Toxicity of Lactobacillus casei

¹ University of Pennsylvania School of Dental Medicine, Philadelphia, Pennsylvania

The pathogenic potential of encapsulated and non-encapsulated cells of L. casei has been investigated, using viable cells and various subcellular fractions. Although a dermonecrotic factor located in the insoluble cell wall fraction is present in both encapsulated and non-encapsulated cells, the minimum number of encapsulated viable cells required to produce a lesion is twenty times less than that required for non-encapsulated viable cells. The capsular material is non-toxic by itself but appears to act as an aggressive factor allowing for continued multiplication of the lactobacilli with resultant increases in tissue damage.