Select the best definition of Bacterial meningitis.

A. Obstruction of pulmonary arteries, commonly by thrombus originating in deep veins. B. Acute pancreatic inflammation commonly presenting with severe epigastric pain and elevated pancreatic enzymes. C. Heavy proteinuria with hypoalbuminaemia, oedema and often hyperlipidaemia. D. Acute infection of the meninges requiring urgent antimicrobial treatment.