Abstract
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 Escherichia coli 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, bla (NDM-53), bla (SHV-12), and BRP(MBL) 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.