S. faecalis has been said to be a better indicaor of fecal contamination over E. coli. Can somebody please explain why?
Commonly fecal contamination by Enterococcus family, E.coli is gram negative organisms, but enterococcus classification group D are streptococcus family and it is gram positive. Growth rate of ecoli is maximum 17 minutes but s. faecalis growth time is high.
Several authors suggested that the fecal streptococci group is not a better indicator of fecal contamination in tropical marine waters than the fecal coliform group. Please see the following article for example:
https://www.ncbi.nlm.nih.gov/pubmed/15092468
In environmental waters the Enterococcus levels are lower but more persistent than E.coli levels. If you need to monitor faecal pollution is a good alternative, however I prefer the E.coli rule for potable waters.
As Francesc Codony wrote, Enterococci persist longer in water than E. coli, moreover in tropical and equatorial regions/ climate where temperature reaches high many of the E. coli dies out while Enterococci may persist even at 60C for hours together, Enterococci are more resistant to even chlorination and through using Enterococcus faecalis as indicator bacteria you may detect faecal contamination in partly treated waters. For the method, you may look the following links.
Moreover, we have seen several faecal samples where E. coli is absent but hardly any without enterococci, especially in patients treated with antibiotics.
Therefore, E. faecalis appears to be better indicator of faecal contamination, but E. coli detection is always preferred for fresh faecal contamination.
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1) Enterococci are more persistent against different treatments of water like chlorination compare to E. coli
2) Enterococci are also more persistent against high temperature compare to E.coli. So for example, in high climate countries or regions like in the Philippines, Enterococci can withstand temperature even until 60+ degrees Celsius. On the other hand, E.coli immediately dies with that temperature, hence they will be absent in samples.
1) Enterococci are more persistent against different treatments of water like chlorination compare to E. coli
2) Enterococci are also more persistent against high temperature compare to E.coli. So for example, in high climate countries or regions like in the Philippines, Enterococci can withstand temperature even until 60+ degrees Celsius. On the other hand, E.coli immediately dies with that temperature, hence they will be absent in samples.
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