Fish and environment samples from the Vogtland Region, Germany

Wastewater Treatment Plants (WWTP) lack effective mechanisms for the removal of antibiotic resistance bacteria (ARB) and antibiotic-resistance genes (ARGs) during sewage treatment. As a result, WWTP effluent is discharged into receiving water bodies enriched with ARB and ARGs, where they can be taken up and harbored by the indigenous river microbiome. Significant enrichment in ARBs and ARGs is regularly found in the waters and sediments downstream of WWTPs.However, whether such enrichment is also observable in the wildlife colonizing the river environments downstream of WWTPs is unknown. In theory, ARB can attach to fish skin and gills as one of the most accessible and abundant surfaces in water. The ingestion of food and water containing higher levels of ARB and ARGs can also lead to the accumulation of ARGs in the fish intestines. Depending on their lifestyle, fish can transport the ARGs and ARB to unpolluted reservoirs and introduce resistance to new environments.In this study, we explored if changes in the environmental resistome caused by WWTP effluent can also be observed in fish.