Bacteremia due to Escherichia coli: a study of 861 episodes.

Escherichia coli accounted for 861 (23.9%) of 3,605 episodes of bacteremia in an 18-year prospective survey at St. Thomas' Hospital, a proportion that changed little during the survey. The most common focus of infection leading to nosocomial and community-acquired bacteremia due to E. coli was the urinary tract. Twenty-six percent of adult female patients with E. coli bacteremia resulting from a urinary tract infection were diabetic. The O antigen serotypes identified most often were O6, O2, O1, O4, O15, and O75; the multiply resistant O15 serotype of E. coli was implicated in a community outbreak of urinary tract infection. Ampicillin resistance in strains causing community-acquired infection increased to the same level as that of strains causing nosocomial infection (almost 50%). The overall mortality was 20.7% and was greater in the presence of shock (52.4% vs. 15.3%). Death due to infection occurred in 2.6% and 10.3%, respectively, of cases with urinary tract and non-urinary tract foci. The adverse influence of inappropriate initial therapy on outcome was more marked in the latter half of the study.