Modulating the microbial colonization of the gastrointestinal tract by oral administration of defined Escherichia coli strains. II. Influencing the biotope by means of geographically unrelated Escherichia coli strains.

An effective increase in the rate of colonization can be accomplished, in analogy with the pathogenetic mechanism of what is known as travelers' disease, through the administration of geographically unrelated strains. As compared to Escherichia coli strains isolated in the GDR, metabolic drift-optimized and Ethiopian strains showed an increase from 20 to 50%. It was not, however, possible to maintain a greater than or equal to 50% share in the population of Enterobacteriaceae over a period of more than up to three days. Immunologic mechanisms are considered to be responsible for this.