Antibiotic Resistance Genes in Air Near Farms
DAVID KORMOS, Amy Pruden, Gabriel Isaacman-VanWertz, Jactone Ogejo, Linsey Marr,
Virginia Tech Abstract Number: 73
Working Group: Bioaerosols
AbstractThe spread of antimicrobial resistance is a growing global threat according to the World Health Organization. Previous studies have mainly focused on antibiotic resistant genes (ARGs) in water and soil, while less is known about ARGs in the atmosphere. Their potential for long-distance transport is especially concerning. We are characterizing ARG emissions to the atmosphere at a swine farm and a dairy farm over the course of a year. We collected particles using a custom-built sampler with a cascade impactor and collected culturable bacteria using a viable Andersen impactor. At the swine farm, concentrations of total bacteria in terms of 16S rRNA ranged from 10
5gc/m
3 to 10
8gc/m
3, with concentrations decreasing as particle size decreased between 5 and 0.5μm. The concentration of the ARG
sul1 reached a maximum of ~10
4gc/m
3 and decreased with particle size. At the dairy farm, total 16S rRNA concentrations ranged from ~10
5gc/m
3 to ~10
6gc/m
3 and decreased with distance from 0 to 100m away from the animal pen. The concentration of
sul1 decreased as particle size decreased and was highest at an upwind site and at 0 and 50 m downwind of the sick pen. No culturable
E. Coli was observed at the dairy farm in fall and winter, but growth on
S. aureus-selective medium was observed in particles >1.1μm in the fall and >3.3μm in the winter. The ratio of resistant to non-resistant bacteria was higher in the fall. At the swine farm, culturable
E. Coli was observed in particles >2.1μm and colonies on
S. aureus-selective media were observed in particles >1.1μm in fall and winter. The ratio of resistant to non-resistant
E. Coli colonies was the same in fall and winter and was higher than the ratio of resistant to non-resistant bacteria on the
S. aureus-selective media.