Detection of Morganella morganii bound to a plastic substrate in surface water

Objectives: Around the globe, escalation in rare opportunistic microbial infections is alarming as they are heading steadily towards ’superbug’ status. In aquatic ecosystems, plastic fosters multidrug-resistant pathogenic bacteria and plays a significant role in trafficking antibiotic-resistant genes. In this study, we focused on a multidrug-resistant bacterial strain isolated from microbial communities found on plastic substrates of a volcanic lake in central Italy. Methods: Extended-spectrum beta-lactamase-producing strains were isolated from both raw water and plastic substrates for a comparative investigation using microbiological and molecular methods, and an- tibiotic susceptibility profiling was performed against a panel of ten antibiotics. Results: Molecular identification and Basic Local Alignment Search Tool analysis confirmed an almost identical sequencing pattern of two isolated strains and their homology with Morganella morganii . An- tibiotic susceptibility tests revealed their resistance to almost all tested antibiotics. Class 1 integron- associated gene (intI1) and seven antibiotic resistance genes were detected in both strains, confirming their superbug status. Conclusion: To our knowledge, this is the first study on the characterization of extended-spectrum beta- lactamase-producing M. morganii isolated from the biofilm of plastic substrates, depicting the poten- tial toxicity of plastic in harbouring and dispersing virulent, multidrug-resistant, opportunistic human pathogens.