WASHINGTON -- Like most patients in the infectious disease ward at Walter Reed Army Medical Center, Jon Harris has an "A" written next to his name on the white board by the nursing desk. The 23-year-old Army specialist had a leg amputated below the knee after a bombing in Iraq.
But the capital letter indicates another medical problem that increasingly worries military doctors -- an infection from a resilient bug known as Acinetobacter.
The Missouri soldier, who arrived at Walter Reed on April 10, said he is certain he picked up the infection when he fell to the ground in the attack.
However, military doctors say they don't know exactly what is causing infections such as the one Harris has, and they are racing to find effective treatments.
Four types of bacteria are causing severe and hard-to-treat infections for many troops wounded in Iraq and Afghanistan: Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus.
The infections have occurred in more than 600 injured troops from the two war zones who have had an arm or leg amputated, doctors tracking the cases say, and in other troops with lesser wounds.
Such infections also can occur among civilians with traumatic wounds or other health problems, but the rate of infection for injured troops is higher than expected.
In response, the US Army Institute of Surgical Research awarded a $1.6 million grant in February to a University of Missouri research team to work with doctors at Walter Reed in Washington, and Brooke Army Medical Center in Texas. The researchers' aim is to simulate the bomb blast wounds that seem especially vulnerable to the infections and to study how the infections respond to antibiotics.
Jason Calhoun, chairman of orthopedic surgery at the University of Missouri at Columbia School of Medicine, who will help lead the four-year study, said there are many unanswered questions about the infections.
"Many are resistant to common types of antibiotics," Calhoun said. He said the research could lead to new methods to reduce extremity infections, surgeries, and amputations.
The nature of the wounds sustained in Iraq and Afghanistan has complicated efforts to control the infections.
Darren Linkin, director of infection control at the Veterans Affairs Medical Center in Philadelphia, said bomb blasts cause a large amount of tissue damage, making infections more likely to occur and harder to treat. "If there's not blood flow to the dead tissue, the antibiotics can't get to the infection," he said.