ELITex Bicolor albi-dubli

Intended use

Candidas are usually commensal yeasts of the digestive and urogenital mucosas. They become pathogenic only when favorable conditions arise in the host.

C. albicans are the most often isolated species (60 to 80% of clinical isolates) and the most pathogenicCandida species. The rapid identification of Candida strains has become essential for determining the correct therapeutic option.

Principle

ELITex Bicolor albi-dubli test features 2 reagents:

• TEST LATEX reagent, made up of red latex particles in suspension with a green counter dye. These particles are sensitized with a monoclonal antibody specific for a C. albicans / C. dubliniensis antigen that is present primarily in the yeast cell wall.
• R-DIS reagent, containing enzymes that are able to dissociate the cells and to uncover the intraparietal antigen that is recognized by the monoclonal antibody.

When one adds the TEST LATEX reagent to colonies of C. albicans or C. dubliniensis previously placed in suspension with the R-DIS reagent, agitation of the suspension results in coagglutination between the blastospores, carrying the antigen that is recognized by the monoclonal antibody and the sensitized latex particles.

A positive reaction results in a red agglutination on a more or less intense green background. With yeast colonies other than C. albicans and C. dubliniensis, no agglutination is observed and the suspension remains homogeneous and brown.
Handling is simple and fast, with results obtained within 5 minutes.

Simple protocol

1. R-DIS reagent reconstitution
   a. Remove the external capsule then raise the stopper slightly without removing it completely so that air can enter the vial. Then, remove the stopper whilst taking care not to spill any of the lyophilizate.
   b. Add the exact volume of distilled water to the vial.
   c. Close the vial and shake the contents by turning the vial upside down in order to dissolve the lyophilizate.
2. Slide test realization
   a. For each culture to be tested, add 20 µL of R-DIS reagent into separate circle on the slide.
   b. Using a Pasteur pipette or a wire loop, take 3 – 4 colonies.
   c. Transfer the colonies in a drop of R-DIS reagent and spread them to cover the entire surface of the circle.
   d. After ensuring that the TEST LATEX reagent is well mixed, add with the aid of the dropper provided, 1 drop of reagent to the circle.
   e. Using a disposable stick, mix and spread them to cover the entire surface of the circle until a homogeneous suspension is obtained.
   f. Manually, gently rock the slide for 5 minutes. A red agglutination may appear on a green background.

Easy-to-read and easy-to-interpret results

Reagents and material

• TEST LATEX:
  Vial of 1 mL of sensitized latex
  Ref. 44500 Quantity: 1
  Ref. 44501 Quantity: 1
• R-DIS:
  Vial of lyophilized dissociating reagent, to be reconstituted with 0.45 mL of distilled water
  Ref. 44500 Quantity: 3
  Ref. 44501 Quantity: 3
• TEST CARD:
  Disposable reaction card
  Ref. 44500 Quantity: 8
  Ref. 44501 Quantity: 50
• STICK:
  Disposable mixing sticks
  Ref. 44500 Quantity: 60
  Ref. 44501 Quantity: 360
• DROPPER:
  Ref. 44500 Quantity: 1
  Ref. 44501 Quantity: 1

Stability and storage

• Reagents stored at 2-8°C, in their original state, are stable up to the expiry date indicated on the box. They must not be frozen.
• The shelf life of the product, from its manufacture, is 15 months. The lyophilized dissociating reagent keeps its performance and is stable 45 days when reconstituted and stored between 2-8°C.

Performance
ELITex Bicolor albi-dubli consists of latex particles sensitized with monoclonal antibodies. This monoclonal antibody ensures the sensitivity and specificity of the reaction.

A. Sensitivity compared to the Blastèse test (germ tube test)

• Protocol:
  
  • 192 identified strains or isolates of C. albicans or C. dubliniensis (ID.32C system) were tested with the ELITex Bicolor albi-dubli and the Blastèse (germ tube test) tests (Culture 24h at 37°C on Sabouraud + incubation of the blastopores for 3h at 37°C on human serum + reading of the tests under an inverted microscope).
• Results:
  

  	Positive	%	Negative	%
  Blastèse Test	176	91.66	16	8.33
  ELITex Bicolor albi-dubli	192	100	0
  ID.32C	192		0

• Conclusion: ELITex Bicolor albi-dubli has a better sensitivity than the Blastèse test (germ tube test).

B. Sensitivity/specificity compared to the ID.32C identification system

• Protocol:
  • 2404 yeast isolates, of which 1747 were Candida of the C. albicans/C. dubliniensis group and 657 other yeasts that were not C. albicans and C. dubliniensis (identified by the ID.32C system, BioMérieux) were tested with ELITex Bicolor albi-dubli, after culture on Sabouraud agar at 37°C for 24 or 48 hours.
  • 3 or 4 colonies were taken and tested with ELITex Bicolor albi-dubli.
• Results:
  

  		Identification ID.32C
  		C.albicans orC.dubliniensis(1747)	Non C.albicans or Non C.dubliniensis(657)
  ELITex Bicolor albi-dubli	+	1744 (99.8%)	4*
  	–	3	653 (99.4%)

  • * 4 yeasts were identified with the ID.32C as being:
    – Candida parapsilosis
    – Candida glabrata
    – Candida kefyr
    – Candida guilliermondii
• Conclusion:
  • The results indicate:
    – A very good correlation (99.7%) between ELITex Bicolor albi-dubli and the ID.32C identification system
    – A sensitivity and a specificity greater than 99% for the ELITex Bicolor albi-dubli product

Material required but not provided

• Automatic pipette(s) with a pipetting volume adapted to the volume that will be measured
• Distilled water
• Pasteur pipette or wire loop
• Contaminated waste container