Risk Factors Associated with Multidrug-Resistant Gram-Negative Bacilli Colonization in Wounded Military Personnel Deployed to Iraq and Afghanistan
Previous studies have shown high rates of colonization and infection with multidrug-resistant gram-negative bacilli (MDR GNB) in patients injured during deployment to Iraq and Afghanistan. Using data from a longitudinal military trauma registry, we evaluated the risk factors associated with MDR GNB colonization.
Injury circumstances and post-injury management were collected from the Department of Defense Trauma Registry. Antibiotic use, microbiology results, and infection data were collected from the Trauma Infectious Diseases Outcomes Study (TIDOS). MDR GNB colonization was defined as growth of MDR (ESBL production or resistance to 3 or more of: carbapenems, aminoglycosides, fluoroquinolones, or beta-lactams) GNB from active surveillance cultures (groin/axilla) performed within 48 hrs of U.S. admission. Multivariate logistic regression was used to evaluate risk factors associated with colonization. Odds ratios (OR) are presented with 95% confidence intervals.
From June 2009 to May 2012, 2079 deployment-injured patients were admitted to TIDOS-participating U.S. hospitals. Of these patients, 289 (14%) were colonized with a MDR GNB including E. coli (74%), A. baumannii (15%), K. pneumoniae (10%), E. cloacae (1%), and Citrobacter spp. (< 1%). There was no difference in duration between injury and admission between those with and without colonization (median 5 d in both). In the multivariate model, factors significantly associated with MDR GNB colonization include injury during fighting season (April – September, OR 1.8 [1.4-2.4]), massive blood transfusion (OR 2.7[1.7-4.2]), fluoroquinolone use post injury (OR 1.8 [1.4-2.5]), and infection prior to U.S. arrival (OR 1.7 [1.1-2.6]). Factors not associated include branch of service, country of injury, mechanism of injury, ICU admission, injury severity score, indwelling orthopedic hardware, cefazolin, or carbapenem use.
Although several factors are associated with higher rates of MDR GNB colonization post deployment-related injury, fluoroquinolone use is the only modifiable one. This finding provides further support for current guidelines which do not recommend routine fluoroquinolone use for post-injury prophylaxis.
C. K. Murray, None
H. Yun, None
D. Aggarwal, None
D. Tribble, None
A. Weintrob, None
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