The additional value of blood cultures in patients with complicated urinary tract infections.

We evaluated 800 hospitalized patients with a complicated urinary tract infection, from whom both a blood and a urine culture were obtained on the first day of antibiotic treatment. Urine cultures were positive in 70% of patients, and blood cultures were positive in 29%. In 7% of patients, uropathogens caused bacteraemia with a pathogen that was not isolated from urine. Receiving antibiotic therapy at the moment of hospitalization was the only factor independently associated with discordant culture results (OR, 2.06; 95% CI, 1.18-3.61). For those receiving antibiotics at the moment of hospitalization, blood cultures have additional diagnostic value over urine cultures.