The recovery of microorganisms from the fissures of rat molar teeth

Abstract

Bacteria were recovered from rat molar fissures by splitting the teeth transversely in the plane of the fissures with a sterile scalpel. Growth on mitis-salivarius and trypticase soy-agar plates was recorded, and three organisms presenting distinctive colony morphology on mitis-salivarius agar were identified on the basis of biochemical characteristics as Streptococcus salivarius, sanguis and mutans. Together these three organisms accounted for an average of 87 per cent of total growth on mitis-salivarius agar from fissure plaque, but for only 35 per cent of total growth on the same medium from a swab taken directly before killing the animal. When any one of these three streptococci from fissure plaque accounted for more than 40 per cent of total growth on mitis-salivarius agar, it was also recovered on the swab.