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

Abstract

A plasmid-located fosfomycin resistance gene, <i>fosA8</i>, was identified from a CTX-M-15-producing <i>Escherichia coli</i> 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 <i>fosA8</i> gene was located on a transferable 50-kb plasmid of IncN type encoding high-level resistance to fosfomycin. <i>In silico</i> analysis and cloning experiments identified <i>fosA8</i> analogues (99% identity) in the genome of <i>Leclercia decarboxylata</i>, which is an enterobacterial species with natural resistance to fosfomycin. This finding adds <i>L. decarboxylata</i> to the list of enterobacterial species that are a reservoir of <i>fosA</i>-like genes which have been captured from the chromosome of a progenitor and are then acquired by <i>E. coli</i>.