Specific features of Escherichia coli that distinguish it from coliform and thermotolerant coliform bacteria and define it as the most accurate indicator of faecal contamination in the environment

The outbreak situation in Germany caused by an unusual serotype of intestinal coliform bacterium revealed difficulties in investigating and detecting the nature and source of such bacteria. It also exposed a certain lack of knowledge and information in society regarding the origin of coliform bacteria, resulting in misinterpretation of faecal pollution risk. It is therefore essential to provide basic knowledge and information on the coliform group, in particular coliform bacteria (CB), thermotolerant coliform bacteria (TCB) and Escherichia coli (E. coli), and to clarify which bacteria within this group represent the most accurate indicator of faecal contamination in the environment. The CB comprises a large group of bacteria that can originate from faecal matter of human and warm-blooded animals, and/or from the environment. Within the CB, there is a sub-group of TCB, i.e. faecal and non-faecal coliforms that are resistant to high temperatures. The main bacterium in the TCB group is E. coli, found exclusively in the faeces of humans, other mammals, and birds. Most strains of E. coli are harmless; however many are associated with human and animal diseases. Nevertheless, the occurrence of E. coli in the environment does not necessarily result in the threat of disease; however its presence definitely indicates pollution with faecal matter.