A Longitudinal Study of Escherichia coli in Cows and Calves with Special Reference to the Distribution of O-antigen Types and Antibiotic Resistance

The faecal excretion of E. coli from 6 adult cows was followed over a period of 105 days. E. coli were excreted in only 23·4% of specimens and the patterns of excretion varied between animals. All isolates of E. coli were antibiotic sensitive and fell into 6 O-antigen types; very few were non-typeable. The O-types excreted by each animal, compared with those from other cows in the same house, were traced with time. A similar but less intense study was undertaken in 8 calves. In contrast E. coli was excreted from all samples and included both antibiotic sensitive and resistant strains; 37 O-types were represented. The persistence of specific O-types within each calf and their spread to other calves in the same house were studied. A comparison of the O-types in the bovine species with those isolated from man has been made.