Decreased cerebrospinal fluid cyclic adenosine 3',5'-monophosphate in bacterial meningitis

The concentration of cyclic adenosine 3',5'-monophosphate (cAMP) in 16 cerebrospinal fluid samples from eight patients with bacterial meningitis due to several different organisms was determined. An age- and sex-matched control group of 12 patients with a variety of acute, noninfectious systemic neurological diseases was also examined. To quantitate the amount of cAMP, a new, improved radioimmunoassay was used with the ability to measure 2.5x10^-15 mol of cAMP. The mean concentration of cAMP in the cerebrospinal fluid from patients with meningitis was 0.05 nM, and from patients in the control group it was 1.18 nM. The difference between these two values is statistically significant. The decreased cAMP concentration in the cerebrospinal fluid from patients with bacterial meningitis did not seem to be secondary to metabolism by bacteria or leukocytes, increased enzymatic degradation within the cerebrospinal fluid, or an artifact introduced by the collection and storage procedure. Since the concentration of cAMP in the cerebrospinal fluid is normally found to be within narrow limits and probably reflects intracellular cAMP levels, the results described in this study suggest that interference with cAMP metabolism in central nervous system tissue occurs in bacterial meningitis. This finding seems to be independent of the causative organism and might explain the pathogenesis of selected, neurological manifestations of this disease.