The effect of systemic antibiotic prophylaxis and wound irrigation on penetrating combat wounds in a return-to-duty population.

BACKGROUND Systemic antibiotic prophylaxis (SAP) for combat wounds is controversial. Current military practice favors its use, despite scant supporting evidence. OBJECTIVE To analyze outcomes of combat casualties returned to duty after initial wound care for penetrating trauma, comparing infection rates based on whether SAP was administered and whether wounds were irrigated. SETTING Forward operating base in Central Iraq, with units engaged in urban combat. METHODS This was a retrospective cohort study using field medical records. Wound mechanism, location, antibiotic use, and clinical course were abstracted. Subjects were excluded if injuries were isolated burns or eye trauma or if follow-up was not documented. STATISTICAL ANALYSIS Contingency table analysis, Fisher's exact test, and odds ratios were used. RESULTS Fifty-eight eligible cases were identified; five were excluded for incomplete follow-up (four) or confounding injuries (one). Of the remaining 53 cases, 43 included receipt of SAP (81%). Wound mechanisms and anatomic locations were comparable between groups. Infections developed within 48 hours in 7% of the SAP cases versus 40% without SAP (no SAP); odds ratio 0.11 (95% confidence interval [CI] 0.02 to 0.57); number needed to treat (NNT) 3 (95% CI 2 to 14). Forty-four subjects received wound irrigation (83%). Infections developed within 48 hours in two (4.5%) irrigated cases versus five (55%) without irrigation (no irrigation); odds ratio 0.04 (95% CI 0.006 to 0.24); NNT 2 (95% CI 1.4 to 4.7). Further 4 x 2 contingency table analysis yielded wound infection rates as follows: no SAP/irrigation, 17%; SAP/no irrigation, 40%; SAP/irrigation, 2.6%; no SAP/no irrigation, 75% (Fisher's exact p < 0.0005). CONCLUSIONS We detected independent and combined associations among SAP, irrigation, and significantly decreased wound infection rates. Effects of SAP and irrigation may be synergistic. Copious irrigation with potable water or sterile isotonic solution should be performed at the earliest practical juncture after a wound occurs. SAP should be administered if irrigation cannot be performed, and may be warranted in addition to irrigation for complex or contaminated wounds or if expeditious return to duty is required. Larger epidemiologic studies are needed to validate our findings.