Escherichia is a genus of gram-negative bacteria found in the gastrointestinal tract. The word Escherichia has various synonyms that are used in scientific literature. One synonym is E. coli, which is the most well-known and extensively studied member of the genus. Another synonym is Bacterium coli commune, which was the name used before the current nomenclature system was adopted. Other synonymous terms include Bacillus coli, Micrococcus ovalis, and Bacillus eneteritidis. In medical, scientific, and research contexts, the use of Escherichia as a synonym may be preferred to avoid confusion with other organisms or strains.