Impacts of antimicrobial stewardship programme intensity level on antimicrobial prescribing rates in general veterinary practice

Antimicrobial resistance (AMR) is a major health threat globally. Although essential in human or veterinary medicine, the misuse of antimicrobials cannot be justified. Antimicrobial stewardship programmes (ASPs) have been implemented in medical practice over the past decade to reduce selection pressure for the development of pathogens resistant to multiple drugs and improve antimicrobial prescribing. Large-scale implementation and assessment of antimicrobial stewardship programmes (ASPs) have not been reported. The study aimed to investigate how to reduce antimicrobial use in the long-term through the enrolment of a corporate group of general practice veterinary clinics in an ASP trial in 2018. The veterinary clinics were assigned to one of three levels of ASP intervention: education only (CON), which acted as a control; intermediate (AMS1) and intensive (AMS2). De-identified prescribing data (1 October 2016 to 31 October 2020) for dogs and cats were sourced from VetCompass Australia. Antimicrobial prescribing records, from the pre-trial, two-year period (1 October 2016 to 30 September 2018), were compared with the implementation period (1 October 2018 to 31 July 2019) and the post-implementation period (1 August 2019 to 31 October 2020).

On initiation of the implementation period, a prescribing poster was sent to all clinics. The education or control intervention consisted of eight webinars. In addition to the poster and webinar series, AMS1 and AMS2 involved appointing stewardship champions, who coordinated a traffic light system to categorise low, medium, and high-importance antimicrobials. The AMS2 intervention went further by restricting the use of antimicrobials with a high-importance rating. Clinics were allocated to one of the three interventions using a random number generator. However, this was then reviewed and altered depending on various human factors that could affect clinic ability to implement the programme.

The study found that an AMS intervention bundle can impact prescribing behaviour in general veterinary practice. The overall pre-intervention incidence rate of antimicrobial prescribing (3.7 per 100 consultations) declined to 2.4 per 100 consultations during the implementation period, and even further post-implementation (1.9 per 100 consultations). A greater reduction in overall antimicrobial use was found in AMS2 compared with CON. AMS1 saw a 17% increase in prescribing of low-importance antimicrobials during the implementation period but no change in medium- and high-importance antimicrobial prescribing. Post-implementation, in AMS1, there was a 10% increase in low-importance antimicrobials and a 5% increase in medium-importance antimicrobials but no change in high-importance antimicrobial prescribing. A change in the prescribing rate of high-importance antimicrobials was only seen in AMS2 (24% reduction in both implementation and post-implementation periods, compared with CON). Furthermore, in the AMS2 group, during the post-implementation period, there was a 6% reduction in medium-importance antimicrobial prescribing and 12% increase in low-importance antimicrobial prescribing.

Limitations of the study are discussed by the authors, which include the approach used, with the identification of practices that needed to start at a lower intervention level initially (unlike a randomised controlled study); not knowing which interventions were fully implemented in each clinic, as well as not being able to evaluate the effectiveness of each intervention in the bundles. Further research is recommended, including a participant evaluation survey to help determine which elements were most useful within veterinary practice to guide future AMS intervention. Overall, the AMS interventions had a positive impact in a large group of general veterinary practices, a decline in overall antimicrobial use was seen as well as a shift towards use of antimicrobials rated as low importance, with the greatest impact in high-prescribing clinics.

Hardefeldt LY, Hur B, Richards S, Scarborough R, Browning GF, Billman-Jacobe H, Gilkerson JR, Ierardo J, Awad M, Chay R and Bailey KE (2022) Antimicrobial stewardship in companion animal practice: an implementation trial in 135 general practice veterinary clinics JAC – Antimicrobial Resistance