one side and the immune response on the host on the other. GF piglets represent a model exceptionally suited for such studies because only extremely low concentrations of antibodies are present in their sera as a result of a special type of placentation in this animal species.1,11 In addition, higher weight of organs and mesenteric lymph nodes (MLN) facilitates quantitative estimation of translocated bacteria.