What we learned about antimicrobial resistance genes in bioaerosols: a canadian multi-centre study

Introduction. Bioaerosols are airborne particles of biological origin that can contribute to the long-distance dissemination of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs). Despite their potential impact, bioaerosols remain largely overlooked in antimicrobial resistance (AMR) surveillance.
Objectives. This transdisciplinary project aimed to characterize the role of bioaerosols in the environmental dissemination of ARGs across Canada and evaluate their presence in remote areas. Dispersion modelling, integrated risk assessment, animal models and whole-genome analyses were also included.
Methods. Air and environmental samples were collected in hospitals, wastewater treatment plants, agricultural environments, and during manure-spreading activities. Long-range ARG transport was assessed through sampling in northern territories, high-altitude locations, and over the Atlantic Ocean. Alternative air sampling strategies were evaluated using car cabin filters, HVAC filters, and trees. A panel of 40 ARGs and mobile genetic elements (MGEs) was quantified using high-throughput PCR.
Results. A total of 2,600 air and environmental samples were collected and compiled into a database available for collaboration. ARG emission rates from agricultural activities were quantified, and mitigation strategies during manure spreading were tested. Dispersion modelling was used to estimate population exposure to ARGs originating from agricultural sources. Selective culture and whole-genome sequencing linked bacterial taxa with ARGs, MGEs, genomic contexts, and antimicrobial susceptibility profiles. Horizontal gene transfer in an animal model was evaluated using airborne isolated bacteria. Results were incorporated into the Integrated Assessment Model for Antimicrobial Resistance (iAM.AMR).
Conclusion. This study demonstrates the feasibility of incorporating air into AMR surveillance using affordable sampling and analysis approaches, such as HVAC filters and high-throughput PCR. Integrated risk assessment highlights AMR as a global, cross-sectoral challenge requiring integrated solutions.