‘New Delhi’ superbug: what’s the story?

Perhaps a particular group of superbugs has been getting an unfair share of the spotlight over the past few months…

The headlines began last August, when a study reported the emergence of bacteria that can resist carbapenems – a type of antibiotic given to patients once other drugs have failed. These bacteria withstand the treatment by breaking down the drugs using an enzyme (carbapenemase), which is encoded by a gene called New Delhi metallo-ß-lactamase 1 (NDM-1); this gene can be transferred from one bacterium to another. The cases of infection documented in the study were seen in the UK, in people who previously had medical treatment in the Indian subcontinent.

At the Forum we covered [PDF] the research in the news section; and we weren’t alone. In fact the media coverage of this – the ‘New Delhi’ or ‘NDM-1′ superbug’ – was extensive, the tone serious. And reports, or sightings, of these bacteria around the world, even single cases, have kept popping up.

Something about this made me uneasy. Why so much attention on these particular superbugs? The fact that they carry genes that can transfer resistance to last-line antibiotics from one bacterium to another was a satisfactory answer at the time. The potential for resistance-gene transfer isn’t an attribute that comes with your average superbug. But I still questioned whether that much spotlight was justified.

Until recently, when Eurosurveillance published three papers on NDM-1 bacteria – and crucially, other bacteria that use the same mechanism to resist carbapenems. It turns out that outside the UK, other carbapenemase-producing bacteria are more prevalent. I wrote [PDF] about these articles last month, quoting the European Centre for Disease Prevention and Control which was explicit in saying this.

So why did the ‘New Delhi’ superbug get so much press?

One clue may be right there in the name. What I think mattered in raising the profile of this group of bacteria was the fact that it could be traced to a clearly identifiable source, a particular location – outside the UK. So in a world where science usually throws up multiple possible answers and uncertain causes, this was a rare instance of clarity.

Infections with this type of superbug were also linked to medical tourism, which does carry risks in places where healthcare quality isn’t up to standard. This would, at least indirectly, be associated with the countries where the infections were picked up.

It’s worth mentioning that the focus on South Asia as a source for these infections didn’t go down that well with the Indian government. A story by T. V. Padma published on SciDev.Net did give a voice to protests against the naming of the pathogen, as well as the conclusions of the study. There is a history of naming bugs by the location associated with their discovery, for example, or first victims – although sensitivity to the implications of this seems to be increasing (a case in point: the WHO’s efforts to do away with ‘Mexican’ flu and ‘swine’ flu after the new A/H1N1 virus emerged).

But I think there’s more behind the intense media coverage. Importantly, the study that documented the infections was published in none other than Lancet Infectious Diseases. And with that you have a report in a prestigious journal, where I thought the language used by the authors was a little more alarmist than that of many other reports of drug-resistant pathogens.

Add to that the lack of information on other bugs that release carbapenemases, either as part of the coverage for ‘New Delhi’ or separately, and you get an inflated perception of the importance of this particular pathogen.

I don’t subscribe to blanket accusations of The Media as villains, carelessly giving science the shallow treatment. When done well, research and journalism serve each other enormously by challenging views, informing, cross-pollinating ideas.

But I do think that this is one example where media attention has skewed the issue. Not so much with the volume of coverage, which can’t really be helped, but more so with the lack of information to put the article in context. I would like to think that at the Forum we’ve made up for it with the second story.