Burden of community-onset Escherichia coli bacteremia in seniors

Background. Although Escherichia coli is a well-recognized cause of urinary tract infection in seniors, little is known about the burden of invasive E. coli infection in this population. Methods. We conducted a population-based cohort study of 46,238 noninstitutionalized Group Health Cooperative members >= 65 years of age to ascertain incidences of community-onset E. coli bacteremia and, for comparison, pneumococcal bacteremia, and we then performed a case-control study to identify risk factors for community-onset E. coli bacteremia. Results. The overall rate of community-onset E. coli bacteremia in the study cohort was 150 cases/100,000 person-years, which was similar to 3 times higher than the rate of pneumococcal bacteremia. In the case-control study, urinary catheterization and urinary incontinence were the only factors associated with an increased risk of E. coli bacteremia in men (62 cases), whereas cancer, renal failure, congestive heart failure, coronary artery disease, and urinary incontinence were associated with an increased risk of E. coli bacteremia in women (119 cases). Conclusions. E. coli appears to be the leading cause of community-onset bacteremia in seniors, and, on the basis of these rates, we estimate that 53,476 cases occur in noninstitutionalized seniors each year in the United States. Community-onset E. coli bacteremia in seniors is, therefore, an infection of public health importance.