Aromatic microbial metabolites in the cerebrospinal fluid determined by gas chromatography–mass spectrometry as promising markers of secondary bacterial meningitis

Introduction: The diagnosis of infectious complications, in particular secondary bacterial meningitis, in patients who have undergone neurosurgical interventions is an urgent task, since, regardless of the cause of their occurrence, their differential diagnosis is an important factor in the successful treatment of patients. Aromatic metabolites of tyrosine, phenylalanine and tryptophan, determined by chromatography–mass spectrometry, are promising markers of infectious complications in patients of different groups. The goal of this study was to identify the aromatic metabolites that are clinically significant for the diagnosis of secondary bacterial meningitis in patients who have undergone neurosurgical interventions.

Methods: Residual cerebrospinal fluid (CSF) samples obtained from neurosurgical patients after routine laboratory analysis were analyzed by gas chromatography–mass spectrometry (n=82) and high-performance liquid chromatography–tandem mass spectrometry (n=29). The levels of 11 phenyl- and indole-containing acids were determined. Patients were divided into two groups depending on the presence or absence of signs of secondary meningitis based on the clinical picture and clinical and laboratory analysis of CSF.

Results: Chromatography–mass spectrometry methods were used to determine the levels of aromatic metabolites in CSF samples of neurosurgical patients at the level of μmol/L and nmol/L. Metabolite profiles were compared in groups of patients with or without signs of secondary meningitis. Statistically higher levels of 4-hydroxyphenyllactic (p = 0.005), phenyllactic (p = 0.002), 3-indolelactic (p = 0.006) and 3-indolecarboxylic (p = 0.027) acids were found in patients with signs of secondary meningitis.

Conclusions: CSF levels of aromatic microbial metabolites may be potential markers of secondary bacterial meningitis in patients undergoing neurosurgery.