Geospatial Patterns of Antimicrobial Resistance Genes in the US EPA National Rivers and Streams Assessment Survey

Area of Science:

• Environmental science
• Microbiology
• Public health

Background:

• Antimicrobial resistance (AR) is a growing global threat driven by antimicrobial overuse.
• Environmental spread of AR genes (ARGs) and their impact on public health remain poorly understood.
• Aquatic environments receiving waste are potential hotspots for ARG dissemination.

Purpose of the Study:

• To investigate national patterns of ARGs and the integrase gene (intI1) in US rivers and streams.
• To identify environmental factors influencing the distribution of ARGs.
• To inform public health risk assessments and mitigation strategies for AR.

Main Methods:

• A stratified, probabilistic survey of nearly 2000 sites across 1.2 million kilometers of US rivers and streams.
• Quantification of the class I integron integrase gene (intI1) and several ARGs.
• Analysis of geographic and environmental condition patterns in gene distribution.

Main Results:

• National distribution patterns of intI1 and ARGs were determined for the first time.
• Higher concentrations of ARGs were found in eastern US regions compared to western regions.
• Rivers and streams in poorer condition exhibited greater ARG concentrations.

Conclusions:

• Environmental ARGs are unevenly distributed across the US, with higher levels in the East and degraded aquatic ecosystems.
• Findings provide critical data for assessing public health risks associated with environmental ARGs.
• This research supports the development of targeted mitigation strategies to combat antimicrobial resistance spread.