A liquid, colorimetric presence-absence coliphage detection method.

A liquid, colorimetric presence-absence coliphage detection method based on the induction of beta-galactosidase by Escherichia coli is described. The release of beta-galactosidase in the medium due to lytic cell infections by coliphages permits the hydrolysis of a yellow chromogenic substrate that develops into a distinct red coliphage positive sample, while a coliphage negative sample remains yellow. This method has proven to be rapid, simpler to perform than an agar medium assay, easy to read and interpret, inexpensive, and highly sensitive.