Clinical clues to the bacterial etiology include a hectic febrile course, progressive cardiac decompensation, and a brisk polymorphonuclear leukocytosis in the peripheral blood and the pleural and pericardial fluids. Acute meningococcal endocarditis would be suggested by the development of valvular dysfunction in conjunction with acute meningococcemia. Fortunately, both subacute and acute meningococcal endocarditis are very rare. Joint involvement in meningococcal disease includes primary acute pyogenic arthritis as well as acute monoarticular or polyarticular arthritis in association with meningococcemia. Synovial fluid from infected joints is typical of pyogenic arthritis.
Meningococcal pneumonia is contracted through inhalation.
The symptoms, which are primarily respiratory, evolve gradually and are not distinctive. Pleuritic chest pain and small pleural effusions occur in 20 percent of patients, but frank empyema is very rare. A patchy alveolar bronchopneumonia is demonstrated radiologically in 80 percent of patients. The remainder have segmental or lobar consolidation. Bacteremia is uncommon, occurring in 15 percent of patients, and a meningococcemic syndrome is seen rarely in this group.