Description
This medium is similar to that described by Hobbs and Allison; a modification of the medium documented by Leifson, who investigated the properties of selenite and promoted it’s use in a paper in 1936.
Years earlier, Klett had described the selective and inhibitory effects of selenite. It appears that selenium reacts with sulphur and sulphydral groups in critical cell components but the reasons for this have not been fully explained. In a comparison study performed by Hobbs and Allison, the addition of mannitol as fermentable carbohydrate, in place of lactose used in the original Selenite F formulation, appeared to give slightly higher recovery of S. typhi on sub-culture to selective and inhibitory medium.
Mannitol Selenite Broth has also been shown to be superior to a number of other liquid media in it’s selective value for S. typhi and equal in performance to tetrathionate broth for recovery of S. paratyphi B.
Faecal coli and enterococci are not inhibited completely; they are reduced in the first 8-12 hours, and thereafter increase rapidly.
