Facts About CDC NARMS: Timeline of Progress

Introduction

The National Antimicrobial Resistance Monitoring System (NARMS) was formed in 1996 as a partnership among the Centers for Disease Control and Prevention (CDC), the Food and Drug Administration (FDA), the U.S. Department of Agriculture (USDA), and state and local health departments. NARMS tracks antimicrobial resistance in enteric (intestinal) bacteria from sick people (CDC), retail meats (FDA), and food-producing animals at slaughter (USDA).

NARMS is a key source of vital data for sectors across One Health including public health, human and veterinary medicine, academia, and the food and food animal industries. These data are used to combat antimicrobial resistance, improve food safety, and protect the health of humans and animals.

CDC NARMS

At CDC, the NARMS program helps protect public health by providing information about antimicrobial resistance in enteric bacteria, the ways in which resistance spreads to other bacteria, and the differences between resistant and susceptible infections.

Over the decades, CDC NARMS has:

• Expanded testing nationwide and to include Campylobacter, E. coli O157, nontyphoidal and typhoidal Salmonella, Shigella, and non-cholerae Vibrio
• Adopted advanced DNA sequencing techniques
• Incorporated technology to predict resistance to antibiotics
• Shared data through reports, journal articles, publicly available real-time dashboards, and partner engagements

Evolution over the last decade

CDC NARMS has advanced from phenotypic-based testing methods to real-time, genomics-driven antimicrobial resistance surveillance that informs patient care and outbreak prevention and response.

Modernized surveillance

Whole genome sequencing enables CDC NARMS to detect resistance patterns more quickly than traditional methods with increased sensitivity and resolution. These advantages give public health officials a more complete understanding of ways resistance emerges and spreads, allowing for earlier detection of threats, more precise outbreak response, and better-informed prevention strategies.

Public health impact

• Rapid detection of resistance in bacteria making people sick
• Earlier signals of emerging enteric disease threats
• Ability to contain resistance before it spreads to other bacteria

Examples

• 2016: CDC funded and trained state health departments, enabling all 50 states and Washington, D.C. to sequence human isolates of Salmonella.
• 2016: NARMS researchers published the first large study showing that genomic data can be used to predict antimicrobial resistance in Salmonella.

• 2016: NARMS began using genomic DNA sequences to predict resistance.
• 2019: NARMS began receiving genomic data from PulseNet to improve real-time detection of emerging resistance, leading to an almost 20-fold increase in antimicrobial resistance surveillance.

• 2025: NARMS performed genomic analysis for antimicrobial resistance on more than 96,000 isolates from people, animals, food, and the environment—an increase from 19,000 isolates in 2020.

Accessible data for action

Resistance data from NARMS are readily and publicly available, enabling quick action by decision makers across public health, human and veterinary medicine, academia, and agricultural industries.

Public health impact

During outbreaks, public health professionals can rapidly assess real-time information on resistance patterns to respond more precisely and effectively.

Examples

• 2015: CDC NARMS began to release data on antimicrobial-resistant bacteria through NARMS Now: Human Data, a publicly available data tool updated every 24 hours.
• 2019: CDC, FDA, and USDA launched NARMS Now: Integrated Data, a second publicly available online data tool for comparing antimicrobial resistance in bacteria from sick people, retail meats, and food-producing animals.
• 2022: CDC upgraded NARMS Now: Human Data with a suite of new visualizations, including an option to view predicted resistance vs. traditional susceptibility results and to see trends in minimum inhibitory concentration (MIC) data.
  
• 2023: CDC updated the Bacteria, Enterics, Ameba, and Mycotics (BEAM) Dashboard with NARMS data to include the percentage of outbreak-associated isolates with clinically important antimicrobial resistance.
• 2023: CDC NARMS developed a user-friendly tool for epidemiologists and laboratory scientists to analyze complex genetic data and visualize previously hidden connections and patterns. The tool provides deeper insight into how pathogens spread, evolve, and acquire new traits, such as antimicrobial resistance.
• 2025: CDC migrated NARMS Now: Human Data to the BEAM Dashboard.

Informed clinical decision-making

NARMS data are used to develop national clinical standards that inform antibiotic use decision-making.

Public health impact

NARMS data have been used to update clinical treatment guidance for enteric illnesses. For example, NARMS data have informed the Infectious Diseases Society of America's guidelines on infectious diarrhea; the American Academy of Pediatrics' Red Book guidance for treating childhood illnesses; the CDC Yellow Book's guidance for travel medicine; and UpToDate's clinical decision support.

Examples

• 2014: CDC NARMS and the Foodborne Diseases Active Surveillance Network (FoodNet) demonstrated that people infected with antimicrobial-resistant strains of Salmonella have more severe outcomes and are more likely to need hospitalization.
• 2020: Recommendations from CDC-funded research served as the basis of the Clinical & Laboratory Standards Institute's (CLSI) azithromycin susceptibility breakpoints for Shigella infections.
• 2021: CDC NARMS data informed the first clinical breakpoints for azithromycin for Shigella—an advancement for clinical laboratory testing that can improve patient care and outcomes—published by CLSI and supported by data from collaborators at the University of Virginia, the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), and the California Department of Public Health.
• 2019-Present: To help keep travelers healthy abroad and prevent the spread of antimicrobial resistance in the United States, CDC NARMS has monitored antimicrobial-resistant infections acquired through international travel, including extensively drug-resistant typhoid fever and multidrug-resistant Salmonella Newport. Data on these strains inform recommendations for travelers and clinicians, including steps to prevent and treat these infections, which CDC NARMS regularly reviews and updates.

Faster detection and response

Since 1996, CDC NARMS has tracked antimicrobial resistance in more than 3,000 outbreaks and shared real-time outbreak resistance data with state, local, and federal agencies.

Early outbreak detection enables a faster and more precise response that can lead to fewer infections and stronger prevention efforts.

Public health impact

• Resistant strains of enteric bacteria can be detected earlier, before they become widespread public health threats.
• Resistance data help outbreak investigators understand severity, transmission, and treatment implications for sick people and animals. These data also can prompt rapid response, communications, and prevention measures during an outbreak. Knowing whether certain strains are especially difficult to treat can help prioritize resources for outbreak response.
• CDC's outbreak investigation notices include NARMS resistance data. This information helps clinicians know whether to expect resistance (and what type) following specific exposures. These data also help industries know when certain products or exposures are associated with resistant strains.

Examples

• 2017: CDC investigators used NARMS data in an analysis of multidrug-resistant Salmonella Dublin bacteria causing infections in both people and cattle. Although infections are still rare among people, they were increasing in number and severity. The analysis showed that improved management practices and judicious use of antimicrobial drugs in cattle can help control the infections.
• 2017: Ceftriaxone resistance in Salmonella poses a significant public health risk because this antibiotic is often used to treat severe Salmonella infection, especially in children. An analysis led by CDC NARMS found that resistant strains of Salmonella Newport, Typhimurium, and Heidelberg causing human infections are linked to resistant strains found in ground beef, cattle, and poultry. Food animal industries can use this information to help stop the spread of ceftriaxone resistance.
• 2018: NARMS reported the emergence of a multidrug-resistant strain of Salmonella Infantis linked to international travel, particularly to South America. The strain is characterized by an extended-spectrum beta-lactamase gene, which has been associated with increased hospitalization rates. This study highlighted the need for action to prevent the spread of this strain in the United States.
  

• 2024: CDC NARMS and partners at FDA and USDA published an Interim Data Update (updated in 2026) describing an increase in Salmonella with predicted azithromycin resistance. NARMS agencies are working to better understand how these strains originated, how they spread, and which genes are responsible for their resistance profiles.
• 2024: CDC NARMS investigated the emergence of resistance to azithromycin in Salmonella Typhi. NARMS serves as an important global sentinel for detection of Salmonella Typhi with emerging antimicrobial resistance, especially from places without routine surveillance.
• 2025: Several outbreaks of Salmonella Enteritidis with resistance to ciprofloxacin made more than 700 people ill. Analysis by CDC NARMS and partner agencies revealed that this strain is increasing the burden of Salmonella Enteritidis illnesses in people and displacing existing strains of Enteritidis circulating among domestic poultry. Further work to understand the sources of this emergent strain is underway, with the goal of informing prevention measures to reduce the public health burden.

• 2025: CDC NARMS tracked resistance in clusters of Shigella infections, including a multistate outbreak with 283 cases in 7 states.
• 2026: NARMS identified the first-known outbreak of Salmonella infections carrying an NDM-1 gene. The outbreak, linked to moringa powder capsules, led to CDC sharing clinical guidance for the outbreak strain, including treatment recommendations and considerations.
• 2023–Present: CDC NARMS posted and continues to update webpages on reoccurring, emerging, and persisting (REP) strains of extensively drug-resistant Campylobacter jejuni, multidrug-resistant Salmonella Newport, multidrug-resistant Salmonella Infantis, and extensively drug-resistant Salmonella Typhi. Despite prevention efforts, these strains have caused illnesses and outbreaks over many years. CDC uses information gained from REP strain investigations to better understand their sources, track how they change over time, and collaborate on measures to reduce their spread.