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Volume 32, Number 6—June 2026
Etymologia
New Delhi metallo-β-lactamase 1 [nū del′ē mә-tal′ō bāt′ә lak′tә-mās wuhn]
Suggested citation for this article
New Delhi metallo-β-lactamase 1 (NDM-1) is an Ambler class B β-lactamase enzyme named after the capital of India, New Delhi. This class of enzymes requires Zn2+ ions for activity, hence metallo-β-lactamase. The transmissible genetic element–associated blaNDM-1 encodes NDM-1, which confers resistance to all β-lactam antibiotics except monobactams. The gene was first identified and reported in 2009 from a urinary tract infection–causing carbapenem-resistant Klebsiella pneumoniae isolate. Reportedly, the blaNDM-1–harboring K. pneumoniae strain (linked to sequence type 14) was isolated from an India-born patient in Sweden who acquired a urinary tract infection while visiting New Delhi.
NDM’s eponymous association with New Delhi sparked anguish among authorities in India, who saw the terminology as a means to tarnish the country’s growing medical tourism industry. Some suggested changing the term to PCM (plasmid-encoding carbapenem-resistant metallo-β-lactamase). However, the sporadic concerns regarding nomenclature were never formally addressed, and the term NDM-1 eventually gained universal acceptance within the scientific community. By the end of 2025, >63 distinct NDM variants had been reported worldwide and sequentially designated NDM-1 through NDM-63.
References
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- Mohapatra PR. Metallo-β-lactamase 1—why blame New Delhi & India? Indian J Med Res. 2013;137:213–5.PubMedGoogle Scholar
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- Yong D, Toleman MA, Giske CG, Cho HS, Sundman K, Lee K, et al. Characterization of a new metallo-β-lactamase gene, blaNDM-1, and a novel erythromycin esterase gene carried on a unique genetic structure in Klebsiella pneumoniae sequence type 14 from India. Antimicrob Agents Chemother. 2009;53:5046–54. DOIPubMedGoogle Scholar
Suggested citation for this article: Chakraborty S. New Delhi metallo-β-lactamase 1. Emerg Infect Dis. 2026 Jun [date cited]. https://doi.org/10.3201/eid3206.251434
Original Publication Date: May 15, 2026
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Table of Contents – Volume 32, Number 6—June 2026
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Please use the form below to submit correspondence to the authors or contact them at the following address:
Surajit Chakraborty, Department of Microbiology, All India Institute of Medical Sciences (AIIMS), Bathinda-151001, Punjab, India
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