Patients with signs of post-neurosurgical meningitis (n = 30) had lower median values of glucose and higher values of cell count, neutrophils, lactate, protein, 3-(4-hydroxyphenyl)lactic acid (p-HPhLA), and interleukin-6 (IL-6) than patients without signs of post-neurosurgical meningitis (n = 52). Here, IL6 is linked to infectious meningitis.