Risk factors for otitis media and carriage of multiple strains of Haemophilus influenzae and Streptococcus pneumoniae

We studied genetic diversity in Streptococcus pneumoniae and Haemophilus in fluenzae in throat culture isolates from 38 children attending two day-care centers in Michigan. Culture specimens were collected weekly; 184 S. pneum oniae and 418 H. influenzae were isolated from the cultures. Pulsed-field g el electrophoresis identified 29 patterns among the S. pneumoniae isolates and 87 among the H, influenzae isolates. Of the cultures, 5% contained mult iple genetic types of S. pneumoniae, and 43% contained multiple types of H. influenzae. Carriage of multiple H. influenzae isolates, which was associa ted with exposure to smoking, history of allergies, and age 36 to 47 months , may increase risk for otitis media in children.