Microbiology of acute mastoiditis and complicated or refractory acute otitis media among hospitalized children in the postvaccination era.

In the post-heptavalent pneumococcal conjugate vaccine era, Streptococcus pneumoniae remains the leading cause of acute mastoiditis and other complicated or refractory acute otitis media among hospitalized children in our settings. Serotype 19A is predominant, invasive and multidrug resistant causing more than half of all mastoiditis cases, two-thirds of cases with subperiosteal abscess and all those requiring mastoidectomy. Continuous surveillance is required.