Haemophilus influenzae Type b in a Nursery School: The Value of Biotyping

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Abstract
Meningitis due to H. influenzae serotype b biotype II occurred in a 2 yr old child who attended a nursery school along with 26 other 2 yr old children. Nasal swabs from these 26 contacts revealed a H. influenzae type b colonization rate of 50% (13/26); simultaneously performed throat swabs detected a colonization rate of 4% (1/26). Biotyping of the H. influenzae type b isolates revealed that only 46% (6/13) were the same biotype as the index case; the remaining 7 isolates were biotype III. All children received treatment with 20 mg/kg/day of rifampin administered by the nursery school attendant as a single dose for 4 days before the results of the cultures were known. Eradication of H. influenzae type b carriage was successful in 3 of the 6 biotype II carriers and 5 of the 6 biotype III carriers available for follow-up culture. The culture site utilized in determining H. influenzae type b colonization rates may markedly influence the results obtained. Biotyping may be a valuable epidemiologic tool in investigating the contacts of patients with H. influenzae type b disease. Failures of rifampin to eradicate the carriage of H. influenzae type b from the nasopharynx may occur. The purdent approach to the management of young contacts of patients with serious H. influenzae type b disease is to recognize their high risk status and to maintain close surveillance of them. The role of chemoprophylaxis with rifampin remains to be established.