Why is the glucose level decreased in the cerebrospinal fluid of patients with bacterial meningitis?

Analyzing cerebrospinal fluid changes in meningitis requires knowledge of pathophysiology and microbial metabolism. One must understand how pathogens cross the blood-brain barrier and the metabolic requirements of bacteria compared to normal physiological states in the central nervous system during acute infection. Choice A rationale Liver glucose production, or gluconeogenesis, is typically increased during the stress of systemic infection due to cortisol and glucagon. A decrease in CSF glucose is a localized metabolic phenomenon within the subarachnoid space rather than hepatic failure. Choice B rationale Bacteria and leukocytes in the CSF consume glucose as a primary energy source for metabolism and replication. Normal CSF glucose is 40 to 70 mg/dL, but in bacterial meningitis, this level drops significantly as pathogens utilize it. Choice C rationale While the blood-brain barrier is affected during inflammation, it generally becomes more permeable, not less. The low glucose level is not due to a blockage of entry but rather the rapid consumption of glucose once it enters. Choice D rationale While systemic glucose uptake might change during illness, it does not explain the specific drop in CSF levels relative to blood levels. The hallmark of bacterial meningitis is the decreased ratio of CSF glucose to serum glucose..