Flushing into the ocean: Tracking antibiotic resistance in the marine environment

Avløpsvann vil inneholde avføringen fra befolkningen som bor i et bestemt område. Dermed kan prøver av avløpsvann brukes til overvåking av antibiotikaresistens hos bakterier som finnes i denne befolkningen. Selv renset avløpsvann som slippes ut, er en viktig kilde til forurensning av det marine miljøet med antibiotikaresistente bakterier og gener for antibiotikaresistens. I Res-Marine-prosjektet optimaliserte vi metoder for overvåking av antimikrobiell resistens i avløpssystemer og viste at antibiotikaresistens er utbredt blant sykdomsfremkallende bakterier påvist i avløpsvann. Vi viste videre at avløpsvann fra sykehus er en kilde til klinisk viktige patogener og nye antibiotikaresistensfaktorer, som når det marine miljøet også gjennom renset avløpsvann. Faktisk påviste vi den samme klonen av en multiresistent E. coli i renset avløpsvann som forårsaket utbrudd på sykehus i Bergen, noe som tyder på et behov for bedre strategier for håndtering av sykehusavløpsvann. Vi viste også at mobilt DNA som bærer resistensfaktorer fra sjøvann, kan overføres til bakterier som finnes i menneskekroppen gjennom direkte kontakt. Prosjektet vårt viste og at selv i på forhånd urørte miljøer som Arktis, førte forurensning fra avløpsvann til økt antibiotikaresistens i fjordsedimentenes mikrobielle samfunn. Våre funn understreker behovet for tiltak for å begrense spredning av resistens i miljøet gjennom avløpsvann. Res-Marine-prosjektet optimaliserte metoder som kan tas i bruk av lokale myndigheter for overvåking av resistens i miljøet. Prosjektet har økt bevisstheten om problemet med miljøspredning av antimikrobiell resistens og peker sterkt mot en Én helse-tilnærming («One Health») i studiet av antimikrobiell resistens.

The Res-Marine project significantly enhances our understanding of the largely unknown situation about the prevalence and persistence of antibiotic resistance in wastewater treatment systems and the impacted coastal environments in Norway. It shows that resistance towards last resort antibiotics is prevalent in pathogens found in sewage. It also shows that hospital effluent is a major source of clinically important pathogens reaching the marine environment. It demonstrates the impact of wastewater pollution on Arctic fjord and highlights the need for protection of the Arctic environment. The methods and data obtained will serve as basis for local authorities for surveillance of antimicrobial resistance in the environment, especially for the new EU wastewater directive 2025. The project highlights the need for mitigation strategies to stop/reduce the spread of antibiotic resistance into the marine environment in Norway through sewage and especially the hospital sewage. The project had direct implications for several Sustainable Development Goals, particularly Good Health and Well-being, Clean Water and Sanitation, Life Below Water and Life on Land.

Wastewater treatment systems in Norway rarely carry out disinfection, before discharge of treated effluents into the aquatic environments. Clinically relevant antibiotic resistance genes (ARGs) and resistant pathogens are disseminated into the environment via wastewater-related discharges, their fate in the environment, especially the marine environment, is largely unknown. The overall aim of Res-Marine project is to understand the role of the marine environment in dissemination and emergence of antibiotic resistance. The Res-Marine project will analyze wastewater effluents, impacted marine water and sediments, as well pristine Polar regions, using a time series sampling strategy and state of the art methodologies like genomics, shotgun metagenomics, functional metagenomics and plasmid capture; in order to understand the persistence of pathogens and antibiotic resistance genes in the marine environment. We will characterize novel antibiotic resistance factors and plasmids from the wastewater/sea interface that may end up in clinics in future. Further, we plan to design an assays for screening of identified genetic markers in the environment as well as build a computational model for understanding and predicting the dynamics of antibiotic resistance genes and antibiotic resistant bacteria in the marine environment. The outcomes of Res-Marine project will significantly enhance our understanding of antibiotic resistance in wastewater treatment systems and the impacted coastal environments in Norway. Data obtained in Res-Marine project would serve as a basis for the local authorities to undertake appropriate research, monitoring as well as proper prevention and mitigation actions and may provide a framework for surveillance of antibiotic resistance in the marine environment.