Antimicrobial resistance trends: Improvement, but more work needed

This digitally-colorized scanning electron micrograph (SEM) depicts red-colored Salmonella sp. Bacteria  in the process of invading a mustard-colored immune cell. (Photo: National Institute of Allergy and Infectious Diseases)

This digitally-colorized scanning electron micrograph (SEM) depicts red-colored Salmonella sp. bacteria in the process of invading a mustard-colored immune cell. (Photo: National Institute of Allergy and Infectious Diseases)

The federal government’s latest report on antibiotic resistance, released last week, shows encouraging progress in battling drug-resistant strains of bacteria but also points to more work that is needed in this arena.

The 2012-2013 National Antimicrobial Resistance Monitoring System (NARMS) Integrated Report was released by the U.S. Food and Drug Administration (FDA), and reflects a new sampling scheme, implemented in 2013, that provides random and nationally representative samples on the animal side.

The latest report shows improvement in a significant number of resistance trends:

  • Overall resistance remains low for most human infections.
  • There are improvements in resistance levels for numerous drugs:
    • Animal sources showed little or no ciprofloxacin-resistant E. coli. (Ciprofloxacin is an important drug in fighting many human infections; E. coli is used as an indicator bacteria in these studies.)
    • Resistance to ceftriaxone – another important drug for treating human infections – has declined in Salmonella and E. coli.
    • At the retail level, there has been a decline in the presence of multidrug-resistant Salmonella in chicken. The presence or absence of drug-resistant bacteria in retail meats is particularly important because this is the consumer-facing point in the food chain. Since the 2008-2012 reporting period, we have seen the following decreases in retail chicken:
      •    12% decrease in Salmonella resistance to ceftriaxone
      •    15% decrease in multidrug-resistant Salmonella
      •    8.2% decrease in Campylobacter jejuni resistance to ciprofloxacin (C. jejuni, although not necessarily in chicken, is responsible for 90% of human Campylobacter infections.)
      •    Additionally, compared with the 2004-2008 reporting period, there has been a 5.3% decrease in Campylobacter coli.
    • About 80% of Salmonella found in humans is not at all resistant to any antibiotics.  This has been stable for the last 10 years.
    • Resistance to three particularly important human drugs – ceftriaxone, azithromycin and ciprofloxacin – remains below 3% in Salmonella found in humans.

Concerns do remain, however:

  • Resistance in some human Salmonella isolates has increased, even though it has remained low in general. Also, since 2004-2008, there has been a 33% increase in Salmonella resistance in ground beef.
  • Resistance to ciprofloxacin and erythromycin in human Campylobacter coli isolates has increased. (However, gentamicin resistance in C. coli has declined steeply, and the presence of Campylobacter in retail meats has declined overall. Also, as noted above, only 10% of Campylobacter infections in humans are due to C. coli; the other 90% are due to C. jejuni, which has shown low levels of resistance.)
  • Rare examples of extremely drug resistant Salmonella and E. coli demonstrate a need for continued monitoring and responsible use.

NARMS is a partnership among the FDA, the U.S. Centers for Disease Control and Prevention (CDC), and the U.S. Department of Agriculture to track antibiotic resistance in foodborne Salmonella, Campylobacter, Enterococcus and E. coli bacteria.

The AVMA has long advocated for the responsible use of antibiotics in all animals, including livestock. Antibiotics are powerful tools in protecting animal health, but they must be used appropriately to preserve their effectiveness, protect animal health and welfare, and provide a safe food supply.

AVMA engaged with FDA for several years prior to the development of the new Veterinary Feed Directive regulations, helping to determine how best to achieve greater veterinary oversight of antibiotics. We’ve continued to work closely with FDA, providing valuable input as the regulations were being developed. And now, as we all persist in our efforts against antibiotic resistance and the final rule is being implemented, we are working to ensure that the process is as effective and efficient as possible to protect human and animal health.

For more information on antimicrobial use and antimicrobial resistance, visit

One thought on “Antimicrobial resistance trends: Improvement, but more work needed

  1. Not an expert in microbes and drug resistance, but the increasing antibiotic resistance by various bacteria is pretty alarming. I never had to use these drugs on my pets (mostly used natural cures, with my vet’s advice), but I’m afraid that they won’t be effective by the time I do.