A Primary Division of the Genus Shigella Based on the Trimethylamine Test.

As pointed out by Neter (1942) S. ailkalescens is not infrequently mistaken for S. paradysenteriae. To a lesser extent a similar condition holds true for S. sonnei cultures fermenting lactose much more slowly than the average strain. Diagnostic laboratories without adequate antiserums could use either the Eijkman or the trimethylamine test or both to good advantage with ShigeUa cultures. Considering the large number of cultures tested the single group I, Eijkman positive exception and the single group I, trimethylamine positive exception (Wood et al. 1943) detract but little from the practicability of these two tests.