Wednesday, August 11, 2010

NDM-1: A New Acronym To Memorize



UPDATE: 8/14/10    This has turned into a rapidly evolving story.  To see a list of the latest blog entries on NDM-1 click this link.



UPDATE: 1900 hrs EST 8/11/10    Maryn McKenna has posted this evening on NDM-1 on her Superbug blog, going into far more depth and detail than I have here.


By all means, you’ll want to read her post  NDM-1: Novel, global, complex and a serious threat.



# 4796



New Delhi metallo-ß-lactamase-1, or NDM-1, is an  emerging enzyme that can confer resistance to certain gram negative bacteria like E.coli and Klebsiella against a class of antibiotics called carbapenems.


Carbapenems are newer generation beta-lactam antibiotics (a class that includes penicillins, cephalosporins, cephamycins, and carbapenems) that are usually reserved as an antibiotic of last resort.


Up until recently, Carbapenems have been generally resistant to Beta-lactamases - enzymes bacteria use to breakup the ring structure of “beta-lactam” antibiotics - that renders them ineffective.


But in recent years a new enzyme has been spreading in India, Bangladesh, and Pakistan that helps certain types of bacteria to defeat Carbapenem antibiotics; NDM-1.   


Although NDM-1 has been around for some time, it is making the news today after the release of a Lancet Infectious Diseases article on its growing prevalence on the Indian sub-continent and its recent importation into the UK, US, and other countries.


Travelling abroad for elective (usually cosmetic) surgery has become much in vogue in Europe and the United States, and that has created an opportunity for this enzyme to spread.


While the numbers being reported in the UK are still small, one of the concerns is that this enzyme may find its way into other gram negative bacteria that may already have partial resistance to other classes of antibiotics, which could create a new multi-drug resistant superbug.


The Lancet Infectious Diseases, Early Online Publication, 11 August 2010

doi:10.1016/S1473-3099(10)70143-2Cite or Link Using DOI

Emergence of a new antibiotic resistance mechanism in India, Pakistan, and the UK: a molecular, biological, and epidemiological study



We identified 44 isolates with NDM-1 in Chennai, 26 in Haryana, 37 in the UK, and 73 in other sites in India and Pakistan. NDM-1 was mostly found among Escherichia coli (36) and Klebsiella pneumoniae (111), which were highly resistant to all antibiotics except to tigecycline and colistin. K pneumoniae isolates from Haryana were clonal but NDM-1 producers from the UK and Chennai were clonally diverse.


Most isolates carried the NDM-1 gene on plasmids: those from UK and Chennai were readily transferable whereas those from Haryana were not conjugative. Many of the UK NDM-1 positive patients had travelled to India or Pakistan within the past year, or had links with these countries.



The potential of NDM-1 to be a worldwide public health problem is great, and co-ordinated international surveillance is needed.



For more on this story, the BBC has a Q&A style report at: Q&A: NDM-1 superbugs  and Reuters reports in Scientists find new superbug spreading from India.


Some of the other media reports I’ve seen this morning are unnecessarily hyperbolic, although the potential threat is quite real. 


Antibiotics are fleeting victories against bacteria at best, since from the minute they are introduced, bacteria begin to evolve ways to defeat them.  


With very few new antibiotics in the pipeline, the world is in genuine danger of facing a future with far fewer resources to combat infections.


Short of seeing a devastating pandemic, this may well be the `big’ medical story of the next couple of decades.


Given the gravity of the situation, I can think of no better introduction to the world of antibiotic resistance than Maryn McKenna’s superb Superbug: The Fatal Menace of MRSA, which I reviewed last March.

If you haven’t already read it, I highly recommend it.


Superbug (MRSA) Book 
My Review of SUPERBUG