Characterization of transferable antibiotic resistance plasmids in airborne particulate matter from ICU environments

Intensive care units (ICUs) are critical environments for the emergence of antibiotic-resistant bacteria, with numerous studies focusing on resistant pathogens in these settings. However, transferable antibiotic resistance plasmids (TARPs)-regardless of their origin from pathogenic or non-pathogenic bacteria-are key drivers of resistance gene dissemination and the emergence of resistant strains. This study investigated TARPs in ICU air. Air samples were directly used to isolate resistant plasmids using <i>Escherichia coli</i> CV601 as the recipient. Plasmid types, antibiotic resistance genes (ARGs), and virulence factors were identified through sequencing, and resistance phenotypes were validated. A total of 30 distinct plasmid types were detected, with IncX3 being the most prevalent. Among 245 ARGs identified, <i>bla</i> _NDM-53, <i>bla</i> _SHV-12, and <i>BRP(MBL)</i> were dominant. Phylogenetic analysis indicated that these TARPs originated from bacteria commonly colonizing human mucosa. ICU airborne TARPs may significantly contribute to the spread of ARGs and antibiotic resistance transmission.