Role of cerebrospinal fluid procalcitonin in identification of intracranial bacterial infection and aseptic meningitis

Objective To investigate the role of the cerebrospinal fluid procalcitonin (PCT) in the identification of intracranial bacterial infection and aseptic meningitis in adults. Methods A total of 178 patients with the suspected symptom of intracranial bacterial infection at 48 to 72 h after neurosurgical brain tumor surgery at the Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University from October 2013 to March 2014 were analyzed retrospectively. The cerebrospinal fluid routine, biochemical and procalcitonin tests were performed. According to the diagnostic criteria of intracranial infection, they were divided into either a bacterial infection group (n=50) or an aseptic meningitis group (n=128). The cerebrospinal fluid PCT and its changes of the traditional cerebrospinal fluid detection index were compared. The receiver operating characteristic curve (ROC) was used to analyze the values of cerebrospinal fluid PCT for identifying the infection and aseptic meningitis. Results Compared with the aseptic meningitis group, the white blood cell count, polynuclear cell ratio, protein content, and PCT content were all increased in the cerebrospinal fluid of bacterial infection, and the blood glucose was reduced. There were significant differences (all P<0.01). There was no significant difference in chloride. The median (range) of cerebrospinal fluid PCT in the bacterial infection group was 0.15 ng/ml (0-3.09 ng/ml), and in the aseptic meningitis group was 0 ng/ml (0-0.46 ng/ml). The ROC results showed that the area under curve of the differential diagnosis of intracranial bacterial infection was 0.746. The diagnostic threshold was 0.075 ng/ml, the sensitivity was 68.0%, specificity was 72.7%, positive predictive value was 49.3%, and negative predictive value was 85.3%. The PCT in cerebrospinal fluid was positively correlated with the leukocyte, proportion of multinucleated cells, and protein (r=0.446, 0.453, and 0.482, respectively, all P<0.01). It was negatively correlated with glucose (r=-0.201, P=0.007). Conclusion The detection of PCT in cerebrospinal fluid has an important clinical application value for the diagnosis of intracranial bacterial infection after neurosurgical operation. Key words: Central nervous system bacterial infections; Meningitis, aseptic; Neurosurgical procedures; Procalcitonin; Cerebrospinal fluid