Cortisol levels in cerebrospinal fluid correlate with severity and bacterial origin of meningitis

Introduction Outcomes following bacterial meningitis are significantly improved by adjunctive treatment with corticosteroids. However, little is known about the levels and significance of intrathecal endogenous cortisol. The aim of this study was to assess cortisol as a biological and diagnostic marker in patients with bacterial meningitis. Methods Forty-seven consecutive patients with bacterial meningitis and no prior treatment were evaluated. For comparison, a group of 37 patients with aseptic meningitis and a group of 13 healthy control individuals were included. Results The mean age of the bacterial meningitis patients was 42 years, and the mean Glasgow Coma Scale, Acute Physiology and Chronic Health Evaluation II, and Sequential Organ Failure Assessment scores on admission were 12, 13 and 4, respectively. Altogether, 40 patients ( 85%) were admitted to the intensive care unit, with a median ( interquartile range) length of stay of 8 ( 4 to 15) days. A bacterial etiology was confirmed in 35 patients ( 74%). The median ( interquartile range) cortisol concentration in cerebrospinal fluid ( CSF) was 133 ( 59 to 278) nmol/l. CSF cortisol concentrations were positively correlated with serum cortisol levels ( r = 0.587, P < 0.001). Furthermore, CSF cortisol levels correlated with Acute Physiology and Chronic Health Evaluation II score ( r = 0.763, P < 0.001), Sequential Organ Failure Assessment score ( r = 0.650, P < 0.001), Glasgow Coma Scale score ( r = - 0.547, P < 0.001) and CSF lactate levels ( r = 0.734, P < 0.001). CSF cortisol was only weakly associated with intrathecal levels of IL-6 ( r = 0.331, P = 0.02) and IL-8 ( r = 0.296, P < 0.05). CSF cortisol levels in bacterial and aseptic meningitis significantly differed ( P < 0.001). The CSF cortisol concentration of 46.1 nmol/l was found to be the optimal cutoff value for diagnosis of bacterial meningitis. Conclusion CSF cortisol levels in patients with bacterial meningitis are highly elevated and correlate with disease severity. Moreover, our findings also suggest that intrathecal cortisol may serve as a valuable marker in discriminating between bacterial and aseptic meningitis.