Genetic and functional characterization of an MCR-3-like producing Escherichia coli recovered from swine, Brazil [PublishAheadOfPrint]

A collection of 126 pigs were screened for carriage of colistin-resistant Enterobacteriaceae in a farm in Minas Gerais, Brazil. Out of this collection, eigth colistin-resistant Escherichia coli isolates were recovered, including one from Minas Gerais State, producing a new MCR-3 variant (MCR-3.12). Analysis of the lipopolysaccharide revealed that MCR-3.12 had a similar function as MCR-1 and MCR-2 by adding a phosphoethanolamine group to the lipid A. Genetic analysis showed that the mcr-3.12 gene was carried by an IncA/C₂ plasmid and was embedded in an original genetic environment. This study reports the occurrence of the MCR-3-like determinant in South America and firstly demonstrates the functionality of this group of enzymes as a phosphoethanolamine transferase.

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