Severe trauma is not an excuse for prolonged antibiotic prophylaxis.

Hypothesis: For critically injured patients, a limited course of antibiotics is as effective as a prolonged course in preventing sepsis and organ failures.

Design: Prospective nonrandomized study.

Setting: Surgical intensive care unit (SICU) of an academic hospital with a level I trauma center.

Patients: A population of 250 trauma patients who required an operation and SICU stay of 3 days or more received antibiotic prophylaxis by 1 antibiotic for 24 hours (SHORT group, n = 133) or 1 or more antibiotics for more than 24 hours (LONG group, n = 117).

Main Outcome Measures: Twenty-two outcome variables, including 9 conventional outcomes (eg, sepsis, septic shock, and organ failure) and 13 objective outcomes (days with temperature >38.5 degrees C, days with white blood cell count >14.0 x10(3)/microL, positive cultures, cultures with antibiotic-resistant bacteria, SICU and hospital stay, and death).

Results: The LONG group included more patients with orthopedic injuries (60 patients [51%] vs 52 [39%], P =.05) and orthopedic operations (47 patients [40%] vs 30 [23%], P =.003) than did the SHORT group. No other difference was identified in compared characteristics between the 2 groups. There was no difference in any of the examined outcomes except for a higher incidence of resistant infections in the LONG group compared with the SHORT group (59 patients [50%] vs 47 [35%], P =.02). Patients with resistant infections stayed in the hospital longer (mean +/- SD, 33 +/- 18 vs 15 +/- 11 days, P<.001) and had a higher mortality rate (13% vs 1%, P<.001) compared with patients without resistant infections. Prolonged prophylaxis by multiple antibiotics was an independent risk factor of resistant infection (odds ratio, 2.13, 95% confidence interval, 1.22-3.74; P =.008).

Conclusions: The prophylactic administration of more than 1 antibiotic for more than 24 hours following severe trauma does not offer additional protection against sepsis, organ failure, and death, but increases the probability of antibiotic-resistant infections.