Which organisms are used to indicate the likelihood that pathogenic bacteria may be present?

Coliform bacteria are significant indicators of the potential presence of pathogenic bacteria in water systems. These bacteria are a diverse group found in the environment, primarily in soil, vegetation, and the feces of warm-blooded animals. The presence of coliform bacteria in water suggests that it has been contaminated with fecal material, which may harbor harmful pathogens.

Monitoring for coliform bacteria is crucial for assessing water quality, as they serve as a general indicator of sanitary quality and the possible presence of harmful microorganisms, including viruses and other bacteria that can cause illness. If coliform bacteria are detected, further testing for specific pathogens, including E. coli, Salmonella, or other disease-causing organisms, is typically conducted to assess the risk to public health.

While E. coli is specifically associated with fecal contamination and is a direct indicator of potential harmful effects, coliform bacteria encompass a broader group and are used as a standard measure in water quality assessment because of their ease of testing and significant correlation with the presence of pathogens.