CAPSULAR POLYSACCHARIDES OF ESCHERICHIA COLI, TYPES K28A AND K34A

Abstract

Examination of Escherichia coli isolates from 100 diagnostic stool, urine, or blood cultures yielded 13 mucoid strains, identified by strict biochemical criteria. Specific capsular and agglutination reactions identified four strains as K28A (O group 8), four as K34A (O group 9), and two as K42A, whereas three strains were serologically distinct from each other and from the recorded A types.Polysaccharides, identified as the respective capsular materials by inhibition of the specific capsular reactions, were isolated from a K28A strain and a K34A strain, grown in a chemically defined medium. The serological individuality of these polysaccharides correlated with a difference in their component monosaccharides, as determined by chromatography and colorimetry. Both contained galactose, glucose, mannose, and from 10 to 14% of a hexuronic acid, but the K28A polysaccharide contained in addition 13% of fucose.Normal human sera collected in the Rochester area contained antibodies to the K28A and K34A polysaccharides very infrequently and in very low titer. On the other hand, two thirds of such sera contained O group 8 antibody and the other third contained O group 9 antibody, both in much higher titer.