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A bad houseguest

Like some houseguests, this bug just doesn't know when to pack up and go away. "It's a germ that, once it becomes endemic in your population, is extremely difficult to get rid of," explains Jake Nania, M.D., chief epidemiologist of the Monroe Carell Jr. Children's Hospital at Vanderbilt.

The germ he's talking about is VRE – vancomycin-resistant enterococcus – and the children's hospital has been waging an all-out assault against it for more than a year.

Enterococcus, a bacterium that commonly lives in the intestine, can cause trouble under the right conditions, primarily urinary tract, surgical site and bloodstream infections. VRE, once on the list of pathogens that infection control specialists didn't lose much sleep over, is its nasty cousin once removed. This form of the germ has developed a hearty resistance to vancomycin, one of the drugs commonly used to treat enterococcus-related infections.

"For so long, we thought it (VRE) was wimpy bacteria," explains Thomas R. Talbot, M.D., M.P.H., chief epidemiologist for Vanderbilt University Medical Center.

But some newer studies have painted a different picture, linking VRE with a high rate of patient morbidity and mortality. And, at the same time, this new, non-wimpy view of VRE hasn't settled all the questions.

"We don't know exactly why it leads to greater mortality," Nania said. It's a big missing link, but one the VCH is responding to by aiming to stop this pathogen in its tracks. That means testing the most vulnerable of its young patients to determine if they're carrying the germ – called colonization when it hasn't caused illness. Patients fighting cancer, or who have had bone marrow transplants, can be particularly susceptible to VRE, Nania adds.

"We basically have to isolate the person who is even just colonized," he explains. That's because VRE is a determined pathogen, attaching itself to people and objects to travel to a new residence, where it can live a long time – resisting antibiotic treatment – then move on again.

And the really sticky question, Talbot says, is if you decide to isolate a patient, when do you decide to stop? While medical best practices are outlined for this – for VRE that's negative cultures from two different body sites taken three weeks apart – it's still a problematic issue, especially since some bugs can hang out with patients for months, just waiting to cause trouble.

"The problem is, there really are no national guidelines," explains Talbot.

VRE occurs mainly in hospitals – where it was first reported in the United States in 1989 – and it can still be treated successfully with other antibiotics. In addition, newer drugs not well known to today's resistant pathogens are being thrown into play, even though some have not been tested on young patients, and therefore, are considered "experimental" or "investigational" for use in children.

The small patients at the VCH create a fertile playground for VRE, Nania explains. Many have had frequent and sometimes long hospital stays for chronic illnesses; they may require antibiotics a number of times, or cancer chemotherapy that can injure the bowel, where enterococcus live – in pop culture lingo, Nania observes – "a perfect storm."

"I describe it as a seed falling on fertile ground," he says.

But the proper mindset, Nania says, is not to be paranoid, just always attentive. That's a challenge when somewhere out there at this very moment, for reasons not entirely clear to modern science, some pathogens are becoming resistant to the drugs that used to knock them flat.

"The bugs are always one step ahead of us," Nania says.
- Elizabeth Older


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