Cat. no. K65 Tetrathionate Broth, 16x125mm Tube, 10ml 20 tubes/box
Cat. no. Z129 Iodine-Iodide Solution, 2oz. Glass Bottle, 50ml** 50ml
Cat. no. Z139 Iodine-Iodide Solution, 1L Polycarbonate Bottle, 990ml** 990ml
** sold separately


Hardy Diagnostics Tetrathionate Broth, with the addition of Iodine-Iodide Solution (Cat. no. Z129 or Z139), is recommended for the selective enrichment of Salmonella spp.

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


Mueller first described use of Tetrathionate Broth for the cultivation of Salmonella spp. (12) He found the medium to be inhibitory to lactose-fermenting Enterobacteriaceae while allowing unrestricted growth of Salmonellae . Schaeffer later demonstrated the medium to posses enrichment properties for Salmonellae . (13) Formula modifications were made by Kaufman who reported enhanced recovery of Salmonella spp. (14,15)

Tetrathionate Broth contains bile salts which are inhibitory to gram-positive and gram-negative microorganisms other than Salmonella spp. Iodine-Iodide Solution (Cat. no. Z129 or Z139) is added to the prepared medium just prior to inoculation. Addition of the Iodine-Iodide Solution promotes production of tetrathionate which inhibits the normal intestinal flora of fecal specimens. (5)

Hardy Diagnostics Tetrathionate Broth conforms to the formulation recommended by the American Public Health Association (APHA), the Food and Drug Administration (FDA), and The United States Pharmacopeia (USP). (8-11)


Ingredients per liter of deionized water:*

Tetrathionate Broth (Cat. no. K65):
Sodium Thiosulfate 30.0gm
Calcium Carbonate 10.0gm
Pancreatic Digest of Casein 2.5gm
Peptic Digest of Animal Tissue 2.5gm
Bile Salts 1.0gm

Final pH 8.4 +/- 0.2 at 25ºC.

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

Iodine-Iodide Solution (Cat. no. Z129 or Z139) not included:**
Iodine 15.0gm
Potassium Iodide 12.5gm
Deionized Water 50.0ml

** sold separately


Storage: Upon receipt store at 2-30ºC. Products should not be used if there are any signs of contamination, deterioration, or if the expiration date has passed. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing. Iodine-Iodide Solution (Cat. no. Z129 or Z139) should be stored in the dark.**



Specimen Collection: Consult listed references for information on specimen collection. (1-4,6) 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 onto an appropriate transport medium and refrigerated until inoculation.

Method of Use:

1. Immediately before inoculation, add 0.2ml (approximately four drops) of Iodine-Iodide Solution (Cat. no. Z129 or Z139) to each 10ml tube of Tetrathionate Broth.

2. Place 1.0 to 3.0gm (heavy inoculum) of specimen to each tube. Swab specimens may be inserted directly into the broth.

3. Emulsify the specimen thoroughly.

4. Incubate aerobically for 18 to 24 hours at 35ºC.

5. Place one to two drops of the incubated broth onto selective plate media, such as MacConkey Agar (Cat. no. G35) and streak for isolated colonies.

6. Incubate aerobically at 35ºC.

7. Examine for presence of typical colonies at 18-48 hours.

Industrial Samples (e.g. food, potable water):
Refer to listed references for the isolation and identification of Salmonella spp. from non-clinical samples. (10,11,16)


Culture analysis is made from the media to which the enriched specimen is subcultured. Consult listed references for the interpretation of growth and other biochemical and serological tests necessary to identify growth of organism in the medium to which subculture has been made. (1-4,6,10,11,16)



Standard microbiological supplies and equipment such as loops, slides, staining supplies, Iodine-Iodide Solution (Cat. no. Z129 or Z139), other culture media, microscopes, incinerators, and incubators, etc., as well as serological and biochemical reagents, are not provided.


Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Salmonella enterica**

ATCC ® 14028
I 18-24hr 35°C Aerobic Growth on MacConkey upon subculture
Escherichia coli**

ATCC ® 25922
I 18-24hr 35°C Aerobic Partial to complete inhibition on MacConkey upon subculture

Note: Tetrathionate Broth is inoculated with organism, incubated for 18-24 hours, then subcultured to a MacConkey Agar plate. The MacConkey plate should show heavy growth of Salmonella spp. after 24 hours. E. coli will show partial to complete inhibition.

** Recommended strains for User Quality Control.

User Quality Control



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, 9th ed. 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. Isenberg, H.D. Clinical Microbiology Procedures Handbook, Vol. I, II & III. American Society for Microbiology, Washington, D.C.

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

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

7. Koneman, E.W., et al. Color Atlas and Textbook of Diagnostic Microbiology, J.B. Lippincott Company, Philadelphia, PA.

8. The United States Pharmacopeia , 21st rev. 1985. U.S. Pharmacopeial Convention, Rockville, MD.

9. Speck. 1984. Compendium of Methods for the Microbiological Examination of Foods , 2nd ed. APHA, Washington, D.C.

10. Greenberg, et al. 1992. Standard Methods for the Examination of Water and Wastewater , 18th ed. APHA, Washington, D.C.

11. 11. U.S. Food and Drug Administration. Bacteriological Analytical Manual. AOAC, Arlington, VA. www.fda.gov/Food/FoodScienceResearch/LaboratoryMethods/ucm2006949.htm .

12. Compt. Rend. Soc. Biol. ; 89:434, 1923.

13. Zentr. Bakt. I. Abt. Orig. ; 133:458, 1935.

14. Zentr. Bakt. I. Abt. Orig. ; 119:148, 1930.

15. Zeit, Hyg. ; 117:26, 1935.

16. Official Methods of Analysis , 15th ed. 1990. AOAC, Arlington, VA.

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