Trehalose Fermentation in the Differentiation of the Paratyphoid-Enteritidis Group

In a study of the availability of trehalose for the various members of the paratyphoid-enteritidis group, it was found that B. suipestifer is unable to attack this disaccharide, whereas B. paratyphosus, B. schottmulleri, the animal para B sub-group, and B. enteritidis ferment trehalose with the production of acid and gas. Furthermore, it is possible to differentiate by cultural methods the B. schottmulleri strains from the closely allied animal para B group, hitherto separable only by serologic means. This has been accomplished by employing small amounts of a serum water medium containing 0.5% trehalose and 1% Andrade indicator. In this medium the animal para B strains produce a red coagulum after 3 to 4 days' incubation, while the B. schottmulleri cultures present a light pink or colorless coagulum. This separation has been found to parallel the differentiation of these 2 groups by agglutinin absorption tests. B. enteritidis is similar in its reaction to the animal para B cultures and in contrast to B. schottmulleri.