Investigation of the nasopharyngeal bacterial flora in children with otitis media with effusion.

A study was undertaken to evaluate the incidence of alpha-streptococci with inhibitory activity against pathogens, a defense mechanism of the normal flora against bacterial infection, in the nasopharynx and tonsils of 37 children with otitis media with effusion (OME). In the patients with OME, the detection rates of alpha-streptococci with inhibitory activity against Haemophilus influenzae, Streptococcus pneumoniae, Staphylococcus aureus and group A streptococci in the nasopharynx were significantly lower than those of alpha-streptococci isolated from the tonsils. Furthermore, the detection rates of nasopharyngeal alpha-streptococci with inhibitory activity against H. influenzae and S. pneumoniae in OME patients were lower than those in patients with tonsillitis. In conclusion, low nasopharyngeal levels of alpha-streptococci with inhibitory activity against pathogens appear to render children susceptible to attacks of OME. We suggest that it is important to investigate the relationships between the prevalence of pathogens and the inhibitory activity of alpha-streptococci against them in the nasopharynx.