D-069. Surface-Attached Pneumococcal Communities in the Chinchilla Model for Otitis Media

K. E. Dew, W. Hong, S. D. Reid, W. E. Swords;
Wake Forest Univ. Hlth. Sci., Winston Salem, NC.

Otitis media is one of the most common pediatric public health problems worldwide, and may be initiated by bacterial opportunists. Once established, these bacteria can establish recurrent and/or persistent infections. One hypothesis for bacterial persistence during recurrent/persistent otitis media is the presence of a bacterial biofilm. Streptococcus pneumoniae (pneumococcus) is among the leading causes of otitis media, as well as community-acquired pneumonia and meningitis. Work from a number of laboratories shows that S. pneumoniae forms biofilms in vitro, and surface-attached pneumococci have been visualized within patient tissue samples. In this study, we used an established animal model for otitis media to test the hypothesis that S. pneumoniae forms biofilms in vivo within the middle-ear chamber. Chinchillas were infected via transbullar injection with S. pneumoniae strain TIGR4. All animals exhibited clinical symptoms of otitis media within 48 h of infection. At 3 d, 7 d, and 12 d post-infection, dense material was observed within the middle-ear chambers of euthanized animals. This putative biofilm was excised, fixed and examined by cryosection and immunohistochemical staining. Cryosections showed immunofluorescence with pneumococcal-specific antibodies, indicating the presence of pneumococcal bacteria. Live/Dead staining of unfixed samples revealed the presence of viable diplococci within the putative biofilm, and fibrous matrix material that stained with propidium iodide. Taken together, these results indicate that pneumococcal otitis media includes the formation of biofilm communities.