Grain feeding and the dissemination of acid-resistant Escherichia coli from cattle. Science 281:1666–1668

The gastric stomach of humans is a barrier to food-borne pathogens, but Escherichia coli can survive at pH 2.0 if it is grown under mildly acidic conditions. Cattle are a natural reservoir for pathogenic E. coli, and cattle fed mostly grain had lower colonic pH and more acid-resistant E. coli than cattle fed only hay. On the basis of numbers and survival after acid shock, cattle that were fed grain had 106-fold more acid-resistant E. coli than cattle fed hay, but a brief period of hay feeding decreased the acid-resistant count substantially. Foods can be cooked or irradiated to kill bacteria, but there are;30 million food-borne illnesses each year in the United States (1). A variety of hypotheses have been for-mulated to explain the increased incidence of food-borne illness (2, 3). Modern societies tend to “dine out ” more often and consume more processed food. Modern detectio