Evaluation of C-Reactive protein in CSF for diagnosis of acute bacterial meningitis at a tertiary care hospital

Primary aim of this study was to evaluate the role of C-reactive protein (CRP) in cerebrospinal fluid to establish the diagnosis of Acute Bacterial Meningitis (ABM), and to measure the specificity, sensitivity, positive and negative predictive values of CRP in Cerebrospinal Fluid (CSF) in the diagnosis of Acute Bacterial Meningitis.

Fifty patients between age 0 to 15 years with fever and convulsion were screened, randomly selected and divided into three groups on the basis of CSF findings i.e. bacterial meningitis, non-bacterial meningitis and no meningitis as control group. CSF CRP was measured in all cases along with CSF cytology, biochemistry and culture-sensitivity. Complete blood count, random blood sugar done to treat all cases. All patients were treated adequately (if culture positive according to sensitivity) and were monitored as long as they stayed in hospital. Outcome was assessed clinically during discharge.

Twenty patients had acute bacterial meningitis, 15 had aseptic meningitis and 15 cases had CSF findings normal (control). CSF-CRP was positive (>6mg/L) in 40% of the cases of ABM but it was found negative in all aseptic meningitis and in the control groups. Sensitivity of CSF-CRP was low (40%) but specificity was high (100%). The positive predictive value of CSF-CRP was 100% and negative predictive value 55.5%. Among the organisms isolated H. influenzae was the leading pathogen (52%) in infancy followed by S. pneumoniae (42%) and N. meningitidis (5%). Outcome of the treatment of CSF-CRP positive ABM cases was found poor (p= 0.035).

Study concludes that significant level of CRP in CSF is highly specific for diagnosis of ABM and ruled out aseptic meningitis. But negative CSF-CRP could neither exclude pyogenic meningitis nor did it rule out aseptic meningitis.