NDM1

NDM-1, or New Delhi metallo-beta-lactamase-1, is a gene encoding the NDM-1 enzyme, a metallo-beta-lactamase that hydrolyzes beta-lactam antibiotics, including most penicillins, cephalosporins, and carbapenems. The enzyme requires zinc for activity and belongs to class B beta-lactamases. Bacteria carrying blaNDM-1 often show resistance to multiple drug classes, limiting treatment options.

NDM-1 is carried on plasmids, enabling horizontal transfer between diverse Gram-negative bacteria, such as Klebsiella pneumoniae, Escherichia coli, and other Enterobacterales, and has been found in non-fermenters as well. The global spread has been linked to international travel and medical tourism, with outbreaks in hospitals in multiple regions. The gene was first identified in 2008 in a Klebsiella pneumoniae isolate from a patient who had received care in India; its naming reflects New Delhi.

Detection relies on molecular methods targeting blaNDM-1 and on phenotypic carbapenemase tests; confirmatory testing and localization studies are used in clinical microbiology laboratories. Treatment options for NDM-1–producing infections are limited; clinicians may use combinations or non-beta-lactam agents based on susceptibility testing, and newer regimens such as beta-lactam–beta-lactamase inhibitor combinations may be considered in some cases (for example, aztreonam in combination with a beta-lactamase inhibitor when feasible).

Public health responses emphasize surveillance, infection-control measures, antimicrobial stewardship, and rapid diagnostic testing to limit transmission. Research continues to monitor the emergence of new NDM variants and to develop effective therapies.