Long-term outcome and risk factors for late mortality in Gram-negative bacteraemia: a retrospective cohort study

Abstract

Objectives: The long-term outcomes of patients following Gram-negative bacteraemia (GNB) are poorly understood. Here we describe a cohort of patients with GNB over a 2-year period and determine factors associated with late mortality (death between Days 31 and 365 after detection of bacteraemia).

Methods: This was a single-centre, retrospective, observational cohort study of 789 patients with confirmed Escherichia coli, Klebsiella spp. or Pseudomonas aeruginosa bacteraemia with a follow-up of 1 year. Multivariable survival analysis was used to determine risk factors for late mortality in patients who survived the initial 30-day period of infection.

Results: Overall, 1-year all-cause mortality was 36.2%, with 18.1% of patients dying within 30 days and 18.1% of patients suffering late mortality. An adverse antimicrobial resistance profile [hazard ratio (HR) = 1.095 per any additional antimicrobial category, 95% confidence interval (CI) 1.018-1.178; P = 0.014] and infection with P. aeruginosa (HR = 2.08, 95% CI 1.11-3.88; P = 0.022) were independent predictors of late mortality. Other significant factors included Charlson comorbidity index and length of hospitalisation after the index blood culture.

Conclusion: Patients with GNB have a poor long-term prognosis. Risk factors for greater mortality at 1 year include co-morbidity, length of hospitalisation, and infecting organism and its resistance profile.

Keywords: Bacteraemia; Escherichia coli; Gram-negative bacteria; Klebsiella; Mortality; Pseudomonas aeruginosa.