This piece is co-authored by Dr. Robert Lawrence and Tyler J. Smith of the Johns Hopkins Center for a Livable Future.
We read Dr. Richard Raymond’s recent article on antibiotic use in food animals with great interest. Dr. Raymond is a physician who has served this country as Under Secretary for Food Safety at the U.S. Department of Agriculture, so we take his writing on this topic quite seriously.
The number of inaccuracies in his commentary surprised us, however. In particular, his discussion of antibiotic sales data collected by the Food and Drug Administration (FDA) under the Animal Drug User Fee Act (ADUFA) was incorrect and neglected the basic science of antibiotic resistance. Startlingly, he also seems to have access to unpublished ADUFA data that the FDA withholds from the public.
Just the Facts, Please
Dr. Raymond discusses antibiotic sales data at length but does not adequately explain what these data mean. For example, he labels the statistic that 80 percent of antibiotics in the United States are sold for use in food animals “a distraction from the real truth.”
He notes that “a 2,500 pound prize bull with pneumonia is going to be treated with a much larger dose of an antibiotic than an 8 pound newborn with the same bacterial infection,” so we should expect food-animal use to be much greater than human use.
This misses the point. We do not compare the quantity of antibiotics sold for use in food animals to the quantity used in humans to argue that human use should or should not exceed animal use. We compare these quantities to illustrate that food-animal use is extensive and cannot be ignored by efforts to prevent antibiotic resistance, which have focused primarily on human use.
Furthermore, Dr. Raymond misinterprets antibiotics sales data collected under ADUFA and neglects the basic science of resistance. He writes, “87 percent of antibiotics used in animals are either never, or very rarely, used in human medicine,” and we should not focus on the misuse of these drugs in food animal production.
First, the 87 percent figure is inaccurate. According to Dr. Raymond, it comprises tetracyclines, which are important to human medicine, as well as ionophores and other drugs “not approved for use in human medicine.” In 2010, 70 percent of antibiotics sold for use in food animals were ionophores or tetracyclines. What drugs not approved for human use make up the remaining 17 percent?
Under ADUFA, the FDA reports the sales of eight antibiotic classes, including ionophores and tetracyclines. The agency then lumps together the sales of additional classes and reports these as one “not independently reported” (NIR) category, as fewer than three companies manufacture drugs in each of these classes and revealing the sales of each class could reveal the sales of individual companies.
All eight classes reported separately (except ionophores) include drugs approved for human use, so the additional 17 percent could not have come from any of these classes. The NIR category includes drugs of all levels of importance to human medicine, from none to critical. Even if he added all NIR drugs to ionophores and tetracyclines, however, Dr. Raymond would only reach 83 percent of the total.
Beyond this questionable math, the larger point is inaccurate: the World Health Organization considers tetracyclines “highly important” to human medicine. Dr. Raymond even lists diseases of public health importance that tetracyclines are still used to treat, such as chlamydia, Lyme disease, and Rocky Mountain Spotted Fever. Other drugs may have superseded tetracyclines for many indications, but that does not mean their misuse in food animal production should not concern us.
Finally, a drug used in food animals but not in humans can still select for resistance to drugs that are essential to public health, as Dr. Raymond surely knows. This is because the same gene can encode resistance to multiple drugs or because two genes, each encoding resistance to a different drug, may be linked. The “one bug, one drug” he implies is too simplistic.
Interestingly, Dr. Raymond somehow knows the quantity of ciprofloxacin or that of all drugs in its class, fluoroquinolones, sold each year. These antibiotics are critical to human medicine but fluoroquinolones are NIR drugs under ADUFA and the FDA does not report sales of specific drugs like ciprofloxacin. Dr. Raymond reports that 11,000 kilograms of either ciprofloxacin or all fluoroquinolones are sold for use in food animals each year, but data on these sales are not available to the public.
Where did Dr. Raymond obtain this datum? Either the FDA disclosed the figure, which seems unlikely, or he received this information from the drug industry—perhaps from the Animal Health Institute (AHI). Dr. Raymond cites the AHI for its specious “best guess” at the percentage of antibiotics used in food animal production for growth promotion. He neglects to mention that the AHI is the lobby for animal-drug companies. This obvious conflict of interest compromises the AHI as a credible source.
Furthermore, receiving unpublished data on antibiotic sales from the drug industry for use in an op-ed would violate the spirit, although not the letter, of Dr. Raymond’s disclaimer, which suggests that he wrote the piece without industry involvement.
The Path Forward
Dr. Raymond is right on one point: the public lacks detailed data on the use of antibiotics in food animal production. The Johns Hopkins Center for a Livable Future (CLF), which Dr. Lawrence directs and at which Mr. Smith works, and the Government Accountability Project (GAP) requested additional ADUFA data from the FDA but the agency refused. GAP sued the agency for these data last month.
CLF and others asked the FDA to enhance ADUFA data collection overall but the agency declined. Fortunately, Rep. Henry Waxman has announced the Delivering Antibiotic Transparency in Animals (DATA) Act. This bill would provide the public with essential information, and we strongly support it.
The FDA has not taken antibiotic misuse in food animals seriously enough—we must push the agency to do more. More and better data and greater transparency would be a start. The guidance documents praised by Dr. Raymond will likely amount to little; a lawsuit by the Natural Resources Defense Council and others to force stronger action is more promising. This year could be a year of action on antibiotic resistance, but as public health advocates we have our work cut out for us.