Serum Antibody Response to Five Streptococcus pneumoniae Proteins During Acute Otitis Media in Otitis-prone and Non–otitis-prone Children

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Background:Streptococcus pneumoniae (Spn) is one of the common bacteria responsible for episodic acute otitis media (AOM; non–otitis-prone), recurrent AOM (otitis-prone), and AOM treatment failure (AOMTF) in children.Objective:From a population of 268 children, we sought to compare the serum IgG antibody titers of 5 different Spn proteins (PhtD, LytB, PcpA, PhtE, and Ply) that are vaccine candidates in children with episodic AOM (n = 34), who were otitis prone (n = 35) and who had AOMTF (n = 25) caused by Spn.Methods:Antibody was quantitated by enzyme-linked immunosorbent assay.Results:At their AOM visit, anti-PhtD, -LytB, -PhtE, and -Ply IgG antibody titers in otitis-prone children were significantly lower compared with non–otitis-prone children (P < 0.05) and children with AOMTF (P < 0.05). On comparing acute to convalescent geometric mean IgG antibody titers after AOM against the 5 proteins we found that otitis-prone, AOMTF, and non-otitis-prone children had no significant change in titers (except for PhtE in children with AOMTF), but detailed analysis showed that about one-third of the children in each cohort had a 2-fold rise in antibody to the studied antigens. Although non–otitis-prone children had significant increases (P < 0.001) between 6 and 24 months of age in anti-PhtD, PcpA, PhtE, and Ply IgG antibody titers as a consequence of nasopharyngeal colonization and AOM, otitis-prone children either failed to show rises or the rises were significantly less than the non–otitis-prone children.Conclusion:Otitis-prone and AOMTF children mount less of an IgG serum antibody response as compared with non–otitis-prone children to Spn proteins after AOM and nasopharyngeal colonization.

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