- Glycerol saline transport medium is used to preserve Salmonella and Shigella species and Escherichia coli in facial specimens. It is not suitable for Vibrio cholera, Campylobacterspecies or Yersinia enterocolitica.
Composition of Glycerol saline transport medium
- Sodium chloride…………………………………….. 4.2 g
- di-sodium hydrogen phosphate……………………..3.1 g
- potassium dihydrogen phosphate …………………..1 g
- phenol red, 1% w/v* ………………………………… 0.3ml
- Glycerol………………………………………………300 ml
- Distilled water ……………………………………….700 ml
Preparation of Glycerol saline transport medium
- Dissolve the dry chemicals in the water and adjust the pH to 7.2.
- Add the phenol red solution and the glycerol. Mix well. Dispense in 7 ml amounts in screw cap bottles.
- Sterilize by autoclaving (with caps loosened) at 121°C for 15 minutes. When cool, tighten the caps.
- Label the bottles. Date the medium and give it a batch number.
Quality control
- pH of medium: this should be within the range pH 7.1-7.3 at room temperature.
- Store in a cool dark place or at 2-8°C.
- Shelf-life:up to 2 years providing there is no change in the volume or appearance of the medium to suggest contamination or an alteration of pH.
Use of Glycerol saline transport medium:
- Used as transport medium for Salmonella, Shigella and E. coli from faecal sample but not for Vibrio and Yersinia and Campylobacter