UTILIZATION AND DIAGNOSTIC YIELD OF BLOOD CULTURES IN A SURGICAL INTENSIVE-CARE UNIT

Objective: To evaluate the diagnostic yield of blood cultures obtained in a surgical intensive care unit (ICU) and to assess factors potenti ally influencing yield. Design: Retrospective, descriptive study. Sett ing: Surgical ICU in a university hospital. Subjects: All patients who had a blood culture obtained during their admission to the trauma/neu rosurgical ICU of Presbyterian University Hospital from January 1, 199 3 to December 31, 1993. Measurements and Main Results: Blood culture i solates were categorized as pathogens or contaminants and overall diag nostic yield was determined, Blood cultures were positive for pathogen s in 4.6% of all culture episodes, while contaminants were isolated in 5.5% of all culture episodes. A total of 23 true bacteremias were ide ntified in 21 patients, for an overall rate of bacteremia of 3.6 per 1 00 admissions (5.9 per 1,000 patient days). Concurrent antibiotics wer e being used at the time of blood culture in 65.3% of all culture epis odes. The yield for pathogens was significantly lower (2.2%) when cult ures were obtained on antibiotics compared with culture episodes obtai ned off antibiotics (6.4%) (p < .05). Single set blood culture episode s were obtained in similar to 32% of all culturing episodes with the o verall yield for pathogens of these culturing episodes lower (2.9%) th an that of multiple set culture episodes (5.3%) (p = NS). Conclusions: Blood culture yield in this surgical ICU was relatively low in compar ison with other published studies. The data further suggest that concu rrent use of systemic antibiotics and inappropriate or excessive cultu ring may negatively influence blood culture yield.