The varied clinical presentations of meningococcal infection.

The clinical presentation of Neisseria meningitidis may include bacteremia, septic shock, or meningitis. The polysaccharide capsule of the organism appears to be the major determinant and is necessary for specific immunity. Colonization of the nasopharynx is required for invasion, and persons with complement component deficiencies are particularly at risk of infection. The organism can be detected by culture of blood or spinal fluid, or by antigen detection in spinal fluid. Prompt therapy with penicillin G is necessary for a good outcome. The occurrence of secondary cases requires that prophylactic therapy be administered to close contacts of index cases. The cases presented herein illustrate a variety of manifestations of meningococcal infection, and all of the patients initially were seen in primary care settings. It is important for physicians to be vigilant for these infections so that appropriate therapy may be instituted rapidly.