On the indicators of faecal co

A. An indicator of faecalcontamination can be defined as an organism used in the detectionand estimation of fecal contamination in water. They arenot serious human pathogens but can indicate fecal contaminationand serious enteric pathogens in water.  Thecharacteristics of an ideal indicator organism are

1. The indicator is present wheneverenteric pathogens are present.
2. The organism is present in morenumbers than the serious pathogens.
3. The organism has a higherresistance to antimicrobial agents than the hardiest entericpathogen.
4. The organism does not proliferatein water.
5. The organism is easily culturableand detectable than the pathogens.
6. The indicator grows independent ofother organisms.

The processindicator is different from a fecal indicator. The fecalindicator indicates the fecal contamination and presence of entericpathogens in water, whereas the process indicator indicatesthe progress and efficacy of a wastewater treatmentprocess. For example, Coliforms are used as processindicators to check efficacy of chlorination process.

B. Total coliforms,or a subset of this group, the Fecal coliformswere the most used organisms as indicators of fecal contamination.Total coliforms were the first bacteria used as indicators. Fecalcoliforms are more useful than Total coliforms as the formerinclude some bacteria which are the normal inhabitants of soil andwater. One disadvantage in using Coliforms is that they canproliferate in water under some circumstances. E.coli and F+RNA Coliphage are another examples ofindicator organisms. Repeated and frequent screening for E.coli in water is an effective method for predicting pathogensin it. A qPCR-based E. coli assay is very efficient inthis regard. Screening for F+RNA coliphage is also effective inpredicting bacterial pathogens, but not very sensitive forpathogens like Rotavirus.

C. The traditionalfecal indicators mainly include Coliforms. But they are notspecific to human fecal material and can grow outside the hostbody. To overcome these disadvantages, anaerobic enteric bacterialike Bacteroidales could be used. Quantitativereal time PCR can be used to detect these host specificBacteroidales. Species PrevotellaandBacteroides are examples of Bacteroidales in humangut. Fecal anaerobes are more effective asindicators because they will not grow once released from their hostinto the environment, in contrast to E. coli andEnterococci, which have been shown to persist and even grow inbeach sand.