Effect of Colicine Production on Escherichia coli in the Normal Human Intestine

Abstract

Summary

To re-evaluate the effect of colicine production on Escherichia coli in the normal human intestine, the E. coli flora of 5 healthy individuals was studied for 6 months. Each isolate was identified as to serotype or hyperimmune antisera were prepared to check similar but less readily identifiable strains. The E. coli isolates were assayed for colicine production using organisms isolated from one month against organisms isolated the preceding month and against the colicine indicator strain, E. coli phi, by the chloroform and simultaneous pour plate methods. Results indicate that there was an association between multiplicity of serotypes and little or no colicine production as compared with few serotypes and high colicine production. Also, resident serotypes produced colicine more consistently than did transient serotypes. It is suggested that the ability of some E. coli strains to maintain themselves in the human intestine as dominant residents is associated with the production of colicines.