Antimicrobial-resistance genes in bioaerosols from Livestock Operations

Antibiotic resistance is increasing, and infections with resistant microorganisms that are typically related to hospital settings are now being seen away from hospital settings. There is a pressing need to understand factors that contribute to the rise in antibiotic resistance. It is known that the use of antibiotics, the presence of residuals of antibiotics, high microbial density, and human activity are potentially contributing to antibiotic-resistant microorganisms. Livestock operations are known to produce bioaerosols and emit them via their ventilation systems. These operations are thought to be contributors to the development of antimicrobial resistance genes.
There is compelling evidence that workers’ health and animals in confinement buildings are affected by bioaerosol exposure. Livestock operations have been shown to develop and emit bioaerosols with antibiotic resistant and non-antibiotic-resistant microorganisms. However, the identity, abundance, dispersion, and role of ARG emitted with bioaerosols from livestock operations is unknown.
Two swine and poultry barns were visited twice in summer and twice in winter to determine the presence and dispersion of ARGs. Samples were collected at the exhaust, at 10m, 100m, and 1km from the exhaust, and on the opposite side of the building exhaust (n=8). The samples were attained via a high-volume SASS 3100 air sampler and real-time air quality monitoring. Five swine gestation barns using stall housing and five using group housing were visited once in winter, with samples being collected in triplicate. DNA was extracted from the SASS filters for 16S analysis, and ARGs were evaluated using Takara SmartChip high-throughput Real-Time qPCR, and MiSeq sequencing. Bioinformatics was carried out using mothur and imported into the R environment for further analysis.
As the distance from the exhaust increased, total bacteria and particulate matter decreased. The bacteria and ARG diversity changed with distance and livestock housing type. These results enhance our understanding of the role of bioaerosols in AMR and potential sources of ARGs.