E. coli reduction in cattle is possible, but economics are debated

Two approaches could dramatically reduce the presence of E. coli O157:H7 from cattle, though who should foot the bill is cause for debate. One option is Pfizer's three-series vaccine that has shown E. coli elimination in 85% of vaccinated cattle, while the other option, probiotics, when given in the right amounts, can reduce E. coli up to 50%.

http://www.usatoday.com/money/industries/food/story/2011-12-01/safe-meat/51447546/1