The Food and Drug Administration unveiled a plan today that will begin to curb the use of antibiotics in food-producing animals. The guidance aims to phase out the use of some antibiotics that are considered medically important for humans. Because some of these antibiotics are widely used for promoting growth in animals — rather than directly treating infections — the FDA has shown concern that they could contribute to the creation of bacteria resistant to those antibiotics, making them drugs less effective in humans. The new FDA guidance asks pharmaceutical companies to relabel some of their antibiotics, allowing them to be used for fighting infections but not for growth purposes.