Communities of plasmids as strategies for antimicrobial resistance gene survival in wastewater treatment plant effluent

A study of 173 plasmids transferred from wastewater treatment plant effluent into E. coli revealed numerous multidrug-resistant and large mega-plasmids, most existing as part of plasmid communities rather than alone. These communities allow non-resistant plasmids to persist under antimicrobial pressure by co-existing with resistant counterparts, highlighting a previously unrecognised survival strategy. The findings underscore the high variability of plasmids, their capacity to carry mobile elements and resistance genes, and the need to better understand their ecology, persistence, and role in horizontal gene transfer across different environments.