Community-acquired bacteraemia with sepsis in adults admitted to the intensive care unit: a prospective multicentre study

Background

The main objectives of this study were to describe the epidemiology and microbiology of community-acquired bacteraemia (CAB) in patients with sepsis and to determine the associated crude mortality.

Materials and methods

A prospective, multicentre, cohort, study, was performed on community-acquired bloodstream infections with sepsis admitted to Portuguese intensive care units (ICUs), from 1 December 2004 to 30 November 2005, with a follow-up until discharge. CAB was defined as an infection that was present on admission or within the first 48 hours, with positive blood cultures drawn in the same period. Bacteraemia was considered to be healthcare related (HCRB) if: (a) patients had wound dressing or intravenous treatments in the previous 30 days, (b) patients were observed at a hospital or haemodialysis centre or had chemotherapy in the previous 30 days, (c) patients were admitted to an acute care hospital for 2 days or more in the previous 90 days, (d) patient lives at a nursing home or institution.

Results

Seventeen units entered the study from north to south Portugal, corresponding to 41% of all mixed national ICU beds. Over this period 4,142 patients were admitted to the study – 897 (22%) had community-acquired sepsis, and of these 804 (90%) had blood cultures done in the first 48 hours. Significant isolates were grown from samples of 160 patients (20%). The following focus of infection was identified: respiratory (37%), intraabdominal (19%), urinary (16%), endovascular (14%), skin and soft tissue (7%), central nervous system (5%) and other (2%). Of these 31% were health-care related (HCRB). Comparing patients without HCRB with those who had HCRB, an inversion in the microbiological profile was found with Gram-positive dominating the first (55% versus 29%) and Gram-negative dominating in the latter (29% versus 54%). When compared with patients without bacteraemia, the 28-day crude mortality was higher for patients with positive blood cultures (39% versus 29%, P = 0.014); however, when adjusted to other variables, it was not found to be an independent determinant of 28-day mortality.

Conclusion

CAB with severe sepsis accounts for 4% of all ICU admissions with a crude 28-day mortality rate of 39%, although not representing an independent risk factor for 28-day mortality. The microbiological profile is quite different in healthcare-associated bacteraemia, making their identification extremely important to prompt an initial adequate antibiotic approach.