Objectives: The purpose of this study was to describe the bacteriology of middle ear effusions in children who have received the pneumococcal polysaccharide vaccine (Prevnar) compared with unvaccinated children.
Methods: A prospective review of medical records from July 2001 to July 2002 was conducted on children with middle ear effusion at time of tympanostomy tube insertion. Middle ear fluid was plated onto culture media immediately after acquisition, and antimicrobial resistance of cultured organisms along with serotyping of Streptococcus pneumoniae was examined. Vaccination status, demographics, and risk factors were determined from patients' medical records, parent interviews, or contact with their primary care physicians.
Results: After adjusting for age and number of previous infections, children vaccinated with Prevnar are two times less likely to have non-S. pneumoniae pathogenic bacteria isolated than children not vaccinated. Of those with growth, vaccinated children were almost three times more likely than nonvaccinated children to have the presence of H. influenzae. Vaccinated children with H. influenzae were 7.5 times less likely to have beta-lactamase producing H. influenzae than nonvaccinated children with H. influenzae.
Conclusion: Because the incidence of S. pneumoniae was low, no inference could be made whether Prevnar decreased otitis media with effusion or recurrent acute otitis caused by the S. pneumoniae serotypes covered by the vaccine. However, vaccinated children did appear to have the unexpected benefit of having a certain level of protection to growth of typical acute otitis media pathogens.