Experimental otitis media after nasal inoculation of Streptococcus pneumoniae and influenza A virus in chinchillas

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Abstract
Otitis media developed in 67% of chinchillas inoculated intranasally with type 7 S. pneumoniae and influenza A virus. Only 4% of chinchillas inoculated with influenza alone and 21% of chinchillas inoculated with S. pneumoniae alone developed otitis media. Among the chinchillas that developed otitis media after inoculation with pneumococcus and influenza, 73% of the affected ears contained effusion and 27% of the affected ears showed tympanic membrane inflammation without middle ear effusion obtained on paracentesis. Although a majority of the ears with effusion yielded S. pneumoniae on culture, 1/3 of the effusions were sterile for aerobic bacteria. This model resembles conditions accompanying otitis media in humans and suggests that respiratory viral infection contributes significantly to the pathogenesis of acute otitis media.