Antibiotic resistance genes in an urban stream before and after a state fair

Abstract

The global spread of antibiotic resistance genes (ARGs) concomitant with a decrease in antibiotic effectiveness is a major public health issue. While research has demonstrated the impact of various urban sources, such as wastewater treatment plant (WWTP) effluent, stormwater runoff, and industrial discharge on ARG abundance in receiving waters, the impact of short-term gatherings such as state fairs is not comprehensively understood. The objective of this research was to explore the impact of a 2-week Wisconsin State Fair gathering – over 1.1 million visitors and 7,100 farm animals – on the abundance of the ARG blaTEM, the integrase of the class 1 integron (intI1), a marker for horizontal gene transfer, and the 16S rRNA gene, a marker for total biomass, in an urban stream receiving runoff from the state fair. Stream samples downstream of the state fair were taken before and after the event and quantified via a droplet digital polymerase chain reaction. The absolute abundance of all genes was significantly higher (p<0.05) following the event. This research showcases the prevalence and persistence of ARG contamination in an urban stream before and after a state fair gathering, suggesting that short-term events can be a significant source of ARGs into the environment. HIGHLIGHTS The concentration of three genes was quantified from an urban stream before and after a short-term event which was characterized by the large presence of people and animals.; Five storms occurred during the short-term event with runoff conveyed from the fairgrounds to the urban stream.; The absolute abundance of all genes, including one antibiotic resistance gene and one integron, was elevated after the event compared to the before event.;

Keywords

• antibiotic resistome
• droplet digital pcr
• mobile genetic elements
• short-term events
• urban stormwater runoff