meningococcus /-kok’əs/ pl. meningococci [Gk, meninx + kokkos, berry] , a bacterium of the genus Neisseria meningitidis, a nonmotile gram-negative diplococcus, frequently found in the nasopharynx of asymptomatic carriers, that may cause septicemia or epidemic cerebrospinal meningitis. Meningococcal infections are not highly communicable. However, crowded conditions, such as may be found in army camps and college dormitories, concentrate the number of carriers and reduce individual resistance to the organism. Hemorrhagic skin lesions are significant clues to the diagnosis. Stained smears of these lesions or of cerebrospinal fluid must be examined quickly because meningococci are fragile and lyse readily. Early treatment with an appropriate antibiotic such as penicillin G is essential for cure. Contacts may receive prophylaxis with rifampin. Several meningococcal vaccines are available. See also meningitis. −meningococcal, adj.
