Animals in factory farms are given doses of antibiotics -- both to keep them alive in stressful, unsanitary conditions, and to make them grow faster. The practice leads to new strains of antibiotic-resistant bacteria, such as the now-widespread form of staph (MRSA) known as ST398.
Federal regulators have in the past refused to release estimates of just how much antibiotics the livestock industry uses. But recently the FDA released its first-ever report on the topic. And the amount? Twenty-nine million pounds of antibiotics in 2009 alone.
According to Grist:
"[T]he Animal Health Institute, a veterinary-drug trade group, estimated total use in livestock at 17.8 million pounds. The industry has been clinging to that number ever since ... [T]he industry figure is woefully off -- about 40 percent lower than the real one."