Antagonisms Among Enteric Pathogens and Coliform Bacteria

That some strains of the coliform group of bacteria exert inhibitory effects on other micro-organisms, when grown in association in liquid media, was reported first by Nissle in 1916. Because of the multiplicity of factors involved when organisms are growing in heterogeneous mixtures in liquid media, the nature of the in-hibiting agent is difficult to ascertain. Gratia of Belgium (1925) observed a strain of Escherichia which, when grown on a solid medium, produced a diffusible substance that was antibiotic against another coliform strain and ShigeUa dysenteriae. It was demonstrated later by Gratia and Fredericq (1946) that anti-biotic coliform strains are not at all infrequent