Epidemiological and clinical characteristics of occult bacteremia in an adult emergency department in Spain: influence of blood culture results on changes in initial diagnosis and empiric antibiotic treatment.

A prospective study was carried out to analyze the usefulness of blood culture results for adult patients who were discharged from the emergency department with bacteremia. Over a 29-month period, 110 patients with significant bacteremia who were seen in the emergency department and discharged home were studied. The mean age of the patients was 61.8 years. The most frequent initial major diagnosis was urinary tract infection (UTI) (n=63; 57.3%). Gram-negative organisms were isolated in 79 (71.8%) cases. A change in diagnosis (44.5% cases) was more common when the initial diagnosis was something other than UTI or when empiric antimicrobial therapy was ineffective or was not given (P<0.001). The significant predictors of modification of the initial empiric antibiotic therapy were ineffective empiric antimicrobial therapy and transfer of the patient from the emergency department to an infectious diseases outpatient clinic (P=0.01). Blood culture results may be useful for achieving the correct diagnosis in adult patients with bacteremia and for guiding treatment in the subsequent management of outpatients.