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  1. The National Antimicrobial Resistance Monitoring System


What is NARMS?
Who are the NARMS partners?
What does NARMS do?
What bacteria are tested in NARMS?
What kind of information does NARMS collect?
Why is resistance monitoring important?
What kind of data and reports are published by NARMS?
How are NARMS data used?
Help for consumers

What is NARMS?

Antibiotic resistance is an adverse event associated with the use of antibiotics. It is directly related to the safety and effectiveness of antibiotics, which FDA is responsible for ensuring. Its main function is to serve the FDA Center for Veterinary Medicine (CVM) as a source of data for the approval of new animal antibiotics and for the post-approval safety monitoring of these compounds. Thus, NARMS is used to assess the risks associated with new drugs and to monitor the continued safe use of older agents. NARMS was established in 1996 as a partnership between the FDA, the Centers for Disease Control and Prevention (CDC), and the U.S. Department of Agriculture (USDA) to track antibiotic resistance in foodborne bacteria from humans (CDC), retail meats (FDA), and food animals (USDA).


Who are the NARMS partners?

The National Antimicrobial Resistance Monitoring System (NARMS) is a U. S. public health surveillance system that tracks antimicrobial resistance in foodborne and other enteric bacteria. NARMS works closely with a number of partners who play complementary roles in antibiotic resistance to address this important issue.

The National Antimicrobial Resistance Monitoring System (NARMS) is a U. S. public health surveillance system that tracks antimicrobial resistance in foodborne and other enteric bacteria. NARMS works closely with a number of partners who play complementary roles in antibiotic resistance to address this important issue.

Sources represented by NARMS: Humans Retail Meats Food-Producing Animals
Who is involved in NARMS?
  • Centers for Disease Control and Prevention (CDC)
  • Health departments in 50 states
  • U.S. Food and Drug Administration (FDA)
  • Health departments in 15 states
  • Institutions of higher education in 4 states
  • United States Department of Agriculture (USDA) including:
    • Food Safety and Inspection Service (FSIS)
    • Agricultural Research Service (ARS)
    • Animal Plant Health Inspection Service (APHIS)
Where do the samples that are tested come from?
  • Ill persons
Retail meats from consumer grocery stores including:
  • Chicken
  • Ground Turkey
  • Ground Beef
  • Pork
Ceca and regulatory samples§ from farm animals including:
  • Chickens
  • Turkeys
  • Cattle
  • Swine
What bacteria does NARMS test for resistance?
  • Salmonella
  • Campylobacter
  • Escherichia coli 0157
  • Vibrio
  • Shigella
  • Salmonella
  • Campylobacter
  • Escherichia coli
  • Enterococcus
  • Salmonella
  • Campylobacter
  • Escherichia coli
  • Enterococcus

California, Colorado, Connecticut, Georgia, Louisiana, Maryland, Minnesota, Missouri, New Mexico, New York, Oregon, Pennsylvania, South Carolina, Tennessee, and Washington have health departments participating. As of September 2016 Kansas State University, Iowa State University, Texas Tech University, and South Dakota State University participate in the NARMS retail meat surveillance program.

Each USDA NARMS agency tests bacteria samples taken from food-producing animals at different stages of production.

§Regulatory samples include ground products (chicken, turkey, beef), carcass swabs (turkey, cattle, swine), and carcass rinsates (chicken).

Most Escherichia coli and Enterococcus do not cause human illness, but antibiotic resistance in these bacteria can be transferred to other bacteria that can make people sick.


What does NARMS do?

  • Monitor trends in antimicrobial resistance among foodborne bacteria from humans, retail meats, and animals
  • Disseminate timely information on antimicrobial resistance to promote interventions that reduce resistance among foodborne bacteria
  • Conduct research to better understand the emergence, persistence, and spread of antimicrobial resistance
  • Assist the FDA in making decisions related to the approval of safe and effective antimicrobial drugs for animals


What bacteria are tested in NARMS?

NARMS monitors antibiotic resistance among the following four major foodborne bacteria: Salmonella, Campylobacter, Escherichia coli, and Enterococcus. This section describes these bacteria and the importance of monitoring their resistance to antibiotics. CDC also conducts surveillance of resistance among Vibrio species other than V. cholera, and the non-foodborne enteric organisms Shigella, and typhoidal Salmonella from humans. More information on these organisms can be found on the CDC website.

Non-typhoidal Salmonella enterica is widely dispersed in nature. It can be found in intestinal tracts of vertebrates including wildlife, livestock, domestic pets, and also in environmental sources such as pond water. It is spread through the fecal oral route and through contact with contaminated foods. An estimated 1.2 million people get sick from Salmonella infection in the United States each year. Of these, about 23,000 are hospitalized, and 450 die from their infections. Symptoms include nausea, vomiting, abdominal cramps, diarrhea, fever, headache generally lasting 4 to 7 days with acute symptoms lasting 1-2 days. Serious disease can develop in the very young, the elderly and the immunocompromised. Fluoroquinolones and cephalosporins are used as first-line therapies for the treatment of serious Salmonella infection in adults. Cephalosporins are recommended for the treatment of pediatric infections. More information can be found in FDA’s Bad Bug Book.

Campylobacter is part of the natural gut flora of most food-producing animals such as chickens, turkeys, swine, cattle and sheep. It is estimated to cause over 1.3 million illnesses and 76 deaths in the United States each year. More than 80% of Campylobacter infections are caused by C. jejuni. However, other Campylobacter species, such as C. coli and C. fetus can cause disease in humans. C. coli and C. jejuni cause similar disease symptoms including fever, diarrhea, abdominal cramps, and vomiting lasting anywhere from 2 to 10 days. Most cases of Campylobacter gastroenteritis are self-limited and typically, antibiotic therapy is not needed. When antibiotic therapy is indicated, macrolides and fluoroquinolones are most commonly prescribed. Major food sources linked to C. jejuni infections include improperly handled or undercooked poultry products, raw milk and cheeses made from raw milk, and contaminated water. More information can be found in FDA’s Bad Bug Book.

Escherichia coli (E. coli) is one of the predominant enteric species in the normal intestinal flora of vertebrates. However some serotypes of E. coli can cause severe diarrheal diseases in humans. One of these pathogenic strains is E. coli O157, which is monitored for antibiotic resistance by CDC in the human population. More information can be found on the CDC website. USDA and FDA monitor resistance among generic (non-serotyped) E. coli from food animals and retail meats. Generic E. coli are used by NARMS as an indicator organism to detect both emerging resistance patterns and specific resistance genes that could potentially be transferred to other pathogenic gram negative bacteria, like Salmonella.

Enterococcus is ubiquitous in nature and can be found in the gastrointestinal tracts, genitourinary tracts, oral cavities, and skin of humans and animals, as well as in insects, plants, soil, and water. Enterococcus is the only gram positive organism that NARMS routinely monitors. Because it is consistently present in both meats and food animals, NARMS uses Enterococcus as an indicator organism to track resistance to antibiotics with activity against gram positive organisms that may result from antimicrobial use. Enterococcus infection is notable largely as a hospital or community-acquired illness, and not much information is known about its role as a direct cause of foodborne illness. However, it is known that poorly processed meat and milk are among the foods that can transmit it. More information can be found in FDA’s Bad Bug Book.


What kind of information does NARMS collect?

In addition to monitoring antimicrobial resistance, NARMS partners collaborate on epidemiologic investigations and microbiologic research studies. Data and targeted research studies are reported at scientific meetings and published in peer reviewed scientific journals.

NARMS performs whole-genome sequencing (WGS) as part of routine processes in the analysis of Salmonella and Campylobacter, in addition to some sequencing of resistant strains of E. coli and Enterococcus. This information is primarily used to understand the mechanisms underlying observed resistance phenotypes, and as a result, NARMS has begun reporting resistance genotypes of Salmonella isolated from retail meats, food-producing animals, and humans. In addition, WGS information is being used for bacterial speciation, serotyping, and to improve the understanding of emerging resistance phenomena and the passage of resistant bacteria through the food chain.

Historically, NARMS examined foodborne bacteria for genetic relatedness using pulsed-field gel electrophoresis (PFGE) and stored the results in CDC’s PulseNet database or USDA’s VetNet database. Whole genome sequencing is becoming the tool of choice for this work, and is expected to replace PFGE in the future. 


Why is resistance monitoring important?

  • Document resistance levels in different reservoirs (Baselines)
  • Describe the spread of resistant bacterial strains and resistance genes (Spread)
  • Identify temporal and spatial trends in resistance (Trends)
  • Generate hypotheses about sources and reservoirs of resistant bacteria (Attribution)
  • Understand the association between use practices and resistance (Veterinary Use)
  • Identify risk factors and clinical outcomes of infections caused by antimicrobial resistant bacteria
  • Provide data for education on current and emerging hazards (Education)
  • Guide evidence-based policies and guidelines to control antimicrobial use in hospitals, communities, agriculture, aquaculture, and veterinary medicine (Policy)
  • Pre-approval – Support risk analysis of foodborne antimicrobial resistance hazards (GFI 152)
  • Post-approval – Identify interventions to contain resistance and evaluate their effectiveness (Extra-label use, fluoroquinolones in poultry, GFI 209)

Antimicrobial drugs have been widely used in human and veterinary medicine for more than 60 years, with tremendous benefits to both human and animal health. The development of resistance to these medicines poses a serious public health threat. Antimicrobial drug use creates selective evolutionary pressure that enables antimicrobial resistant bacteria to increase in numbers and thus increases the opportunity for individuals to become infected by resistant bacteria. When antimicrobial drugs are used in food-producing animals, they can enrich the resistant strains that reach humans via the food supply.


What kind of data and reports are published by NARMS?

  • NARMS publishes an annual integrated report that consolidates data from humans, retail meats, and food animals into one format. Since 2009, these reports describe the most salient data points. To view the newest report, click on Integrated Reports/Summaries.
  • NARMS publishes interactive graphs of antimicrobial resistance data over time from bacteria isolated from humans, retail meats, and food animals to accompany the NARMS Integrated Report. Genetic data associated with particular antimicrobial resistances can also be dynamically graphed. To access and download the data, click on Integrated Reports/Summaries.
  • Interagency partners publish source specific annual summary reports on antimicrobial resistance among select bacteria isolated from the sources tested by each agency. Summary reports for each of these sources can be found at the following links: Human, Retail Meats, Food Animals


How are NARMS data used?


The FDA's Center for Veterinary Medicine is responsible for the regulation of antibiotics used in animals, including animals raised for food. The FDA arm of NARMS provides data about resistance in bacteria isolated from retail meats. This is important, because these data represent the major route of human exposure.

FDA uses NARMS to:

  • understand how resistance emerges, persists, and spreads;
  • support risk analysis of foodborne antimicrobial resistance hazards when evaluating a new animal antibiotic for safety;
  • help understand the nature and magnitude of antibiotic resistance trends;
  • help guide evidence-based action to limit or reverse worsening antibiotic resistance trends;
  • measure the impact of new FDA policies and regulations that relate to the use of antibiotics in animal agriculture;
  • assist USDA and CDC with outbreak detection.

NARMS supports the FDA regulatory mission

  • FDA first used NARMS surveillance results to address an adverse resistance trend in the early 2000s in response to data showing a rapid increase in fluoroquinolone-resistant Campylobacter, a major foodborne pathogen. In 2005, FDA undertook a lengthy legal process that resulted in withdrawing the approval for fluoroquinolones in poultry, a major source of Campylobacter infection. Since this action, resistance has stopped increasing, but has not declined to levels seen before these compounds were approved in the late 1990s. This is an example of an intervention that stopped, but did not reverse, a worsening trend. NARMS continues to watch this situation and highlight it in its annual reports.
  • NARMS observed increasing resistance to extended-spectrum cephalosporins (ESC) among certain strains of Salmonella. Because this class of drugs is vital for treating Salmonella infections, resistance to these compounds is considered a significant threat to human health. In response, the FDA issued an extra-label (unapproved) use prohibition, which prohibited certain uses of ESC in cattle, swine, chickens and turkeys. Specifically, the prohibited uses include using ESC at unapproved dose levels, frequencies, durations, or routes of administration; using ESC in cattle, swine, chickens or turkeys that are not approved for use in that species (e.g., ESC intended for humans or companion animals); and, using ESC for disease prevention. This regulation went into effect in April of 2012.
  • In December 2013, the FDA announced plans to end the long-term practice of administering medically important antibiotics to food producing animals for promoting animal growth and increasing feed efficiency, practices based on economic efficiency rather than medical necessity. This judicious use strategy is part of the agency’s multipronged approach to preserving the power of antibiotics for treating infectious diseases in humans and animals. By tracking resistance to the antimicrobial compounds affected by this policy, NARMS will play a role in measuring the strategy's impact on overall resistance in foodborne bacteria.

CDC NARMS helps protect public health by providing ongoing surveillance of enteric bacteria causing antibiotic resistant infections in people. CDC scientists track antibiotic resistance and study emerging resistance in bacteria that infect people commonly through food. The CDC arm of NARMS provides data about resistance in both sporadic cases and outbreaks. Investigations of outbreaks of resistant enteric infections provide data about the sources of both sporadic and outbreak-associated infections.

Preventing enteric (intestinal) infections caused by food and other sources reduces both antibiotic-susceptible and antibiotic-resistant infections.

CDC helps protect public health by using NARMS data to:

  • detect and track resistant infections;
  • study how resistance emerges and spreads;
  • estimate how many resistant infections occur in the United States;
  • determine the health impact of resistant infections;
  • determine the sources of resistant infections;
  • improve antibiotic prescribing and use;
  • educate consumers and industry about food safety; and
  • prevent infections.

The Food Safety and Inspection Service (FSIS) is the public health agency in the U. S. Department of Agriculture (USDA) responsible for ensuring that the nation’s commercial supply of meat, poultry (e.g., young chickens and turkeys), and egg products (e.g., liquid eggs) are safe, wholesome, and properly labeled. Within the FSIS mission, the agency examines the hazards and risks associated with FSIS-regulated products to reduce human exposure to foodborne pathogens and prevent foodborne illness. As such, FSIS collaborates with the USDA Animal Plant Health Inspection Service (APHIS), USDA Agriculture Research Service (ARS), FDA, and CDC to monitor and characterize foodborne pathogens and bacteria isolated from humans and animals to identify patterns of resistance in antibiotics of human health concern through the NARMS program.

FSIS uses NARMS data to:

  • increase scientific knowledge regarding the emergence, persistence, and spread of antimicrobial resistance among foodborne bacteria;
  • evaluate potential associations between antimicrobial resistance in preharvest, postharvest and other production settings in collaboration with other USDA agencies;
  • communicate the significance of PFGE patterns, serotypes, and AST results to industry on a case by case basis;
  • support hypothesis generation during outbreak investigations;
  • continuously evaluate and seek to understand and employ new or innovative mission-supporting processes, methodologies, and technologies; and
  • collaborate with other USDA agencies to develop an action plan for a comprehensive, integrated approach for future surveillance, research and development, and education and outreach activities.


Help for consumers

Consumers should always follow four basic food safety tips to prevent against bacteria, including antibiotic resistant bacteria: clean, separate, cook, chill. Learn more at http://www.foodsafety.gov/keep/basics/index.html.  


Additional Information