The chemoprophylaxis of cerebrospinal meningitis using rifampin in a military population.

Since February 5th 1990, the prevention of secondary cases of cerebrospinal meningitis (CSM) in France has been obtained by the use of rifampin. Following the detection of a case of N. meningitidis of antigenic formula B:NT:P1.15,16 in a military population, 89 contacts subjects received 600 mg rifampin twice a day during 2 days. Meningococcal carriage rate was investigated by nasopharyngeal swab sampling of the 89 subjects and 62 non-contact controls from the same community. Twenty-three days after the initial case of meningitis, carriage rate was 5.6% for treated subjects and 37.1 for controls. Sero-grouping, serotyping and subtyping failed to detect the initial virulent strain; it demonstrated the heterogeneity of circulating strains. Since rifampin-resistant mutants may occur, two strains in the treated group, it is essential that chemoprophylaxis in a community be limited strictly to the contact subjects.