Relationship of host antibody to fluctuations of Escherichia coli serotypes in the human intestine.

Robinet, Harriette G. (Walter Reed Army Institute of Research, Washington, D.C.). Relationship of host antibody to fluctuations of Escherichia coli serotypes in the human intestine. J. Bacteriol. 84:896-901 1962.-A study was undertaken to determine the relationship of host antibody to the changes which take place among Escherichia coli serotypes present in the intestine. A survey of six healthy persons examined for E. coli monthly for 6 months reaffirmed the periodic fluctuations of antigenic types. Serotypes were studied from each individual and their appearance and maintenance or disappearance closely followed. Representative strains were chosen each month and used to prepare a heated sodium hydroxide lipopolysaccharide extract for sensitizing human group O Rh-negative red blood cells for the hemagglutination test. These antigens were tested with the sera drawn from each of the six individuals at the time monthly cultures were made. Results showed that antibody levels for each serotype remained basically constant over the 6-month period. Titer levels tended to be characteristic of the host rather than related to the E. coli bacteria, as shown by tests with serotypes both from the individual's own intestinal tract and from other individuals in the study. High normal antibody levels for autologous E. coli serotypes did not act as a deterrent to the ability of the organisms to establish themselves in the bowel, nor did antibody titer for E. coli strains determine whether they would continue as residents over several months or depart as transient flora.