(Antibiotic-Resistant) E. coli in the Dutch-German Vecht Catchment─Monitoring and Modeling

Area of Science:

• Environmental microbiology
• Water quality assessment
• Public health microbiology

Background:

• Fecally contaminated waters pose risks of human infections.
• Antibiotic-resistant bacteria, such as extended-spectrum beta-lactamase (ESBL)-producing E. coli (ESBL-EC) and carbapenemase-producing E. coli (CP-EC), are emerging public health concerns.

Purpose of the Study:

• To investigate the occurrence and distribution of E. coli and antibiotic-resistant E. coli (ESBL-EC, CP-EC) in the Dutch-German transboundary Vecht River catchment.
• To model and predict bacterial concentrations in surface waters.
• To assess potential human exposure risks during recreational activities.

Main Methods:

• One-year monitoring of E. coli, ESBL-EC, and CP-EC in wastewater treatment plant (WWTP) influents and effluents, and surface waters.
• Application and parametrization of the GREAT-ER model for predicting microbial concentrations under average flow and dry summer scenarios.
• Statistical analysis of bacterial data from WWTPs.

Main Results:

• A significantly higher proportion of ESBL-EC was found in German WWTPs compared to Dutch WWTPs (factor 2).
• CP-EC were detected in 43% of influent samples.
• The GREAT-ER model accurately described microbial concentrations for the average flow scenario.
• Predicted E. coli levels exceeded the good bathing water quality threshold at less than 10% of potential swimming sites.
• Potential ingestion of ESBL-EC and CP-EC during swimming events was quantified.

Conclusions:

• Wastewater treatment plants are significant sources of E. coli and antibiotic-resistant strains in the Vecht River.
• Transboundary water management is crucial for controlling antimicrobial resistance spread.
• Recreational water use in the Vecht River may pose a risk of exposure to antibiotic-resistant bacteria, particularly ESBL-EC.