Antibiotics are drugs that are used to treat bacterial infections. Antibiotics work by killing or slowing the growth of bacteria and they are not effective against nonbacterial infections, such as those caused by viruses. Antibiotic resistance is the result of bacteria changing in ways that reduce or eliminate the effectiveness of antibiotics to cure infection. Antibiotic use forces bacteria to either adapt or die in a process known as “selective pressure.” Selective pressure means that when an antibiotic is used, some bacteria will be killed by the antibiotic while other bacteria will survive. Bacteria are able to survive, in part, because they have certain genetic material that allows them to avoid the effects of the antibiotic. The surviving bacteria will multiply and pass on to future generations their genetic material that is coded for resistance to antibiotics. Any use of antibiotics—appropriate and inappropriate—creates selective pressure among bacteria. (For more information on resistant bacteria, see app. II). The inappropriate use of antibiotics, or the additional use of antibiotics that could have been avoided, can occur when healthcare providers prescribe antibiotics when they are not beneficial, such as to treat a viral infection, or when antibiotic treatments are not targeted to the specific bacteria causing the infection. Inappropriate antibiotic use also occurs when healthcare providers do not prescribe the correct antibiotic dose and duration of treatment. Further, inappropriate use includes when patients do not complete a full course of prescribed antibiotics. Individual consumers, health care facilities, pharmacies, and pharmaceutical manufacturers dispose of unused antibiotics using various methods. For the purposes of this report, the disposal of antibiotics refers to the discard of unused antibiotics by consumers, companies, and others. Common disposal methods for individual consumers include throwing unused antibiotics in the trash, flushing them down the toilet, and pouring them down the drain. According to EPA officials, healthcare facilities and pharmacies often return unused or expired drugs to contracted companies, known as reverse distributors, for manufacturer credit. The reverse distributor is then instructed by the manufacturer to return the unused drug to the manufacturer, or in most cases, the reverse distributor is instructed to dispose of the drugs. The unused drugs are then most likely incinerated as solid waste, subject to state and local environmental regulations. The federal guidelines on how consumers should properly dispose of their unused drugs, including antibiotics, recommend that consumers dispose of their unused drugs either by returning them through a drug take-back program, where available, or by mixing them with coffee grounds or kitty litter and throwing them in the household trash. Unused antibiotics intended for human use may enter the environment through various pathways such as sewage systems and landfills, depending upon the method of disposal and other factors. Unused antibiotics enter sewage systems after they are flushed down the toilet or poured down the drain. Unused antibiotics that enter the sewage system then flow to wastewater treatment plants where, if not removed during the treatment process, they are released into the environment, such as in rivers and streams, as wastewater effluent. In addition, some areas may use onsite septic systems to treat wastewater and in these systems wastewater is discharged below the ground’s surface. Unused antibiotics that are disposed of in the trash could enter the environment if landfills were to leak. Although modern landfills are designed with liners and systems to limit this process by rerouting leachate, that is, liquid generated in landfills, to wastewater treatment plants, the antibiotics that are contained in the leachate may ultimately enter the environment. This can occur if antibiotics are not removed during the wastewater treatment process. In general, wastewater treatment plants are not designed to remove low concentrations of drug contaminants, such as antibiotics. In addition, antibiotics that have been used by humans to treat infections can also enter the environment. Most used antibiotics enter the sewage systems after they are ingested and excreted by individuals because antibiotics are not fully absorbed by the human body. Like unused antibiotics that enter the sewage systems, used antibiotics flow from sewage systems to wastewater treatment plants and may be released into the environment as wastewater effluent or biosolids. Agricultural manure is another potential source of antibiotics entering the environment; some antibiotics used for agriculture are similar to those used by humans. Within HHS, the Centers for Disease Control and Prevention (CDC), FDA, and the National Institutes of Health (NIH) have responsibilities for protecting Americans from health risk, including risk associated with antibiotic-resistant infections. These agencies have a variety of responsibilities related to the surveillance, prevention, and research of infectious disease. CDC has a primary responsibility to protect the public health through the prevention of disease and health promotion. One of CDC’s primary roles is to monitor health, and part of this role involves monitoring antibiotic-resistant infections and the use of antibiotics. CDC’s statutory authority to conduct such surveillance derives from the Public Health Service Act. Tracking the emergence of antibiotic resistance, and limiting its spread, is also part of CDC’s mission. Consistent with this mission, CDC implements prevention strategies, such as educational programs, that are designed to limit the development and spread of antibiotic resistance and the agency monitors antibiotic prescriptions in humans to help reduce the spread of antibiotic resistance. Part of FDA’s responsibility for protecting the public health involves assuring the safety and efficacy of human drugs. FDA reviews and approves labels for antibiotics and provides educational information to consumers and healthcare providers about the appropriate use of antibiotics, and the risk of the development of antibiotic resistance associated with their inappropriate use. FDA also licenses vaccines for use in humans to prevent bacterial infections—including certain antibiotic- resistant infections—as well as viral infections and has the authority for the review of diagnostics, including tests to detect bacterial infections. As the nation’s medical research agency, NIH is responsible for conducting and funding medical research to improve human health and save lives. According to its research agenda on antibiotic resistance, NIH supports and conducts research on many aspects of antibiotic resistance, including studies of how bacteria develop resistance, the development of diagnostic tests for bacterial infections that are or are likely to become resistant to antibiotics, as well as clinical trials such as those to study the effective duration for antibiotic treatments. CDC, FDA, and NIH are also co-chairs of the Interagency Task Force on Antimicrobial Resistance (Task Force) and released A Public Health Action Plan to Combat Antimicrobial Resistance (Action Plan) in 2001. The Action Plan identified actions needed to address the emerging threat of antibiotic resistance and highlighted the need to improve federal agencies’ ongoing monitoring of antibiotic use and of antibiotic-resistant infections. Specifically, the Action Plan stated that establishing a national surveillance plan for antibiotic-resistant infections should be a high priority, and that improved monitoring of such infections was needed to identify emerging trends and assess changing patterns of antibiotic resistance as well as to target and evaluate prevention and control efforts. The Action Plan also specifically stated that surveillance of antibiotic use in humans should be a high priority and was needed to better understand the relationship between antibiotic use and antibiotic resistance. For example, identifying a specific pattern of antibiotic use associated with increased antibiotic resistance could support a response from policymakers, such as to affect change in antibiotic use practices. Further, improved antibiotic use monitoring would help identify prevention activities and anticipate gaps in the availability of existing antibiotics effective in treating bacterial infections. A revised draft Action Plan was published for public comment on March 16, 2011. EPA’s mission includes protecting Americans from significant environmental health risks. As part of its role, EPA sets national standards for the disposal of solid and hazardous waste and the quality of drinking water. EPA generally regulates the disposal of waste, including some unused or expired drugs, under the Resource Conservation and Recovery Act (RCRA). EPA also promulgates national requirements for drinking water quality of public water systems under the Safe Drinking Water Act (SDWA). EPA conducts research on topics related to human health and the environment, including research aimed at understanding drug disposal practices and the potential human and ecological health risks of drugs, such as antibiotics, found in the environment. Within DOI, USGS is responsible for providing scientific information to better understand the health of the environment, including our water resources. USGS conducts large-scale studies to gather information that can provide a basis for evaluating the effectiveness of specific policies; these studies can also be used to support decision making at the local and national levels—for example, decisions related to protecting water quality. In 1998, USGS initiated the Emerging Contaminants Project to improve the scientific understanding of the release of emerging contaminants to the environment, including where these contaminants originate and whether they have adverse effects on the environment. As part of the project, USGS has conducted national studies to measure the presence of unregulated contaminants, including antibiotics, in the environment, and conducts targeted local studies to assess the impact of specific pathways by which antibiotics can enter the environment. CDC has six surveillance systems that provide information to monitor antibiotic resistance that occurs in healthcare and community settings. According to CDC, public health surveillance is the ongoing and systematic collection, analysis, and interpretation of data for use in the planning, implementation, and evaluation of public health practice. The surveillance systems collect information about antibiotic resistance among certain bacteria that cause infections in humans, and the infections are transmitted either in healthcare settings or in the community. For example, CDC’s National Healthcare Safety Network (NHSN) monitors infections that occur in healthcare settings, including those that are resistant to antibiotics, such as MRSA, while CDC’s Active Bacterial Core Surveillance (ABCs) system monitors bacterial infections such as meningitis and pneumonia that are spread in the community or in healthcare settings. Table 1 provides information about the purpose of each CDC surveillance system that monitors antibiotic resistance and summarizes the settings in which the monitored infections are spread. (See app. III for additional information about each of the six systems.)