Cigarette smoking promotes the spread of antimicrobial resistance in the human lung and the environment

While immediate health risks of cigarette smoking are well-established, indirect health impacts of cigarette-derived pollutants through proliferation of antimicrobial resistance (AMR) among bacteria remain understudied. Here, exposure to cigarette smoke condensate at relevant concentrations resulted in >2-fold elevated transfer rates of a multi-drug-resistance encoding plasmid between Pseudomonas strains in artificial lung sputum medium. This effect was connected to elevated reactive oxygen species production as part of the bacterial stress response when exposed to cigarette-derived toxicants. Similar results were obtained under exposure to cigarette ash leachate in environmental medium. Further, used cigarette filters enriched in toxic residues were submerged in a wastewater stream, and colonized by altered microbial communities compared to unused filters. These communities were significantly enriched in pathogens and AMR. Hence, filters could facilitate hitchhiking of high-risk bacteria to novel environments. We demonstrate that cigarette-derived compounds can promote the spread of AMR within the human lung and natural environments.