By Ransdell Pierson and Charles Abbott
(Reuters) - U.S. regulators announced new guidelines on Wednesday to phase out the use of antibiotics as a growth enhancer in livestock, in an effort to stem a surge in human resistance to these drugs.
The Food and Drug Administration said the antibiotics could still be used to treat illnesses in animals raised for meat, but should otherwise be pared back over the next three years under a program to keep them out of the human food supply.
The program is voluntary, but the agency expects drugmakers to fully adhere to the guidelines. It said two of the biggest purveyors of these antibiotics, Eli Lilly & Co and Zoetis Inc, had agreed to narrow their use.
Doctors and hospitals have become increasingly worried by new strains of bacteria that cannot be controlled by a wide range of current antibiotics. It is suspected that part of the reason for the emergence of "super bugs" is that people who eat meat containing antibiotics can develop resistance to the drugs as bacteria mutate to thwart them.
"Because antimicrobial drug use in both humans and animals can contribute to the development of antimicrobial resistance, it is important to use these drugs only when medically necessary," the FDA said in a release.
In a "guidance" document, the FDA told global drugmakers and animal health companies to revise the labels of medically important antibiotics by removing references to use in animal production. The FDA said voluntary compliance was the fastest way, but that it could propose regulations if necessary.
When the labels are changed, it would become illegal to use the drugs to promote growth in livestock, Deputy FDA Commissioner Michael Taylor told journalists. The agency said about 25 to 27 animal health companies could be affected by the guidelines.
In the future, the antibiotics could be used only under a veterinarian's direction to prevent or treat disease. Over-the-counter sales would end.
The FDA said it will require animal pharmaceutical companies to notify the agency within three months of their intent to adopt its strategy. The companies would then have three years to complete the transition.
The antibiotics at issue include penicillins, macrolides and tetracyclines. The FDA said it would release a complete list on Thursday.
CRITICS QUESTION ENFORCEMENT
Critics said the guidelines give drugmakers too much discretion in policing their own use of antibiotics.
Democratic lawmaker Louise Slaughter called the FDA move an inadequate response to the overuse of antibiotics, "with no mechanism for enforcement and no metric for success."
Her view was echoed by consumer and environmental advocacy groups.
"Our fear ... is that there will be no reduction in antibiotic use as companies will either ignore the plan altogether or simply switch from using antibiotics for routine growth promotion to using the same antibiotics for routine disease prevention," said Steven Roach, a senior analyst with advocacy group Keep Antibiotics Working.
Morningstar analyst David Krempa said the FDA issued similar voluntary guidelines in April 2012, meant to limit use of important antibiotics in food-producing animals, but they appear to have been largely ignored by farmers.
He said compliance with the FDA's latest set of voluntary guidelines could be equally spotty.
"Compliance will be tough because all the farmers and meat producers know these products increase the size of their animals," Krempa said. "They can continue to use them and just say there's a disease going through their herds."
But even if antibiotics use in livestock does comes down, Krempa said it would be only a "small negative" for Zoetis because it, like other animal health companies, sells such a wide range of products for both livestock and pets.
Jeff Simmons, president of Elanco Animal Health, said the Lilly unit was looking at "alternative innovations, such as enzymes and vaccines" at the same time it complied with FDA on antibiotics.
"We don't see this as having a financially material impact on our company," Simmons told Reuters.
Other companies with animal health businesses include Merck & Co Inc, Novartis AG, Sanofi SA and Bayer AG.
Bayer and Sanofi said the FDA strategy would not affect the products they sell, and both said they support the agency's position.
Agriculture Secretary Tom Vilsack said the new rules would require producers to be more "sensitive" about antibiotic use, but added: "I don't think a producer necessarily needs to go to great lengths to build a new barn" to satisfy the new rules.
A trade group for veterinary drug companies, the Animal Health Institute, said "only a small percentage" of antibiotic use in livestock was for growth promotion.
"There is a risk of additional animal disease from this action," the group said about the FDA rules.
(Additional reporting by P.J. Huffstutter in Chicago and Esha Dey in Bangalore.; Editing by Michele Gershberg, Ros Krasny, Matthew Lewis, Andrew Hay, Bob Burgdorfer and Andre Grenon)