Meningitis — Bacterial and Viral

A 28-year-old man presents with acute onset fever, headache, and neck stiffness. CSF analysis shows pleocytosis with predominant neutrophils, elevated protein (180 mg/dL), and low glucose (25 mg/dL with simultaneous blood glucose 120 mg/dL). Gram stain is pending. Which single CSF finding best distinguishes bacterial meningitis from viral meningitis in this clinical context?

A 35-year-old woman with fever and meningeal signs has CSF pleocytosis. You are comparing the likelihood of bacterial versus viral meningitis. Which finding would most strongly favor a diagnosis of viral meningitis over bacterial meningitis?

A 5-year-old girl from Mumbai presents with a 3-day history of fever, headache, and vomiting. On day 3, she develops a non-blanching petechial rash over the trunk and extremities. Her parents report she attends a crowded school. On examination, she is febrile (38.8°C), alert, with neck stiffness and a positive Kernig's sign. CSF analysis shows: protein 150 mg/dL, glucose 65 mg/dL (serum glucose 110 mg/dL), WBC 200/μL (60% neutrophils, 40% lymphocytes), Gram stain is negative, culture pending. Blood culture grows gram-negative diplococci. What is the most likely causative organism and the immediate management priority?

A 32-year-old woman presents with a 3-day history of fever, headache, and neck stiffness. Lumbar puncture is performed. CSF analysis shows: WBC 250/μL (85% lymphocytes), protein 120 mg/dL, glucose 55 mg/dL (serum glucose 110 mg/dL), Gram stain negative, and bacterial culture negative after 24 hours. What is the most appropriate next investigation to confirm the diagnosis?

Which cerebrospinal fluid (CSF) finding is most characteristic of bacterial meningitis compared to viral meningitis?