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Dehydrated Culture Media

THIOGLYCOLLATE BROTH USP- ALTERNATIVE

Code: CM0391

Used in place of Thioglycollate Medium USP CM0173 for testing turbid or viscous products.

Typical Formula*

gm/litre

L-cystine

0.5

Sodium chloride

2.5

Glucose

5.5

Yeast extract

5.0

Pancreatic digest of casein

15.0

Sodium thioglycollate

0.5

pH 7.1 ± 0.2 @ 25°C

 

* Adjusted as required to meet performance standards 

Directions
Suspend 29g in 1 litre of distilled water. Bring to the boil and dissolve the medium completely. Distribute into tubes or bottles and sterilise by autoclaving at 121°C for 15 minutes.
PREPARE FRESHLY OR BOIL AND COOL THE MEDIUM JUST BEFORE USE.

Description
Thioglycollate Medium USP - Alternative, is intended for sterility testing with certain biological products that are turbid or otherwise do not lend themselves readily to culturing in Thioglycollate Medium USP (CM0173) because of its viscosity.

The formulation, which omits the agar and resazurin present in Thioglycollate Medium USP, is described in the N.I.H. Memorandum1 and the U.S. Pharmacopoeia XXI. These omissions make it essential that the medium should be freshly prepared or boiled and cooled within four hours of use.

The containers of choice for the medium are tubes of 20 x 150mm size. The use of 15ml of medium in this tube provides adequate medium for inocula up to 3ml and sufficient thioglycollate to inactivate a mercurial preservative, when present in the inoculum, in a concentration not greater than 0.03% w/v. Other preservatives will need to be inactivated by adequate dilution unless an effective inactivator is used.

If larger volumes of medium are required, cylindrical or square bottles or containers which provide approximately the same ratio of surface exposed to depth of medium as in the test-tube above, should be used.

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

Whilst storage of the prepared medium is not recommended, autoclaved volumes of Thioglycollate Medium USP - Alternative, should be held at 20-30°C in the dark. Storage at lower temperatures increases oxygen absorption.

Appearance
Dehydrated medium: Straw coloured, free-flowing powder
Prepared medium: Straw coloured solution      

Quality control

Positive controls:

Expected results

Candida albicans ATCC® 10231*Flocculent growth
Clostridium sporogenes ATCC® 19404*Turbid growth and or colonies
Peptostreptococcus anaerobius ATCC® 27337*

Turbid growth and or colonies

Negative control:

 

Uninoculated medium

No change

* This organism is available as a Culti-Loop®

Precautions
This medium lacks agar and reducing indicator, therefore it is essential that the medium is freshly prepared and used within four hours of preparation.
Thioglycollate media should not be reheated more than once because toxic oxygen radicles are formed on reheating.

References
1. N.I.H. (1955) Memorandum: `Culture media for sterility tests’ 4th Revision.
2. US Pharmocopoeia XXI (1985) `Sterility tests’.

 
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