Novel resistance ICEs carrying the metallo-β-lactamase gene from an ST235 sublineage.

FIM-1 is an acquired metallo-β-lactamase identified in a multidrug-resistant (index strain FI-14/157) of clinical origin isolated in 2007 in Florence, Italy. Here we report on a second case of infection by FIM-1-positive (FI-17645), which occurred in 2020 in the same hospital. Both FIM-1-positive strains exhibited resistance to all anti- antibiotics except colistin and cefiderocol. Comparative genomic characterization revealed that the two FIM-positive strains were closely related [core genome difference, 16 single nucleotide polymorphisms (SNPs)], suggesting a local circulation of similar strains. In the FI-14/157 index strain, the gene was associated with an IS-like element that likely contributed to its capture downstream an integron platform inserted aboard a Tn-like transposon, named Tn, which was associated with a large integrative and conjugative element (ICE) named ICE.1, integrated into an site located within the 3'-end of tRNA CCC gene of the chromosome. In strain FI-17645, was associated with a closely related ICE, named ICE., integrated in the same chromosomal site. Similar ICE platforms, lacking the -containing region, were detected in other ST235 strains from different geographic areas, suggesting a common ancestry and underscoring the role of these elements in the dissemination of resistance genes in . Sequence database mining revealed two draft genomes, one from Italy and one from the USA (both isolated in 2012), including a contig with , suggesting that this resistance gene could have a broader distribution than originally anticipated.