National Antimicrobial Resistance
Monitoring System (NARMS) Retail Data 

Dr. David G. White
Center for Veterinary Medicine
U.S. FDA

Veterinary Medicine Advisory Committee
September 25, 2006

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NARMS

• The National Antimicrobial Resistance Monitoring System (NARMS) is a national collaborative network between the FDA, CDC and USDA as well as public health laboratories in all 50 states and local health departments in four major cities
• NARMS was developed to monitor changes in susceptibility/resistance of select zoonotic bacterial pathogens and commensal organisms recovered from animals, retail meats and humans to antimicrobial agents of human and veterinary importance 
• NARMS monitors susceptibility/resistance phenotypes using three testing sites:
  • FDA/CVM (retail meat and poultry)
  • CDC (humans)
  • USDA (animal/slaughter)

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NARMS/Retail Meats Overview

• 10 FoodNet sites
• Similar sampling scheme
  • Random sampling of stores
  • Each site purchases 10 packages each of chicken breasts, pork chops, ground turkey, and ground beef
• All ten sites culture meat and poultry rinsates for Salmonella and Campylobacter
• In addition, four sites (GA, MD, OR and TN) culture rinsates for E. coli and Enterococcus
• Isolates are sent to FDA-OR for confirmation of identification and antimicrobial susceptibility testing 

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NARMS Retail meats sampled for Salmonella

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NARMS/Retail food preliminary data
Salmonella 2002 - 2005  

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NARMS/Retail food Salmonella
Ceftriaxone MIC Distributions by Year  

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NARMS/Retail food Salmonella
Ceftriaxone MIC Distributions by Meat Type  

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NARMS/Retail food Salmonella Ceftiofur
MIC Distributions by Year  

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NARMS/Retail food Salmonella
Ceftiofur MIC Distributions by Meat Type 

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ß-lactamases

• Can be either chromosomal or plasmid borne
• Plasmid mediated TEM-1 and TEM-2 ?-lactamases are the most widely disseminated among Gram negative bacteria
• Class A extended-spectrum ß-lactamases (ESBLs) (CTX-M or enzymes derived from the classic TEM-1 and SHV-1) and plasmidic class C ß-lactamases (FOX and CMY, among others) have been described among Salmonella and E. coli isolates recovered from animals

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ß-lactamases among NARMS
Salmonella recovered from retail meats
2002 - 2005

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Ceftiofur vs. Cefquinome MIC Distributions among
Ampicillin Resistant Salmonella Recovered from
Retail Foods (N=97) 

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Cefquinome MIC Distributions among
Ceftiofur Susceptible and Resistant
Salmonella isolates (N=97) 

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NARMS Retail meats sampled for E. coli 

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NARMS/Retail food preliminary data
E. coli 2002 - 2005  

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NARMS/Retail food E. coli 
Ceftriaxone MIC Distributions by Year 

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NARMS/Retail food E. coli
Ceftriaxone MIC Distributions by Meat Type 

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NARMS/Retail food E. coli
Ceftiofur MIC Distributions by Year 

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NARMS/Retail food E. coli
Ceftiofur MIC Distributions by Meat Type 

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ß-lactamases among NARMS E. coli
recovered from retail meats 2002 - 2004

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Summary

• NARMS currently monitors susceptibility to several ß-lactam antimicrobials including cefoxitin, ceftiofur, and ceftriaxone among Salmonella and E. coli isolates
• Among 1,044 Salmonella recovered from retail foods between 2002 – 2005
  • 13.2% ceftiofur resistant (> 8 µg/ml)
  • 0.7% ceftriaxone resistant (> 64 µg/ml)
• Among 3,669 E. coli recovered from retail foods between 2002 – 2004
  • 2.4% ceftiofur resistant (> 8 µg/ml)
  • 0% ceftriaxone resistant (> 64 µg/ml)

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Summary

• NARMS secondary ESBL plate includes the 4th generation cephalosporins, cefepime and cefquinome
  • 0.06 – 32 µg/ml
  • In 2007, all ampicillin resistant Salmonella and E. coli will be further
     tested on secondary ESBL plate
• Detection of ß-lactamases among ceftiofur resistant Salmonella and E. coli
  • No CTX-M extended-spectrum ß-lactamases (ESBL) were detected
  • CMY genes most commonly identified
    • Are not currently associated wtih resistance to 4th generation cephalosporins
    • Associated with shifts in cefquinome MICs to a less susceptible population, however, MICs are still below CLSI resistant breakpoint established for other 4th generation cephalosporin (cefepime > 32 µg/ml)
• NARMS will continue to monitor any shifts in decreased susceptibility to cefquinome and other cephalosporins of animal and human health significance

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Acknowledgements