Efficacy of rifampin in eliminating pharyngeal carriage of Haemophilus influenzae type b.

Household contacts less than 6 years of age of children with Haemophilus influenzae type b meningitis are at increased risk of developing systemic H influenzae type b disease. Positive oropharyngeal cultures for H influenzae type b were found in 17/97 patients (18%) and 7/62 staff members (11%) at a chronic area facility at which two patients had developed ampicillin-resistant H influenzae type b meningitis. H influenzae type b colonization was eliminated in 8/9 carriers treated with a single daily oral dose of rifampin, 20 mg/kg/day (maximum 600 mg) for four days; colonization persisted in 9/10 control subjects (Fisher's exact test P < .001; corrected chi 2 P < .005). After treatment of additional H influenzae type b-positive individuals and the remaining control subjects, rifampin was found to have eradicated H influenzae type b in a total of 24/25 carriers (96%). All isolates of H influenzae type b were sensitive to rifampin at either 0.5 or 1.0 microgram/ml. Rifampin is effective in eliminating the H influenzae type b carrier state and may be useful in preventing associated H influenzae type b disease in close contacts of children with H influenzae type be meningitis.