Frequencies of lipopolysaccharide core types among clinical isolates of Escherichia coli defined with monoclonal antibodies.

Mouse monoclonal antibodies (MAbs) specific for the lipopolysaccharide (LPS) core types R1, R2, and R3 of Escherichia coli and a cross-reactive MAb that binds to the LPS core of almost all E. coli were used in ELISA to determine the frequency of cores resembling R1, R2, and R3 in strains of E. coli isolated from clinical samples (blood and urine specimens) and from the feces of asymptomatic individuals. Of the 180 wild-type isolates, 123 were assigned to R1 core type, 14 to R2, and 18 to R3. Twenty-five wild-type E. coli isolates could not be assigned to a particular core type and may have either an R4 or K12 core or a previously unrecognized core type. R1 core type was associated with O types 1, 4, 6, 8, and 18 and with K1 or K5 capsules. R3 was associated with O15. O75 isolates could be of either R1 or R2 core type.