A triple sugar-ferrous sulfate medium for use in identification of enteric organisms

Abstract 1.1. A modification of the Krumwiede triple sugar medium is described for use in the differentiation of the colon-typhoid-dysentery group of organisms. 2.2. Tryptone (bacto) is more suitable than other peptones from a viewpoint of available sulfur content, growth-promoting properties, and uniformity of results. 3.3. The ferrous sulfate-sodium thiosulfate indicator system is more sensitive than the ferric ammonium citrate-sodium thiosulfate system for the detection of hydrogen sulfide. 4.4. The sensitivity of bismuth citrate is not affected by changes in pH, ferrous sulfate is only slightly affected, and ferric ammonium citrate reacts very poorly in an acid menstruum. 5.5. The use of bismuth citrate, which is an extremely sensitive indicator, would necessitate revision of the generally accepted classification of the enteric organisms. 6.6. In recording the presence or absence of hydrogen sulfide in cultures the medium and indicator system used should be stated.