There is disclosed an improved method for testing for the presence of a particular microorganism or group of microorganisms characterized by a particular enzyme. The method uses a dye-forming substrate throughout a polymer matrix or on the surface of a solid support member that forms a colored precipitate when cleaved by the enzyme. The precipitate is concentrated to the polymer matrix and/or solid support member to create a visible reaction product, wherein the amount of dye-forming substrate needed is independent of the sample size. The present invention further comprises an enzyme indicator device comprising a dye-forming substrate throughout a polymer system or on the surface of a solid support member.