UC Davis

Antimicrobial stewardship programs integrate multiple disciples that aim to preserve the effectiveness and availability of antimicrobial drugs, through judicious antimicrobial use, proper disease diagnosis, and medical decision-making while preserving animal health and welfare. This dissertation presents different strategies to improve antimicrobial stewardship on dairy farms using educational, epidemiological, and genomic approaches. My doctoral dissertation projects have common focus research on antimicrobial stewardship and antimicrobial resistance on the dairy farm and are divided into four main strategic areas: 1) Development and evaluation of on-farm animal health and diagnostic training program for farm workers; 2) Use of a scoping review to improve accuracy and consensus for diagnosis of metritis in dairy cows; 3) Genomic screening of Escherichia coli form cows with metritis, with a focus on AMR and virulence genes; 4) Reducing the consequential effect of antimicrobial use on dairy farms through novel approaches to degrade antimicrobials in waste.

The findings of this dissertation highlight the current disparity in robust and clear criteria used to diagnose puerperal metritis in literature, with a considerable variation in the clinical signs of disease used for diagnosis and consequent treatment decisions; the importance of educational training programs targeting farmworkers to improve antimicrobial stewardship knowledge, that considers individual factors, farm size management practices, among other factors. This dissertation also contributes to the understanding of the role of Escherichia coli in the pathogenesis of metritis in dairy cattle, showing a high genetic diversity in the pangenome. Lastly, it shows that alkaline pH and heat treatments might be alternative cost-effective on-farm strategies that could increase the degradation of antimicrobials in waste milk.