Quantitative and qualitative evaluation of anti-pneumococcal specific antibodies in children with recurrent acute otitis media.

Background: Pneumococcal conjugated vaccine (PCV) has contributed to a dramatic reduction in invasive pneumococcal diseases. However, its impact upon nasopharyngeal carriage and upper respiratory tract infections is unclear.

Aims/objectives: This study was aimed to evaluate the humoral immunity against Streptococcus pneumoniae in children with recurrent acute otitis media (rAOM) in the post PCV era.

Materials and methods: We evaluated the humoral immunity against eight representative serotypes included in PCV13 (3, 6 A, 6B, 9 V, 14, 18 C, 19 F, and 23 F) among children with rAOM.

Results: Serum total immunoglobulin levels were typically within the normal range, but there was a decrease in IgG2 in >20% of cases. Serotype-specific antibody titers were not significantly different for any serotype in the rAOM group compared with the healthy controls, except for serotype 3. Conversely, the ability of serotype-specific antibodies to induce opsonophagocytic killing was increased in the rAOM group for three serotypes (6 A, 6B, and 14). There was a positive correlation between the titer of antibodies and the opsonophagocytic killing activity in five serotypes (6 A, 6B, 9 V, 19 F, and 23 F).

Conclusion and significance: Quantitative and qualitative evaluation of serotype-specific antibodies would be an important method for evaluating humoral immunity in children with rAOM.