meningitis

A 3-year-old boy is brought to the emergency department by his parents due to a high fever and irritability. He has had a runny nose and cough for the past two days. On examination, he is lethargic and has a bulging fontanelle. A lumbar puncture is performed, and the cerebrospinal fluid (CSF) analysis shows elevated protein, low glucose, and a high white cell count with a predominance of neutrophils. What is the most likely diagnosis?

A 25-year-old man presents to the emergency department with a 2-day history of severe headache, photophobia, and neck stiffness. He has no significant past medical history and is not on any medications. On examination, he is febrile with a temperature of 39°C, and there is a positive Brudzinski's sign. What is the most appropriate initial investigation to confirm the diagnosis?

A 32-year-old woman presents to the emergency department with sudden onset of severe headache, nausea, and photophobia. She has no significant past medical history and is not on any medications. On examination, she is alert but in distress due to the headache. Her vital signs are stable, and there is no neck stiffness. A CT scan of the head is performed and shows no abnormalities. What is the most appropriate next step in the management of this patient?