For more than 50 years, veterinarians and producers have administered antibiotics to food animals, primarily poultry, swine, and cattle, mostly to fight or prevent diseases. The practice has not been without controversy, with some going so far as to call for eliminating antibiotic use in livestock altogether, characterizing it as too risky for public health. On the other side, many believe at least as strongly that not treating diseased animals carries significant risk for people’s health, in addition to a real set-back in animal welfare.
Experts do agree that as the global population and mobility of humans and animals grow so does the threat of zoonotic pathogens (those that infect both animal species and humans) like prions, Salmonella and the Avian Influenza virus. And studies show that sick animals carry more zoonotic pathogens, like Salmonella, with them to the slaughter house. Most contend that these facts and the need to protect animal welfare make a strong case for the availability of approved vaccines and antibiotics to prevent and treat livestock diseases.
Antibiotic Residues in Meat and Milk?
While treating sick animals with antibiotics may sound reasonable to the public and consumers, they still have questions about their use in livestock as it relates to their health. Questions, such as, “Are there residues of antibiotics in milk and milk products, and can they harm me?” often arise. The short answer is: There are no antibiotic residues of any consequence to human health when antibiotics are used according to FDA regulations. When administering antibiotics, producers must adhere to FDA’s “withdrawal time” that is specific to the antibiotic used to ensure that the antibiotic has cleared the animal’s system to a safe level before any meat or milk enters the food supply. Therefore, producers must withhold animals and their products from the market until the withdrawal time has elapsed.
As an added level of consumer protection, FDA, USDA and processors regularly sample milk and meat to ensure that producers are adhering to all requirements. For example, every tanker of milk is tested and any found to be in violation is discarded and never reaches the consumer. Regulatory actions and stiff fines can be levied against producers found to be noncompliant.
What about Antibiotic Resistance?
Many consumers also wonder if antimicrobial resistance, as it relates to meat and milk, is something about which they should be concerned. The scientific complexity of this issue makes it difficult for easy answers. The bottom line is that scientific evidence must drive the decisions on the use of antimicrobials in the food system as well as in people to help ensure not only safe food but also an effective arsenal of antibiotics to fight disease-causing pathogens.
FDA plays a major role in addressing antimicrobial resistance by carrying out a stringent drug approval process. Companies are required to provide data and assess the risks that the drug would foster antimicrobial resistance in animals or transfer to humans via food. Based on the findings, FDA has authority to deny the application or to restrict the antibiotic’s use in various ways, such as restricting use in different species and diseases to minimize risks. In addition, several U.S. agencies work together through the National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS) to monitor resistance trends and changes in antibiotic susceptibilities of foodborne pathogens.
IFT Report
To analyze the food sector’s potential contribution to antimicrobial resistance, the Institute of Food Technologists (IFT) created an expert panel, chaired by Michael P. Doyle, PhD, from the University of Georgia, to take an exhaustive look at the issue. Released in 2006, this comprehensive report, “Antimicrobial Resistance: Implications for the Food System,” summarizes recent scientific findings and presents science-based recommendations to help policymakers and food industry stakeholders. (http://members.ift.org/IFT/Research/IFTExpertReports/antimicrobial_report.htm)
Bacteria have an innate ability to adapt to environmental stressors—quite simply, it’s their survival mechanism. Expose bacterial populations to a stressor like a lethal antimicrobial, and if a few are present that have a genetic make-up that is impervious to that particular antimicrobial, they may survive and grow. Studies also show that resistant organisms may spread even without the presence or use of an antimicrobial.
Does this mean there’s a risk of illness from eating poultry, pork, beef or dairy products tainted with bacteria that have become resistant? Does this signal a change in food safety procedures, such as discontinuing antibiotic use in food animals?
Not so fast to judgment, cautions the IFT report. “Availability of antibiotics has radically improved human and animal well-being,” says Doyle. “The key with present scientific knowledge,” Doyle emphasizes, ‘is prudently using antibiotics and continuing with science-based efforts to reduce this risk even lower than it is today. Experience shows that eliminating antibiotic drugs from animal production may have little positive effect on resistant bacteria that threaten human health.” In Europe, for example, the elimination of antibiotic uses in certain cases did not seem to reduce the prevalence of some antibiotic resistant strains affecting human medicine. Quite the opposite--some pathogens even have increased resistance, concluded the IFT report.
Although food can be contaminated with bacteria, some of which may be resistant, we do not know the extent to which antibiotic use in food animals actually leads to clinically important antibiotic-resistant infections in people. Doyle points out, “Extensive research, however, has shown that prior human exposure to antibiotics is a major risk factor for acquiring an infection with resistant bacteria.” Physicians and consumers, then, have a responsibility to use antibiotics prudently and only when appropriate, in the same manner that veterinarians and producers prudently use antibiotics.
The IFT panel stated that decisions on current or future antimicrobial use in livestock must be based on risk assessments. Moreover, the report states that “applying interventions to control foodborne pathogens in general, rather than focusing specifically on antibiotic-resistant strains, would have the greatest impact in reducing overall foodborne illness.”
“Like with so many complex issues, there isn’t a silver bullet that solves the antimicrobial resistance issue,” the panel said. The strategy should continue to grow as a multi-layered one of research, prudent use of antimicrobials, reduction of foodborne pathogens overall, and proper food handling.
For more information see the new IFIC Foundation's Questions and Answers: Animal Antibiotics, Antimicrobial Resistance and Impact on Food Safety.
