Sepsis caused by bloodstream infection in patients in the intensive care unit: the impact of inactive empiric antimicrobial therapy on outcome

Abstract

Background: Sepsis is one of the leading causes of death in the UK.

Aims: To identify the rate of inactive antimicrobial therapy (AMT) in the intensive care unit (ICU) and whether inactive AMT has an effect on in-hospital mortality, ICU mortality, 90-day mortality and length of hospital stay. A further aim was to identify risk factors for receiving inactive AMT.

Methods: This was a retrospective observational study conducted at Glasgow Royal Infirmary ICU between January 2010 and December 2013. In total, 12,000 blood cultures were taken over this time period, of which 127 were deemed clinically significant. Multi-variate logistic regression was used to identify risk factors independently associated with mortality. Univariate analysis followed by multi-variate analysis was performed to identify risk factors for receiving inactive AMT.

Results: The rate of inactive AMT was 47% (N = 60). Multi-variate analysis showed that receiving antibiotics within the first 24h of ICU admission led to reduced mortality [relative risk 1.70, 95% confidence interval (CI) 1.19-2.44]. Furthermore, it showed that severity of illness (as defined by SIRS criteria sepsis vs septic shock) increased mortality [odds ratio (OR) 9.87, 95% CI 1.73-55.5]. However, inactive AMT did not increase mortality (OR 1.07, 95% CI 0.47-2.41) or length of hospital stay (53.2 vs 69.1 days, P = 0.348). Fungal bloodstream infection was found to be a risk factor for receiving inactive AMT (OR 5.10, 95% CI 1.29-20.14).

Conclusion: Mortality from sepsis is influenced by multiple factors. This study was unable to demonstrate that inactive AMT had an effect on mortality in sepsis.

Keywords: Antibiotics; Bacteraemia; Fungal; Intensive care; Organism; Sepsis.