House dust—a Pandora's box of antimicrobial resistance (AMR) activity?

Abstract The presence and spread of Antibiotic Resistant Bacteria (ARB) and Antibiotic Resistant Genes (ARGs) in the environment is now recognised as one of the top ten global public health threats to humanity. In a previous study, we used citizen science and MiSeq to target 16S rRNA gene amplicons to investigate house dust microbiomes across diverse households and found a core microbiome. In this study, we used shotgun metagenomics to target antimicrobial resistance (AMR) genes in order to investigate the potential for functional differences and to test the hypothesis that there was a core resistome associated with this core microbiome, including any patterns in a core resistome in terms of likely origin and mechanisms of action. In this study we did not find a core resistome, but found that the predominant and most diverse mechanisms of Anti-Microbial Resistance (AMR) in the dust samples were antibiotic target alteration and antibiotic efflux, accounting for ∼70% of cumulative RPKMs detected, potentially representing a compromise between the certainty of working and energy investment required. Despite the core home microbiome previously detected in diverse house dust samples, there was only limited evidence for a core resistome, with only two AMR genes present in all samples.