Bacterial flora in the external ear canal and in induced cholesteatoma in the Mongolian gerbil.

We report on the bacterial flora of the external ear canal and of induced aural cholesteatoma in 14 Mongolian gerbils (Meriones unguiculatus). In the control, nonmanipulated external ear canal, gram-positive and gram-negative organisms were isolated. In the contents of the cholesteatoma sac, only monomicrobial, gram-negative isolates were found; in each animal they were different from the isolates from the nonmanipulated external ear canal. Obligate anaerobes were absent in all cases. Ligation of the external ear canal in the left ear provoked cholesteatoma in all cases.