Map of life expectancy at birth from Global Education Project.

Thursday, May 13, 2010

The most dangerous place in town

Go ahead, take a guess? What is the sixth leading cause of death in the United States? (Jeopardy theme song plays.)

According to one way of looking at it, the answer is Hospital Associated Infections -- the cause of about 99,000 deaths in the United States in 2002. There were a total of 1.7 million such infections altogether.

Now, this is a bit tendentious, as is any claim about "causes" of death, because what you call the cause of death all depends on how far back you want to go. Why were those people in the hospital in the first place? Most of the ones who died were probably already pretty sick and frail and likely didn't have a long life expectancy anyway. Still, it's a big problem. Peleg and Hooper, in the new NEJM, discuss a particular class of bacteria that cause a lot of HAIs, called gram negative bacteria. Abstract only, for you contemptible swine. Since you aren't allowed to read it, I'll play Prometheus and steal what you need:

Infections caused by gram-negative bacteria have features that are of particular concern. These organisms are highly efficient at up-regulating or acquiring genes that code for mechanisms of antibiotic drug resistance, especially in the presence of antibiotic selection pressure. Furthermore, they have available to them a plethora of resistance mechanisms, often using multiple mechanisms against the same antibiotic or using a single mechanism to affect multiple antibiotics. Compounding the problem of antimicrobial-drug resistance is the immediate threat of a reduction in the discovery and development of new antibiotics. Several factors have contributed to this decline, including the increasing challenges of screening for new compounds, the high capital costs and long time required for drug development, the growing complexity of designing and performing definitive clinical trials, and the concern about reduced drug longevity due to the emergence of resistance. As a consequence, a perfect storm has been created with regard to these infections: increasing drug resistance in the absence of new drug development.

Let me put that in plain English. Drug companies aren't all that interested in developing new antibiotics because there isn't a whole lot of profit to be made. They like to invent pills that people have to take forever, like statins and antidepressants; stuff you only have to take for a week or two, that actually cures you, just isn't worth it.

Bacteria are a real PITA to deal with because they can pick up genes from any old place -- they don't just have to "mate" with their own species. They don't exactly mate anyway, although they can rub up against each other and exchange genes; but they can also pick up genes from dead cells and even just debris that's lying around in the slime. So once a gene that confers resistance is in your hospital, it can get around fast.

It's a bit disconcerting to be walking through the halls here every day, but basically health people who work in hospitals, including physicians and nurses, are at low risk of acquiring these infections. The problem is that the patients tend to have extra holes in them, with tubes and appliances going into those as well as some of their natural orifices; and to be weak and immunocompromised. However, as Peleg and Hooper discuss, people are showing up with what are presumed to be community acquired infections that really come from something that got loose from a hospital. These little nasties are out there, more and more.

Just one more way we may get our comeuppance.

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