Thermo Scientific™ Oxoid™ EC Broth with Reduced Bile Salts (Dehydrated)

Thermo Scientific™ Oxoid™ EC Broth with Reduced Bile Salts (Dehydrated) is a selective enrichment medium specifically formulated for the isolation and enrichment of Escherichia coli O157 from food and environmental samples. The medium includes a buffered lactose broth with reduced bile salts, enabling the recovery of sub-lethally injured E. coli O157 while inhibiting competing organisms such as spore formers and enterococci. Supplementing the broth with Novobiocin Selective Supplement (SR0181) enhances selectivity by reducing background flora.

Key Features

1. Selective Enrichment

• Facilitates the growth and recovery of Escherichia coli O157 while inhibiting other bacteria, such as spore formers and enterococci.

2. Enhanced Selectivity with Novobiocin

• The addition of Novobiocin (20 mg/L) suppresses Gram-positive bacteria and non-target Gram-negative organisms, improving the isolation of E. coli O157.

3. Designed for Sub-lethally Injured Organisms

• Ideal for frozen food samples where E. coli O157 may be sub-lethally damaged.

4. Compliance with Regulatory Standards

• Recommended by USDA/FSIS and AIFST for the detection of E. coli O157and O157(Non-Motile) from meat and poultry products.

5. Ready-to-Use Format

• Supplied as a dehydrated medium for easy preparation, with clear directions for supplementation and usage.

Composition (Typical Formula)

Preparation Instructions

1. Dissolve 18.3g of EC Broth in 500mL of distilled water.
2. Sterilize by autoclaving at 121°C for 15 minutes.
3. Cool the medium to 50°C.
4. Aseptically add:
   • 20mg/L Novobiocin Supplement SR0181 (1 vial for 500mL of medium), reconstituted as directed.
5. Dispense into sterile containers.

Applications

1. Food Safety Testing:
   • Detects Escherichia coli O157 in meat, poultry, and other food products.
2. Environmental Monitoring:
   • Isolates E. coli O157 from water and environmental samples.
3. Clinical Diagnostics:
   • Enriches E. coli O157 from clinical specimens for further analysis.
4. Veterinary Testing:
   • Used in testing for E. coli O157 in animal feed and specimens.

Methodology

1. Sample Preparation:
   • Dilute the sample 1:10 in EC Broth (Reduced Bile Salts) supplemented with Novobiocin.
   • Blend for 2 minutes in a stomacher.
2. Incubation:
   • Incubate the broth at 37°C for 6 hours on a rotary shaker at 100 rpm, or
   • Incubate statically at 35°C for 24 hours.
3. Plating:
   • Dilute the incubated culture and streak onto Sorbitol MacConkey Agar (CM0813) or SMAC with BCIG (CM0981), supplemented with Cefixime Tellurite Selective Supplement (SR0172) if required.
   • Incubate plates at 37°C for 24 hours.
4. Identification:
   • Presumptive E. coli O157 colonies appear clear and colorless.
   • Confirm with E. coli O157 Latex Test (DR0620) or Dryspot E. coli O157 (DR0120).

Storage and Shelf Life

1. Dehydrated Medium:
   • Store at 10–30°C and use before the expiration date on the label.
2. Novobiocin Supplement:
   • Store in the dark at 2–8°C. Stable until the printed expiration date.

Physical Appearance

• Dehydrated Medium: White, free-flowing powder.
• Prepared Medium: Straw-colored solution.

Quality Control

Advantages

1. Increased Selectivity:
   • Novobiocin supplementation minimizes background flora, improving detection accuracy.
2. Versatile Applications:
   • Effective for food, environmental, and clinical microbiology.
3. Regulatory Compliance:
   • Meets USDA/FSIS and AIFST standards.
4. Efficient Recovery:
   • Designed for sub-lethally injured E. coli O157, ensuring reliable isolation.

Why Choose Thermo Scientific™ Oxoid™ EC Broth with Reduced Bile Salts?

This medium is a trusted tool for isolating and enriching E. coli O157 in food safety and environmental testing applications. Its selective properties, coupled with regulatory approvals and compatibility with confirmatory tests, make it indispensable for microbiological laboratories.