Implementing an antimicrobial resistance stewardship program

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At the 2025 American College of Veterinary Internal Medicine (ACVIM) Forum in Louisville, Kentucky, Alyssa Y. Castillo, MD, medical director of antimicrobial stewardship at the University of Colorado Hospital in Aurora, Colorado, presented a lecture on antimicrobial stewardship through the lens of human medicine for veterinary practice. Antimicrobial resistance (AMR), Castillo emphasized, has created an inextricable link between veterinary and human medicine, and it cannot be overlooked.

Antimicrobial resistance genes can spread between humans, animals, and shared ecosystems.¹ With extensive antibiotic use in livestock and poultry, the risk of direct transmission via food products is rising. According to Castillo, there is a case report documenting multi-drug resistant Salmonella from poultry, cephalosporin-resistant E. coli from veal calves, and carbapenem-resistant Pseudomonas and Myroides from seafood.¹

“What we know is that antimicrobial resistance genes readily develop because these microbes are incredibly smart, and they respond to the environmental pressures of antibiotics,” stressed Castillo.¹ “We know, of course, that it can transmit between humans and animals, and perhaps more importantly, that there are unique environmental reservoirs that are shared with animals and humans, and if we don't acknowledge and consider the involvement of those, our impact is certainly going to be limited, especially in a world where humans and animals are living in closer and closer proximity, or our environments are changing to force these groups in closer proximity than before.”

With an increase in AMR, antimicrobial stewardship has also seen a rise, though the practice is relatively new. According to Castillo, human medicine has seen a “steep growth” in the last 15 years in antimicrobial stewardship, most of which is tied to requirements by The Joint Commission and the Centers for Medicare & Medicaid Services.¹ This stewardship is also encouraged by the World Health Organization and Infectious Disease Society of America and is now a licensing requirement in human medicine.

Building an AMS program

The first step to implementing an antimicrobial stewardship (AMS) program is identifying a champion, as outlined by the Society for Healthcare Epidemiology of America/Infectious Diseases Society of America Clinical Practice Guidelines for Implementing an Antibiotic Stewardship Program.^1,2 “I [will] emphasize that there is tremendous power in teams,” said Castillo, explaining that selecting a multidisciplinary team is best, as well as leveraging high performers.

The next step is to obtain leadership support and buy-in. “Having leadership back you is important because they will verbally say it to peers, and that lends an air of credibility. But often, there will also need to be an ask about [full-time equivalent] (FTE) support to do this work, and potentially financial support as well, in the form of information technology or IT support,” said Castillo.

“And so, I think this is an important conversation to have early, so that you know whether you will have the backing that you need to succeed, and if not, where you might be able to get that buy-in or build that buy-in over time,” she continued.

Once that step is complete, a needs assessment should be conducted. This includes identifying where the clinic or hospital is performing highly and poorly and determining whether the clinic’s selection, dose, and duration of antimicrobials is poor or excellent. Additional questions that should be considered include whether there are areas of high prescriber variation and, importantly, if there are working structures to reliably collect this data.¹

Following this assessment, key areas of intervention should be identified to find the “lowest hanging fruit,” greatest needs, and clinical interest and momentum. To achieve this, members should implement one or more stewardship strategies.

Strategies can include education, prospective audit and feedback, integration into computerized order entry (COE), restriction or antimicrobial approval, and communications training (e.g. “How do you teach your clinicians to talk to other clinicians? How do you teach your clinicians to talk to patients and their families?”).^1,2 Handshake stewardship—which is the “idea of managing medications and restrictions while also coming in person and...shaking the hand of the people you're talking to” to build relationships—can also be implemented as a strategy.¹

Why build an AMS program?

According to Castillo, antimicrobial stewardship programs are linked to a 10% reduction in antibiotic prescriptions and a 28% reduction in antibiotic consumption.¹ “These are important numbers that I think really show that this is data driven, and [AMS programs] work and will have real, palpable impacts on your communities,” said Castillo.

References

1. Castillo AY. Joining Forces: Antimicrobial Stewardship Lessons from Human Medicine for Veterinary Practice. Presented at: American College of Veterinary Internal Medicine Forum; Louisville, KY; June 18, 2025.
2. SHEA/IDSA Clinical Practice Guidelines for Implementing an Antibiotic Stewardship Program. Infectious Diseases Society of America. August 16, 2018. Accessed June 18, 2025. https://www.idsociety.org/practice-guideline/implementing-an-ASP/