When we analyzed the CNS infections all together (encephalitis, ASM, and ABM), a significant correlation between serum and CSF levels were found only for TNF (Rho 0.4, p = 0.03), IL-1Ra (Rho 0.4, p = 0.03), IL-6 (Rho 0.5, p = 0.004), and MCP-1 (Rho 0.3, p = 0.04) suggesting intrathecal production of most of the examined mediators (Additional file 4: Table S3). This evidence concerns the gene IL6 and encephalitis.