22 Jan Antibiotic Resistance: Very Critical to Your and My Health
By Consumer Reports |
The scientists here at Consumer Reports read Dr. Richard Raymond’s op-ed “Antibiotics and Animals Raised for Food: Lies, Damn Lies and Statistics” with great interest. We were particularly struck by his assertion that most antibiotics used in animal production are not used to treat humans and are therefore “not critical to your or my health.”
This claim is not scientifically justifiable. While it is true that not all of the antibiotics used in food animal production are used in human medicine, a majority of them belong to the same drug “classes”. Antibiotics in the same class often work to stop the growth of bacteria by using a similar mechanism of action. This becomes important when you consider the scientific principles of cross-selection and co-selection.
Cross-selection means that the gene for resistance to one antibiotic will often also confer resistance to other antibiotics in the same class that work by the same mechanism of action. So giving one antibiotic to an animal that may not be used in human medicine may lead to the development of a bacteria resistant to an antibiotic in the same class that is used in human medicine. For example, cepharin (first generation cephalosporin) is used to treat mastitis in cattle but not used in human medicine, while cephalexin (first generation cephalosporin) is used in human medicine to treat Staphylococcus aureus. Bacteria that become resistant to cepharin, due to overuse in cattle, will also be resistant to cephalexin. Interestingly, Dr. Raymond cites cephalosporin as an antibiotic critical to human health.
Another important principle is co-selection, where multiple resistant genes can be transferred together, because they are physically located next to each other in the bacteria’s genetic material, either the main chromosome or extra-chromosomal DNA. This means that feeding a specific antibiotic to food animals that is not used in human medicine could actually lead to the development of bacteria that are resistant to other antibiotics in different classes that are important in human medicine.
Yet despite these scientific principles, Dr. Raymond believes “that the majority of antibiotics used in animals are of little or no importance to me as a physician or a grandparent.” However, the basic point he misses is that bacterial species can readily swap resistance genes with each other and bacteria in other species, genera and even other families–hardly of “little or no importance.” That resistance is accelerated and amplified by feeding healthy animals low doses of antibiotics everyday.
When it comes to antibiotics like tetracyclines, unlike Dr. Raymond, we agree with the World Health Organization that there is a benefit to guarding their effectiveness. Tetracyclines are used against infectious diseases, including chlamydia, typhus, syphilis, Lyme disease, Legionnaire’s disease, malaria, Rocky Mountain Spotted Fever, cholera and the bubonic plague. Bacterial resistance to tetracycline was identified as early as the 1950s, the FDA tried to ban the use of tetracycline for growth promotion purposes in animal production as far back as 1977, and in 1986, Sweden prohibited the use of antibiotics including tetracycline for growth-promotion purposes. All of Europe followed in 2006.
In this country, however, we have continued to allow tetracycline and other antibiotics to be fed indiscriminately for growth promotion purposes to healthy animals everyday. It remains to be seen if FDA’s 2012 request to drug producers and the livestock industry to voluntarily phase out this use by 2015 will produce any real reduction in antibiotic use in food animals.
Dr. Raymond spends a lot of time focusing on the amounts of antibiotics used in humans versus animals. The fact that the inappropriate use of antibiotics–regardless of whether or not they are used in humans or animals–leads to an acceleration of the development of antibiotic resistance is a scientific fact. We agree with Dr. Raymond that the overuse of antibiotics in human medicine is an important issue. But since the same science that applies to the overuse in humans also applies to animals, we can not understand why he does not see overuse of these important drugs in animals as a problem.
As for the exact numbers of how many antibiotics are used in food animal production—that data isn’t well disclosed to the public and is the subject of much debate. Dr Raymond uses his own numbers of unknown (or not easily obtainable) origin, which introduces a lack of transparency in his analysis. This is why groups like Consumers Union, the policy and advocacy arm of Consumer Reports, are supporting legislation to make this information readily available to everyone.
Finally to answer Dr. Raymond’s question: “So when you read a report funded by Consumers Union, stating that they found Salmonella sp. bacteria resistant to Cipro (a fluoroquinolone), where do you think that resistance came from?” The answer is not–as Dr Raymond implies– from the human use of Cipro.
Salmonella is a bacteria found on chicken or pork and not normally on humans. Salmonella therefore will have only been marginally exposed to all those flouroquinolones used in humans, compared to the flouroquinolone use in animals. So, resistance to cipro found in Salmonella from pigs or chickens, is likely due to use of flouroquinolones in animal agriculture not human medicine. Flouroquinolones were approved for all uses in poultry production in 1996 but were banned in 2005 because resistance rates went up after use.
As one of the few independent consumer organizations that has been regularly testing meat and poultry for pathogens and antibiotic resistance for fifteen years, we believe that the the routine daily administration of antibiotics to animals is dangerous for public health. The problems and consequences of amplifying antibiotic resistance from feeding healthy animals antibiotics everyday is hardly a “Lie” or a “Damn lie”—it is a serious problem—a problem that was not invented by consumer organizations. In fact, groups like WHO, FDA, CDC, the EU, and medical and public health communities have all acknowledged the importance of addressing this issue.
Healthy people don’t eat antibiotics everyday and neither should animals. It’s time for the industry to stop making excuses and stop inappropriately using these medically important drugs.
Truth and Transparency: Unlike Dr. Raymond, Consumer Reports accepts no money from the antibiotic industry or any industry for that matter. Since 1936, Consumer Reports has been singularly focused on the consumer interest and refuses advertising, free samples, and corporate contributions. It is supported by the sale of its products and services and donations from consumers and foundations.
Urvashi Rangan, PhD is an environmental health scientist and toxicologist. She leads Consumer Reports’ Consumer Safety and Sustainability Group and serves as the Executive Director of its Food Safety and Sustainability Center. Dr. Rangan directs all of the organization’s scientific risk assessments related to food and product safety, which she translates into actionable recommendations for both lawmakers and consumers. Most recently, she was the architect of the organization’s studies of arsenic in apple juice and rice and is a national expert on labels.
Michael K. Hansen, PhD is a Senior Scientist with Consumers Union, the policy and advocacy arm of Consumer Reports. He works primarily on food safety issues and has been largely responsible for developing the organization’s positions on the safety, testing and labeling of genetically engineered food and “mad cow” disease. Dr. Hansen served on the USDA Advisory Committee on Agricultural Biotechnology from 1998-2002, and on the California Department of Food and Agriculture Food Biotechnology Advisory Committee, from 2001-2002.
Michael Crupain, MD, MPH is the Director of Consumer Reports’ Food Safety and Sustainability Center where he directs the day-to-day operations of the organization’s food-safety testing. He joined Consumer Reports in 2012 and is a trained physician in Preventive Medicine with expertise in public health-based risk assessment. Dr. Crupain received his Masters in Public Health from the Johns Hopkins School of Public Health, where he is also an adjunct professor.