This monograph has been assessed by members of the IUMS–ICFMH Working Party on Culture Media and given ‘Approved’ status.

This broth is a modification of MacConkey's liquid medium for the isolation of Enterobacteriaceae, formulated by Dunham and Schoenlein in 1926 to attain maximum recovery of bacteria of the coli–aerogenes group, while inhibiting most Gram-positive organisms which might hinder the development of the bacteria sought. It contains brilliant green and bile as the inhibitory agents for Gram-positive organisms and lactose as the carbon source, which is dissimilated rapidly by the coli–aerogenes group, mostly by a heterofermentative pathway, leading to gas formation. Mackenzie et al. (1948) found it markedly superior to MacConkey broth for confirmation of Escherichia coli at 44°C and it is now common practice to carry out preliminary MPN tests using a less selective medium such as lauryl tryptose broth or minerals modified glutamate medium and confirm any tubes showing a positive reaction by subculture to BGB broth.