Increased cerebrospinal fluid free amino acid concentrations in children with bacterial meningitis

Cerebrospinal Fluid Concentrations of Biogenic Amines: Potential Biomarkers for Diagnosis of Bacterial and Viral Meningitis

Catecholamine and serotonin are biogenic amines (BAs) that serve as neurotransmitters and play an important role in the regulation of cardinal functions that are mainly altered during central nervous system (CNS) infections. A total 92 samples of cerebrospinal fluid (CSF) were classified into 4 groups based on their etiology. In these samples, BAs/neurotransmitters i.e., dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5HIAA) were detected and quantified by high performance liquid chromatography with electrochemical detection (HPLC-EC) to determine the neurophysiology of the CNS infections by bacteria (Listeria monocytogenes (Lm) and Neisseria meningitidis (Nm)) and herpes simplex virus (HSV). CSF concentration of DA, DOPAC, HVA, and 5HIAA were found significantly elevated in all test cohorts. Present study highlights that the analysis of BAs is pivotal for the early diagnosis of bacterial and viral meningitis. In addition, coinfections of varied etiology can also be diagnosed by their quantification. Thus, BAs can serve as potential biomarkers of these CNS infections.

Excess glutamate in the cerebrospinal fluid in bacterial meningitis

We investigated possible neurotoxic components in the cerebrospinal fluid (CSF) of patients with bacterial meningitis. On murine cerebellar neuronal cell cultures, CSF exerted a dose-dependent toxic effect, which was attenuated by the NMDA receptor antagonist MK-801. Glutamate concentrations in the CSF of patients with bacterial meningitis were measured by an enzymatic assay and found to be significantly elevated (p < 0.001) as compared to viral meningitis and non-inflammatory neurological diseases. The concentration of glutamate in the CSF of patients with bacterial meningitis varied considerably and correlated with the severity of the disease as scored by the Glasgow Coma Scale. Cells in the CSF, mainly comprising polymorphonuclear granulocytes, did not release any glutamate into the culture medium, whereas blood monocytes produced remarkable amounts. These findings implicate an important role of monocytic inflammatory cells in bacterial meningitis by the release of glutamate, which may contribute to neuronal cell death.

Use of high performance liquid chromatography in defining the abnormalities in the free amino acid patterns in the cerebrospinal fluid of patients with aseptic meningitis

Free amino acids were quantitatively determined in cerebrospinal fluid (CSF) and plasma samples from patients with aseptic meningitis by a newly developed high performance liquid chromatographic (HPLC) method. The method of analysis was based on precolumn derivatization of orthophthaladehyde in the presence of 2-mercaptoethanol and detection was made at Eex = 340 nm and Eem = 450 nm. The method was sensitive and the limit for detection was less than 1 pmol for most of the amino acids. It took 45 min to separate 26 amino acids with highly reproducible results, giving a coefficient of variance for retention times and integrated areas less than 0.4% and 2%, respectively, after five replicate runs. The results accumulated in 10 patients were compared statistically with 11 age-matched healthy controls. Among the amino acids almost all the neurotransmitter candidates, such as aspartic acid, glutamic acid, glutamine, glycine, tyrosine, phenylalanine and gamma-aminobutyric acid (GABA), were significantly increased in the patients' CSF, whereas arginine and threonine were low. No change was observed in plasma amino acids in patients as compared to healthy controls. The higher levels of most of the neurotransmitters, especially GABA, aspartic acid and glutamic acid, could be used diagnostically in assessing the progression and remission in aseptic meningitis.

Free amino acid pattern of cerebrospinal fluid in meningeal pathology

Free amino acid concentrations of CSF were measured in bacterial meningitis, aseptic meningitis, meningoradiculitis Garin-Bujadoux-Bannwarth, multiple sclerosis, carcinomatous meningitis, and controls. Almost all CSF amino acids were highly elevated in bacterial but not in aseptic meningitis, meningoradiculitis Garin-Bujadoux-Bannwarth or carcinomatous meningitis thus providing a laboratory tool for their differential diagnosis. In carcinomatous meningitis the amino acid pattern indicates metabolic activity of tumor cells. Minimal alterations were found in multiple sclerosis which have no diagnostic value.

Comparison between cerebrospinal fluid concentrations of glucose, total protein, chloride, lactate, and total amino acids for the differential diagnosis of patients with meningitis

The purpose of this study was to compare the ability of cerebrospinal fluid (CSF) concentrations of glucose, protein, chloride, lactate, and total amino acids, as well as CSF/blood glucose ratio to distinguish bacterial meningitis from aseptic meningitis. 56 patients with proven bacterial meningitis, 102 patients with aseptic meningitis, and 108 controls were investigated. On admission CSF lactate determination was the most sensitive and the most efficient test to distinguish bacterial meningitis from aseptic meningitis. In patients with bacterial meningitis reexamined after 24-48 h of treatment with antibiotics and compared with patients with aseptic meningitis also reexamined 24-48 h after admission determination of CSF total amino acids was the most sensitive and efficient test.