Bacteria are everywhere on the planet: on and in other living beings, but also in the air, the water and the soil. They are not all relevant for humans and animals – but without bacteria there would be no life on earth. Antibiotic-resistant bacteria (both those that cause disease and those that don’t) can be found in the most remote corners of the planet, because microbes and fungi have been producing antibiotics themselves for billions of years to protect themselves. However, various forms of bacterial resistance have also evolved since humans started to use antibiotics in order to treat themselves and their pets or farm animals.

Antibiotic-resistant bacteria and antibiotics are excreted in the urine or faeces. They pass through the sewer system into the wastewater treatment plants (WWTPs). The 700 or so WWTPs in Switzerland filter out up to 99% of the resistant bacteria, meaning that few resistant bacteria enter water bodies (rivers, lakes etc.) in the effluent of the WWTPs.

Further discharges into surface waters can be caused by runoff from the soil after heavy rains. WWTPs and municipalities need to collaborate closely to minimise these rainwater-induced discharges of untreated wastewater into rivers and lakes. This would also reduce the seepage of antibiotic-resistant bacteria from slurry and manure in the fields.

Like many other drugs and chemicals, antibiotics are not completely eliminated from wastewater by the WWTPs, and can have a negative impact on aquatic organisms. In order to improve wastewater treatment in this area too, selected WWTPs in Switzerland are currently being upgraded and modernised to improve their effectiveness in removing numerous micropollutants, including resistant bacteria, from the water. In the medium term, this should reduce the occurrence of antibiotic residues and resistant bacteria in the water bodies…find out more