Biotypes and serotypes of Haemophilus influenzae from patients with meningitis in the city of São Paulo, Brazil.

A total of 1,094 Haemophilus influenzae isolates from cerebrospinal fluid were examined by biochemical and serological means. Most of them belonged to biotype I (70.9%) and to serotype b (99.4%). The relationship of biotypes I and II to the ages of the patients was shown to be significant (P < 0.001).