Blood Stream Infections of Abdominal Origin in the Intensive Care Unit: Characteristics and Determinants of Death

Background: Blood stream infections (BSI) of abdominal origin are associated with a high mortality rate. We hypothesized that both patient and microbiological factors determine death in critically ill patients who develop such infections. Methods: Ninety-six consecutive patients who developed BSI of abdominal origin in an 11-year period (1992-2002) in the intensive care unit (ICU) of the Ghent University Hospital were studied. Patient data were retrieved from a prospective registry of BSI. Demographics, disease severity, source of the BSI, incidence of organ failure, and outcome were recorded. Microbiological data were retrieved from the patient file and the hospital laboratory. Results: Secondary peritonitis and intra-abdominal abscesses were the source of the BSI in the majority of patients. The majority of the organisms involved were gram-negative, with Escherichia coli isolated most frequently. Twenty-one patients (22%) had polymicrobial BSI, and in 39 patients, at least one of the micro-organisms was antibiotic resistant (41%). The mortality rate in the whole patient group was 62.5% (60/96), which was significantly higher than the Acute Physiology and Chronic Health Evaluation (APACHE) II-based expected mortality rate (p < 0.001). Patients who died were older, had a tendency to have a higher APACHE II score on admission, and were more likely to suffer from acute renal failure and cardiovascular failure during their ICU stay. Logistic regression analysis revealed that the following factors were independently associated with death: Age (odds ratio [OR] 1.09; 95% confidence interval [CI] 1.04, 1.14; p <0.001) (per year increase) and the occurrence of acute renal failure (OR 4.18; 95% CI 1.22, 14.31; p = 0.023). Conclusions: The mortality rate of ICU patients who develop BSI of intra-abdominal origin is high. Gram-negative micro-organisms were isolated most frequently, and 41% of all organisms were antibiotic-resistant. Two patient-related factors (greater age and the development of acute renal failure) were associated independently with a higher mortality rate.