We examined combat-related open extremity fracture infections as a function of whether posttrauma antimicrobial prophylaxis included expanded Gram-negative (EGN) coverage.METHODS
Military personnel with open extremity fractures sustained in Iraq and Afghanistan (2009–2014) who transferred to participating hospitals in the United States were assessed. The analysis was restricted to patients with a U.S. hospitalization period of ≥7 days. Prophylaxis was classified as narrow (e.g., IV cefazolin, clindamycin, and/or amoxicillin-clavulanate) or EGN, if the prophylactic regimen included fluoroquinolones and/or aminoglycosides.RESULTS
The study population included 1,044 patients, of which 585 (56%) and 459 (44%) received narrow and EGN coverage, respectively (p < 0.001). Skin and soft-tissue infections (SSTIs) were more common among patients who received narrow prophylaxis compared to EGN coverage (28% vs. 22%; p = 0.029), whereas osteomyelitis rates were comparable between regimens (8%). Similar findings were noted when endpoints were measured at 2 and 4 weeks postinjury. There was no significant difference related to length of hospitalization between narrow and EGN regimens (median: 34 and 32 days, respectively) or operating room visits (median: 5 and 4). A higher proportion of EGN coverage patients had Gram-negative organisms isolated that were not susceptible to fluoroquinolones and/or aminoglycosides (49% vs. 40%; p < 0.001). In a Cox proportional model, narrow prophylaxis was independently associated with an increased risk of extremity SSTIs (hazard ratio: 1.41; 95% confidence interval: 1.09–1.83).DISCUSSION
Despite seeing a small benefit with EGN coverage related to a reduction of SSTIs, it does not decrease the risk of osteomyelitis, and there seems to be a cost of increased antibiotic resistance associated with use. Overall, our findings support the current post-combat trauma antibiotic prophylaxis guidelines, which recommend the use of cefazolin or clindamycin with open fractures.LEVEL OF EVIDENCE
Prognostic/Epidemiological, Level II; Therapy, level IV.