CHROMagar™ TBX, for 5L medium

For the Detection and Enumeration of β-Glucuronidase Positive Escherichia coli

ISO 16649 Compliant

CHROMagar™ TBX (Tryptone Bile X-glucuronide) is a chromogenic culture medium used for the selective detection and enumeration of β-glucuronidase positive E. coli in food products and animal feed, in accordance with ISO 16649 and NF EN ISO 16649 standards.

Colonies of E. coli appear as distinctive blue or blue-green due to the enzymatic cleavage of X-glucuronide by β-glucuronidase, providing a reliable and standardized method for identifying fecal contamination.

Colony Appearance

Performance

The presence of E. coli in food and animal feed is a critical indicator of fecal contamination and is often associated with the potential presence of pathogenic bacteria, viruses, and parasites. CHROMagar™ TBX enables:

• Accurate quantification of hygienic indicators in compliance with ISO 16649-1 and ISO 16649-2
• Rapid identification of contaminated samples in quality control workflows
• Use in routine HACCP, ISO, and regulatory microbiological programs

Note: Rare strains of E. coli that do not express β-glucuronidase (such as E. coli O157:H7) will not appear on this medium. For detection of these specific pathogenic strains, refer to CHROMagar™ O157.

Intended Use

CHROMagar™ TBX is intended for:

• Enumeration of β-glucuronidase positive E. coli from:
  • Raw and processed food
  • Dairy products
  • Animal feed
  • Environmental swabs in food production zones

This medium is particularly useful for:

• Food microbiology testing laboratories
• Veterinary feed inspection authorities
• Regulatory compliance with ISO standards

Advantages

1. ISO 16649 Compliant
   Trusted worldwide as the reference method for E. coli enumeration in food testing.
2. Easy Identification
   E. coli colonies appear as blue or blue-green, enabling straightforward colony counting.
3. Reliable Indicator of Fecal Contamination
   Supports food safety programs by detecting E. coli as a proxy for sanitation control.
4. Validated Format
   Available in 500 g dehydrated powder format, convenient for laboratories preparing custom plate volumes.

Test Procedure

1. Sample Preparation: Follow ISO 16649-2 for sample homogenization and dilution.
2. Inoculation: Use pour plate or membrane filtration method.
3. Incubation:
   • Temperature: 44 ± 1 °C
   • Duration: 18–24 hours
   • Atmosphere: Aerobic
4. Interpretation:
   • Blue/blue-green colonies = β-glucuronidase positive E. coli
   • Countable results per ISO method requirements.

Ordering Information

Storage & Shelf Life

• Storage: 2–8 °C, dry and sealed
• Shelf Life: Up to 24 months from manufacture date when stored properly
• Prepared media: Use within validated expiration period

Scientific Note

This medium is highly effective for standard hygiene testing but does not detect β-glucuronidase-negative strains, such as E. coli O157:H7. For detection of such pathogenic E. coli, use CHROMagar™ O157.

CHROMagar™ TBX is a reliable, ISO-compliant medium for the routine detection of β-glucuronidase positive E. coli in the food and feed industries. Its chromogenic clarity, regulatory acceptance, and simplicity make it an essential tool for food safety assurance and quality control laboratories worldwide.