4 Important Things to Know About Microbial Source Tracking

Microbial source tracking is a process by which researchers determine the sources of water contamination by fecal matter whether the source be human, wildlife or domesticated animal. It’s used to test the safety of water that we use for drinking, for harvesting seafood, and for recreation (i.e., public beaches.) However, most people don’t realize how microbial source tracking works, or why it is so important. Here are four things that everyone should know about microbial source tracking:

1. Microbial Source Tracking (MST) Relies on Microorganisms in Feces
MST procedures work by tracking host-associated characteristics of the many microorganisms present in human and animal feces, including viruses, bacteria, and protozoa. (Selection and Application of MST Procedures) Essentially, this means that researchers choose an identifier, often genotypes or phenotypes of E. Coli bacteria, as they can be found in various life forms, as well as other identifiers such as RNA markers.

2. Many Different Identifiers Can be Used
Because physiological differences in the host (be it human, wild or domestic animal) cause differences in the variety and characteristics of the microorganisms in feces, many different identifiers can be used. What identifier researchers choose is based largely on the objective of the microbial source tracking, usually to test the concentration of specific pathogens in water used for drinking or harvesting seafood. Common identifiers include antibiotic resistance, optimal temperature for microorganisms, and phenotypes or genotypes of common bacteria such as E. Coli.

3. MST is Often Federally Mandated
Federal U.S. institutions such as the FDA and EPA frequently require microbial source tracking tests for certain pathogens in waters used for consumption or recreation. For example, the EPA requires tests on the concentration of E.Coli and enterococci bacteria for any recreational waters, while they have also proposed tests on coliform and coliphage concentrations in drinking water. In addition, the FDA uses MST test for fecal coliform concentrations as the identifier to test the quality of water used for shellfish harvesting.

4. Water Contaminated by Human Feces Poses the Greatest Risk
Out of the three primary sources for fecal contamination (humans, wildlife and domestic animals,) it is human feces that is most dangerous. This is because waters contaminated by human waste are more likely to contain human-specific pathogens, such as the Hepatitis A Virus, Norwalk Viruses, and strains of Salmonella bacteria. (Microbial Source Tracking: Methodology and Future Directions) This type of contamination is a particular risk in recreational waters frequented by large numbers of people, but even in bodies of water used for drinking or fishing, contamination from animal feces can occur.