Characteristics of Bloodstream Infections in Burn Patients: An 11-year Retrospective Study

Aims: The principal aim of this study was to describe infection related characteristics of blood stream infections (BSI) in patients with burns. We sought to determine the organisms that caused BSI and factors that could predict the outcome of BSI.

Methods: Data was collected on admitted patients with burns from January 1998 to December 2008. Selected information from databases was analysed using SPSS version 17 (SPSS Inc., Chicago). Descriptive, univariate and multivariate analysis was undertaken to determine factors predictive of clinical outcome. The factors analysed by univariate analysis were selected on clinical plausibility. Multivariate analysis used a crosstabs procedure initially to estimate maximum likelihood. Factors that were associated with a p value <0.15 were entered into a binary logistic regression to detect which factors were independent predictors of mortality in BSI and outcome according to specific organisms.

Results: Ninety-nine out of 2364 (4%) patients developed 212-documented BSI. The median time from burn to BSI was 7 (interquartile range 3-16) days. Gram-positive organisms, in particular Methicillin resistant Staphylococcus aureus and Coagulase negative Staphylococci, were the most common bacteria associated with BSI in the first week of hospital admission. The mortality rate for all admissions over the data collection period was 3%. Of the 99 patients with BSI, 13 died giving a mortality rate, in the presence of BSI, of 13%. Univariate analysis found that the factors predictive of P. aeruginosa mortality were inhalational injury, higher total body surface area burns, total days of antibiotic treatment and elevated Acute Physiological and Chronic Health Evaluation (APACHE) II scores. Multivariate analysis identified inhalational injury to be the only factor associated with BSI-related mortality.

Conclusion: Whilst the overall mortality in our cohort was low, the presence of BSI increased this four-fold. Whilst infections caused by Gram-positive pathogens occurred earlier in the patient stay than Gram-negative organisms, the highest mortality was associated with P. aeruginosa infections. This study highlights the negative effects of BSI on clinical outcomes in burn patients.