Genetic and Functional Characterization of an MCR-3-Like Enzyme-Producing Escherichia coli Isolate Recovered from Swine in Brazil

Abstract

A collection of 126 pigs was screened for carriage of colistin-resistant <i>Enterobacteriaceae</i> in a farm in Minas Gerais, Brazil. Out of this collection, eight colistin-resistant <i>Escherichia coli</i> 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 function similar to that of MCR-1 and MCR-2 as a result of the addition of a phosphoethanolamine group to the lipid A moiety. Genetic analysis showed that the <i>mcr-3.12</i> 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 is the first to demonstrate the functionality of this group of enzymes as a phosphoethanolamine transferase.