What are the common CSF findings in a patient with acute bacterial meningitis?

In cases of acute bacterial meningitis, the common cerebrospinal fluid (CSF) findings are typically characterized by an increased white blood cell (WBC) count with a predominance of neutrophils, elevated protein levels, and decreased glucose levels.

When a bacterial infection occurs in the central nervous system, the body's immune response leads to the migration of neutrophils to the site of infection, resulting in a markedly increased WBC count in the CSF. This neutrophilic response is a hallmark of acute bacterial meningitis and is in contrast to viral meningitis where lymphocytes are more prevalent.

The presence of elevated protein in the CSF indicates an inflammatory response and increased permeability of the blood-brain barrier, which occurs during infection. Additionally, a decrease in glucose levels in the CSF occurs because bacteria consume glucose for their metabolic processes, and the inflammatory response further contributes to reduced glucose availability.

This combination of findings—neutrophilic pleocytosis, elevated protein, and low glucose—provides a diagnostic hallmark for distinguishing bacterial meningitis from other types of meningitis or neurological conditions.