Comparison of Two Air Samplers for Outdoor Monitoring of Low Concentration Bioaerosols and Antibiotic Resistance Genes
NATHALIE TURGEON, Mahsa Baghdadi, Samantha Leclerc, Amélia Bélanger Cayouette, Joanie Lemieux, Patrick Brassard, Stéphane Godbout, Caroline Duchaine, Université Laval
Abstract Number: 321
Working Group: Bioaerosols in Agriculture: Sources, Risks and Mitigation
Abstract
Background: Various activities such as intensive farming and wastewater treatment can generate bioaerosols containing antimicrobial-resistant microorganisms, which carry antibiotic resistance genes (ARGs). These bioaerosols can travel long distances outdoors, necessitating a better understanding of ARG emission and dispersion for the development of mitigation strategies. This study aimed to develop an outdoor air sampling strategy suitable to monitor bioaerosols (including ARGs) emitted outdoors.
Procedure: Two high flowrate air sampling devices (SASS3100 at 300 L/min and SASS4100 at 4000 L/min) were used to collect upwind, on-site, and downwind of wastewater treatment plants, animal feeding operations, and during manure spreading activities, both in an experimental wind tunnel and on farmland. Samples were analyzed using qPCR for the quantitation of total bacteria, fecal indicators, and 38 ARGs.
Findings: Both SASS3100 and SASS4100 proved suitable for outdoor air sampling near barns, wastewater treatment plants, and during manure spreading activities. However, SASS4100 underestimated concentration in the air by a factor of 5 compared to SASS3100. Nevertheless, SASS4100 exhibited better sensitivity for ARGs and fecal indicators detection due to its collection of a 13x larger air volume during a similar sampling time. Fifty percent of samples collected with the SASS4100 tested positive for ARG compared to 33% of samples collected with SASS3100 near wastewater treatment plants. Among samples collected during manure spreading in a wind tunnel with SASS4100, 35% tested positive for ARGs and 89% tested positive for fecal indicators, compared to 31% for ARGs and 87% for fecal indicators for those collected with SASS3100. Samples collected during spreading on farmland were on average 5x less concentrated compared to those collected during spreading in a wind tunnel, suggesting fugitive emissions in all directions.
Implications: This study highlights challenges and limitations of outdoor air sampling and proposes a comprehensive strategy for bioaerosols and ARGs surveillance.