The American Society for Microbiology (ASM) would like to comment on HR 3804, the "Preservation of Antibiotics for Human Treatment Act of 2002," which would prohibit the nontherapeutic use in feed animals of eight specific antimicrobial drugs that could select for resistance to drugs used in human medicine. The legislation introduced by you, Louise Slaughter and Henry Waxman, responds to widespread concern over the role that agricultural drug use may play in the antimicrobial resistance now spreading among human pathogenic microorganisms. The ASM, which represents more than 42,000 members in microbiology related professions, strongly believes that microbial resistance to therapeutic drugs threatens public health in the United States and worldwide, and that only aggressive and prompt action will decrease damage done by microbial resistance to human medicine.
The ASM commends the legislators for confronting a critical health issue, and last year endorsed HR 1771, their "Antimicrobial Resistance Prevention Act" authorizing new funding to address this emerging threat.Such legislation recognizes that antimicrobial resistance is a priority concern for numerous health associated organizations, including the American Medical Association, the Food and Drug Administration (FDA), the Centers for Disease Control and Prevention (CDC), the Department of Agriculture (USDA), the National Institutes of Health (NIH) and the World Health Organization (WHO).The ASM has written to the House and Senate Labor, Health and Human Service and Education Appropriations Subcommittees recommending that $25 million in new funding be appropriated in FY 2003 for CDC to implement the interagency Public Health Action Plan to Combat Antimicrobial Resistance.
Each year, nearly 2 million patients in the United States develop infections while hospitalized, and about 90,000 die as a result.More than 70 percent of bacteria causing such hospital-acquired infections are resistant to at least one of the drugs most commonly used to treat them.According to the Institute of Medicine, the annual financial cost of treating resistant infections in this country may be as high as $30 billion.The rising morbidity and mortality associated with antimicrobial resistance, along with the serious economic losses involved, mandate that we mobilize considerable resources to prevent further increases in resistance and control the current problem.One factor that contributes to resistance is the use of large quantities of antibiotics in producing the nation's food supply.HR 3804 seeks to limit this type of antimicrobial use.
For more than forty years, low concentrations of antimicrobial compounds have been added as growth promoters to animal feed. Exactly why subtherapeutic concentrations of antimicrobials enhance the growth of some animals is not completely understood, although the antimicrobials seem to work by increasing absorption of nutrients and reducing mucosal cell turnover. Antibiotics are also added to feed and water to prevent or treat disease in flocks or herds. The use of antibiotics to medicate flocks or herds to prevent disease, often in the absence of any cases of disease, is widespread.The use of antibiotics for prophylaxis or as growth promoters involves long-term, low-dose exposure to antibiotics - a type of use that is more likely to select for resistant bacteria than the short-term regimens usually used to treat sick animals.
It is well established that antibiotic resistant bacteria from the intestines of animals enter the food supply and can then be introduced into the human intestine when food is consumed.There is also some evidence that resistance genes carried by these bacteria can be transferred to bacteria that are normally human-specific. In recent years, scientists have been studying links between agricultural use of antibiotics and increased resistance to antibiotics among human pathogens. Two examples of such links are the use of the drug avoparcin as a growth promoter to subsequent appearance of vancomycin-resistant enterococci in human intestines and the link between the rise of fluoroquinolone-resistantbacteria in chickens and infections of humans who ate meat contaminated with the bacteria.
ASM has worked consistently towards prevention of antimicrobial resistance and a reduction of antimicrobial resistance in general.In 1994, ASM formed a Task Force on Antimicrobial Resistance to analyze the best available information related to this issue and to assist in making well-informed public health policy.ASM subsequently provided extensive expert commentary on the interagency Antimicrobial Resistance Action Plan, released last year by the Department of Health and Human Services.This action plan, like on-going activities at FDA's Center for Veterinary Medicine, reflects the emphasis placed by the federal government on enhanced surveillance and prevention of antimicrobial resistance linked to food animals. These agencies use an open and rational process to arrive at science-based measures after consulting through public meetings and requests for comments with experts in the field of antimicrobial resistance and with interested groups like animal health professionals and consumers, a broadly collaborative approach endorsed by the ASM.During the same time period, the Alliance for Prudent Use of Antibiotics released a report entitled "The Need to Improve Antimicrobial Use in Agriculture."Both reports, and the earlier WHO report on agricultural use of antibiotics reached similar conclusions:Antibiotic use in agriculture increases the number of antibiotic-resistant bacteria, and these bacteria may well contribute to increases in resistance of important human pathogens.Because of this, agricultural use of antibiotics should be examined carefully to seek ways in which to limit drastically the use of antibiotics in agriculture.
ASM is well aware that antimicrobial resistance will never entirely disappear, but is confident that specific actions can be taken to ameliorate the problem.These actions, however, must be predicated on the understanding that there are multiple causes and thus each should receive appropriate attention for improvement.Not only should there be reduced inappropriate use of antimicrobials in food animals, but also in human patients.
Specific Comments on HR 3804
The ASM circulated the proposed legislation to twenty-five experts in the field of antimicrobial resistance for review and comment.These experts included researchers, physicians and veterinarians from academic, industrial and government institutions.Virtually all of these experts supported the intent of HR 3804 to reduce the inappropriate use of antibiotics in the United States. The ASM experts who reviewed the bill, however, were troubled by potential problems that might arise from differing interpretations of the term "nontherapeutic."The issue is whether the term includes only the use of antibiotics as growth promotants or whether it also includes prophylactic use of antibiotics.The concern about the definition of the term "nontherapeutic" is an important issue for this legislation.
A survey of the widely varying numbers given by different groups for the amount of antibiotics used as growth promoters or the amount of antibiotics used for prophylaxis shows how uncertain the definition of "nontherapeutic" currently is.The definition of "prophylactic use" is similarly open to differing interpretations.The terms "therapeutic" and "nontherapeutic" should receive further consideration and be defined carefully in this legislation.
The removal of antimicrobial growth promoters from US food production should include an examination of anticipated outcomes, with the participation of multiple stakeholders who provide the nation's food and medicine.Some of the issues that could be examined are the following: the effect of prohibited use on future new drug development by industry; the incidence of overt disease in flocks without the now common practice of adding low-level antibiotics to poultry drinking water and the effect on production and the general food supply; and how the effect of possible economic losses for farmers can be addressed.
The ASM strongly supports the precept that legislation and regulations should be science-based.There is a growing body of scientific literature that supports the intent of HR 3804.Certainly, there is enough evidence to support the drastic curtailment of antimicrobial use in agriculture. Nonetheless, there is still need for further research to guide future policy and identification of selection pressures for antimicrobial-resistant bacteria that might not be fully appreciated today. The need for further research does not mean that we cannot act today, but such additional research is prudent in the sense that it may influence the legislative and regulatory path of the future.
The ASM appreciates the opportunity to provide comments on HR 3804, an important proposal that reflects an encouraging level of interest among Congress and the public in difficult health issues.ASM hopes that these comments are of assistance to the Congress in assuring success against antimicrobial resistance.Only through education and prudent antimicrobial use practices will we be able to decrease the current prevalence of resistant pathogens.And only through aggressive, well supported research programs will we find alternatives to curtail the future spread of these and other, newly resistant pathogens.The ASM would be pleased to participate as this legislation is considered in the congressional process.