Selenite F Broth- Composition, Principle, Preparation, Results, Uses


Selenite F Broth is a type of enrichment medium that is used for the isolation and cultivation of Salmonella spp. from various samples, such as feces, urine, water, foods and other materials of sanitary importance. It is also useful for the detection of some species of Shigella and the transport of strains of Vibrio cholerae.

Selenite F Broth was devised by Leifson, who demonstrated that selenite was inhibitory for coliforms and certain other microbial species, such as fecal streptococci, present in fecal specimens, and thus, was beneficial in the recovery of Salmonella species. He found that the inhibited strains would eventually breakthrough, but if subcultures were made from the enrichment broth after 8–12 h incubation, the isolation of Salmonella was possible without overwhelming growth of many members of the intestinal flora.

Selenite F Broth is a buffered Lactose Peptone Broth to which Sodium Biselenite is added as the selective agent. The F in Selenite F Broth stands for Faeces, because it is mostly used for the isolation of Salmonella and Shigella from faecal specimens.

Selenite F Broth works by inhibiting many species of gram-positive and gram-negative bacteria, including enterococci and coliforms, with sodium selenite, while allowing the growth of Salmonella and some Shigella species. The medium also maintains a neutral pH with lactose fermentation and sodium phosphate buffering, which reduces the toxicity of selenite.

Selenite F Broth is an important tool for the diagnosis and surveillance of salmonellosis, shigellosis and cholera, which are serious infectious diseases that can cause diarrhea, fever, abdominal cramps and dehydration. These diseases can be transmitted through contaminated food or water, or through contact with infected animals or people. Therefore, it is essential to identify and isolate the causative agents as quickly and accurately as possible. Selenite F Broth can help achieve this goal by enriching the target organisms and suppressing the background flora.