Wastewater-Based Assessment of Antimicrobial Resistance and Bacterial Communities in Urban and Rural Areas in the Province of Trento (Italy).

Wastewater-based epidemiology can supplement clinical surveillance for assessing the spread of antimicrobial resistance (AMR) across the population. We have analysed sewage samples from seven wastewater treatment plants in the Province of Trento (Italy) using both culture-based and metagenomic DNA methods to investigate the prevalence of antimicrobial resistant bacteria and resistance genes in urban and rural areas. ESBL E. coli prevalence was higher in urban areas than rural ones. As determined by qPCR and dPCR, intI1 and genes associated to widespread resistances, namely to tetracyclines (tetA), sulfonamides (sul1), and fluoroquinolones (qnrS), were abundant regardless the area of origin. Among the genes coding for clinically relevant resistances, only that related to macrolides resistance (ermB) was abundant, while the others, namely those to third-generation cephalosporins (blaCTX-M), carbapenems (blaKPC), vancomycin (vanA), and methicillin (mecA), were detected at much lower concentrations. Further, the abundances of ermB, blaKPC, and vanA were significantly higher in urban areas. 16S rRNA amplicon sequencing showed the occurrence of complex bacterial communities and the abundance of Acinetobacter, Pseudomonas and Streptococcus, genera that may include antimicrobial resistant bacteria reported in the WHO Bacterial Priority Pathogens List, with the latter showing higher prevalence in urban areas. Taken together, our data highlights the importance of implementing wastewater-based epidemiology studies across geographical areas with different characteristics in term of vocation, number of municipalities and population size, such as urban and rural ones. By providing a comprehensive understanding of AMR at the population-level, this approach can inform and support more effective public health interventions.