Otitis media caused by non-typable, ampicillin-resistant strains of Haemophilus influenzae.

Strains of Haemophilus influenzae, which did not belong to any of the known capsular serotypes and which were resistant in vitro to ampicillin, have been isolated from middle ear exudates of two children with otitis media. These children failed to improve with ampicillin therapy, and the resistant organisms persisted at the site of infection. Patients infected with such ampicillin-resistant organisms require therapy with antimicrobial agents which are not susceptible to degradation by penicillinase.