Which of the following statements about the presumptive phase of the MPN test is accurate?

The correct statement regarding the presumptive phase of the Most Probable Number (MPN) test is that it is the first step that determines if further testing is needed. In this phase, samples are inoculated into a selective growth medium to promote the growth of coliforms or other target microorganisms. The growth observed during this stage indicates whether there is a likelihood of contamination. Ifpositive growth is seen, it signals the need for additional confirmatory tests to specifically identify and quantify the pathogens or indicator organisms present in the sample.

This phase serves as an initial screening method. It does not directly confirm the presence of pathogens, nor does it estimate the number of viable microorganisms. Instead, it indicates the need for further testing based on observable results, guiding laboratory analysts on how to proceed with sample analysis. The MPN test further includes subsequent phases that involve confirmation and enumeration, which are essential for accurate quantification and identification.