Clinical significance of healthcare-associated infections in community-onset Escherichia coli bacteraemia

Background: The increasing antimicrobial resistance of Escherichia coli infection is of great concern, even for community-onset infections. Methods: We conducted a retrospective cohort study of patients with E. coli bacteraemia who visited the emergency department of the Samsung Medical Center from February 2002 to December 2005 to identify the risk factors for mortality and association between healthcare-associated (HCA) infection and mortality. We classified community-onset E. coli bacteraemia into community-acquired (CA) and HCA infections. Results: A total of 508 patients with E. coli bacteraemia were enrolled (mean age, 61.8 +/- 14.3 years; male/female, 191:317). The HCA E. coli bacteraemia had significantly higher severity of illness and higher antimicrobial resistance rate than CA bacteraemia. The overall 30-day mortality rate was 13.6% (69/508) and the mortality of HCA infections was significantly higher than that of CA infections (26.4% versus 9.6%, P < 0.001). In multivariate analysis, high Charlson's co-morbidity index (OR 4.84, 95% CI 2.14-10.95, P < 0.001), high Pitt bacteraemia score (OR 32.03, 95% CI 13.08-74.43, P < 0.001), presentation with acute renal failure (OR 4.11, 95% CI 1.90-8.89, P < 0.001) and HCA bacteraemia (OR 2.34, 95% CI 1.09-5.01, P = 0.030) were found to be the significant risk factors for 30-day mortality in E. coli bacteraemia. Conclusions: The mortality rate of HCA E. coli bacteraemia was higher than twice that of CA bacteraemia and HCA bacteraemia was one of the significant risk factors for mortality, even after adjusting for a large number of potential confounders.