Liofilchem® Urea Agar Base (Christensen)

Liofilchem Urea Agar Base is a dehydrated culture medium formulated to detect urease activity in microorganisms. It is recommended by ISO 6785 and IDF 93 for microbial diagnostics. This medium supports the identification of urease-positive bacteria, such as Proteus spp., by providing the necessary environment for urease activity.

Key Features:

1. Selective Urease Detection:
   • Enables differentiation between urease-positive and urease-negative microorganisms.
   • Phenol red acts as a pH indicator, showing a color change (amber to pink) when urease-positive organisms metabolize urea.
2. Standardized Formula:
   • Contains peptone, glucose, sodium chloride, and monopotassium phosphate to ensure consistent growth and detection.
   • Urea is added via UREA 40% Supplement (Ref. 80292) for enzymatic activity testing.
3. ISO and IDF Compliance:
   • Follows international standards (ISO 6785 and IDF 93) for urease testing, making it ideal for quality assurance in clinical and industrial applications.
4. Visual Clarity:
   • Features a reddish-orange appearance post-preparation, aiding in clear and reliable observation of results.
5. Extended Shelf Life:
   • Dehydrated medium remains stable for up to 4 years under proper storage conditions.

Applications:

• Clinical Diagnostics:
  • Differentiation of urease-positive pathogens (Proteus vulgaris, Klebsiella spp.) from urease-negative species (Escherichia coli, Salmonella spp.).
• Food and Dairy Testing:
  • Detection of urease activity in foodborne pathogens, particularly in milk and dairy products.
• Microbial Research:
  • Supports biochemical studies related to bacterial metabolism and urease enzyme activity.

Composition (per liter):

Final pH: 6.8 ± 0.2 at 25°C.

Preparation Instructions:

1. Suspend 24 g of Urea Agar Base powder in 950 mL of distilled or deionized water.
2. Heat and dissolve the medium completely.
3. Autoclave at 121°C for 15 minutes.
4. Cool to 45-50°C.
5. Aseptically add 50 mL of UREA 40% Supplement (Ref. 80292) to the autoclaved medium.
6. Mix thoroughly and dispense into sterile test tubes, allowing the medium to solidify in a slanting position.

Usage Protocol:

1. Inoculation:
   • Using a heavy inoculum, streak a pure 18-24 hour bacterial culture across the slanted surface of the medium.
   • Avoid stabbing the butt of the slant as it serves as a color control.
2. Incubation:
   • Loosen the tube caps and incubate at 36 ± 1°C for 6-24 hours.
3. Observation:
   • Positive urease activity results in a red or pink color on the slant.
   • No color change indicates a negative reaction.

Interpretation of Results:

Storage Conditions:

• Dehydrated Medium: Store at 10-30°C in a dry environment, tightly sealed.
• Prepared Plates: Store at 2-8°C, protected from light.

Quality Control:

1. Physical Characteristics:
   • Powder: Free-flowing, homogeneous, orange in color.
   • Prepared Medium: Slightly opalescent, reddish-orange.
2. Microbial Testing:
   • Productivity and specificity validated using Proteus vulgaris and Escherichia coli.

Warnings and Precautions:

• For in vitro diagnostic use by trained professionals.
• Avoid direct inhalation or ingestion.
• Consult the Safety Data Sheet (SDS) for handling guidelines.
• Dispose of waste as per local and national regulations.

Packaging:

References:

1. Christensen, W.B. (1946). Journal of Bacteriology 52:461-466.
2. Maslen, L.G.C. (1952). British Medical Journal 2:545-546.
3. ISO 6785:2001 / IDF 93:2001.

Liofilchem Urea Agar Base provides a reliable and effective solution for detecting urease enzyme activity, making it indispensable in clinical diagnostics, food testing, and microbial research. Its compliance with international standards ensures consistent performance and dependable results across diverse applications.