By Brenda L. Mooney

Even after they are safely transported for medical treatment far from the combat zone, wounded servicemembers face powerful adversaries: multidrug-resistant organisms, which pose a greater risk to today’s injured servicemembers than those of past wars.

“Antimicrobial-resistant strains of bacteria threaten U.S. military personnel deployed in the Middle East and Afghanistan from combat- and noncombat-related infections caused by these highly resistant pathogens. Acinetobacter baumannii-calcoaceticus complex, P. aeruginosa, Klebsiella and E. coli are common pathogens, but, compared to past wars, the acquisition of multidrug-resistant isolates appears to be significantly increased,” according to a report issued last year by the DoD’s Armed Forces Health Surveillance Center-Global Emerging Infections Surveillance and Response System (AFHSC-GEIS) network. Clinical studies suggest that the source of these bacterial infections includes nosocomial transmission in both deployed hospitals and receiving military medical centers (MEDCENs).

Controversy over resistant bacteria — especially Acinetobacter, which has been dubbed Iraqibacter in some circles because of its prevalence in that region — has focused on DoD and its response to the problem, even prompting a congressional hearing in 2010. What has been lost in the discussion and in the sometimes-hysterical general media coverage is that military medicine actually has made significant strides in overcoming infections caused by multidrug-resistant organisms (MDRO).

Oregon National Guard Soldiers help evacuate wounded from a dusty battlefield in Fallujah. The wounded were flown to a rear medical facility for attention. Photo from the Defense Video and Imagery Distribution Center.

For example, colonization with Acinetobacter showed an especially significant decline from 2005 to 2010, dropping from 7% to 1% in wounded troops tested at Landstuhl Regional Medical Center in Germany, and 21% to 4% in those treated at Level V centers, including Walter Reed Army Medical Center in Washington, National Naval Medical Center in Bethesda, MD, and Brooke Army Medical Center in San Antonio.

At a House Armed Services Oversight and Investigations Subcommittee hearing in 2010, the scope of the problem was revealed by the then-chairman, Rep. Vic Snyder, MD (D-AR). He said more than 3,300 servicemembers developed Acinetobacter infections from 2004 to 2009. Legislators also were told that most civilian U.S. hospitals report MDRO infections among those with a long hospital stay, such as the elderly with multiple complicated medical problems, but that it was unclear why Acinetobacter infection was occurring so frequently in young, combat-injured patients.

More recently, a study from the University of Maryland reported that Acinetobacter pathogens were found in 48% of hospital rooms tested in a survey, although the CDC notes the bacteria actually account for less than 2% of all nosocomial infections.

The problem for military-treatment facilities wasn’t that the bacteria had mutated into some kind of “superbug,” as some articles and groups had suggested, but involved much more practical issues, such as infection-control procedures, according to Col. Duane R. Hospenthal, MD, PhD, an infectious-disease physician at Brooke Army Medical Center in Texas. Furthermore, despite the hype, he said that essentially no military deaths can be directly attributed to Acinetobacter infection.

Cross-Contamination Opportunities

This SEM depicts a highly magnified cluster of Gram-negative, non-motile Acinetobacter baumannii bacteria; Mag - 27600x

Hospenthal, who served as an infectious-disease consultant to the Army Surgeon General from 2005-2011, told U.S. Medicine that one contributor to the problem is the multitude of transmission opportunities created when wounded warriors are transferred thousands of miles from one treatment location to another.

“These folks are handed off by hundreds of people. They may be transported 6,000 to 8,500 miles within days of being wounded,” Hospenthal noted. “It’s not like someone who is hit on the freeway and brought to the nearest trauma center and gets all of his treatment there.”

Acinetobacter baumannii, found in soil and water and even on the skin and in the guts of healthy people, can be spread by person-to-person contact or contact with contaminated surfaces, according to the CDC. Patients with compromised immune systems are most susceptible to infection. Long flights, multiple airport landings and being moved from stretcher to ambulance to helicopter mean “lots of opportunity for cross-contamination,” Hospenthal added.

The wounded servicemembers, who often suffer polytrauma, tend to see numerous physicians during the transport. While the old trauma practice was to clean out a wound, debride it, pack it and not look at it for two or three days, physicians at far-flung locations may “want to see what is wrong” when the patient arrives, he explained. “There’s not one guy seeing the patient every day for the last three days.”

Another issue cited by Hospenthal is the overuse of antibiotics, especially when resistant bacteria such as Acinetobacter were first identified in wounded troops.

Without adequate clinical-microbiology backup during the early years of Operation Iraqi Freedom, physicians had to use their best judgment on when and how to treat infections. If they saw that more pressure was required to ventilate a patient or that the wound had a greenish ooze, they often would “broaden antimicrobial empiric coverage,” he noted. The lack of conclusive information led to “overuse and indiscriminate use of broad-spectrum agents,” which tends to increase pathogens’ antibiotic resistance.

In addition, especially in Iraq, “We kept a lot of host nationals in hospitals way too long because we had no place to send them because of sectarian violence,” Hospenthal said. Some studies suggested that Acinetobacter colonization is more common in native Iraqis, which could have played a role in cross-contamination.