Method for detecting bacteria using bacteriophage, contrast-coloring dye and precipitable dye

Abstract

Bacteria are detected in a test sample by contacting the test sample with a bacteriophage that is capable of replicating in the bacteria, adding the resultant sample to a water-proof surface of a support for bacterial growth that contains a contrast-coloring dye and a precipitable dye, forming a bacterial lawn of a bacteria in which the bacteriophage can replicate on the support and detecting plaques on the bacterial lawn as an indication of the presence of the bacteria. The combination of precipitable dye and contrast-coloring dye improves visualization of plaques. A precipitate is formed in plaques by enzymatic cleavage of the precipitable dye by an enzyme of the bacterial lawn. A procedure for detecting bacteriophage is similar to that for detecting bacteria, except that a test sample suspected of containing bacteriophage is combined with bacteria in which the bacteriophage can replicate, and plaques detected indicate presence of the bacteriophage. The bacteria and bacteriophage detections are carried out with a disposable device containing at least one well having a water-proof surface and substantially vertical sides that extend at least 5 millimeters in height from the surface. A hydratable material containing the precipitable dye and the contrast-coloring dye is positioned on the water-proof surface. A removable cover rests on top of the sides of the well.

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