COMPUTATIONAL RESEARCH DAY

The advent of next-generation sequencing has made it increasingly feasible to survey microbes in situ, including inside buildings where many people spend extended periods of time. Microbes in buildings, and specifically in dust, are linked to various health outcomes, and the amount of antimicrobial chemicals in dust is associated to the abundance of antibiotic resistance genes (ARG). However, it is unknown how many of the microbes we detect using DNA sequencing are in fact viable or whether it matters for the dissemination of ARG. To our knowledge, this is the first study to examine the potential for ARG dissemination within dust microbial communities. Here, we used metagenomics to characterize dust microbial communities and their potential for ARG dissemination. Sequences were assembled, annotated and screened for integrons, transposons, plasmids and associated ARGs. These ARGs are being further investigated in the same dust samples for their potential presence and transferability via cultivation and molecular biology approaches. In 167 dust metagenomes from 63 different buildings, we found 873 ARGs within 1075 bacterial taxa. Of those, 111 ARGs were mobile, i.e., on a plasmid, transposon or integron. Among mobile ARGs, the gidB gene conferring streptomycin resistance was exclusively found on plasmids in different dust samples. Screening for streptomycin-resistant isolates revealed several streptomycin-resistant strains (including Staphylococcus) that contain plasmids potentially carrying gidB. Presence and transferability of a mobile gidB gene in those strains are currently being investigated. This study sheds light on the presence and transferability of mobile ARG in the dust microbiome.