Exposure factors associated with antimicrobial resistance and identification of management practices for preharvest mitigation along the broiler production systems: a systematic review.

Objectives: This systematic review aims to [1] determine the risk of AMR development associated with AMU and other exposure factors in broiler, and [2] identify the best management practices to mitigate preharvest AMR development in enteric bacteria along the broiler production.

Methods: Study selection criteria was PECO/PICO framework and included broiler (population), AMU or other management practices (exposure or intervention), organic or antibiotic-free production (comparator), and presence of AMR-enteric bacteria/genes (outcome). Peer-reviewed primary research studies were searched in PubMed on December 19, 2022, and AGRICOLA, Embase, Scopus, and Web of Science on February 10, 2023. The risk of bias in studies was assessed using modified ROBIS-E risk of bias assessment tool. Results were synthesized and presented narratively according to PRISMA-2020 guidelines.

Results: 205/2699 studies were subjected to full-text review, and fifteen included in the final synthesis. Enteric bacteria Escherichia coli, Salmonella and Campylobacter exhibited AMR and multidrug resistance (MDR) against several critically important antimicrobials (aminoglycoside, cephalosporin, chloramphenicol, macrolide, penicillin, quinolone, tetracycline, and sulfonamide) for human health. The risk of AMR development in bacteria is potentially higher with AMU in broiler production. Substandard farm management practices, poor biosecurity measures, and conventional production system are also associated with dissemination of AMR in bacteria.

Conclusion: Findings indicate, AMU exposure is associated with considerably higher risks of AMR development in enteric bacteria. Antimicrobial stewardship, organic/antibiotic-free broiler production, good farm management practices, and high-level biosecurity measures can substantially mitigate preharvest AMR development in enteric bacteria. However, most of the studies are cross-sectional and therefore, causal inference cannot be established.