Antigenic Relationships of the Coliform Bacteria

Abstract

Monovalent antiserums were prepared in rabbits for 9 Aerobacter, 9 intermediate and 10 Escherichia cultures from soil, water, milk and normal feces and for 12 paracolon. cultures isolated from feces of patients during a gastro-intestinal epidemic. Over 8000 agglutination and several hundred adsorption tests were made to determine antigenic relationships. Serological reactions were compared with fermentation reactions and motility. Confirmation of the biochem. division of the coliform bacteria into Aerobacter, intermediates, and Escherichia was found in the serological reactions but the relationships between the groups were considered sufficient to recommend that they be classified as 3 spp. of a single genus. The paracolon group appeared to be less closely related antigenically to typical Escherichia than were the 3 groups of typical coliforms to each other. Although the correlation between serological and fermentation reactions was higher in the paracolon group than in the typical coliforms, the biochem. reactions were not regarded as an adequate basis for classification of the paracolon group. Variants of coliform bacteria which differed biochemically from the parent culture ranged from antigenic identity with the parent culture to almost complete dissimilarity to it.