Himedia - Sim Medium (M181-500G).

 
This medium is used to differentiate enteric bacilli particularly Salmonella and Shigella on the basis of sulphide production, indole formation and motility. Peptonized iron and sodium thiosulphate are the indicators of H2S production. This H2S reacts with peptonized iron to form black precipitate of ferrous sulphide (6,7). Motile organisms intensify the H2S reaction. Motile organisms grow away from line of inoculation showing diffused growth while non-motile organisms grow along the stab line.