Epidemiology of community-acquired bacteremia patients admitted to the intensive care unit

Background

Community-acquired bacteremia (CAB) is a common cause of hospital and intensive care admission, with a case fatality rate of 20–30%. Its early identification and association with the probable source of infection and agents will permit an early and effective antibiotic therapy, and would probably contribute to a decrease in the morbidity and mortality.

Materials and methods

A prospective, observational study of all the patients with community-acquired sepsis (CAS) admitted to a tertiary, mixed, 12-bed, intensive care unit (ICU), at a University Hospital, between 1 December 2004 and 30 November 2005. In this study the CAB subgroup was analyzed. CAB was defined by an infection present at hospital admission or within the first 48 hours with a positive blood culture obtained in the same period.

Results

Throughout the study period, 347 patients were admitted; 149 (43%) with CAS. Blood cultures were obtained in 137 patients (93%), and 24 patients (17.5%) had CAB. From these, 67% were male, with a median age of 57 years (interquartile range = 47–71). The median SAPS II score was 51. Distribution by focus of infection was as follows: respiratory (35%); endovascular (21%); intraabdominal (17%); urinary (13%); central nervous system (8%) and skin and soft tissue (8%). All patients admitted with skin and soft-tissue CAS had CAB. Gram-positive microorganisms represented 50% of all isolations, followed by Gram-negative (33%). No fungus was isolated. Streptoccocus pneumoniae and Escherichia coli were the more frequent, representing 45% of all isolations. Patients with CAB had more septic shock than patients with negative blood cultures (75% versus 49%, P = 0.039) and higher ICU (50% versus 28%, P = 0.049), 28-day (54% versus 28%, P = 0.014) and hospital (57% versus 33%, P = 0.041) mortalities, although the median SAPS II score was not significantly different between both groups (51 versus 45, P = 0.112).

Conclusion

CAB represented 7% of all ICU admissions, with an associated ICU crude mortality of 50%. Respiratory and endovascular focuses of infection were the two most frequent, with Gram-positive microorganisms representing one-half of all isolations.