| dc.description.abstract | Widespread use and availability of antibiotics has led to infectious and pathogenic bacteria developing antibiotic resistance. Various environmental factors, such as temperature, relative humidity, and wind, can also induce stress in bacterial cells, activating antibiotic resistance mechanisms to increase their survivability against harsh and extreme conditions. These bacteria can survive for a longer time and travel further distances if they become airborne, which is the case in many livestock facilities. Despite the increasingly recognized role of the environment in spreading pathogens, the mechanisms underlying environmental effects on the transmission of airborne bioparticles including viruses, bacteria and fungi remain poorly understood. In this research, aerosol, manure, and lagoon samples were collected from multiple locations throughout an open stall dairy facility in summer, winter, and spring to estimate the microbiome richness, taxonomic diversity, and antibiotic resistance. Temperature, relative humidity, and air velocity measurements at each sampling location were also recorded to examine environmental effects. Computational fluid dynamics (CFD) was utilized to investigate air flow movements and patterns within and around the dairy facility. CFD simulation results were compared with experimental air velocity measurements to confirm and validate their accuracies. Among the aerosol samples from three different seasons, samples collected in winter had the highest number of sequenced denoised reads, but had the least bacterial diversity. Disk diffusion test against eight different antibiotics revealed that bacteria showed strongest resistance in the winter aerosol samples and weakest resistance in spring aerosol samples. Air velocities obtained by CFD simulations using ANSYS closely matched with experimental measurements around the dairy barn, but were slightly off inside due to the lack of obstacles in the simulations. It was shown that in winter, there was a high turbulence in the western side of the barn where also the strongest antibiotic resistance was detected in aerosol samples. Antibiotic resistant bacteria were revealed to be transported with air flow from the dairy barn out into the environment. This research as able to demonstrate the correlation of environmental factors on the microbiome diversity and antibiotic resistance of bacteria samples collected in different seasons as well as show the CFD can be used to estimate and model the air flow around a dairy facility accurately. | |
