Which group of bacteria is used to indicate the possible presence of a pathogen?

The group of bacteria known as coliforms is commonly used to indicate the potential presence of pathogenic organisms in water. Coliform bacteria are a broad class of bacteria, found in the environment, human and animal waste, and in contaminated water. The presence of coliforms in water samples is used as a key indicator of water quality and safety. Specifically, the detection of fecal coliforms, a subset of total coliforms, can suggest that fecal contamination has occurred, which might include harmful pathogens that cause diseases.

Salmonella is a specific type of pathogenic bacteria and is not used as an indicator organism because it requires more extensive testing to detect and does not represent a broad class of contamination like coliforms do. E. coli is part of the coliform group, especially the non-pathogenic strains; while some strains show pathogenic potential, the broader category of coliforms is favored as an indicator of overall sanitation quality. Staphylococcus, while it includes some pathogenic species, is not a standard indicator for water quality. Therefore, coliforms serve as an effective and established method for indicating possible pathogen presence in water supplies.