Moving up the Charts: Drug-resistant bug invades military, civilian hospitals

A common bacterium is becoming more virulent and drug resistant in hospitals. The Infectious Diseases Society of America (IDSA) now ranks Acinetobacter baumannii on its list of “bad bugs” alongside two perennial chart toppers, vancomycin-resistant Enterococcus faecium and methicillin-resistant Staphylococcus aureus.

The reported cases of nasty A. baumannii infections “may be just the tip of the iceberg,” says Robert Bonomo of Case Western Reserve University in Cleveland. “I don’t think the statistics … do justice to the current problem. I hear people saying, ‘It’s all over my hospital.'”

Some strains of the bug resist nearly all antibacterial drugs, forcing physicians to rely on colistin, an antibiotic that fell out of favor in the 1970s after reports that it caused kidney damage. “We’re resurrecting colistin from antiquity,” says physician Michael Zapor of the Walter Reed Army Medical Center in Washington, D.C. But he adds that “it’s only a matter of time before we lose [it], too.”

At an IDSA meeting in San Diego last week, Zapor reported a spike in A. baumannii infections among soldiers at Walter Reed who were injured in Iraq and Afghanistan. In 2002, the hospital saw only 10 such infections, but in 2004, 279 wounded soldiers contracted the bug. By 2006, with more-stringent infection-control procedures in place, the number of cases dropped to 177. Zapor says that the hospital spent more than $1 million on intravenous antibiotics in 2006, up from $400,000 in 2000.

Bonomo described the case of a soldier with a blast wound infected by a strain of A. baumannii that became “flesh eating.” More and more such strains are appearing, he says.

Timothy Whitman of the National Naval Medical Center in Bethesda, Md., says that an infectious-diseases team traced an A. baumannii outbreak there to a military hospital in Germany and a Navy hospital ship in the Persian Gulf. Marines and sailors apparently picked up the bug at those sites and carried it to Bethesda, where 11 civilian patients contracted the same strain. Four of the civilians subsequently died, although Whitman says that they were all very ill before becoming infected.

And, in the first reported case of a health care worker contracting A. baumannii, a nurse at the Bethesda naval hospital developed pneumonia and a serious blood infection after using a small vacuum to clean the wound of an infected sailor, an act that apparently dispersed the bug. The nurse spent 2 months in the Georgetown University Hospital in Washington, D.C., before recovering. “Our theory is that it was an airborne infection,” says Georgetown researcher Sonia Qasba.

Patients in intensive care units are at the highest risk of contracting A. baumannii, according to infectious-disease experts. Mortality estimates for infected patients range from 10 to 60 percent.

The microbe, says Bonomo, “is incredibly hardy. It survives well in the [hospital] environment, and it’s very hard to know where patients pick it up.”

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