Recurrent bacteremia: A 10-year retrospective study in combat-related burn casualties

Introduction: Surviving the first episode of bacteremia predisposes burn casualties to its recurrence. Herein, we investigate the incidence, mortality, bacteriology, and source of infection of recurrent bacteremia in military burn casualties admitted to the U.S. Army Institute of Surgical Research Burn Center over a 10 year period. Methods: Bacteremia was defined as the growth of Gram-positive or Gram-negative organisms in a blood culture that excluded probable skin contaminants. Recurrent bacteremia was defined as a subsequent episode of bacteremia ≥7 days after the first episode. Polymicrobial bacteremia was the presence of more than one pathogen in the same blood culture. Bacteremia was attributed to UTI, pneumonia, or wound sepsis. All other bacteremias were considered non-attributable bloodstream infections. Univariate and multivariate analyses determined factors predictive of clinical outcome. Results: Out of 952 combat-related burn casualties screened, 166 cases were identified; 63% (non-recurrent) and 37% (recurrent) with median time to recurrence of 20 days. Univariate and multivariate analysis showed that the mortality rate was two and nine-fold, respectively, higher with recurrent bacteremia. Univariate analysis found that except for urinary tract infection, large burn size (>20%), 3rd degree burns, increased injuiry severity, perineal burns, and mechanical ventilator days were independent factors predictive of recurrence of bacteremia as well as increased mortality in the recurrent bacteremia cohort. Acinetobacter baumannii complex (63%) was prevalent in the non-recurrent group, while Klebsiella pneumoniae (46% vs. 30%) and Pseudomonas aeruginosa (35% vs. 26%) were prevalent in recurrent bacteremia. Half of the recurrent bacteremia cases were polymicrobial, compared to 9% in non-recurrent bacteremia. Pneumonia was prevalent in non-recurrent bacteremia (38%) and a combination of pneumonia and wound sepsis (29%) in recurrent bacteremia casualties. Conclusions: Recurrent bacteremia increases mortality in military burn casualties. Additional research is needed to address and mitigate the underlying causes, thereby improving survival.