Clinical value of serum procalcitonin level in the diagnosis of bloodstream infection

Objective To evaluate the clinical value of serum procalcitonin levels in bloodstream infection. Methods 568 patients who had both PCT detection and blood culture were collected from our hospital,538 of them were involved in this study. The relationship between serum PCT level and blood culture result was investigated. The PCT levels in patients with gram-negative bacterial bloodstream infection,gram-positive bacterial bloodstream infection and fungal bloodstream infection were compared. The bloodstream infection patients who had several PCT detection results were divided into three groups:better group,delay group and death group according to the infection outcome in three weeks. PCT levels between the three groups were compared and the correlation with prognosis of bloodstream infection were analyzed. Rank sum test and Fisher’s test were used to analyze PCT values and prognosis among all the groups. Results In patients with positive blood culture result,the median of PCT [3.39(0.69~6.52)μg/L]was significantly higher than that [0.31(0.09~1.48)μg/L] in patients with negative blood culture result(P<0.05). The median of PCT in gram-negative bacterial infection,gram-positive bacterial infection and fungal infection were 4.39(1.80~10.85)μg/L,1.98(0.42~4.05)μg/L and 0.62(0.39~3.98)μg/L respectively,the differences among them were statistically significant(P<0.05). According to receiver operating characteristic curve,if 3.315μg/L was taken as a critical value,the sensitivity of PCT in diagnosis of gramnegative bacterial infection and fungal infection was 67.9%,and the specificity was 75.0%. And if 4.1μg/L was taken as a critical value,the sensitivity of PCT in diagnosis of gram-negative bacterial infection and gram-positive bacterial infection was 57.7%,and the specificity was 76.5%. In the 46 patients who detected PCT repeatedly,the prognosis of whom with decreasing PCT level was better than the others. Conclusions Serum PCT level is proved to be an effective marker for rapid diagnosis of bloodstream infection,and is valuable to discriminate gram-negative bacterial infection,gram-positive bacterial infection and fungal infection. Dynamic monitoring of PCT level has a certain reference value for the prognosis of bloodstream infection patients.