| Summary |
The objective was to determine pathogenic potentials of anaerobic bacteria and known mixtures of anaerobic bacteria to cause otitis media. Gerbils were inoculated per cutaneously into the middle ear bulla with 4.5 X 10 bacteria per ear. Evaluation was by ototoscopic and histologic observations. Nine different anaerobes and one facultatively anaerobic bacterium used were: Peptococcus magnus, Peptostreptococcus anaerobius, Ps. intermedius, Propionibacterium acňs, Gaffyka anaerobios, Clostridium perfringens, Bacteroides fragilis, B. melaninogenicus, Fusobacterium nucleatum and Escherichia coli. The ability of both living and dead cultures, as well as mixed cultures, to cause otitis media was compared using a predetermined scoring system. The time course and sequellae (persistant granulation tissue, bone damage, and new bone formation) of the otitis media were similarly compared for a period of up to 4 weeks. Inflammatory responses with no sequellae were produced by 2 of the pure cultures but none of the mixtures. Moderate otitis media was caused by 6 of the pure cultures and 7 of the mixtures. Severe otitis media with granulation tissue and remarkable bone changes were found caused by 2 of the pure cultures and 5 of the mixtures. Synergy appeared to be responsible for more severe otitis media with 5 of the mixtures as compared to the response to the individual pure cultures of the mixture. We conclude that experimental otitis media can be caused by anaerobic bacteria in the gerbil. In humans, natural otitis media caused by or contributed to by anaerobes probably occurs as secondary infections following acute otitis media during which conditions for anaerobes to grow are extablished. |
