Carriage of Haemophilus influenzae among Brazilian children attending day care centers in the era of widespread Hib vaccination

Haemophilus influenzae type b vaccine was introduced into the Immunization Program of Brazil in 1999 and no study has evaluated the impact of Hib vaccination in H. influenzae carriage so far. In June 2010, Brazil introduced the 10-valent pneumococcal nontypeable H. influenzae (NTHi) conjugate vaccine (PHiD-CV). We investigated the prevalence of encapsulated H. influenzae and NTHi isolates in nasopharyngeal samples of 1192 children attending day-care centers in Goiânia, central Brazil. H. influenzae carriage rate was 32.1% and 38.4% of them carried β-lactamase TEM-1 gene. Serotype f (4.6%) was the most frequent encapsulated isolate, type b was recovered in only 0.7% and carriage rate of NTHi was 23.3%. Recurrent acute otitis media and NTHi were independently associated with colonization by β-lactamase producing H. influenzae. Changes in frequency of H. influenzae carriage isolates should be carefully monitored to assess the impact of the PHiD-CV on NTHi carriage in young children.