Utilitat de la procalcitonina en líquid cefaloraquidi en el diagnòstic d’infeccions del sistema nerviós central (SNC)

Abstract

Introduction: Meningitis is a serious infection that in order to be treated efficiently needs a quick diagnosis. The current diagnosis is based on molecular biology and other microbiological techniques such as bacterial culture, which requires a lot of time and makes it difficult for an early diagnosis. For this reason, a new biomarker is sought especially in bacterial meningitis, since they are the ones that show a worse evolution in patient. We are looking for a specific and sensitive biomarker for cerebrospinal fluid (CSF) samples that give us relevant information for infections of the central nervous system (CNS). It has been shown that serum procalcitonin (PCT) is a protein that increases quantitatively in the presence of a bacterial infection. Objectives: To assess the use of PCT as a meningitis biomarker in CSF samples comparing it with other existing specific biomarkers: PCT in serum and lactate in CSF. Methods: From the clinical laboratory of the Hospital Universitari Doctor Josep Trueta for a period of six months, we collected data of PCT in serum and LCR, lactate, count of the cells and leukocyte, proteins and glucose in LCR of 48 patients with clinical suspicion of meningitis. We included patients with bacterial meningitis, either acquired in the community or post-surgical, viral meningitis and a control group without a disease and we compared the use of the biomarkers with ROC curves and Mann-Whitney tests. Results: The average concentration of PCT in CSF for the different groups studied was: 0.16 ng/mL (IQR=0.12, SD=0.13) for the bacterial meningitis group (n=7), 0.147 ng/mL (IQR=0, SD=NA) for the group of viral meningitis (n=1) and 0.52 ng/mL (IQR=0.11, SD=2.05) for the noninfectious group (n=37). The median differences (95%) between the bacterial and non-infectious group presented a p-value of: 0.7949 at PCT levels in CSF, 0.06184 at serum PCT levels and 0.008075 at levels of lactate in CSF. The results of the ROC curves comparing the bacterial group to the non-infectious group resulted in an AUC 0.9063 (95%, IC:0.7591-1.0534) for PCT in plasma, an AUC 0.5336 (95%, IC:0.287-0.7797) for PCT in CSF and an AUC 0.9167 (95%, CI:0.7661-1.0672) for lactate in CSF. Conclusions: It is suggested that PCT in LCR is not a good biomarker for the diagnosis of meningitis compared to the PCT in serum and lactate. In contrast, it is suggested that lactate is a valid biomarker for the diagnosis of bacterial meningitis