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Reduction of antibiotic use: For Johnny and his hamburger
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A frequent theme of this column over the years has been increasing resistance to antibiotics by microbial pathogens and recommendations by national organizations and leading experts on methods to limit this resistance. Recently published studies have suggested that pediatric clinicians’ prescribing habits of antibiotics have to some extent become more “judicious.” It is well accepted that increasing use of antibiotics leads to increased microbial resistance patterns. Thus, clinicians are advised to use antibiotics only when necessary. What has not been discussed in this column, however, is use of antibiotics by the livestock (meat and poultry) industry. By recent estimates, the amount of antibiotics used in the livestock industry far outweighs antibiotics prescribed for humans.
Antibiotic use by food-producing animals
The Center for Science in the Public Interest, a nonprofit health advocacy and education organization, in a 2012 document, titled “Antibiotic Resistance in Foodborne Pathogens,” states that food-producing animals consume approximately 80% of all antibiotics sold in the United States. This figure is derived from information reported by the FDA from 2009 to 2010, as antibiotic drug manufacturers were required from 2008 to report sales of antibiotics to food-producing animals. Of the antibiotics used in the livestock industry, 65% are identical or similar to antibiotics given to humans. Livestock industry trade groups have disputed these numbers, however.
One may wonder: Why are so many antibiotics given to food-producing animals (eg, chickens, turkeys, cattle)? Antibiotics are given to food-producing animals for several uses: 1) control of infectious diseases in a heard or flock of animals, when morbidity and/or mortality is greater than baseline; 2) prophylaxis of disease in animals at higher risk for infection and disease; 3) treatment of specific infectious clinical diseases; and 4) “growth promotion” — antibiotics given to growing animals over time, to improve weight gain and feed efficiency. This growth-promoting effect of supplementing animal feed with antibiotics has been known for more than 60 years. Animals are often raised in large, concentrated (and potentially unsanitary) livestock areas, and animal growth and production has been shown to benefit from antibiotic-supplemented feed (“antimicrobial growth promoters”).
The FDA has long been concerned about the use of antibiotics in the livestock industry and its potential implications upon foodborne pathogen antimicrobial resistance. This year, the FDA’s Center for Veterinary Medicine (CVM) published official recommendations on the use of antibiotics in food-producing animals (“The Judicious Use of Medically Important Antimicrobial Drugs in Food-Producing Animals”). This document outlines two major principles to control antibiotic use in food-producing animals: 1) The use of medically important antimicrobial drugs in food-producing animals should be limited to those uses that are considered necessary for assuring animal health; and 2) the use of medically important antimicrobial drugs in food-producing animals should be limited to those uses that include veterinary oversight or consultation. More specifically, the FDA states that using antibiotics for growth production “represents an injudicious use of these important drugs.” These guidelines and recommendations to the food-producing animal industry are voluntary, and thus, their effect may be limited.
In the guidelines on judicious antibiotic use issued by the FDA, a literature review is summarized. Reports by various governmental and professional organizations, from as early as 1969, concluded that the administration of antimicrobials to food-producing animals posed a potential risk to human health. Earlier reports, despite finding little evidence of this risk, expressed concern and the need for further study. More recent reports concluded that widespread use of antibiotics leads to selection of antibiotic-resistant bacteria.
In 1997, a report published by WHO recommended the ban of antibiotics for growth promotion in food-producing animals if the antibiotics given to animals were also used in humans. In another report issued in 2000, WHO similarly recommended that antibiotics not be used for growth promotion in the livestock industry. In a 2003 joint report issued by several world human and animal health organizations (including WHO), more specific conclusions and recommendations included “clear evidence of adverse human health consequences due to resistant organisms resulting from non-human usage of antimicrobials.”
Also in 2003, the Institute of Medicine recommended in a report the banning of antimicrobials for animal growth promotion if the antibiotics are also used in humans. The US Government Accountability Office (GAO) additionally studied antibiotic use in food-producing animals and concluded that antibiotic-resistant bacteria have been transferred from animals to humans. Specifically, the GAO report cited evidence that animal-to-human transfer of specific strains of antibiotic-resistant Campylobacter and Salmonella have increased. The Department of Health and Human Services reviewed the GAO report and concluded: “We believe that there is a preponderance of evidence that the use of antimicrobials in food-producing animals has adverse human consequences. There is little evidence to the contrary.”
Upon release of the report and recommendations described by the FDA, the AAP also issued a statement in support of these recommendations.
Impact of survey
One could argue that because the FDA recommendations to limit antibiotic use by the livestock industry are voluntary, they will have little effect. Consumers Union and the publication Consumer Reports recently issued a report describing consumer sentiment on antibiotic use in foods and specific recommendations that consumers can take. In a poll conducted by Consumer Reports (n=1,000), 86% of consumers believed that meat raised without antibiotics should be available in stores.
For its report, Consumer Reports visited 136 supermarkets in 23 states and evaluated more than 1,000 different meat and poultry items. A variety of results were found, including all meat and poultry items at one supermarket chain were labeled as raised without antibiotics. Other chains sold items not specifically labeled as raised with or without antibiotic use. Some supermarkets did not sell any meat or poultry items indicated as raised without antibiotics.
Additionally evaluated in this report is the variety of potentially misleading and confusing labels used by sellers, describing antibiotic use in animals raised for meat and poultry products. Many labels on meat and poultry products were found, including “organic,” “no antibiotics administered,” “never given antibiotics,” “humanely raised on family farms without antibiotics,” “never ever administered antibiotics,” “natural,” “antibiotic free,” or “no antibiotic residues,” among many others. According to investigation and research of these labels by Consumer Reports, the most meaningful labels to look for on specific products are “organic,” and “no antibiotics administered,” especially when these terms include the “USDA Process Verified” shield. These terms are useful because manufacturers of food products that place them on their products must adhere to specific guidelines issued by the US Department of Agriculture (USDA). These guidelines state that antibiotics or ionophores (antibiotic-like compounds fed to cattle to enhance growth) cannot be used at any time during animal raising and production. Thus, many other labels that may be found on food products, such as “natural,” or “antibiotic free,” are likely to be meaningless. Consumers Union recommends that all supermarkets carry only meat and poultry products from animals raised without antibiotics, and that consumers request these products at their local stores.
Livestock industry assessments
Reports and published studies with ties to the livestock industry reach differing conclusions than those recently issued by the FDA and other governmental and professional organizations.
In a 2004 critical review of published data, authors reviewed data on growth-promoting antibiotic use in food-producing animals and concluded that the actual risk to humans of using antibiotics for this purpose is extremely small. These authors, acting as independent scientists, were invited to assess these data and were convened as an advisory board by the Animal Health Institute, a trade association of animal health care product manufacturers.
In another publication (including an author representing the poultry industry), the authors described the adverse effects of a ban on the use of several antibiotics for animal growth-promotion by the European Union in 1997. The authors concluded that the banning of growth-promoting antibiotic use has resulted in a deterioration in animal health and a consequential increase in the therapeutic use of various antibiotics in food-producing animals, including tetracycline, aminoglycosides, trimethoprim-sulfamethoxazole, macrolides and lincosamides.