Usefulness of Blood Cultures in Acute Pyelonephritis

ABSTRACT

BACKGROUND: Routine cultures of blood in febrile patients being hospitalized with uncomplicated pyelonephritis are parts of accepted management and are advocated in several textbooks of medicine and in several review articles. For a better understanding of the importance of blood cultures for patients admitted with pyelonephritis, we did a retrospective chart review of patients admitted to a medical center over a 2-year period. METHODS: To evaluate the usefulness of blood cultures in patients admitted with pyelonephritis, we conducted a retrospective chart review of patients who were admitted to hospital from 1998 through 1999 with a primary discharge diagnosis of uncomplicated pyelonephritis. RESULTS: Among the 329 patients admitted, 177 patients were included in the study. Sixteen(9.0%) were men, and 161(91%) were women. The mean age was 52.24+/-18.08. The most common precipitating factor was diabetes mellitus (19.2%). Urinalysis results showed E.coli as the causative agent in 155 patients(87.6%). Positive blood culture results were be seen in 67 patients with a 37.9% sensitivity. The usefulness of blood cultures in acute pyelonephritis was statistically significant only in the case of fever(P=0.003). CONCLUSION: In the setting of uncomplicated pyelonephritis in the adults, if urine cultures can be obtained, blood cultures are not usually necessary. Settings where blood cultures might be appropriate include immunosuppressed patients, patients in whom the diagnosis is not clear, patients in whom bacteremic seeding of the kidney is suspected, and patients who have a prior history of urinary tract infection.