Inoculated MacConkey agar culture plate cultivated colonial growth of Gram-negative, small rod-shaped and facultatively anaerobic Klebsiella pneumoniae bacteria. – CDC PHIL.
NDM-1, or New Delhi metallo-ß-lactamase-1, is an enzyme that can confer resistance to certain gram negative bacteria like E.coli and Klebsiella against a class of antibiotics called carbapenems.
Of particular concern, this enzyme is carried by a plasmid – a snippet of portable DNA - that can be transferred to other types of bacteria (see Study: Adaptation Of Plasmids To New Bacterial Species).
Last August a Lancet Infectious Diseases article was published on its growing prevalence on the Indian sub-continent and its recent importation into the UK, US, and other countries.
The Lancet Infectious Diseases, Early Online Publication, 11 August 2010
doi:10.1016/S1473-3099(10)70143-2Cite or Link Using DOI
The reaction from officials out of India was both immediate and disappointing. Rather than taking action against a growing public health threat, they took umbrage instead.
They condemned of the use of `New Delhi’ in the naming of this resistance gene, called the paper a `conspiracy theory’, and issued broad denials of its prevalence in India or that medical tourism to their nation was responsible for its spread.
It is worth noting that the naming convention for pathogens that invoked so much ire traditionally incorporates its place of discovery or emergence.
In 2001 a similar gene was discovered in Brazil and was dubbed SPM-1 (Sao Paulo metallo-beta-lactamase). Another, discovered in 1999 in Italy, is called VIM (Verona integron-encoded metallo-β-lactamase), while SIM stands for Seoul imipenemase found in Korea.
Six months later (April, 2011), the same researchers published a new study, again in The Lancet, that found the NDM-1 enzyme in 4% of New Delhi’s sampled drinking water sources, and 30 per cent of the sewage tested.
The Lancet Infectious Diseases, Early Online Publication, 7 April 2011
Dissemination of NDM-1 positive bacteria in the New Delhi environment and its implications for human health: an environmental point prevalence study
Prof Timothy R Walsh PhD , Janis Weeks BS, David M Livermore PhD , Mark A Toleman PhD
And as feared, the researchers also identified 11 new species of bacteria carrying the NDM-1 gene, including strains which cause cholera and dysentery.
Once again the reaction out of India was one of swift denial (see Hopefully, It’s Just A Stage They Are Going Through).
Indian newspapers, however, have continued to question the government’s response - putting pressure on officials to begin testing for the enzyme.
Over the past couple of days Indian media has carried reports out of Pune - a city of about 3.5 million (8th largest in India) located about 1400 kilometers from New Delhi – regarding the detection of 20 NDM-1 cases at Sassoon hospital.
Pune is less than 200 kilometers from Mumbai (formerly Bombay), which is the largest city in India (12.5 million people) and the 5th largest metropolitan area in the world.
Microbiologists tested samples of blood, urine and puss from 3,172 patients at the hospital and found that 885 had gram negative bacterial infections.
Of those, 181 (20%) were resistant to the carbapenem family of drugs .
And twenty of those tested positive for the NDM-1 gene.
Some of the media coverage follows. From the Indian Express we get:
Posted: Sat Apr 23 2011, 01:11 hrs Pune:
‘Superbug gene detected in 20 patients’
The controversial multi-drug-resistant superbug, the origin of which has been a matter of debate with the Centre taking strong exception to it being named after New Delhi, researchers from the government-run B J Medical College (BJMC) and the National Centre for Cell Science (NCCS), in preliminary findings of a study to find the New Delhi metallobeta lactamase-1 (NDM-1) incidence in Pune, reported the strain in the city.
And from Mid-Day News:
By: Alifiya Khan
20 of 885 patients tested by Sassoon hospital found infected by antibiotic-resistant bug controversially named after Indian capital, says dean of govt healthcare facility
THE NDM-1 superbug has reached the city. So far 20 patients from Sassoon General Hospital have shown the presence of the multi-drug-resistant superbug. Shocking as it may sound, the presence of the New Delhi metallobeta lactamase-1 (NDM-1) superbug in the city is a fact that has been confirmed by the seniormost authority at the hospital.
Absent from these media dispatches are details on the exact types of resistant bacteria that were detected.
While 20 NDM-1 cases may not sound like a lot, these are the results from only 1 hospital over a 2-month period of time.
It undoubtedly only represents the tip of the iceberg.
And as I described in my blog Carbapenemases Rising, the rising rate of regular carbapenem resistance is alarming as well. Carbapenems are often used as the drug of last resort for treating difficult bacterial infections, including Escherichia coli (E. coli) and Klebsiella pneumoniae.
India, of course, isn’t the only country with NDM-1 cases or growing carbapenem resistance - although the Indian sub-continent does appear to be a focal point – a situation often blamed on their longstanding lax controls on the use of antibiotics.
Given the results of these studies published in the Lancet, and these latest findings from Pune’s Sassoon hospital - increased surveillance, openness, and international cooperation – not indignation – are the responses needed today if a major public health crisis is to be averted.
One that has the potential to spread far beyond India, and that could – over time – greatly diminish our ability to fight bacterial infections with our dwindling arsenal of antibiotics.
For more on NDM-1 and antimicrobial resistance, you may wish to check out:
And perhaps the single best place to learn about the dangers and impact of antimicrobial resistance is from our favorite `scary disease girl’ Maryn McKenna’s SUPERBUG BLOG and her terrific book on the subject SUPERBUG: The Fatal Menace Of MRSA.