Escherichia coli bacteraemia in Canberra: incidence and clinical features.

Objective: To determine the population incidence and clinical features of Escherichia coli bacteraemia in Canberra, Australia.

Design, Setting And Participants: Canberra (including the nearby local government areas of Queanbeyan and Yarrowlumla) has a geographically isolated population of about 366 000 people. Its six hospitals also provide tertiary medical services for the surrounding region. Confining our analysis (by residential postcodes) to Canberra residents only, we used microbiology laboratory records and population statistics to calculate the population incidence of E. coli bacteraemia from January 2000 to December 2004. Clinical data were also collected prospectively on episodes occurring within three of the hospitals.

Main Outcome Measures: Population incidence of E. coli bacteraemia; place of acquisition of infection; focus of infection within body; recovery, new morbidity or death at 7 days.

Results: During the 5-year period, 515 episodes of E. coli bacteraemia occurred in Canberra residents, an incidence of 28 per 100 000 population per year. The highest rate was in men aged > or = 80 years (463 per 100 000). Overall, E. coli bacteraemia occurred in equal numbers in males and females, but incidence was higher in males aged < 1 year and > or = 60 years. Most episodes occurred in people aged > or = 60 years (316/511 [62%]) and most were community-associated (347/511 [68%]). Half the infections (257/511) had a genitourinary focus and 28% (141/511) a gastrointestinal focus. The 7-day case-fatality rate was 5%. Prostate biopsies and urinary catheters were notable preventable foci of health care-associated bacteraemia. Resistance of isolates to gentamicin (2.1%), ciprofloxacin (1.8%) and cefotaxime (0.4%) was low.

Conclusions: E. coli is the most common cause of bacteraemia in Canberra, and incidence increases with age. Most cases have a community onset, but many episodes are related to health care procedures. Ongoing surveillance is important for identifying risk factors that may be modified to reduce disease.