Is overlap of antibiotics used in both animal and human health a threat to humans? Maybe, but I will try and explain why I do not think it is near the threat that some opposed to modern agriculture claim it is.
Some antibiotics are approved by the Food and Drug Administration (FDA) for the almost exclusive use in human medicine to treat, prevent and control infectious diseases. These are antibiotics felt to be critical to human health like cephalosporins, flouroquinolones, methicillin and vancomycin.
The FDA also has approved antibiotics for the exclusive use in animal health for the treatment, prevention and control of infectious disease. Control is needed to prevent wide-spread illnesses in flocks and herds when some members are already ill. Prevention is also important at certain times in an animal’s life. These are also animal well-being issues. By controlling the spread of disease, the herd is healthier and the doses used are very small compared to treating full blown illnesses.
The use of antibiotics in animals as growth promoters is another FDA-approved use and the FDA is taking steps to eliminate any crossover by stating that antibiotics important to human medicine cannot be used for this purpose.
Ionophores make up about 30 percent of all antibiotics sold for use in animal health and have never been used in human health. Another 10 percent of antibiotics used in animal health fall into a category termed “Not Individually Reported” and also are not used in human medicine. Tetracyclines, which comprise 42 percent of all antibiotics sold for animal use, are another large class of antibiotic used in animal husbandry. Oxy- and chlortetracyclines were once important in human medicine when we had little else available, but health care providers have better options today. These tetracyclines are very rarely, if ever, used in the United States.
The math is simple. Of all antibiotics sold for use in animal health, 82 percent are either not approved for human use or almost never prescribed by American health care providers. There is another class of antibiotics called macrolides, which are popular antibiotics in both animal and human health. Readers may be familiar with the most commonly prescribed human macrolide known as the Z-Pak. For many common infections ranging from acne to community-acquired pneumonia to Lyme disease and Rocky Mountain spotted fever, macrolides are usually the antibiotics of choice. We need to keep them effective. I will talk about macrolides in more detail next week.