Escherichia coli serotypes throughout the gastrointestinal tract of patients with intestinal disorders.

The O and H serotypes of Escherichia coli that were present along the entire length of the gastrointestinal tract of patients with small intestinal bacterial overgrowth were studied. Multiple sero- and biotypes were represented, although usually a single serotype predominated in each patient. In a number of cases the different O:H serotypes were antigenically related indicating that antigenic degradation was occurring. The serotypes isolated from the stomach and small intestine were represented in the faeces. In general, within the limitations of this study, there appears to be a stable ecosystem in each patient and it may require specific oral antibiotics to alter it.