Blood cultures of adult patients discharged from the emergency department-is the safety net reliable?

We investigated the clinical implications of the practice in our emergency department (ED) of discharging patients with pending blood cultures. We reviewed the medical records of adults discharged with positive blood cultures from the ED of a 330-bed university hospital during a five-year period. Clinical characteristics, laboratory data, and antibiotic treatment prescribed in the ED and at discharge were accessed. Antimicrobial susceptibility profiles were used to determine whether antibiotic treatment was adequate. The outcomes assessed for 90 days following discharge were return to the ED, hospitalization, modified diagnosis, and death. Of 220,681 visits to the ED, 1362 showed positive blood cultures; of these, 307 (22.5%) were from discharged patients. More than half the isolates (56.3%) were considered contaminants. Of 124 visits with true bacteremia, Enterobacteriaceae were the most common pathogens (67.0%). This is concordant with urinary tract infection (UTI) being the most common diagnosis (52.4%). With antibiotic treatment, 69.4% had been discharged with antibiotic treatment, which was adequate in two-thirds of them. Among the 77 who returned to the ED, 27.5% had persistent bacteremia. The diagnosis was changed in 44.2% of them, mostly with brucellosis or bone and joint infections, and 84.4% were subsequently hospitalized. Within three months, 5.6% of bacteremic patients died, all after hospitalization. Bacteremia in discharged patients occurred mainly in association with UTI. Outcomes were generally favorable, although only about half received appropriate antibiotic treatment. Diagnoses were changed in a relatively high proportion of patients following culture results.