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Published on: November 22, 2011
Interferon gamma quantification in cerebrospinal fluid compared with PCR for the diagnosis of tuberculous meningitis
Rafael San Juan1, Carmen Sánchez-Suárez, María J Rebollo
1Infectious Diseases Unit, Hospital General Universitario "Doce de Octubre", Carretera de Andalucía Km. 5.4., 28041, Madrid, Spain. rafasjg@yahoo.es
Purpose:
To assess the utility of interferon gamma (INF-gamma) levels in cerebrospinal fluid (CSF), for the diagnosis of tuberculous meningitis (TBM), and compare these results with aPCR technique.
Methods:
We studied CSF samples from patients with proven or probable TBM and a control group, composed by patients with other causes of meningitis and without meningitis. INFgamma levels were measured by radioimmunoassay. A PCR technique was performed using IS6110 primers.
Results:
Of the 127 patients studied, 20 (15.6%) had TBM, 59 (46%) had meningitis of another aetiology and 49 (38.4%) had were HIV and non-HIV patients with normal CSF. The area below the ROC curve for interferon gamma levels in the diagnosis of TBM was 0.94. A cut-off of 6.4 IU/mL yielded a sensitivity of 70% and a specificity of 94%. False positive results were observed in 7 of the 59 patients (11.8%) with non-TB meningitis, (patients with herpetic meningoencephalitis and meningitis due to intracellular microorganisms). INF-gamma sensitivity was higher than PCR (70% vs. 65%). Both tests performed together showed higher sensitivity (80%) and specificity (92.6%).
Conclusion:
CSF INF-gamma levels (> 6.4 IU/mL) are very valuable in TBM diagnosis. PCR and INF-gamma could be simultaneously used to increase the diagnostic yield.
