Endo-NPS are used for the detection of Escherichia coli and other coliform bacteria in water, wastewater and other samples. The formulation is modified acc. to “Standard Methods for the Examination of Water and Wastewater”. Gram positive bacteria are inhibited by fuchsin and sodium sulfite, whereas gram-negative organisms show good growth. Bacteria that are able to metabolize Lactose develop red to dark red colonies due to the presence of fuchsin. For most of the E. coli strains this reaction is so intense that the fuchsin is crystallized giving the typical green metallic sheen. The medium is manufactured and quality tested in compliance with ISO 11133:2014 standard.