There are many genera those are placed in this group (type) of bacteria. Among those medically relevant are Eubacterium, Propionibacterium, Lactobacillus, Mobilnucus and Bifidobacterium. Other genera in this group, Actinomyces and Archnia are dealt with elsewhere.
Eubacterium, members of this genera are strictly anaerobic and grow very slowly. They are members of the normal mouth and intestinal flora.
Propionibacterium is constantly present on skin. P. acnes is a common contaminant in blood and CSF cultures.
Lactobacillus is present in the mouth, intestines and typically in the adult vagina. It is generally non pathogenic, though L. catenaforme has been associated with bronchopulmonary infections.
Bifidobacterium is a pleomorphic rod that shows true and false branching. It is present in large number in intestine and mouth.Mobiluncus species are motile, curved, anaerobic bacilli that may appear as Gram variable rods.