Data on acquired resistance genes was collected from databases (http://faculty.washington.edu/marilynr/, http://ardb.cbcb.umd.edu/ and http://www.lahey.org/Studies/) and published papers including reviews.5 (link),6 (link) All sequences were collected from the NCBI nucleotide database (http://www.ncbi.nlm.nih.gov/nuccore/) and used to build the ResFinder database. To our knowledge, we have created the largest collection of acquired antimicrobial resistance genes (see Table S1, available as Supplementary data at JAC Online).