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STUART TRANSPORT MEDIUM (MODIFIED)

Code: CM0111

a semi-solid, non-nutritional transport medium for fastidious, pathogenic organisms

* Adjusted as required to meet performance standards

Directions
Suspend 16g in 1 litre of distilled water. Bring to the boil to dissolve completely and dispense into screw-capped 7ml bottles. Fill each bottle to the brim, tighten the cap and sterilise by autoclaving at 121°C for 15 minutes. When sufficiently cool to handle, mix by inversion.

Description
This improved medium originally described by Moffett et al.¹ and Stuart et al.², is a non-nutritional semi-solid substrate for the preservation of Neisseria species and other fastidious organisms during their transport from clinic to laboratory. Originally formulated for the conservation of Neisseria gonorrhoeae and Trichomonas vaginalis, it may also be used for the transport of other bacteriological specimens. Stuart et al.² noted that the transport medium may also be used for Haemophilus influenzae, Streptococcus pneumoniae, Streptococcus pyogenes and Corynebacterium diphtheriae. Cooper³ investigated the extension of Stuart’s method to the transport of swabs of clinical material containing upper respiratory tract and enteric pathogens. Stuart⁴ published an account of his experiences of the medium in a public health bacteriology, whilst Crookes and Stuart ⁵ used the transport medium in combination with polymyxin for the cultivation of Neisseria gonorrhoeae.

Preparation of Charcoal Swabs for use with Transport Medium
1. Prepare swabs by rolling absorbent cotton-wool on wooden sticks.
2. Boil the swabs in a phosphate buffer solution of the following composition: Disodium hydrogen phosphate 0.81 grams Potassium dihydrogen phosphate 0.18 grams Distilled water 100ml pH 7.4
3. Immediately dip the swabs into a 1% suspension of charcoal (pharmaceutical grade).
4. Place in cotton-wool plugged test tubes and sterilise in the autoclave at 121°C for 15 minutes. Dry at 100°C to remove any excess moisture.

Transport of Swabs
After collection of the specimen, place the swab in the middle of the bottle of Stuart Transport Medium. Break off the stick, replace the screw cap tightly and transport to the laboratory as soon as possible.

The transport method will allow the isolation of gonococci from approximately 90% of cases of female gonorrhoea, provided the transport period is under 24 hours; for longer periods the method is still useful up to 3 days².

In all cases, specimens should be cultivated as soon as possible or stored in the refrigerator if delay is unavoidable. Wilkinson⁶ reported successful isolation after as long as six days storage in a refrigerator.

Trichomonas vaginalis remains viable, in the medium, up to 24 hours whilst Cooper³ has reported the recovery of upper respiratory tract and enteric pathogens after 8-12 weeks storage. Stuart et al.² successfully used the transport method for the recovery of Haemophilus influenzae, Streptococcus pneumoniae, Streptococcus pyogenes and Corynebacterium diphtheriae from specimens which had been in transit for 3-5 days.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 15-25°C.

Appearance
Dehydrated medium: Blue green coloured, free-flowing powder
Prepared medium: Off white coloured gel, semi-solid gel

Quality control

* This organism is available as a Culti-Loop®

Precautions
A small amount of blue colour at the top of the bottle indicates oxidation. If this colour extends down into the medium it should be discarded.
Avoid prolonged heating in open flasks, during the preparation of the medium, because thioglycollate is volatile.
Sodium glycerophosphate may be metabolised by some organisms and thus promote their growth.

References
1. Moffett M., Young J.L. and Stuart R. D. (1945) BMJ. 2. 421-424.
2. Stuart R. D., Toshach S.R. and Patsula T.M. (1954) Canad. J. Publ. Hlth 45. 13-83.
3. Cooper G. N. (1967) J. Clin. Path. 10. 226-230.
4. Stuart R. D. (1959) Pub. Hlth Rep. Wash. 74. 431-438.
5. Crookes E.M.L. and Stuart R. D. (1959) J. Path. Bact. 78. 283-288.
6. Wilkinson A. E. (1955) J. Med. Lab. Technol. 15. 184-195.