Serum Procalcitonin and C-reactive Protein Level as an Early Diagnostic Marker of Bacterial Meningitis in the Emergency Department

ABSTRACT

PURPOSE: Immediate identification of bacterial meningitis (BM) is essential in the emergency department. However, diagnosis of BM from analysis of cerebrospinal fluid has low sensitivity. The goal of this study was to determine the ability of serum procalcitonin (PCT) and C-reactive protein (CRP) for differentiation between BM and non-BM in adult patients. METHODS: This retrospective cohort study, which was conducted from Jan 1 2008 to Sep 30 2011, included patients with a diagnosis of meningitis based on compatible clinical features and cerebrospinal fluid (CSF) culture findings with a CSF leukocyte count > 5 /microL. Measurement of Serum PCT and CRP level was performed on initial admission to the emergency department. Patients were divided into two groups, according to the type of meningitis BM or non-BM. Clinical features, laboratory results, including CSF results, serum PCT, and CRP levels were assessed. RESULTS: A total of 63 patients (age, 49+/-19) with confirmed meningitis were admitted 43 patients with non-BM and 20 patients with BM. Significantly higher PCT and CRP levels, CSF white blood cell and neutrophil count, CSF glucose, and protein levels were observed in the BM group. The most highly discriminative parameters for differential diagnosis of BM proved to be serum PCT, with a sensitivity of 90%, a specificity of 100%, a positive predictive value of 100%, a negative predictive value of 96% at a diagnostic cut-off level of 1.0 ng/mL (area under the curve 0.98; 95% confidence interval 0.00-1.00) and CRP, with a sensitivity of 85%, a specificity of 88%, a positive predictive value of 77%, a negative predictive value of 93% at a diagnostic cut-off level of 6.0 mg/dL (area under the curve 0.91; 95% confidence interval 0.76-0.97). CONCLUSION: Serum PCT and CRP levels appear to be the most highly discriminative parameters for differential diagnosis of BM and non-BM.