Streptococcus pneumoniae and three species of anaerobic bacteria in experimental otitis media in guniea pigs.

Three species of anaerobic bacteria commonly isolated in upper respiratory tract infections in humans were studied in an animal model of otitis media. The ability of Propionibacterium acnes to induce acute otitis media was comparable with that of streptococcus pneumoniae, the classic middle ear pathogen. The response to Peptostreptococcus micros was weak and irregular, and no effects of Bacteroides asaccharolyticus were observed despite the use of high doses (10(8) colony-forming unite per ear). The results of this study support the contention that anaerobic bacteria such as P. acnes may be true pathogens in middle ear infections.