Fluid Thioglycollate Medium w/ 0.5% Soya lecithin and Polysorbate 20 (Twin pack)

Intended use

Recommended as sterility test medium, also used for cultivation of wide variety of microorganisms and for determining efficiency of sanitization of containers, equipment surfaces, water miscible cosmetics, etc.

Composition**

Final pH (at 25°C): 7.1±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 34.75 grams of Part A in 960 ml purified / distilled water containing 40 ml Part B. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Cool to 25°C and store in a cool dark place preferably below 25°C.

Note : If more than the upper one-third of the medium has acquired a pink colour, the medium may be restored once by heating in a water bath or in free flowing steam until the pink colour disappears.

Principle And Interpretation

Brewer (1) formulated Fluid Thioglycollate Medium for rapid cultivation of aerobes as well as anaerobes including microaerophiles by adding a reducing agent and small amount of agar. The USP (2), BP (3), EP (4) and AOAC (5) have recommended the media for sterility testing of antibiotics, biologicals and foods and for determining the phenol coefficient and sporicidal effect of disinfectants. However, it is intended for the examination of clear liquid or water soluble materials. Fluid Thioglycollate Medium is also routinely used to check the sterility of stored blood in blood banks (6). This medium is a modification of Fluid thioglycollate medium with the addition of Soya lecithin and Polysorbate 20.

Dextrose, tryptone, yeast extract, L-cystine provide the growth factors necessary for bacterial multiplication. L-cystine and sodium thioglycollate allows Clostridium to grow in this medium even under aerobic conditions(7). Also the small amount of agar used in the medium favors the growth of aerobes as well as anaerobes in the medium, even if sodium thioglycollate is deleted from the medium(1). Sodium thioglycollate act as a reducing agent and neutralizes the toxic effects of mercurial preservatives and peroxides formed in the medium, thereby promoting anaerobiosis, and making the medium suitable to test materials containing heavy metals. (6,8). Any increase in the oxygen content is indicated by a colour change of redox indicator, resazurin to red (9,10,11). The small amount of agar helps in maintaining low redox potential for stabilizing the medium (8). Soya lecithin neutralizes the quaternary ammonium compounds while polysorbate 20 neutralizes phenolic disinfectants, hexachlorophene and formalin (12).

Type of specimen

Pharmaceutical samples for sterility testing

Specimen Collection and Handling

For pharmaceutical samples, follow appropriate techniques for sample collection, processing as per guidelines (2,3,4). After use, contaminated materials must be sterilized by autoclaving before discarding.

Warning and Precautions

Read the label before opening the container. Wear protective gloves/protective clothing/eye protection/ face protection. Follow good microbiological lab practices while handling specimens and culture. Standard precautions as per established guidelines should be followed while handling specimens. Safety guidelines may be referred in individual safety data sheets.

Limitations

1. It is intended for the examination of clear liquid or water-soluble materials.

Performance and Evaluation

Performance of the medium is expected when used as per the direction on the label within the expiry period when stored at recommended temperature.

Quality Control

Appearance Part A: Cream to yellow homogeneous free flowing powder Part B : Colourless to light yellow clear viscous liquid

Colour and Clarity of prepared medium Light straw coloured, clear to slightly opalescent solution with upper 10% or less medium pink -purple on standing, may develop a viscous layer at the bottom.

Reaction Reaction of 3.47% w/v aqueous solution containing 4.0 % Part B at 25°C. pH : 7.1±0.2

pH 6.90-7.30

Cultural Response Cultural characteristics observed after an incubation at 30-35°C for not more than 3 days.

Key : * Corresponding WDCM numbers, **Formerly known as Bacillus subtilis subsp. spizizenii ^ Formerly known as Pseudomonas aeruginosa ## Formerly known as Micrococcus luteus $ Formerly known as Bacteroides vulgatus

Storage and Shelf Life

Store between 10-30°C in a tightly closed container and the prepared medium at 2-8°C. Use before expiry date on the label. On opening, product should be properly stored dry, after tightly capping the bottle in order to prevent lump formation due to the hygroscopic nature of the product. Improper storage of the product may lead to lump formation. Store in dry ventilated area protected from extremes of temperature and sources of ignition Seal the container tightly after use. Product performance is best if used within stated expiry period.

Disposal

User must ensure safe disposal by autoclaving and/or incineration of used or unusable preparations of this product. Follow established laboratory procedures in disposing of infectious materials and material that comes into contact with sample must be decontaminated and disposed of in accordance with current laboratory techniques (13,14).

Reference

1. Brewer, 1940, J. Am. Med. Assoc., 115:598.
2. The United States Pharmacopoeia-National Formulatory (USP-NF), 2022.
3. The British Pharmacopoeia, 2022, Medicines and Healthcare products Regulatory Agency.
4. European Pharmacopoeia, 2022, 10 th volume, European Directorate for the quality of medicines & Healthcare
5. Williams H., (Ed.), 2005, Official Methods of Analysis of the Association of Official Analytical Chemists, 19th Ed., AOAC,Washington, D.C.
6. Federal Register, 1992, Fed. Regist., 21:640.
7. Quastel and Stephenson, 1926, J.Biochem., 20
8. MacFaddin J.F., 1985, Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria, Vol. 1, Williams and Wilkins, Baltimore.
9. Marshall, Gunnison and Luxen, 1940, Proc. Soc. Exp. Biol. Med., 43:672.
10. Nungester, Hood and Warren, 1943, Proc. Soc. Exp. Biol. Med., 52:287.
11. Portwood, 1944, J. Bact., 48:255.
12. Favero (chm.), 1967, Microbiological Sampling of Surfaces, Biological Contamination Control Committee, American Asso. for Contamination Control.
13. Isenberg, H.D. Clinical Microbiology Procedures Handbook 2nd Edition.
14. Jorgensen, J.H., Pfaller , M.A., Carroll, K.C., Funke, G., Landry, M.L., Richter, S.S and Warnock., D.W. (2015) Manual of Clinical Microbiology, 11th Edition. Vol. 1..