Doctors routinely instruct patients that antibiotics should be used only to treat bacterial infections, using the proper dosage, and for the full course of treatment. Otherwise, failure to follow these rules increases the likelihood that some of the bacteria will survive and mutate to become drug resistant.
Yet even if patients follow these medical instructions, they still may suffer from antibiotic-resistant infections. That is because many large producers of meat and poultry feed antibiotics to their healthy food animals to offset the effects of overcrowding and poor sanitation in CAFOs. Up to 70 percent of all antibiotics sold in the United States go to healthy food animals.