Efficacy of point-of-injury combat antimicrobials

Background: Infection is a major complication associated with combatrelated injuries. One strategy to decrease infections is immediate delivery of antimicrobials at or near the point-of-injury by the casualty or the first medical responder. The 75th Ranger Regiment systematically collects data on prehospital battlefield care, including antimicrobial administration. We review infectious complications and colonization rates associated with delivery of point-of-injury antimicrobial therapy. Methods: We retrospectively reviewed casualty treatment data from the 75th Ranger Regiment prehospital trauma registry on patients injured between March 2003 and March 2010 and linked this to electronic medical record data to look for the presence of bacterial infection or colonization within 30 days of injury. Patient demographics, antimicrobial therapy, and outcomes were evaluated. Assessment of colonization included surveillance screening cultures performed for multidrug-resistant bacteria, including Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus, at US military hospitals in the combat zone, Germany, and stateside. Results: Of 405 total casualties, 28 (6.9%) were infected with gram-negative bacteria, primarily A. baumannii. Of those who were not returned to duty or died near the time of injury, 28 of 211 (13.3%) were infected. The only identified risk factor for infection was higher military Injury Severity Score. Prehospital administration of antimicrobials to 113 of 405 casualties (27.9%), including 8 of the 28 infected casualties, did not affect infection or colonization rates. Conclusions: Although limited by population size, a significant difference in infection rates and multidrug-resistant pathogen colonization was not seen in those casualties who received single-dose broad-spectrum antimicrobials at the point-of-injury, confirming neither benefit nor harm. Overall adherence with initiating point-of-injury antimicrobials was low.