Stuart Transport Medium is a nonnutritional medium which maintains the viability of organisms without significant multiplication. The small agar content provides a semisolid consistency which prevents oxidation and drying during transport. Sodium thioglycollate is added to produce a reduced environment so as to improve the recovery of anaerobes. Methylene blue is the oxidation-reduction indicator. The medium appears colorless in the reduced state and blue in the oxidized state. Calcium chloride maintains permeability of bacterial cells and sodium glycerophosphate maintains the pH of the medium.