Low serum procalcitonin level accurately predicts the absence of bacteremia in adult patients with acute fever.

The ability of measurement of serum procalcitonin (PCT) levels to differentiate bacteremic from nonbacteremic infectious episodes in patients hospitalized for community-acquired infections was assessed. Serum samples were obtained from adult inpatients with fever to determine the serum PCT level, C-reactive protein (CRP) level, and erythrocyte sedimentation rate (ESR). Of 165 patients, 22 (13%) had bacteremic episodes and 143 (87%) had nonbacteremic episodes. PCT levels, CRP levels, and ESRs were significantly higher in bacteremic patients than in nonbacteremic patients (P<.001,.007, and.024, respectively). The best cutoff value for PCT was 0.4 ng/mL, which was associated with a negative predictive value of 98.8%. Area under the receiver operating characteristic curve was 0.83 for PCT, which was significantly higher than that for CRP (0.68; P<.0001) and ESR (0.65; P<.05). A serum PCT level of <0.4 ng/mL accurately rules out the diagnosis of bacteremia. The use of PCT assessment could help physicians limit the number of blood cultures to be processed and the number of antibiotic prescriptions.