Thermo Scientific™ Oxoid™ Cefixime-Tellurite Supplement

The Thermo Scientific™ Oxoid™ Cefixime-Tellurite Supplement (SR0172) is a freeze-dried supplement designed to enhance the selectivity of Sorbitol MacConkey Agar (SMAC) for the isolation of Escherichia coli O157. This formulation incorporates two antimicrobial agents, cefixime and potassium tellurite, which effectively suppress non-target organisms, ensuring reliable and specific growth of E. coli O157 colonies.

Key Features

1. Selectivity for E. coli O157

• Cefixime:
  • Suppresses the growth of Proteus spp., a common contaminant, while allowing E. coli O157 to grow.
• Potassium Tellurite:
  • Inhibits competing organisms, enhancing the isolation of E. coli O157.

2. Enhanced Accuracy

• Specifically designed for use with Sorbitol MacConkey Agar to identify E. coli O157, which is incapable of sorbitol fermentation (colorless colonies).

3. Ready-to-Use

• Supplied in a freeze-dried form for convenient preparation.
• Reconstituted supplement can be easily incorporated into SMAC agar.

4. Reliable and Effective

• Backed by Thermo Scientific’s quality standards to ensure consistent results.
• Reduces background flora, improving diagnostic efficiency.

Vial Contents

Applications

1. Clinical Diagnostics

• Detect E. coli O157 in stool samples from patients suspected of hemorrhagic colitis or hemolytic uremic syndrome (HUS).

2. Food Microbiology

• Screen food products (e.g., beef, dairy) for E. coli O157 contamination to ensure public health safety.

3. Environmental Testing

• Identify E. coli O157 in water and other environmental samples during contamination investigations.

Preparation and Use

1. Reconstitution:
   • Dissolve the freeze-dried contents of one vial in 50 mL of sterile distilled water.
2. Incorporation:
   • Add the reconstituted solution to 950 mL of molten Sorbitol MacConkey Agar at a temperature of 45–50°C.
   • Mix thoroughly and pour into sterile Petri dishes.
3. Inoculation and Incubation:
   • Streak the sample onto the prepared medium.
   • Incubate at 35–37°C for 18–24 hours under aerobic conditions.
4. Result Interpretation:
   • E. coli O157: Appears as colorless colonies due to the inability to ferment sorbitol.
   • Other E. coli strains: Appear as pink colonies due to sorbitol fermentation.

Advantages

• High Selectivity: Ensures minimal interference from non-target organisms, improving the detection of E. coli O157.
• Ease of Use: Freeze-dried format simplifies preparation and ensures consistent performance.
• Versatile Applications: Suitable for clinical, food, and environmental microbiology laboratories.
• Improved Diagnostic Accuracy: Reduces false positives and false negatives by effectively suppressing background flora.

Why Use Cefixime-Tellurite Supplement with SMAC?

The Thermo Scientific™ Oxoid™ Cefixime-Tellurite Supplement is essential for laboratories aiming to achieve accurate and reliable detection of E. coli O157. Its targeted inhibition of non-pathogenic organisms streamlines workflows and enhances the accuracy of microbiological testing in clinical, food safety, and environmental contexts.