What diagnostic tests should be done immediately if meningitis is suspected?

A. Blood cultures help identify the causative organism, and a CT scan is often performed before lumbar puncture to rule out increased intracranial pressure or mass effect, which can contraindicate lumbar puncture. B. Stool culture and ultrasound are unrelated to meningitis diagnosis. C. Urinalysis and chest X-ray do not diagnose meningitis. D. ECG and pulmonary function tests are not relevant for meningitis evaluation.