Limited clinical utility of blood and urine cultures in the treatment of acute pyelonephritis during pregnancy

OBJECTIVE: The purpose of this study was to determine the utility of urine and blood cultures in the clinical management of pregnant women with acute pyelonephritis. STUDY DESIGN: Data were pooled from three randomized controlled trials that were conducted at two university-based tertiary care centers and included 391 pregnant women with pyelonephritis. The results of urine and blood cult ures were correlated with clinical management decisions, outcome, length of hospital stay, and cost. RESULTS: Results of 98% of urine cultures (382/391) and 99% of blood cultur es (388/391) were available for analysis. The most common pathogen isolated was Escherichia coli, which was found in 79% of the urine cultures (300/38 2) and in 77% of the blood cultures (27/35). Susceptibility testing reveale d 46% resistance to ampicillin; 7%, 2%, and 0% resistances to first-, secon d-, and third-generation cephalosporins, respectively; and 1% resistance to gentamicin. Six percent of the participants (25/391) required changes in a ntibiotic therapy, most commonly for persistent fever (6/25, 25%). Positive blood culture results directly influenced management by prolonging the dur ation of hospitalization, with means of 4.6 +/- 2.6 hospital days for women with bacteremia and 2.6 +/- 1.5 hospital days for women without bacteremia (P < .001) despite similar durations of symptoms. CONCLUSION: Urine and blood cultures with sensitivity testing had limited u tility in the clinical management of pregnant women with pyelonephritis. De cisions to change antibiotic treatment were affected more by clinical cours e than by culture results. We suggest that elimination of blood and urine c ultures might simplify management and result in significant cost savings wi thout compromising patient care.