Phylogenetic predictions of carbapenemase activity from the Guiana extended-spectrum (GES) family of -lactamases

Objectives We investigated the amino acid substitutions in the GES family of ESBLs that were most likely to be involved in the evolution of carbapenemase activity.Methods To identify the substitutions that are functionally important, we analysed the evolutionary history of the GES beta-lactamases using an alignment and phylogeny to identify sites in GES that show evidence of positive selection and the selected phenotypes.Results and Conclusions Data indicate that the substitutions G170S and G243A are associated with carbapenemase activity. The substitutions Q43E, E104K and T237A are most likely associated with ESBL activity.