Chemoprophylaxis For Contacts Of Children With Invasive Hemophilus-Influenzae Type-B (Hib) Disease

We conducted a multicentered prospective double-blind placebo controlled trial of rifampin (R) chemoprophylaxis (10 mg/kg bid x2 days). 396 contacts of 79 patients with HIB disease participated. HIB carriage eradication rates were 63.6% and 23.9% for R and placebo, respectively, when all carriers were analyzed. However, in carriers < age 5, R was not significantly better than placebo for HIB eradication. We have recently completed a second chemoprophylaxis trial comparing eradication rates of R (10 mg/kg bid x2 days) and an investigational antibiotic trimethoprim/rifampin (TR), (2.6 mg/kg T and 10 mg/kg R bid x2 days). 139 index patients were identified with invasive HIB disease. 142 of 618 contacts were carriers of HIB and received either R or TR. Carriage eradication rates were 76.8% and 76.3% for R and TR respectively. In children <5, eradication rates were 70% and 68.4% for R and TR. Carriers who remained positive after completing 2 days of TR were offered a 4 day course of R (20 mg/kg/day qd x4 days). 4 of 13 carriers who participated in the cross-over trial remained positive after 4 days of R. We conclude that neither R nor TR in these doses and schedules reliably eradicates HIB carriage in culture positive contacts. In addition, a 4 day course of R was not uniformly successful in those individuals who failed TR therapy.