Liofilchem X and V Factor Test discs

The Liofilchem™ X, V, and V+X Factor Test is a diagnostic tool designed for the differentiation of Haemophilus species based on their growth factor requirements. The test uses paper discs impregnated with Hemin (X Factor), Nicotinamide Adenine Dinucleotide (NAD, V Factor), or both (V+X Factor), allowing for the identification of Haemophilus spp. by evaluating growth around the respective discs.

Key Features

1. Species Differentiation:
   • Identifies Haemophilus species based on their specific requirements for X and V growth factors.
2. Ready-to-Use Discs:
   • Pre-prepared discs for convenience and reliability.
3. Validated for Clinical Relevance:
   • Suitable for testing a wide range of Haemophilus spp., including H. influenzae and H. parainfluenzae.
4. Standards-Compliant:
   • Complies with international diagnostic standards for microbiological testing.

Kit Contents

• 2 cartridges of 50 discs each:
  • X Factor Discs (Hemin).
  • V Factor Discs (NAD).
  • V+X Factor Discs (Hemin + NAD).

Method Principle

• Differentiation Based on Growth Requirements:
  • Haemophilus spp. have varying needs for X and V factors, which are present in blood. This test utilizes discs impregnated with these factors to differentiate species by evaluating bacterial growth patterns on blood-free media.

Test Procedure

1. Prepare Test Plate:
   • Inoculate the entire surface of a blood-free agar plate (e.g., Tryptic Soy Agar, Brain Heart Infusion Agar, or Mueller Hinton Agar) with a pure suspension of the test organism.
2. Apply Discs:
   • Place one X, one V, and one V+X Factor disc on the agar in an equilateral triangle, ensuring at least 30-35 mm between discs.
3. Incubation:
   • Incubate at 35 ± 2°C for 24–48 hours in a 5–10% carbon dioxide atmosphere.
4. Interpret Results:
   • Observe growth around the discs to determine the organism's requirements:
     • Growth around X and V+X discs: Requires X factor.
     • Growth around V and V+X discs: Requires V factor.
     • Growth only around V+X disc: Requires both factors.

Interpretation Example

Storage and Shelf Life

• Storage:
  • Store at 2–8°C in original packaging, away from heat and direct sunlight.
• Shelf Life:
  • Valid for 2 years when stored as recommended.

Quality Control

Advantages

• Accurate Differentiation:
  • Provides clear results for species identification based on X and V factor requirements.
• Easy to Use:
  • Simple setup with pre-prepared discs reduces preparation time.
• Cost-Effective:
  • Allows for simultaneous testing of multiple organisms on a single plate.
• Validated:
  • Performance tested with control strains to ensure reliability.

Warnings and Precautions

1. For in vitro diagnostic use only.
2. Use with pure cultures to ensure accuracy.
3. Follow standard aseptic techniques to prevent cross-contamination.
4. Dispose of used materials according to local regulations.

Limitations

• Additional Testing Required:
  • Growth factor requirements alone are not sufficient for complete species identification; further biochemical tests are recommended.
• Nutrient Carryover:
  • Avoid contamination during inoculation as carryover nutrients may affect results.

Packaging

References

1. Public Health England. (2019). X and V Factor Test. UK Standards for Microbiology Investigations.
2. Kilian M. (1980). Haemophilus differentiation using growth factors. Manual of Clinical Microbiology.
3. Hammond GW et al. (1978). Evaluation of hemin and NAD requirements in Haemophilus spp.. J. Clin. Microbiology.

Why Choose Liofilchem X, V, V+X Factor Test?

• Proven Accuracy: Trusted for reliable differentiation of Haemophilus species.
• Ease of Use: Simplifies identification with pre-impregnated discs.
• Validated Performance: Tested with control strains to ensure reliability.