The Effect of Chemoprophylactic Use of Rifampin and Minocycline on Rates of Carriage of Neisseria meningitidis in Army Recruits in Finland

Abstract

During an epidemic caused by sulfonamide-resistant group A Neisseria meningitidis (A Su^R strain), rifampin (600 mg per day for four days) or minocycline (100 mg every 12 hr for five days) was administered as chemoprophylaxis to 1,540 unvaccinated recruits in the Finnish Armed Forces. Rates of carriage of all strains of N. meningitidis were initially reduced by 78% (from 60% to 13%) in the 389 men receiving rifampin and by 62% (from 70% to 26%) in the 1,151 men receiving minocycline but rose to ∼30% in both groups four weeks after prophylaxis. The carriage of A Su^R strains was similarly reduced. An individual follow-up of 636 trainees demonstrated a high rate of new infections. It is suggested that the long-term inefficiency of rifampin and minocycline is due to their inability to reduce the carriage rates enough to prevent further spread of infection after prophylaxis is discontinued. However, no new cases appeared among the men receiving the prophylaxis. Five strains highly resistant to rifampin were found after the use of rifampin (minimal inhibitory concentration, ⩾100 μg/ml), but no minocycline-resistant strains were encountered. No unpleasant side effects were seen in subjects receiving either drug.