Factors associated with mortality in critically injured trauma patients who require simultaneous cultures

Background: In trauma patients surviving their initial injuries, infectious complications and multiple organ failure represent the major causes of death after the first 72 hours. Critically injured trauma patients frequently have bacteria recoverable simultaneously from multiple culture sites; the clinical significance of this event is unknown. The objective of this study was to identify the association between growth patterns of multiple site cultures and mortality among critically injured trauma patients. Methods: We performed a retrospective chart review collecting demographic and medical data on admissions to a state-designated Level I trauma center from April 2000 to December 2002. The inclusion criteria were age >17 years, admission to the trauma intensive care unit (TICU), and simultaneous sampling of blood, sputum, and urine in the setting of fever of undetermined origin or alteration in the white blood cell count. Four mutually exclusive groups were developed according to the number of positive culture sites. We used standard statistical analysis and multivariate logistic regression. Results: During the study period, 3,402 patients were admitted to the trauma service of whom 124 met the inclusion criteria. Eighty percent of these (99) were male, and the average age was 41 years. The median TICU stay was 17 days. The mortality rate was 24.2% (30 non-survivors). The survivors and non-survivors were comparable in injury severity score (ISS), initial base deficit, initial hematocrit, initial blood pressure, and hospital length of stay (p > 0.05), whereas age (p = 0.03), female sex (p = 0.04), and TICU stay (p < 0.01) were higher among non-survivors. More non-survivors showed growth of microorganisms in simultaneous blood, sputum, and urine cultures (p = 0.02). By multivariate analysis, adjusting for age, sex, and TICU length of stay, patients with growth of microorganisms in simultaneous cultures (blood, sputum, and urine) had a 3-fold greater mortality rate (OR, 3.20; 95% CI 1.05, 9.73). Conclusions: In this group of patients, growth of bacteria in simultaneous cultures was associated with higher mortality - a factor that may be considered a poor prognostic indicator. This factor requires further studies to explore the relation with survival in critically injured patients.