Prevalence of antibiotics and antibiotic resistance genes in a wastewater effluent-receiving river in the Netherlands

Antibiotics are being used intensively for humans and livestock worldwide and have led to the presence of antibiotic resistance bacteria (ARB) and antibiotic resistance genes (ARGs) in the environment. Wastewater treatment plants (WWTPs) have been identified as a point source for ARB&Gs, and water catchments consequently are potential receptors of ARB&Gs. The objective of this study was to investigate the occurrence of antibiotics (macrolides, sulfonamides, tetracyclines), ARGs (ermB, sul1, sul2, tetW), and class 1 integron (targeting the integrase gene), in a Dutch river that receives wastewater treatment plant effluent. Sediment and water samples were collected during one year along the river. The WWTP significantly increased the amounts of antibiotics and ARGs in the river as compared to the upstream samples, of which the antibiotics decreased once they entered the river. ARGs were persistent in the water and sediment from the WWTP effluent discharge point until 20 km downstream. This study provides insight in the prevalence of antibiotics and ARGs in a wastewater effluent-receiving river system in the Netherlands. Even though human antibiotic usage is low in the Netherlands, antibiotics, residues of antibiotics, and ARGs are detected in the river surface water-sediment system, which shows that a river has the potential to act as a reservoir of ARGs.