Studies on Lactobacilli: I. Fermentation Reactions of Strains Isolated from Human Mouths

Abstract

Since the demonstration by Kligler and Gies in 19151 and Howe and Hatch in 19172 of the presence of lactobacilli in the lesions of dental caries many investigators have obtained experimental evidence of the occurrence of these organisms in the disease. McIntosh and associates,3 Rodriguez,4 Bunting and associates5 and others have attributed to them a specific etiologic role in caries. That there has not been satisfactory proof of such relationship, however, is illustrated by the claims of Clarke,' Tunnicliff and Hammond,' Pincus8 and others who have incriminated other organisms and by the observations of most workers that the lactobacilli are present also in the mouths of many caries-free individuals, although usually in smaller numbers. Nevertheless, whether lactobacilli are etiologically responsible for all or part of the carious process or whether they are merely secondary invaders, there appears to be little doubt that they are associated with the disease. Lactobacilli obtained from the mouth have been shown to be morphologically and biochemically heterogeneous.3'9,10 It is not unlikely that many of these strains are transiently or adventitiously present while others may be more or less permanently established. It seems reasonable to suppose that if the activities of any micro-organisms are concerned in the development of the carious process, these forms must be resident on the teeth for comparatively long periods of time. Consequently, in order to establish a basis for possible differentiation of exogenous strains from those presumably indigenous in the carious lesion, a series of studies on the characteristics of the oral lactobacilli has been undertaken. The present report is concerned with some of the fermentation reactions of these organisms.