Other Methods

F-RNA bacteriophages

Bacteria such as E. coli can be infected by viruses called bacteriophages. One group, the F-RNA coliphages, has been investigated for MST on the basis of the predominance of four different subgroups in human and animal faeces. Subgroups II and III tend to be isolated from human sewage, subgroup I is more frequently isolated from non-human mammals, and subgroup IV phages are of mixed faecal origin (Sinton et al. 1998 (external link) ).

However, uncertainties remain over the degree of specificity of the different subgroups to human and animal sources (Blanch et al., 2006 (external link) ) and it has also been suggested that Group I may survive longer in lake water than other subgroups. F-RNA phages also tend to be present in very low concentrations in natural waters contaminated by animals, which may limit the usefulness of this approach to identification of sources of contamination in shellfish, which tend to concentrate enteric microbes, including phages.

A promising approach to the application of bacteriophages to MST, at least for the identification of human sources, has been described by Ebdon et al. (2007). (external link)  It involves the isolation of species and strains of Bacteroides associated with human effluents in a particular geographical area. The bacteriophages of these strains are highly specific to their host bacterium. In comparison to their hosts, the phages survive for longer periods and in higher numbers in waterways suggesting they may be useful indicators of human contamination.