NDM2

NDM-2 is a variant of the New Delhi metallo-beta-lactamase (NDM) enzyme, encoded by the bla_NDM-2 gene. It belongs to a family of metallo-beta-lactamases that confer high-level resistance to many beta-lactam antibiotics, including most penicillins, cephalosporins, and carbapenems, in Gram-negative bacteria such as Klebsiella pneumoniae and Escherichia coli. Like other NDM enzymes, NDM-2 is zinc-dependent and hydrolyzes the beta-lactam ring, rendering many antibiotics ineffective. NDM-2 differs from the prototypical NDM-1 by sequence variations in the enzyme, which can alter its substrate range and susceptibility to inhibitors.

NDM-2–producing bacteria are typically associated with plasmids, facilitating horizontal transfer between species and through bacterial populations. Since its first descriptions in the early 2010s, NDM-2 has been reported in multiple countries, but it is less prevalent than NDM-1. The spread of NDM-2 is part of the broader global issue of carbapenem-resistant Enterobacterales.

Clinical management relies on accurate detection and infection-control measures. Molecular methods such as PCR targeting bla_NDM-2, as well as phenotypic carbapenemase tests, are used for diagnosis. Treatment options are limited and often require combination therapy, with antibiotics such as polymyxins (e.g., colistin), tigecycline, and newer agents like cefiderocol considered in certain cases, guided by susceptibility testing. Aztreonam may retain activity in the absence of coexisting beta-lactamases that degrade it, but this is context-dependent. Preventing transmission through stewardship and infection control remains essential.