Thermo Scientific™ Oxoid™ Tetrathionate Broth Base (Dehydrated)

Tetrathionate Broth is a selective enrichment medium recommended for isolating Salmonella typhi and other Salmonella species from fecal, sewage, and food samples. It is particularly effective in suppressing the growth of commensal coliform organisms while promoting the growth of Salmonella. The medium leverages the enzymatic activity of tetrathionate reductase, which is found in Salmonella and Proteus species but not in organisms like Escherichia coli or Shigella.

Key Features

1. Selective Enrichment

• Thiosulphate and tetrathionate act as selective agents to inhibit commensal coliform bacteria while supporting the growth of Salmonella species.

2. Enzymatic Differentiation

• Organisms possessing tetrathionate reductase, such as Salmonella and Proteus, can grow in this medium. E. coli and Shigella are typically suppressed.

3. Enhanced Selectivity with Novobiocin

• Adding 40µg/mL of novobiocin suppresses the growth of Proteus species, which could otherwise interfere with Salmonella isolation.

4. Wide Applications

• Ideal for the detection and isolation of Salmonella from clinical, food, and environmental samples, such as feces, sewage, and contaminated water.

5. Robust Performance

• Suitable for heavily contaminated samples due to its high selectivity and suppression of non-target organisms.

Applications

1. Clinical Diagnostics:
   • Enriching and isolating Salmonella from fecal samples in cases of suspected salmonellosis.
2. Food Safety:
   • Testing for Salmonella contamination in food products, especially poultry, eggs, and dairy.
3. Environmental Testing:
   • Isolating Salmonella from water and sewage samples.
4. Veterinary Microbiology:
   • Detecting Salmonella in animal specimens and feed.

Composition (Typical Formula)

Preparation Instructions

1. Suspend the required amount of the dehydrated medium in distilled water and mix thoroughly.
2. Heat to dissolve completely. Do not autoclave.
3. Cool to below 45°C and add iodine solution (prepared separately) to generate tetrathionate in situ.
4. If required, add novobiocin at 40µg/mL to improve selectivity by suppressing Proteus species.
5. Dispense into sterile containers and use immediately.

Advantages

1. High Selectivity:
   • Effectively inhibits non-Salmonella organisms while enriching for Salmonella.
2. Enhanced Performance with Novobiocin:
   • Suppresses Proteus species, which could compromise the selectivity.
3. Versatility:
   • Suitable for a variety of sample types, including clinical, food, and environmental specimens.
4. Ease of Use:
   • Simple preparation process with clear instructions.

Limitations

• The presence of Proteus species can sometimes reduce the medium's efficacy without the addition of novobiocin.
• Not suitable for the primary isolation of E. coli or Shigella.

Why Choose Tetrathionate Broth?

Tetrathionate Broth is a reliable and effective choice for laboratories isolating Salmonella species. Its selective nature, enhanced by novobiocin supplementation, ensures accurate results even with heavily contaminated samples. Its compatibility with a range of applications, from clinical diagnostics to food safety testing, makes it an essential tool in microbiology.