The subcontinent can cease fretting over the naming of that new bacterial resistance factor NDM, for New Delhi. There’s a newer resistance factor in town, and this one stigmatizes… Italy.
Welcome, Verona integron-encoded metallo-beta-lactamase, or VIM.
To be precise, VIM isn’t new — its very first identification was at the Verona University Hospital in 1999 — but it has just been found in the United States for the first time. The CDC said Wednesday evening that it has identified VIM in an American woman who took a Mediterranean cruise this summer, got diarrhea, was hospitalized (twice) in Greece, developed sepsis and C. diff, and eventually was transferred home and hospitalized here for a further 26 days. In the US, she was found to be infected with Klebsiella pneumoniae, a gram-negative bacterium that’s a common cause of serious-hospital acquired infections — urinary tract infections, abdominal infections and pneumonias. This strain, though, was resistant to all the drugs usually used to treat Klebsiella. (The woman did recover.)
To anyone who followed the NDM-1 news a few weeks ago, this should sound familiar. (If you didn’t, here’s my archive. No, go ahead; we’ll wait.) A resident of one country is unexpectedly hospitalized in another. That second country happens to have high rates of a novel, serious resistance factor — in Greece, 50 percent of Klebsiella isolates in ICUs are multi-drug resistant — that clusters in the organisms most likely to cause hospital infections. The person picks up a resistant infection without knowing it, travels home, and transports the novel resistance factor into his or her home country.
And because the gene that directs production of the problematic enzyme resides on a mobile genetic element — meaning it can move easily from one bacterium or species to another — the public health authorities in the unlucky person’s home country begin a very nervous waiting game.
That’s what happened with the identification of NDM-1, which was first noted in a man of South Asian origin, living in Sweden, who was unexpectedly hospitalized in India in 2007 and then hospitalized again in Sweden in 2008. (NDM was found in the US in June.) Like NDM, VIM has spread across the world; within a few years of its original identification it was in France, Spain and Taiwan. Nor are those two enzymes the only bad actors — they’re merely the most recent and notable in successive waves of multi-drug resistance in gram-negative organisms that are washing across the world. (Almost all of them, by the way, are named for their points of origin. GIM, Germany. SPM, Sao Paolo. DIM, Dutch. And so on.)
And those waves (to torture my metaphor until it whimpers) are really just the most visible points of an ocean of gram-negative resistance that has flooded the globe, and certainly the US. And, just to slosh home the point: These resistance mechanisms knock out the drugs of last resort for gram-negatives, the carbepenems, and there are no new drugs to replace them. The drug-development pipeline for gram-positives such as MRSA has a few drops still rolling down it; the pipeline for gram-negatives, as the Infectious Diseases Society of America has documented in several reports, has just about dripped dry.
The CDC on Thursday warned labs and hospitals to start taking action, in ways that will at least require additional staff time and attention, and probably will cost extra money too :
Cases of (carbepenem-resistant Enterobacteriaceae) are a significant, emerging public health problem regardless of the mechanism of carbapenem resistance, and procedures to rapidly recognize and report CRE cases to infection prevention personnel should be in place in all acute and long-term–care facilities. Facilities that have not identified cases of CRE should undertake periodic laboratory reviews to identify cases. Patients with CRE should be managed using contact precautions, and patients exposed to CRE patients (e.g., roommates) should be screened.
The problem with writing about increases in antimicrobial resistance is that, sooner or later, you inevitably end up sounding like Chicken Little. (Or Cassandra. I’m not sure which is worse. Chicken Little is probably cuter.) Every one of these sounds like the worst possible news. Problem is, every one of them is… until the next one comes along.
Image of Klebsiella pneumoniae courtesy of the Public Health Image Library, CDC.
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