Amies Transport Medium, which contains charcoal to increase the viability and longevity of pathogenic organisms, is an improved transport medium. It is semisolid media that can be used in qualitative procedures to transport clinical swab specimens from the hospital to the laboratory. This modified Stuart’s Transport Medium is made by adding charcoal to the medium and replacing the glycerophosphate. This modified medium produced a higher percentage positive results than Stuart’s transport medium.
Principle of Amies Transport Medium
Amies Transport Medium is a low-stress environment because it contains sodium thioglycollate, and a small amount of agar. Charcoal is used to neutralize toxic substances that can be harmful to sensitive pathogens such as Neisseria gondiiae. Calcium magnesium, potassium and sodium salts are important for the survival of gonococcal cell and control the permeability of bacteria cells. The medium is protected by phosphates.
Composition of Amies Transport Medium
| Ingredients | Gms/liter |
| Sodium chloride | 3.000 |
| Potassium chloride | 0.200 |
| Calcium chloride | 0.100 |
| Magnesium chloride | 0.100 |
| Monopotassium phosphate | 0.200 |
| Disodium phosphate | 1.150 |
| Sodium thioglycollate | 1.000 |
| Charcoal | 10.000 |
| Agar | 4.000 |
Final pH (at 25°C) 7.2±0.2
Preparation of Amies Transport Medium
- Take 20g and mix it with 1 litre of distilled.
- Bring to boil to dissolve the agar.
- Divide the charcoal into small screwcap bottles and stir to ensure that it remains suspended evenly.
- Securely screw the caps on all bottles.
- For 15 minutes, sterilize the bottles by heating them at 121°C. To evenly distribute the charcoal, invert the bottles while they are cooling.
- Keep it in a cool location until you use it.
- To collect the specimen, use sterile cotton-tipped swabs placed on wooden sticks.
- The swab should be pushed down to one-third the medium depth.
- Keep the cap securely on the bottle during transport.
Result Interpretation on Amies Transport Medium
| Organisms | Growth |
| Escherichia coli | Good recovery on subculture |
| Klebsiella pneumoniae | Good recovery on subculture |
| Neisseria meningitidis | Good recovery on subculture |
| Pseudomonas aeruginosa | Good recovery on subculture |
| Salmonella Typhi | Good recovery on subculture |
| Shigella flexneri | Good recovery on subculture |
| Staphylococcus aureus subsp. aureus | Good recovery on subculture |
| Vibrio cholerae | Good recovery on subculture |
| Bacteroides fragilis | Good recovery on subculture |
| Haemophilus influenzae | Good recovery on subculture |
| Neisseria gonorrhoeae | Good recovery on subculture |
| Streptococcus pyogenes | Good recovery on subculture |
Uses of Amies Transport Medium
- It’s used to collect, transport and preserve microbiological specimens.
- It has been formulated to preserve the viability of microorganisms, without any significant growth.
- It’s a medium that transports anaerobes like Neisseria gondorrhea, and other pathogens from swabs.
- It is used to preserve microbiological specimens.
- It is highly recommended for throat, vaginal and wound samples.
Limitations of Amies Transport Medium
- Before using the old medium, it should be re-steamed and the charcoal should be re-suspended.
- During long periods of transport, some contaminants can also grow.
- The specimen should be inoculated immediately after transportation in the correct medium. To achieve optimal results, it is important to reduce the time between sample collection and the inoculum being transferred onto the culture medium.
- It might not be suitable to transport fastidious organisms.
- Gonococci can survive in Amies Transport Medium for 6-12 hours, provided that they are not exposed temperature extremes. If they are present in small quantities at first, their numbers decrease over 24 hours.
