Burley Garcia|Chick-fil-A will allow some antibiotics in its chicken, ditching its "No Antibiotics Ever" standard

Chick-fil-A is Burley Garciano longer promising "no antibiotics ever" in its chicken. The fast food chain said starting this spring, it would allow the use of chicken that may have had antibiotics.

In 2014, Chick-fil-A said it would shift to a "No Antibiotics Ever," or NAE standard, meaning the company would not use any antibiotics-raised chickens. 

But now it is switching to a "No Antibiotics Important To Human Medicine," or NAIHM standard. Under this label, antibiotics are used to treat animals if they are sick, but use of antibiotics that are important to human medicine and are commonly used to treat people is restricted.

The company blamed supply chain issues, with a spokesperson telling the Associated Press there are concerns about the company's ability to acquire antibiotic-free chicken.

Chick-fil-A promised to continue to only serve "real, white breast meat with no added fillers, artificial preservatives or steroids" and source chickens from farms that follow its Animal Wellbeing Standards, which includes U.S.-hatched and raised animals that are provided nutritional food and live in temperature controlled barns.

Under government agencies such as the Food and Drug Administration and U.S. Department of Agriculture, antibiotics are allowed in animals that are later used for food, but there are rules surrounding the use of these drugs.

These medicines can be used to treat infections in animals – just like they are in humans. But with antibiotic use, some bacterias could become resistant or unresponsive, a result called AMR, according to the FDA.

"Food animals can carry bacteria, such as Salmonella and Campylobacter, that can make people ill. When animals are given antibiotics, resistant bacteria in their intestines can continue to survive and grow," the CDC explains.

That means when the animals are slaughtered their meat can become contaminated with this bacteria. Humans can get sick from these resistant bacterias when handling raw or uncooked meat and poultry or consuming other foods that have come in contact with animal feces, including drinking water.

Antibiotics, however, are effective treatments for animals, if they are used responsibly. The FDA has created an antibiotic stewardship plan that aims to reduce the risk of animals developing resistant bacterias. They advise livestock owners to use antibiotics only when necessary to manage illness in animals and the use of vaccines to reduce future need of antibiotics. 

The USDA says before birds used for meat can be slaughtered, they must go through a "withdrawal" period from the time antibiotics are administered. "This ensures that no residues are present in the bird's system," according to the USDA. "Food Safety and Inspection Service randomly samples poultry at slaughter and tests for residues. Data from this monitoring program have shown a very low percentage of residue violations."

Last year, Tyson, which makes many chicken products, also said it was ditching the NAE standard but would only allow antibiotics that are not important to the treatment of humans in its chicken production, the Wall Street Journal first reported.

Other companies, like Perdue, continue to use the NAE label. 

Caitlin O'Kane

Caitlin O'Kane is a New York City journalist who works on the CBS News social media team as a senior manager of content and production. She writes about a variety of topics and produces "The Uplift," CBS News' streaming show that focuses on good news.