18 August 2010

NDM-1: The early warnings

Sorry to drop out of sight, constant readers; a little medical emergency at Casa Superbug, but all better now. There are some new developments regarding the novel resistance factor NDM-1, which renders Gram-negative bacteria resistant to almost all antibiotics:
  • Germany has announced its first identifications — plural, apparently. (Bloomberg News)
  • Vietnam says it has also recorded its presence.  (Thanh Nien Daily, h/t H5N1)
  • And France says that it will begin testing for the gene's presence in bacteria carried by patients being admitted to hospitals, in hopes of keeping the plasmid from transferring to other bacterial species and creating a wider resistance problem. (Agence France Presse) This is a reasonable fear; it is analogous to the process by which MRSA became vancomycin-resistant (VRSA), by acquiring the gene for vancomycin resistance from VRE, vancomycin-resistant Enterococcus. But there's much more to be said about what it will take for a hospital to keep this bug from entering or spreading; more on that in a future post.
Before we  get too much further from the initial news, I want to go back over the history of NDM-1's discovery — because, as with so many superbugs that take the public by surprise (recall the furor when the CDC's estimate of 19,000 MRSA deaths a year was published in late 2007), it turns out that there have actually been alarm bells ringing on this for a while. Largely, of course, unheard.

The first finding was in an older man of South Asian origin, living in Sweden, who went back to India in 2007, was hospitalized in New Delhi as a result of longstanding health problems, returned to his new home, was hospitalized there also in January 2008, and was discovered there to be carrying this resistance factor. The first public description of his case was made in October 2008, during a poster session at the annual ICAAC meeting (Interscience Conference on Antimicrobial Agents and Chemotherapy). That was later expanded to a journal article that was published in Antimicrobial Agents and Chemotherapy in December 2009; the full text is online in PubMed Central.

In the interim, though, the UK's Health Protection Agency published its first alert, in July 2009, describing 19 patients carrying this resistance  in 2008 and the first half of 2009, 9 of whom had received medical care in South Asia:
One UK patient, who developed a bloodstream infection with an E. coli that produced NDM-1 enzyme had received treatment for a haematological malignancy in both India and the UK; two others had undergone cosmetic surgery in India and one of these presented to a UK hospital with a wound infection that grew a mixed microbial flora including K. pneumoniae with NDM-1 enzyme; others had received renal or liver transplantation in Pakistan.
Meanwhile, other researchers in Europe were becoming alert to the threat that NDM-1 posed if it were to spread widely; English researchers warned of it in September 2009, and Scandinavian researchers did the same in November 2009.

And in June 2010, the CDC published its first report and warning of NDM-1 in patients in the US, noting that all three, who lived in different states, had received medical care in India.

But what's important to note is that,  despite the surprise and indignation coming from South Asia after the publication of last week's Lancet Infectious Diseases papers (article, editorial) describing the spread of NDM-1, the existence of that resistance factor has been discussed in Indian medicine since sometime last year.

From August to November 2009. a team of physicians at the Hinduja National Hospital and Medical Research Centre in Mumbai surveyed their ICU patients, and found 22 isolates carrying NDM-1. Their paper was submitted very quickly, in December 2009, and published in March 2010 in the Journal of the Association of Physicians of India:
We sought to identify NDM-1 positive strains among the carbapenem resistant Enterobacteriaceae isolates at our tertiary care centre. In a short span of 3 months, we identified 22 such organisms. The physicians at our institute follow the hospital antibiotic policy and do not indiscriminately use carbapenems. However being a tertiary centre we receive transfer in cases / referrals from other hospitals... The identification of NDM-1 in 22 of 24 isolates is a worrisome development indeed. NDM-1 being present among Enterobacteriaceae has the potential for further dissemination in the community. Such dissemination may endanger patients undergoing major treatment at centres in India and this may have adverse implications for medical tourism. Besides stringent infection control in hospitals, good sanitation in the community is also needed to contain the spread of such clones. (Deshpande et al., JAPI 2010)
News of their finding must have percolated through Indian medicine, because in January 2010 — before their paper was published — a worried letter discussing NDM-1, by a South Asian scientist working at the Royal Infirmary of Edinburgh, was published in the Indian Journal of Medical Microbiology:
The virtual nonexistence of antibiotic policies and guidelines in India to help doctors make rational choices with regard to antibiotic treatment is a major driver of the emergence and spread of multidrug resistance in India. This is augmented by the unethical and irresponsible marketing practices of the pharmaceutical industry, and encouraged by the silence and apathy of the regulating authorities. Poor microbiology services in most parts of the country add to the problem. (Krishna, IJMM 2010, DOI: 10.4103/0255-0857.66477)
 And in March 2010, Dr. K. Abdul Ghafur of the Apollo Hospital in Chennai published a passionate and despairing call to arms ("An obituary — on the death of antibiotics!") alongside the Mumbai team's findings. The full text is online and it is worth reading in its entirety:
Our country, India, is the world leader in antibiotic resistance, in no other country antibiotics been misused to such an extent. Microbes are the ultimate warriors. They have sophisticated weapons and use ingenious methods of attacks. They have always been many steps ahead of us. Even in the twenty first century with all the developments in the modern medicine, when we face microbes, we feel helpless. Whatever weapons we had in the form of antibiotics, we ourselves have ruined them. Indian medical community has to be ashamed of the NDM-1 (“New Delhi Metallo-1”) gene. Even though we have not contributed to carbapenem development, we have contributed a resistance gene with a glamorous name. The overuse of antibiotics is embedded in our Indian gene. It is an Indian tradition. (Ghafur, JAPI 2010)
That Ghafur's plea went unheard is all the more striking — because for almost a decade, Indian researchers had been reporting, in their own journals, a steady and troubling expansion of carbapenem resistance in Indian hospitals. More on that when I post next.


Anonymous said...

Thank you very much for clarification and clarity.

Dan said...

why do NDM-1 reports almost always say something like 'resistant to almost all antibiotics'? what antibiotic(s) is NDM-1 not resistant to?

Maryn McKenna said...

@Dan - the Lancet ID paper last week said that the isolates in Britain were NOT resistant to colistin, which is a pretty old and toxic drug, or to tigecycline (Tygacil), which is relatively new. Some were also susceptible to the drug aztreonam. The isolates from the US that were announced a few months ago, though, were resistant to aztreonam also.

Anonymous said...

Symptoms only present when open wounds?

Maryn McKenna said...

Anonymous: SO according to the ICAAC presentations yesterday, here's what's so tricky. NDM-1 is currently occurring mostly in bacteria that cause UTIs. The issue will not necessarily be that the infection is more virulent - it will be that it is less treatable, or not treatable. In the case of a UTI, that might mean the ongoing infection can climb up the ureters to the kidneys and enter the bloodstream.