Antibiotic Resistance: How Industrial Agriculture Lies With Statistics

This story was written by Robert Lawrence, MD and was originally published on the Center for a Livable Future blog.

The U.S. Farmers & Ranchers Alliance wants to talk to you. The website of the Alliance, a coalition of corporations and trade associations that make up a who’s who of industrial agriculture, says the organization wants “to engage in dialogue with consumers who have questions about how today’s food is grown and raised.” It appears, however, that the organization is more concerned with countering increasing awareness of the public health and environmental harms associated with industrialized agriculture.

Take antibiotic resistance. Just last week, the Centers for Disease Control and Prevention (CDC) released a landmark report estimating that antibiotic-resistant bacteria cause at least 2 million infections and kill at least 23,000 people in the U.S. every year. The “single most important” driver of this epidemic, according to the report, is the inappropriate use of antibiotics, including in agriculture. As the CDC put it, “much of antibiotic use in animals is unnecessary and inappropriate and makes everyone less safe.”

Indeed, Food and Drug Administration (FDA) data have shown that 80 percent of antibiotics sold in the U.S. are sold for use in food animals, not humans. The same data suggest that the vast majority of antibiotics used in food animals are administered to compensate for crowded and unsanitary conditions and to speed animal growth. This use promotes the development of antibiotic-resistant bacteria that can spread to humans on food and through the environment. In addition to the CDC, the World Health Organization (WHO), the American Medical Association, the American Public Health Association, and many others have called for restrictions on antibiotic use in animal agriculture.

Faced with this damning evidence, the drug and food animal industries have tried repeatedly to rebut the 80-percent figure. Initially, they argued that data on antibiotic sales could not be used to determine antibiotic use. There is some uncertainty in these data, but not enough to escape the fact that the vast majority of antibiotics in this country are used in food animals, not to treat sick people.

Now the industry has taken a new tack. The Alliance, which despite its bucolic name includes some of the largest drug and pesticide companies in the world, including Monsanto and Zoetis, the animal drug company controlled by Pfizer, has posted an infographic that uses the same antibiotic sales data to compare antibiotic use in food animals to antibiotic use in humans (apparently, the industry no longer objects to using sales data to describe use). Based on this comparison, the infographic implies that antibiotic use in food animal production plays no role in antibiotic resistance of human pathogens. In doing so, it also ignores basic scientific and medical knowledge of bacteriology and infectious disease.

According to the Alliance, if an antibiotic is not used extensively in human medicine, then its widespread use in food animal production should not be a concern. For example, tetracyclines represent 41 percent of antibiotic sales for use in animals but only 4 percent of sales for use in humans. The infographic also notes that 30 percent of antibiotics sold for animal use are ionophores, a type of antibiotic used widely in food animal production that is not used in humans.

The Alliance’s main message is that high use equals high importance: If tetracyclines are not used widely in humans now, they must not be important to human medicine. In reality, the importance of specific antibiotics waxes and wanes as new antibiotics are developed and bacteria develop resistance to older drugs. Tetracyclines have been prescribed for decades and, in many cases, have been surpassed by other, more effective antibiotics. As the CDC noted, however, the increasing resistance of bacteria to these other antibiotics will make tetracyclines an important treatment option.

Even so, we should not assume the importance of tetracyclines is a future proposition. Antibiotics that are not widely used may still be critical to patients with specific diseases. Dr. Richard Raymond, a former USDA under secretary for food safety and current consultant to a subsidiary of Eli Lilly, noted earlier this year that tetracyclines may be used to treat conditions like chlamydia and Lyme disease. Importantly, the WHO still considers tetracyclines “highly important” to human medicine, too.

Furthermore, one type of antibiotic can promote resistance to other types of antibiotics. 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. This means that drugs used less commonly (tetracyclines, for example) or never used in humans (ionophores, for example) may still promote resistance to drugs with wider use. This is particularly concerning since research has shown that bacteria readily swap genes, meaning that genes that help bacteria resist antibiotics can be spread widely throughout bacterial communities, including to bacteria that can infect humans.

All of this means that, despite its best efforts, the U.S. Farmers & Ranchers [& Drugs & Pesticides] Alliance cannot dance around an incontrovertible fact: the vast majority (about 80 percent) of antibiotics sold in this country are sold for use in food animal production and much of this use threatens public health. Even if we exclude ionophores and only compare antibiotics approved for use in humans, that figure remains well over 70 percent, or more than twice the quantity used in humans.

The science is clear, and the only real debate over antibiotic misuse in food animal production is a policy debate over what should be done to end it. But the Alliance has pressed on. With nothing to stand on, they are reminiscent of the Black Knight in Monty Python and the Holy Grail, who, having lost all four limbs to King Arthur, yells after the once and future king: “Come back here! … I’ll bite your legs off!”