'Superbug' stalked NIH hospital last year, killing six

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As a deadly infection, untreatable by nearly every antibiotic, spread through the National Institutes of Health's Clinical Center last year, staff members resorted to extreme measures. They built a wall to isolate patients, gassed rooms with vaporized disinfectant and even ripped out plumbing. They eventually used rectal swabs to test every patient in the 234-bed hospital.

Still, for six months, as physicians fought to save the infected, the bacteria spread -- eventually reaching 17 gravely ill patients. Eleven died, six from bloodstream superbug infections.

The outbreak of the antibiotic-resistant bacteria known as Klebsiella pneumoniae was not made public until this week, when NIH researchers published a scientific paper describing the advanced genetic technology deployed to trace the outbreak.

This was "the proverbial superbug that we've all worried about for a long time," said infection control specialist Tara Palmore at the Bethesda, Md. hospital.

With some 99,000 U.S. deaths attributed to hospital-borne infections annually, the NIH outbreak provides a stark case study of the dangers of the latest wave of hospital-bred bacteria and extreme measures hospitals must adopt to stem the rising superbug tide.

The NIH Clinical Center now screens every patient transferring from another facility for superbugs, tests every patient in the intensive care unit twice a week and screens every patient monthly. "This was our introduction to [antibiotic-resistant] Klebsiella," Dr. Palmore said. "We hoped we would never see it."

Clinical Center spokeswoman Maggie McGuire said the hospital did not alert the public earlier because Klebsiella infections do not trigger mandated reports to the U.S. Centers for Disease Control and Prevention as do other infectious diseases, such as HIV.

Nationwide, about 6 percent of hospitals are battling outbreaks of the superbug class known as carbapenem-resistant bacteria, which includes Klebsiella, CDC medical officer Alexander Kallen said. These usually live harmlessly in our intestinal tracts and pose little or no threat to patients with healthy immune systems.

But in patients with compromised immune systems, the bacteria can turn dangerous, gaining an enzyme that defeats even the most powerful antibiotics. That's what happened at NIH.

The six who died of bloodstream Klebsiella infections had immune systems weakened by cancer, anti-rejection drugs after organ transplants and genetic disorders.

The CDC detected this type of antibiotic-resistant bacteria in 2000. "Since then, we've seen it spread across the country," Dr. Kallen said, to 41 states.

Later this year, the CDC is launching a program in 10 cities to watch for hospital-borne outbreaks of Klebsiella and related superbugs. CDC staff will review hospital records, Dr. Kallen said, and hospital labs will be asked to report any antibiotic-resistant bacteria to the CDC.

At NIH, the superbug arrived in June 2011. Hours before a 43-year-old female lung transplant patient arrived from New York City, NIH nurses noted something startling in her chart: She was carrying an antibiotic-resistant infection.

Desperately wanting to contain the superbug, the NIH staff isolated the woman in the ICU. Staff members donned gowns and gloves before entering her room. Her nurses cared for no other patients.

After the patient was discharged the next month, Dr. Palmore and her staff thought the measures had worked; there were no signs the bacteria had spread. But weeks later, Dr. Palmore was "horrified," she said, when a second patient tested positive for the bacteria. A third and fourth followed. Those three patients died as the bacteria grew impervious to every known antibiotic, even experimental new ones.

By reading the bacteria's DNA, scientists at the NIH's National Human Genome Research Institute saw that the organisms from patients No. 2 and 3 were so closely related -- differing at just one or two genetic letters out of 6 million -- that they had to have come from the New York patient.

That meant two unsettling things, said genome institute scientist Julie Segre, who led the DNA analysis. The bacteria had lingered for weeks unnoticed, in the hospital or in the new patients; and the hospital's infection-control measures for the New York patient had failed. Details of the genetic analysis and the outbreak were published Thursday in the journal Science Translational Medicine.

With genetic evidence of a single-source outbreak, in mid-August the Palmore-led staff rolled out strict new measures. They built a wall in the ICU and moved Klebsiella-positive patients to a new, six-bed unit. Reusable medical gear was tossed after one use. The hospital hired monitors to ensure that doctors and nurses were donning gowns, gloves and masks and scrubbing their hands.

The strict infection-control measures eventually paid off. The last new case was found in January, and no new cases have occurred since, Dr. Palmore said. But two Klebsiella-positive patients remain at the hospital.



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