Which of the following is most easily identified by laboratory analysis in water contaminated by feces?

The presence of coliform bacteria in water contaminated with feces is most easily identified through laboratory analysis. Coliforms are a group of bacteria commonly found in the intestines of warm-blooded animals and are often used as indicators of fecal contamination in water sources. Their rapid detection is critical for assessing water quality and safety, especially in terms of potential health risks associated with pathogens that may also be present.

Coliform testing is typically less complex and more cost-effective than tests for specific pathogens such as Shigella dysenteriae, Entamoeba histolytica, and Salmonella typhosa. These pathogens require more specialized testing methods and longer incubation periods to cultivate and identify. Consequently, coliform bacteria serve as a reliable indicator in routine water testing for potential fecal contamination, allowing for quicker responses to contamination events and more effective public health interventions.