Non-point source fecal contamination from aging wastewater infrastructure is a primary driver of antibiotic resistance in surface waters

Damashek, Julian; Westrich, Jason R.; McDonald, Jacob M.; Teachey, Morgan E.; Jackson, Charlene R.; Frye, Jonathan G.; Lipp, Erin K.; Capps, Krista A.; Ottesen, Elizabeth A.

doi:10.1016/j.watres.2022.118853

Cited by 20 publications

(19 citation statements)

References 86 publications

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“…In contrast, Damashek et al. (2022) reported that ARG concentrations in river water correlated more strongly with markers of human influence than with ruminant or poultry markers. Similarly, Stange et al.…”

Section: Discussionmentioning

confidence: 89%

“…Both human and bovine fecal sources were associated with ARG contamination of private wells, and neither source dominated in terms of ARG co-occurrence (Table 2). In contrast, Damashek et al (2022) reported that ARG concentrations in river water correlated more strongly with markers of human influence than with ruminant or poultry markers. Similarly, Stange et al (2019) detected four ARGs in lake water that was repeatedly positive for human MST markers, while ruminant and pig markers were only detected periodically.…”

Section: Co-occurrence Of Args and Source-specific Fecal Markersmentioning

confidence: 88%

“…From a One Health perspective, the relative contribution of human versus livestock fecal sources to the occurrence of ARGs in the environment is important because it affects policy and management decisions related to land use, antibiotic use, and water quality. Microbial source tracking has been used to link human and livestock fecal sources to ARGs in surface water (Damashek et al., 2022; Li et al., 2020; Storteboom et al., 2010). However, most studies consider only a single potential fecal source (e.g., see Table 1 of Li et al., 2020).…”

Section: Discussionmentioning

confidence: 99%

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Microbial source tracking and land use associations for antibiotic resistance genes in private wells influenced by human and livestock fecal sources

et al. 2023

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Antimicrobial resistance is a growing public health problem that requires an integrated approach among human, agricultural, and environmental sectors. However, few studies address all three components simultaneously. We investigated the occurrence of five antibiotic resistance genes (ARGs) and the class 1 integron gene (intI1) in private wells drawing water from a vulnerable aquifer influenced by residential septic systems and land‐applied dairy manure. Samples (n = 138) were collected across four seasons from a randomized sample of private wells in Kewaunee County, Wisconsin. Measurements of ARGs and intI1 were related to microbial source tracking (MST) markers specific to human and bovine feces; they were also related to 54 risk factors for contamination representing land use, rainfall, hydrogeology, and well construction. ARGs and intI1 occurred in 5%–40% of samples depending on target. Detection frequencies for ARGs and intI1 were lowest in the absence of human and bovine MST markers (1%–30%), highest when co‐occurring with human and bovine markers together (11%–78%), and intermediate when co‐occurring with just one type of MST marker (4%–46%). Gene targets were associated with septic system density more often than agricultural land, potentially because of the variable presence of manure on the landscape. Determining ARG prevalence in a rural setting with mixed land use allowed an assessment of the relative contribution of human and bovine fecal sources. Because fecal sources co‐occurred with ARGs at similar rates, interventions intended to reduce ARG occurrence may be most effective if both sources are considered.

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Section: Discussionmentioning

confidence: 89%

Section: Co-occurrence Of Args and Source-specific Fecal Markersmentioning

confidence: 88%

Section: Discussionmentioning

confidence: 99%

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Microbial source tracking and land use associations for antibiotic resistance genes in private wells influenced by human and livestock fecal sources

et al. 2023

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“…Similarly, surface waters receiving wastewater effluent typically contain more ARB and resistance genes compared to unimpacted waters [ 30 , 31 ]. However, less is known about the contribution of nonpoint sources, such as septic systems [ 32 ], and few studies have directly assessed the presence and diversity of resistant organisms and genetic elements in septic tanks or effluent plumes [ 32 ]. Therefore, our analysis of a septic tank sample as source material provides key information about resistant E. coli , their genes, and community resistance markers.…”

Section: Discussionmentioning

confidence: 99%

Antimicrobial Resistance Linked to Septic System Contamination in the Indiana Lake Michigan Watershed

2023

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Extended-spectrum β-lactamases confer resistance to a variety of β-lactam antimicrobials, and the genes for these enzymes are often found on plasmids that include additional antimicrobial resistance genes (ARG). We surveyed aquatic environments in the Indiana Lake Michigan watershed in proximity to areas with high densities of residential septic systems to determine if human fecal contamination from septic effluent correlated with the presence of antimicrobial resistance genes and phenotypically resistant bacteria. Of the 269 E. coli isolated from environmental samples and one septic source, 97 isolates were resistant to cefotaxime, a third-generation cephalosporin. A subset of those isolates showed phenotypic resistance to other β-lactams, fluoroquinolones, sulfonamides, and tetracyclines. Quantitative PCR was used to quantify human-associated Bacteroides dorei gene copies (Human Bacteroides) from water samples and to identify the presence of ARG harbored on plasmids from E. coli isolates or in environmental DNA. We found a strong correlation between the presence of ARG and human fecal concentrations, which supports our hypothesis that septic effluent is a source of ARG and resistant organisms. The observed plasmid-based resistance adds an additional level of risk, as human-associated bacteria from septic systems may expand the environmental resistome by acting as a reservoir of transmissible resistance genes.

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“…The urban site, which resides downstream of a CSO and is adjacent to runoff sites but had lower concentrations and fewer detections of crAssphage and HF183/BacR287 throughout the day compared to the natural site. A study conducted by Damashek et al (2022) at 115 sites across the Upper Oconee watershed in Georgia found that highly contaminated waters were more strongly correlated with non-point sources (e.g., sewer density, septic system age) than CSOs. This study, along with our results, support that proximity to natural areas may place individuals at higher risk of exposure to human fecal contamination than previously assumed.…”

Section: Discussionmentioning

confidence: 99%

Fecal indicators and antibiotic resistance genes exhibit diurnal trends in the Chattahoochee River: Implications for water quality monitoring

et al. 2022

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Water bodies that serve as sources of drinking or recreational water are routinely monitored for fecal indicator bacteria (FIB) by state and local agencies. Exceedances of monitoring thresholds set by those agencies signal likely elevated human health risk from exposure, but FIB give little information about the potential source of contamination. To improve our understanding of how within-day variation could impact monitoring data interpretation, we conducted a study at two sites along the Chattahoochee River that varied in their recreational usage and adjacent land-use (natural versus urban), collecting samples every 30 min over one 24-h period. We assayed for three types of microbial indicators: FIB (total coliforms and Escherichia coli); human fecal-associated microbial source tracking (MST) markers (crAssphage and HF183/BacR287); and a suite of clinically relevant antibiotic resistance genes (ARGs; blaCTX-M, blaCMY, MCR, KPC, VIM, NDM) and a gene associated with antibiotic resistance (intl1). Mean levels of FIB and clinically relevant ARGs (blaCMY and KPC) were similar across sites, while MST markers and intI1 occurred at higher mean levels at the natural site. The human-associated MST markers positively correlated with antibiotic resistant-associated genes at both sites, but no consistent associations were detected between culturable FIB and any molecular markers. For all microbial indicators, generalized additive mixed models were used to examine diurnal variability and whether this variability was associated with environmental factors (water temperature, turbidity, pH, and sunlight). We found that FIB peaked during morning and early afternoon hours and were not associated with environmental factors. With the exception of HF183/BacR287 at the urban site, molecular MST markers and intI1 exhibited diurnal variability, and water temperature, pH, and turbidity were significantly associated with this variability. For blaCMY and KPC, diurnal variability was present but was not correlated with environmental factors. These results suggest that differences in land use (natural or urban) both adjacent and upstream may impact overall levels of microbial contamination. Monitoring agencies should consider matching sample collection times with peak levels of target microbial indicators, which would be in the morning or early afternoon for the fecal associated indicators. Measuring multiple microbial indicators can lead to clearer interpretations of human health risk associated with exposure to contaminated water.

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Non-point source fecal contamination from aging wastewater infrastructure is a primary driver of antibiotic resistance in surface waters

Cited by 20 publications

References 86 publications

Microbial source tracking and land use associations for antibiotic resistance genes in private wells influenced by human and livestock fecal sources

Microbial source tracking and land use associations for antibiotic resistance genes in private wells influenced by human and livestock fecal sources

Antimicrobial Resistance Linked to Septic System Contamination in the Indiana Lake Michigan Watershed

Fecal indicators and antibiotic resistance genes exhibit diurnal trends in the Chattahoochee River: Implications for water quality monitoring

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