The role of systemic antibodies against intestinal Escherichia coli in the prevention of bacterial translocation of Escherichia coli in a burn model in mice.

Bacterial translocation (BT) from the gastrointestinal (GI) tract has been proposed to play a role in the pathogenesis of septic complications in severely burned patients. It is well known that severely ill patients such as thermally injured patients may acquire new potential pathogenic microorganisms in the GI tract. Because these patients have no antibodies directed against these acquired microorganisms, BT may be facilitated in these patients. To investigate this hypothesis in a burn model, a study was performed in which two groups of C3H-HeN mice underwent a different period of intestinal overgrowth by a single neomycin-resistant (NR) Escherichia coli strain after oral neomycin-bacitracin treatment. Group I underwent a short period (5 days) and group II experienced a long period (44 days) of intestinal overgrowth before a thermal injury was executed. Two days postburn, plasma antibody titers of IgA, IgG, and IgM isotype against NR E. coli were measured by indirect immunofluorescence (IIF) and BT to various organs was determined by culturing. Although there were no significant differences of BT to organs between the groups, the IgG antibody titer against the NR E. coli strain was significantly increased in group II. Antibody titers of IgA and IgM were not significantly different between the groups. Titers of plasma antibodies of IgG isotype against the intestinal NR E. coli did not correlate with BT. We conclude that increased IgG titers against the NR E. coli used are the result of a longer intestinal overgrowth period and are not associated with prevented or decreased BT.