By allowing big food to self-regulate when it comes to using antibiotics as a growth promoter in animals, the FDA is setting us up for disaster.
Two weeks ago, the Food and Drug Administration (FDA) announced that it would ban certain off-label uses of cephalosporin antibiotics in animal agriculture, asserting that these uses posed an undue risk of selecting for antibiotic-resistant bacteria. Many of us who follow this issue closely recognized FDA's move for what it was: a distraction from the fundamental need for change. The cephalosporin announcement came just two weeks after FDA refused to restrict the use of two other important antibiotics in food animals. It looked to be a thinly veiled effort to deflect criticism of this refusal.
With the occasional exception, like cephalosporins, FDA has failed for decades to take meaningful action on the misuse of antibiotics in food animal production -- misuse that directly contributes to the selection of antibiotic-resistant bacteria and compromises our ability to treat bacterial infections.
THE NEXT EPIDEMIOLOGIC TRANSITION
In 1900, the three leading causes of death in the United States were pneumonia, tuberculosis, and enteritis -- all infectious diseases. A century later, heart disease, cancer, and stroke -- all chronic, non-infectious diseases -- had replaced these at the top of the list. The shift in leading causes of death from infectious to chronic diseases is partly credited with raising average life expectancy by over 30 years. Much of this increase has been attributed to massive reductions in infectious disease mortality, which disproportionately impacts the young. These shifts have come to be known as an "epidemiologic transition," perhaps the most notable achievement in the modern history of public health.
By the 1980s, however, common bacterial pathogens, including certain strains of Staphylococcus aureus, were increasingly found to be resistant to antibiotics. A particularly pernicious strain, methicillin-resistant Staphylococcus aureus, has become a widely recognized cause of serious disease and death. Well-known pathogens like Streptococcus pneumoniae (the causative agent of many pneumonias) and Salmonella are more frequently found to be resistant, and difficult-to-treat infections with these pathogens are becoming more common. Dr. Margaret Chan, director-general of the World Health Organization (WHO), did not mince words when she warned last year, "the world is heading toward a post-antibiotic era, in which many common infections will no longer have a cure and, once again, kill unabated."
The agency responsible for ensuring that animal drugs are used in ways that are safe for humans has been derelict in its duties for decades.
Epidemiologists now contend that we have entered the next transition -- one marked by, among other things, the increasing resistance of bacteria to antibiotics.
When a physician prescribes an antibiotic to treat an infection, he or she will select the specific antibiotic and dose that are most likely to cure the disease. If the wrong antibiotic is chosen or the dose is too low to treat the disease, some bacteria -- those most resistant to the drug used -- will survive and reproduce, allowing the disease to return or prolonging the resolution of the infection.
Most of the food animals fed antibiotics are not diseased. Nor would the amounts they receive be high enough to treat disease if they were. Rather, food animals are continuously fed small quantities of antibiotics throughout their lives to make them grow faster. Today, the overwhelming majority of antibiotics in this country -- nearly 80 percent -- are sold for use in food animals, not humans.
The development of resistance is Darwinian evolution on a microscopic scale. Bacteria compete with each other for limited resources. Some bacteria are more susceptible to antibiotics than others, and become less able to compete when exposed to an antibiotic. Repeated exposure to an antibiotic will continue to make resistant bacteria better competitors, allowing them to increase their numbers relative to the susceptible organisms -- especially when continuously exposed to the low doses of antibiotics typically used in industrial food animal production. This practice facilitates and promotes the development of antibiotic resistance -- and threatens public health.