Escherichia coli in the rumen and colon of slaughter cattle, with particular reference to E. coli O157

The distribution of Escherichia coli O157 and of total E. coli was surveyed in the digestive tract of cattle under 30 months of age, slaughtered between August 1999 and May 2000 in three abattoirs in southern England. Samples were taken from the dorsal and ventral rumen wall, the rumen contents, the colon wall and colon contents, and from faeces or caudal rectal contents. Gut wall samples were processed by vortex-mixer to release loosely adherent bacteria, and by Stomacher to release firmly attached bacteria. E. coli O157 was detected by immunomagnetic separation followed by growth on selective culture media. The numbers of E. coli were higher in the colon than the rumen, and most were located in the digesta phase, rather than associated with the gut wall. The number of E. coli found in the gut and in faeces decreased during the winter months. E. coli O157 was detected more frequently in the colon than in the rumen, but the majority of detections(7/8) were in samples of rumen wall.