Salmonella spp. (most of them are hydrogen sulfide positive; negative are usually e.g., serotype Paratyphi A; serotype Typhi can give only a weakly positive reaction), Citrobacter sp. and Salmonella enterica subsp. arizonae (subspecies IIIa) on triple sugar iron agar.

TSI is used when differentiating bacteria, primarily from the family Enterobacteriaceae, based on their ability to ferment glucose, lactose and sucrose, and to reduce sulfur to hydrogen sulfide.