Growth of Bacteroides fragilis inoculated on rabbit tracheal explant in an atmosphere environment.

Mucous membrane of rabbit tracheal explant on a solid agar medium that was point-inoculated with Bacteroides fragilis, an obligate anaerobe, was exposed directly to air and cultivated in an atmospheric environment, in a simulation of the in vivo condition. Continuous spreading of B. fragilis on the mucous membrane and consistent increase in viable counts in the infected explant were demonstrated. Thus, rabbit tracheal explant exposed to air was successfully inhabited with anaerobic bacteria. In contrast, no bacterial growth was observed on explants inactivated by ultraviolet irradiation, freezing and thawing, or heat. Histologic examinations by light and electron microscopy showed characteristic distribution of the infecting bacteria on the mucous surfaces and in the submucosal tissues.