What laboratory findings are expected in a case of bacterial meningitis?

In cases of bacterial meningitis, the classic laboratory findings in the cerebrospinal fluid (CSF) would indicate a significant inflammatory response. The correct answer reflects these expected findings: elevated protein levels, reduced glucose concentration, and a very high white blood cell (WBC) count with a predominance of neutrophils.

Bacterial infections lead to increased permeability of the blood-brain barrier, resulting in elevated protein levels due to leakage of proteins from the serum into the CSF. The glucose levels in the CSF are lowered because bacteria consume glucose for their metabolic needs, and the inflammatory response can also inhibit glucose transport across the blood-brain barrier. The WBC count rises significantly, often exceeding 1000 cells/mm³, with the majority being neutrophils, which are characteristic of acute bacterial infections.

In summary, the combination of high protein, low glucose, and a very high WBC count aligns with the typical response to a bacterial pathogen in the context of meningitis. This set of findings is essential for differentiating bacterial meningitis from other types, such as viral meningitis, where the glucose levels tend to be normal, and the protein levels may be mildly elevated, with a smaller increase in WBC count primarily involving lymphocytes