Prediction of blood culture results by measuring procalcitonin levels and other inflammatory biomarkers

BackgroundIt would be helpful if we could predict positive or negative blood culture results. This study considered the usefulness of measuring procalcitonin (PCT) level and standard clinical biomarkers such as white blood cell (WBC) count, C-reactive protein (CRP) level, and platelet (PLT) count to predict blood culture results.MethodWe retrospectively analyzed the data from 422 specimens collected at our emergency center within the preceding 36 consecutive months. Primary component analysis (PCA) was used for detecting the degree of the relational contribution of each of the 4 biomarkers to the blood culture results.ResultsProcalcitonin alone (cut-off value, 0.5 ng/mL) yielded a positive blood culture rate of 34.0%. Procalcitonin plus 3 biomarkers (WBC, CRP, and PLT) analyzed by PCA yielded 45.9% or 35.3% when a case was in the first or fourth quadrant, which was significantly higher than cases in the second or third quadrant. Primary component analysis also revealed that positive blood culture results were mainly affected by primary component 1, to which PCT and PLT (not WBC or CRP) predominantly contribute.ConclusionAlthough it is difficult to predict blood culture results, even using 4 biomarkers analyzed by PCA, our new finding that blood culture results are affected not by WBC and CRP, but mainly by PCT and PLT, might help explain the mechanism of sepsis.