Indigenous nasopharyngeal, auditory canal, and middle ear bacterial flora of gerbils: animal model for otitis media.

The indigenous microbial flora of the middle ear cavity of Mongolian gerbils, Meriones unguiculatus, was isolated, characterized, and identified, showing it to be sparse and transitory. Organisms, when found in the middle ear cavity, were most likely to be Staphylococcus epidermidis-like organisms. Cerumen from the external auditory canal of these animals yielded mostly staphylococci, coryneforms, and other gram-positive rods, including some anaerobic species. The nasopharynx supported a flora consisting mainly of staphylococci, lactobacilli, and coryneforms, with a smaller incidence and numbers of many other species. No mycoplasmas were cultured or seen in scanning electron microscope studies. None of the major pathogens of human otitis media were found; therefore, Mongolian gerbils are microbiologically acceptable candidates as a model for induced otitis media, using organisms isolated from human otitic infections.