December 01, 2020

Federal health agencies plan to expand drug resistance testing and analysis to include pathogens in pet food, livestock feed, and surface waters.

That change would include adding analyses of pathogens that affect animals—rather than only pathogens of concern for human medicine—as well as developing environmental surveillance programs.

In a public meeting in October and a draft plan published earlier this year, leaders of the National Antimicrobial Resistance Monitoring System described plans for studies on pathogens and drug susceptibility beyond the current testing programs involving humans with foodborne illnesses, animals presented at slaughter, and meat sold in retail markets, as well as studies. They also described plans to expand use of whole genome sequencing, which can provide more information on how resistances spread and identify sources of new attributes that confer drug resistance.

The additional studies could help improve understanding of how pathogenic bacteria develop resistance to antimicrobials and share those genetic characteristics, as well as indicate which of those components are most likely to spread to other bacteria and which drug-resistant bacteria converge in rivers, lakes, and reservoirs. By collecting samples from pet and livestock foods, the sampling will also provide clues as to how animals become infected and how that increases the risks to humans.

And NARMS leaders plan to expand testing to more animals, such as additional ruminants and seafood species, and test for resistance in more bacteria species.

During the public meeting, Patrick McDermott, PhD, director of the NARMS program, said the changes shift NARMS toward a one-health approach and support a vision of NARMS as a program that helps maintain antimicrobial effectiveness for treatment of infections in humans and animals.

“I think what we’ve put together here is the logical next phase and attempt to fulfill that vision, and we look forward to continuing to work with all of you to do that as effectively as we can,” he said.

Dr. McDermott also described plans for the agency to shift toward faster publication of antimicrobial resistance data and analyses, from every two years to every two weeks.

Jay L. Garland, PhD, senior research scientist in the Environmental Protection Agency Office of Research and Development, described surface waters as a starting point of looking at antimicrobial resistance in natural environments. He said a national pilot study on surface waters will run in fiscal years 2022-25, and a final assessment in fiscal year 2025 will aid decisions as to whether to include surface water sampling in NARMS permanently.

“This is not necessarily a surveillance program,” Dr. Garland said. “This is a research program to evaluate if and what a surface water component to NARMS would look like.”

Beth Harris, PhD, associate coordinator for the National Animal Health Laboratory Network, and Dr. Olgica Ceric, of the FDA Veterinary Laboratory Investigation and Response Network, described in the meeting the ongoing analysis of antimicrobial resistance found in pathogens isolated from livestock and companion animals by veterinary clinics and diagnostic laboratories. The NAHLN pilot project was in its second year in 2019, a collaboration with NARMS and part of a broad federal plan to collaborate against antimicrobial-resistant bacteria in humans and animals.

Leslie Kenna, PhD, a spokesperson for the Food and Drug Administration Center for Veterinary Medicine, said in a message after the meeting that NARMS participants in the FDA also are examining historical Salmonella isolates, gathered from animal foods by the CVM, as well as considering more studies on animal foods. She said the agency had no plans for additional animal food sampling.

The NARMS program is a collaboration of agencies in the Centers for Disease Control and Prevention, Department of Agriculture, and FDA. The strategic plan document indicates that, to further incorporate one-health principles, NARMS officials formed new partnerships with experts in the EPA and additional departments in the CDC, USDA, and FDA.

One of those partners, the FDA Vet-LIRN program, conducted a project from 2017-18 to evaluate use of veterinary diagnostic laboratories to monitor antimicrobial susceptibility of Escherichia coli and Staphylococcus pseudintermedius isolates from dogs and Salmonella enterica isolates from any animal host.

“Approximately 5,000 isolates from clinically sick animals were collected and tested,” the strategic plan document states. “We plan to continue this work and include animal pathogen data in the NARMS annual reports.”

Further studies would evaluate more bacterial species, characterize the prevalence of resistance genes among all bacteria in samples, and examine other animals and animal products for antimicrobial resistance patterns, the plan document states.

But it also describes the potential limitations of money, competing duties, people trained for the work, laboratory capacities, and lack of isolates for testing because of a shift in human medicine toward culture-independent diagnostic tests.

Dr. McDermott, NARMS director, said adding the animal-focused laboratory networks to NARMS helps incorporate animal health into the program and is an important advance in a one-health approach.

NARMS officials are still trying to see how they can best be of value to the veterinary community, he said. But he thought everyone participating in the public meeting agreed with a vision of NARMS as an effort toward preserving antimicrobial effectiveness for treatment of infections in humans and animals and that helps minimize the harm of infections.