A Natural Novel Mutation in the bla NDM-5 Promoter Reducing Carbapenems Resistance in a Clinical Escherichia coli Strain

The worldwide emergence of New Delhi metallo-β-lactamase (NDM) is of great concern. NDM could hydrolyze almost all β-lactam antibiotics, compromising antimicrobial treatments for patients with severe infection (1). Few NDM inhibitors are effective for treating infection caused by carbapenem-resistant bacteria, and no promising compounds have been developed in the process as future NDM inhibitors (2). To the best of our knowledge, no report of a naturally inactivated blaNDM gene has been described so far. In this study, we identified a novel mutation in the promoter of IncX3-plasmid-carrying blaNDM-5 that leads to the reduction of carbapenems resistance in a clinical Escherichia coli strain.