The anaerobic bacteria of the oral cavity.

Abstract

Investigation of 55 samples of saliva collected from 43 individuals showed, 1st, that sporulating anaerobes are not commonly found; 2nd, that when they are found it is usually impossible to detect the same species in subsequent samples from the same mouth.

Only 6 specimens yielded sporulating anaerobes, which included B. Welchii, B. bifermentans, an unidentified non-pathogen, B. tetanomorphus, and a strongly toxicogenic B. tetani. This is believed to be the first record, with rigid proof, for B. tetani from the mouth. No importance is to be attached, however, to the occasional presence of any of these micro-organisms in the oral cavity; all attempts to prove their continued residence there failed. There was likewise no correlation of these findings with dental conditions.

Aerobic spores were also encountered in 16 samples, but not identified owing to the present unsatisfactory status of their taxonomy. Both aerobic and anaerobic sporulating bacteria are evidently transient saprophytes in the mouth, and there is no evidence that either group has any direct pathologic significance in relation to pyorrhea. Certain species, however, may participate in the deposition of salivary calculus and so indirectly contribute to predisposing irritations. Opinion is reserved as to their responsibility for pulp decay in dental caries.

More importance is attached to the non-sporulating anaerobes of the mouth. While we have not failed to apprecbte the numerical frequency of spiral and fusiform organisms in saliva through the use of the dark field microscope, these dild not appear in our cultures.

Our present emphasis is upon the almost universal occurrence of a minute, Gram-negative, non-sporulating, gas-forming obligate anaerobe of which we have isolated 24 strains from 35 samples collected from 23 persons. This organism is mainly responsible for the abundant gas almost invariably seen in primary brain-medium cultures from unheated saliva.