Wastewater-Based Assessment of Antimicrobic Resistance Circulation in Trento Province (Italy)

Background and Aims During the recent pandemic, sewage surveillance contributed to the assessment of SARS-CoV-2 spread and variants, leading to increased interest in Wastewater Based Epidemiology (WBE). The potential of WBE in monitoring antimicrobic resistance (AMR), has been recently recognized by the proposed revision of the EU Urban Waste Water Treatment Directive (UWWTD) and the Italian National Action Plan on Antimicrobial Resistance (PNCAR), both including surveillance programs based on urban sewage. This work reports the circulation of AMR genes in the province of Trento through the analysis of samples from municipal wastewater treatment plants (WWTPs) collecting sewages from urban (95.000-120.000 PE) and rural areas (1.000-7.000 PE). Methods AMR occurrence was evaluated by bacterial cultures (i.e. WHO Tricycle Protocol for ESBL-E. coli), as well as qPCR of AMR-genes (i.e. intI1, sul1, tetA, mecA, blaKPC, blaCTX-M, vanA). Further, bacterial community dynamics were investigated by qPCR and NGS-based profiling of 16S rRNA genes. Results IntI1, commonly used as indicator of anthropogenic impact, was the most abundant gene followed by sul1 and tetA, ARGs conferring resistances frequently detected in the environment. Indeed, these targets did not show significant differences among WWTPs. On the contrary, clinically relevant targets, namely mecA, blaKPC, blaCTX-M, and vanA, showed much lower concentrations. Nevertheless, blaKPC, and vanA seemed to be enriched in samples coming from WWTPs serving larger urban areas, particularly one that includes a large hospital. Conclusions This work highlights how AMR genes recovered from municipal wastewater may provide useful information to assess AMR circulation among the population