Amies Transport Medium Composition, Principle, Preparation, Results, Uses

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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

Sodium chloride3.000
Potassium chloride0.200
Calcium chloride0.100
Magnesium chloride0.100
Monopotassium phosphate0.200
Disodium phosphate1.150
Sodium thioglycollate1.000

Final pH (at 25°C) 7.2±0.2

Preparation of Amies Transport Medium

  1. Take 20g and mix it with 1 litre of distilled.
  2. Bring to boil to dissolve the agar.
  3. Divide the charcoal into small screwcap bottles and stir to ensure that it remains suspended evenly.
  4. Securely screw the caps on all bottles.
  5. For 15 minutes, sterilize the bottles by heating them at 121°C. To evenly distribute the charcoal, invert the bottles while they are cooling.
  6. Keep it in a cool location until you use it.
  7. To collect the specimen, use sterile cotton-tipped swabs placed on wooden sticks.
  8. The swab should be pushed down to one-third the medium depth.
  9. Keep the cap securely on the bottle during transport.

Result Interpretation on Amies Transport Medium

Escherichia coliGood recovery on subculture
Klebsiella pneumoniaeGood recovery on subculture
Neisseria meningitidisGood recovery on subculture
Pseudomonas aeruginosaGood recovery on subculture
Salmonella TyphiGood recovery on subculture
Shigella flexneriGood recovery on subculture
Staphylococcus aureus subsp. aureusGood recovery on subculture
Vibrio choleraeGood recovery on subculture
Bacteroides fragilisGood recovery on subculture
Haemophilus influenzaeGood recovery on subculture
Neisseria gonorrhoeaeGood recovery on subculture
Streptococcus pyogenesGood 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.
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