Surveillance of antibiotic resistant Escherichia coli in human populations through urban wastewater in ten European countries

Antibiotic resistance surveillance data is lacking in many parts of the world, limiting effective therapy and management of resistance development. Analysis of urban wastewater, which contains bacteria from thousands of individuals, opens up possibilities to generate informative surveillance data in a standardized and resource-efficient way. Here, we evaluate the relationship between antibiotic resistance prevalence in E. coli from wastewater and clinical samples by studying countries with different resistance situations as assessed by traditional clinical surveillance. Composite, influent wastewater samples were collected over 24 h from treatment plants serving major cities in ten European countries. Using a broth screening method, resistance to six antibiotic classes was analyzed for 2507 E. coli isolates (n = 247–252 per country). Resistance prevalence in wastewater E. coli was compared to that in clinical E. coli reported by the European Antibiotic Resistance Surveillance Network. Resistance prevalence was lower in wastewater than clinical E. coli but followed similar geographic trends. Significant relationships were found for resistance to aminopenicillins (R² = 0.72, p = 0.0019) and fluoroquinolones (R² = 0.62, p = 0.0072), but not for aminoglycosides (R² = 0.13, p = 0.31) and third-generation cephalosporins (R² = 0.00, p = 0.99) where regression analyses were based on considerably fewer resistant isolates. When all four antibiotic classes were taken into account, the relationship was strong (R² = 0.85, p < 0.0001). Carbapenem resistance was rare in both wastewater and clinical isolates. Wastewater monitoring shows promise as method for generating surveillance data reflecting the clinical prevalence of antibiotic resistant bacteria. Such data may become especially valuable in regions where clinical surveillance is currently limited.