Fluid Thioglycollate, Enriched

Cat. no. K73 Fluid Thioglycollate, Enriched, 16x125mm Tube, 10ml 20 tubes/box


Hardy Diagnostics Fluid Thioglycollate, Enriched contains Hemin and Vitamin K and is recommended for use as a highly nutritious general purpose growth medium for the cultivation of aerobic, microaerophilic and anaerobic microorganisms from sterile materials.

This product is not intended to be used for the diagnosis of human disease.


Fluid Thioglycollate was first described in 1940 by Brewer and the medium is useful for testing normally sterile materials. (4,5,8,9) Agar in the formula promotes the growth of small inocula and anaerobes by impeding the diffusion of oxygen within the medium; it also restricts the dispersion of CO 2 and reducing substances from the microenvironment surrounding the inoculum. Sodium thioglycollate is a reducing agent used to maintain low oxygen tension by removing molecular oxygen: peroxides, which may be lethal to many anaerobic organisms, do not form under this condition. Cystine and casein supply carbon and nitrogenous compounds, dextrose is added as an energy source, and sodium chloride maintains osmotic equilibrium.

Hardy Diagnostics Fluid Thioglycollate, Enriched medium contains resazurin as an oxidation-reduction indicator that turns pink when increased oxidation has occurred. Yeast extract, or papaic digest of soybean meal, is added as a growth enhancer. Fluid Thioglycollate, Enriched includes hemin to supply X-factor for the growth of many fastidious microorganisms and vitamin K to promote the growth of some gram-positive spore-formers and Bacteroides species. (2,3,6,7)


Ingredients per liter of deionized water:*

Pancreatic Digest of Casein 15.0gm
Dextrose 5.5gm
Yeast Extract 5.0gm
Sodium Chloride 2.5gm
L-Cystine 0.5gm
Sodium Thioglycollate 0.5gm
Hemin 5.0mg
Resazurin Indicator 1.0mg
Vitamin K 0.1mg
Agar 0.75gm

Final pH 7.1 +/- 0.2 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.


Storage: Upon receipt store at 2-30ºC. away from direct light. Media should not be used if there are any signs of deterioration, discoloration, contamination, or if the expiration date has passed. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing.



Specimen Collection: Consult listed references for information on specimen collection. (2,3,6,7) Infectious material should be submitted directly to the laboratory without delay and protected from excessive heat and cold. If there is to be a delay in processing, the specimen should be inoculated to an appropriate transport media and refrigerated until inoculation.

Method of Use: Consult listed references for the appropriate cultivation techniques using this medium. (2,3,6,7) It is recommended that liquid media for anaerobic incubation be reduced prior to inoculation by placing tubes (with loosened caps) under anaerobic conditions for 18-24 hours. Alternately, the boiling method described below may be used. Fluid Thioglycollate, Enriched medium should be incubated at 35-37 degrees C. for up to one week and checked daily for signs of growth. Growth or turbidity should be confirmed by Gram stain and subculture onto an appropriate growth medium. Broth cultures should be held for one week before being discarded as negative.

Note: Fluid Thioglycollate, Enriched contains a resazurin indicator which will cause the upper layer of the broth to become pink when exposed to oxygen. Containers that have been agitated recently (as during shipping) will turn pink throughout. This can be reversed by allowing the container to stand still for a few hours or by placing tubes in a boiling waterbath for 10 minutes with loosened caps. The caps should be tightened firmly before the media cools. Also note that a whitish precipitate may form in this medium due to the agar content. This does not affect the performance of this medium and may dissipate when the tubes are heated.


Consult listed references for the interpretation of growth and other indicator tests used to identify growth of organisms in this medium. (2,3,6,7)


It is recommended that the proper surface to volume ratio of Fluid Thioglycollate, Enriched medium be maintained to avoid oxidation, making it unsuitable for microaerophilic and anaerobic growth. (2)

A slight turbidity or haziness may be present due to the small amount of agar in the medium. When the medium has been boiled it appears clear.

Do not boil the medium more than once, as frequent boiling may lead to the production of toxic by-products. (7) If it is suspected that the medium has more than 30% oxidation after boiling, it should be discarded.


Standard microbiological supplies and equipment such as loops, swabs, applicator sticks, other culture media, incinerators, and incubators, etc., as well as serological and biochemical reagents, are not provided.


Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Clostridium sporogenes
ATCC® 19404***
J 24-48hr 35°C Aerobic** Growth
Staphylococcus aureus
ATCC® 6538***
J 24hr 35°C Aerobic** Growth
Pseudomonas aeruginosa
ATCC® 9027
J 24hr 35°C Aerobic** Growth
Bacteroides fragilis
ATCC® 25285
J 24-48hr 35°C Aerobic** Growth

** Tubes are incubated in an aerobic incubator with the caps screwed down tightly to create an atmosphere of low oxygen tension within the tube.

*** Recommended QC strains for User Quality Control according to the CLSI document M22 when applicable.


Physical Appearance

Fluid Thioglycollate, Enriched should appear clear, and light amber in color. Tubes with oxygen present will have a pink layer at the medium-air interface. If the medium appears pink in color, follow the instructions given in the above "Procedure" section to reduce the medium prior to use.


1. Anderson, N.L., et al. Cumitech 3B; Quality Systems in the Clinical Microbiology Laboratory, Coordinating ed., A.S. Weissfeld. American Society for Microbiology, Washington, D.C.

2. Jorgensen, et al. Manual of Clinical Microbiology, American Society for Microbiology, Washington, D.C.

3. Tille, P., et al. Bailey and Scott's Diagnostic Microbiology, C.V. Mosby Company, St. Louis, MO.

4. Brewer, J.H. 1940. J. Amer. Med. Assoc.; 115:598.

5. Federal Security Agency, Food and Drug Administration, Compilation of Regulations for Test and Methods of Assay and Certification of Antibiotic Drugs.

6. Isenberg, H.D. Clinical Microbiology Procedures Handbook, Vol. I, II & III. American Society for Microbiology, Washington, D.C.

7. MacFaddin, J.F. 1985. Media for Isolation, Cultivation, Identification, Maintenance of Bacteria, Vol. I. Williams & Wilkins, Baltimore, MD.

8. National Formulary, 9th ed. p.768, 1950.

9. National Institutes of Health Circular: Culture Media for the Sterility Test, 2nd rev. Feb. 5, 1946.

10. Quality Assurance for Commercially Prepared Microbiological Culture Media, M22. Clinical and Laboratory Standards Institute (CLSI - formerly NCCLS), Wayne, PA.

ATCC is a registered trademark of the American Type Culture Collection.