Accuracy of Procalcitonin in the Diagnosis of Bacteremia and Discrimination from Contamination

Abstract

Objective: In this study, we aimed to evaluate the concordance of blood culture with procalcitonin (PCT) alone and together with C-reactive protein (CRP) in detecting bacteremia and the diagnostic performance of these biomarkers to differentiate contamination from true bacteremia. Materials and Methods: The medical records of 310 patients were analysed retrospectively. Advia Centaur XP immunoassay system and Au analysers were used to determine PCT and CRP levels, respectively. BacT/ Alert3D60 hemoculture system was used to incubate blood specimens, and VITEK2 compact was used to identify isolated strains. Results: The accuracy of PCT and CRP in detecting bacteremia were found to be 68.1% and 36.4%, respectively, and combining PCT and CRP had no added value. In analysis of receiver operating characteristic (ROC), the area under the ROC curve (AUROC) values of PCT and CRP were found to be 0.889 and 0.779 in discriminating the culture-negative group from the culture-positive group, and 0.645 and 0.502 in discriminating bacteremia from contamination, respectively. Conclusion: PCT is a reliable marker that can be used to detect bacteremia. However, its discriminative power was low in differentiating true bacteremia from contamination. Therefore, PCT levels alone should not be used to rule out blood culture contamination.