The second-largest fast food chicken chain in the United States is moving towards eliminating antibiotics in its poultry. Chick-fil-A has committed to serving only antibiotic-free chicken in all of its locations by 2019. The company doesn't provide statistics for how much chicken it uses per year, but in 2010 it sold over 282 million chicken sandwiches. It has nearly 1,800 locations around the US.

To make the changeover, the company says it will be working with its suppliers — which include Tyson, Perdue, and Pilgrim's Pride — and the United States Department of Agriculture (USDA) to make sure that no antibiotics are used anywhere in the process, from the hatchery to the processing plant. The new chicken will be rolled in starting in 2015 as production levels increase, according to a statement.

Overuse of antibiotics has long been a concern to experts, scientists, and activists alike, and animal husbandry accounts for over 80 percent of all antibiotic use in the US, according to a recent report from the Johns Hopkins Center for a Livable Future. Heavy antibiotic use promotes the growth of resistant strains of bacteria that threatens to put humans in danger of illnesses now thought to be benign. The US Centers for Disease Control (CDC) recently warned that "Without urgent action now, more patients will be thrust back to a time before we had effective drugs."

Antibiotics are sometimes used to help keep animals healthy, but misuse primarily comes from the low dosages administered to animals to fatten them up. This application of antibiotics also makes so-called "factory farming" more feasible.

Chick-fil-A says on its website that "avian antibiotics are only used in very limited circumstances to ensure bird health," and if that's the case, it's unclear why a changeover will take five years to complete. An executive tells the Associated Press that the changeover, once completed, would mean higher prices for fast food chicken fans, but the plan is for it to have a "minimal" impact. The company wouldn't be the first large chain to offer antibiotic-free meat: Chipotle has made a point of its "naturally-raised" meats for a long time.