Faecal streptococci as faecal pollution indicators: A review. Part I: Taxonomy and enumeration

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Abstract
The faecal streptococci are the most commonly used alternative or adjunct to coliform bacteria as faecal pollution indicators. They are a group of coccoid bacteria, naturally inhabiting the gut of warm‐blooded animals and humans. Their potential as faecal pollution indicators was recognised in the 1890s, but it was 50 years before the accumulated knowledge of their taxonomy and sanitary significance, together with the development of isolation and enumeration methods, allowed their practical application in water pollution research and management. There is still much disagreement over the classification of the group. Many workers now place some species in a separate genus, Enterococcus, and it is likely that this revised nomenclature will be incorporated into the next edition of Bergey ‘s Manual. Of the enumeration methods available (plate count, MPN, and membrane filtration), the mE‐EIA membrane filtration method, which recovers enterococci (a subset of faecal streptococci) is probably the most important, because it is the basis of current United States Environmental Protection Agency recommendations on bathing water standards. However, there appears to be no universally accepted “best method” for the isolation of faecal streptococci from natural waters. Biochemical and serological identification methods are commercially available, and research has begun into the use of DNA‐based techniques for identifying faecal streptococcal strains and faecal sources.