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Dehydrated Culture Media

GAMMA-IRRADIATED TRYPTONE SOYA BROTH (GAMMA-IRRADIATED TSB)

CODE: CM1016

A general, nutritious medium for the cultivation of a wide range of organisms which has been given a sterilising dose of irradiation. Gamma-Irradiated TSB is particularly suitable for the microbiological validation of aseptic filling (Media Fill Test).

Formula

gm/litre

Pancreatic digest of casein

17.0

Papaic digest of soybean meal

3.0

Sodium chloride

5.0

Dibasic potassium phosphate

2.5

Glucose

2.5

pH 7.3 ± 0.2

Directions
Method 1
Suspend 30 gms in 1 litre of sterile distilled water. Mix well to dissolve. Use for liquid-fill validation procedures.
Method 2
Use powder for dry-fill validations procedures. Ensure that the final concentration of the medium is 30 gms of Gamma-Irradiated TSB suspended in 1 litre of sterile distilled water. Mix well to dissolve.
If required the medium may be prepared by autoclaving. Suspend 30 gms in 1 litre of distilled water. Mix well to dissolve. Dispense into containers. Sterilise by autoclaving at 121°C for 15 minutes.

Description
Gamma-Irradiated TSB is particularly suitable for sterility testing and for the validation of aseptic filling procedures. In the Media Fill Test (MFT), a validation method used to assess the performance of aseptic processing in the pharmaceutical industry, pharmaceutical products are substituted by sterile powder, such as Gamma-Irradiated TSB. The medium is subjected to exactly the same conditions as the product, including filling and closing, to ensure that there is no microbial contamination occurring during the process.
The powder is readily soluble in sterile water, either as part of or at the end of the procedure, then incubated for detection of any organisms present. The use of Gamma-Irradiated TSB simplifies media preparation for MFTs and other applications, and is less time consuming, since it eliminates the need for in-house media sterilisation prior to use.
Gamma-Irradiated TSB is treated at an irradiation level of 40 kGy, as recommended by Annex B of the ISO 11137 Standard1 to ensure the absence of viable vegetative cells and bacterial spores whilst achieving minimal reduction in performance. Quality control testing is carried out before and after irradiation to carefully monitor performance and to check the sterility of the final product. Gamma-irradiation at higher levels, as used by some manufacturers, has been shown to reduce fertility of the medium2.
The formulation of the medium conforms to a range of recognised standards; British Pharmacopoeia Volume II 2000 + Amendment No.1, United States Pharmacopoeia 24 NF19 + 3rd Supplement, European Pharmacopoeia 3rd Edition 2000 + Supplement 2001, Japanese Pharmacopoeia 12th Edition + Supplement II JP XIII.

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

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

 Quality control

Positive controls:

Expected results

Streptococcus pneumoniae ATCC® 6305 *

Turbid growth

Staphylococcus aureus ATCC® 25923*

Turbid growth

Negative control:

 

Uninoculated medium.

No change

* This organism is available as a Culti-Loop®

References
1.
Annex B of the ISO Standard 11137 ‘ Sterilization of health care products – Requirements for validation and routine control – Radiation Sterilization. International Organisation for Standardization Case Postale 56, CH-1221 Geneve 20, Swtzerland (1995)
2. Data on file at Oxoid (2002)

 
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