Antibodies against Streptococcus pneumoniae, Haemophilus influenzae and Branhamella catarrhalis in middle ear effusion during early phase of acute otitis media

Serum type (IgG, IgM and IgA-class) and secretory type antibodies specific to Streptococcus pneumoniae (Pn), Haemophilus influenzae (Hi) and Branhamella catarrhalis (Br) were measured by enzyme-linked immunosorbent assay (ELISA) in 46 serum and 114 middle ear effusion (MEE) samples from 85 children with acute otitis media (AOM). The samples were obtained within 12 h from the onset of the ear symptoms. Serum (but not secretory) type antibodies to the infecting Pn serotype were found in 24% of the MEE samples of the patients with Pn AOM and, correspondingly, serum and/or secretory type antibodies to Hi and Br were seen in 54% and 63% of the MEE samples of the patients with Hi or Br AOM, respectively. Moreover, antibodies against bacteria other than the causative one could also be found in the MEE. The occurrence of the serum type antibodies against these bacteria in the MEE was closely correlated with their serum levels. The findings of this study indicate that during the very early phase of AOM, the MEE contains both serum type antibodies originating from the serum, and secretory antibodies of middle ear origin. Among them there are antibodies specific to the three most common bacteria causing AOM (Pn, Hi, and Br) regardless of the bacterial etiology of the AOM attack in question.