A clinical Escherichia coli isolate resistant to all β-lactams including carbapenems expressed a novel metallo-β-lactamase MBL NDM-4 differing from NDM-1 by a single amino acid substitution Met154Leu. NDM-4 possessed increased hydrolytic activity toward carbapenems and several cephalosporins as compared to NDM-1. This amino-acid substitution was not located into the known active sites of NDM-1 indicating that remote amino-acid subtitutions might also play a role in the extended activity of this MBL.
via NDM-4 metallo-ß-lactamase with increased carbapenemase activity from Escherichia coli.
