Identification of FosA8, a Plasmid-Encoded Fosfomycin Resistance Determinant from Escherichia coli, and Its Origin in Leclercia adecarboxylata.

A plasmid-located fosfomycin resistance gene, , was identified from a CTX-M-15-producing isolate recovered from urine. Identification of this gene was obtained by whole-genome sequencing. It encoded FosA8, which shares 79% and 78% amino acid identity with the most closely related FosA2 and FosA1 enzymes, respectively. The gene was located on a transferable 50-kb plasmid of IncN type encoding high-level resistance to fosfomycin. analysis and cloning experiments identified analogues (99% identity) in the genome of , which is an enterobacterial species with natural resistance to fosfomycin. This finding adds to the list of enterobacterial species that are a reservoir of -like genes which have been captured from the chromosome of a progenitor and are then acquired by .