Laurylsulfate-Tryptose broth is a selective enrichment media used for the detection and enumeration of Escherichia coli and coliforms in water and food products. 
The medium was formulated by Malmann and Darby who showed, in 1941, that sodium laurylsulfate was the best selective agent among a number of surfactants and did not inhibit the growth of coliform bacteria. Levine later showed that the medium reduced the number of false positives by inhibiting the growth of sporulated gas-producing bacteria.