Interventions Targeting the Beef Feedlot Environment to Control Antimicrobial Resistance: A Mathematical Modelling...

Area of Science:

• Environmental microbiology
• Mathematical modeling of infectious diseases
• Antimicrobial resistance dynamics

Background:

• Livestock are a concern for antimicrobial-resistant bacteria and genes.
• Antimicrobial resistance genes persist in cattle pens for years post-removal.
• Global efforts focus on antibiotic use and alternatives in livestock.

Purpose of the Study:

• To develop a mathematical model for antimicrobial-resistant enteric bacteria dynamics.
• To predict and explore resistance gene growth in food-producing animal environments.
• To assess the impact of environmental factors and hygiene on resistance.

Main Methods:

• Developed a difference equation-based compartmental modeling framework.
• Derived an algebraic formula for the relative rate of growth of resistant bacteria (R^AMR).
• Modeled tetracycline-resistant Escherichia coli dynamics in feedlot environments.

Main Results:

• R^AMR > 1 (growth) for tetracycline-resistant E. coli is possible under various conditions, even without antimicrobial use.
• The model reproduced field data showing rapid resistant E. coli growth.
• Hygiene measures like pen floor scraping can significantly reduce resistant E. coli, especially in cold climates.

Conclusions:

• Farm environments like feedlots can support antimicrobial-resistant bacteria persistence and growth without antibiotic use.
• The system demonstrates resilience, making complete elimination difficult.
• Environmental factors, particularly climate (e.g., lack of freeze-thaw cycles), impact the effectiveness of cleaning measures.