Antimicrobial-resistant microorganisms and their genetic determinants in stormwater: A systematic review

Antibiotic-resistant bacteria and antibiotic resistance genes are abundant in stormwater, yet there is no consensus regarding how to assess their public health risks. We systematically reviewed the literature and identified 15 studies that provided quantitative occurrence and/or abundance information that was linked to stormwater. Sampling and data analysis approaches across studies varied widely, emphasizing that standardized approaches are needed to pool data across studies in a risk analysis. The amounts, timing, and intensity of precipitation within the storm sewershed for fate and transport were rarely considered and/or reported in relation to concentrations of resistance determinants among the reviewed studies. Linking hydrologic and sewershed characteristics to microbial community composition and antibiotic resistance determinants may help improve our understanding of risk and improve sampling protocols. Research needs for ARB and ARG quantification and assessment are discussed, with an emphasis on informing quantitative microbial risk assessments.