Seasonal Impacts on Microbiome Diversity and Antibiotic Resistance Patterns in Aerosolized Bacteria in a Dairy Facility

HYOUNGMOOK PAK, Maria King, Texas A&M University

     Abstract Number: 399
     Working Group: Bioaerosols

Abstract
The development and spread of antibiotic resistant bacteria (ARB) pose a serious threat to animal and human health. This is especially relevant to open-stall dairy farms where environmental factors play a significant role. This study identified the presence of ARB and their dissemination within a dairy farm over three seasons. The effects of temperature, relative humidity, and wind on bacterial diversity and antibiotic resistance in aerosol and manure samples were investigated. QIIME2 analysis showed that Firmicutes was the most abundant phylum (49%) followed by Proteobacteria (29 %), Actinobacteriota (17 %), and Bacteroidota (4 %) in all samples. Kirby-Bauer disk diffusion tests revealed that all manure samples were resistant to eight different antibiotics although antibiotics were not given to the cows. Winter aerosol samples was revealed to have the lowest microbiome diversity, but also the strongest antibiotic resistance. Antibiotic resistance mapping indicates that ARB were transported with the wind generated from axial fans and natural ventilation. Computational fluid dynamics (CFD) was utilized to examine the movement of bioaerosols within and around the dairy facility. CFD simulation results were compared with experimental results, such as air velocity measurements and microbiome data, to confirm and validate their accuracies. It was shown that low temperatures and wind correspond with increased antibiotic resistance and spread of ARB in the environment.