A rapid heat-resistant technique for presumptive identification of Salmonella on desoxycholate-citrate agar

A caprylate esterase chromogenic test, which was considered to indicate positivity in 5 minutes if a bright colour appeared on the filter paper inoculum site to which one colony had been applied, was used to test 534 Salmonella, 535 other bacteria capable of growth on desoxycholate-citrate agar (DCA), and 517 non-lactose fermenting colonies from stool cultures on DCA. It was found to be 100% sensitive for Salmonella, 99% specific, and more accurate than either direct antiserum agglutination or a urease test in these respects. The test kit could be stored at room temperature.