TRUST (Toludine Red Unheated Serum Test) For Syphilis



The TRUST reagent containing modified VDRL antigen and toludine red pigment particles, flocclulate when mixed with sample containing “reagin”.

A reactive specimen is indicated by macroscopically visible red clumps against white background, in contrast nonreactive specimen appear to have slightly rough light red background. This test is a screening test and if positive, further testing with specific confirmatory tests are required.  

Specimen: Serum/Plasma  


  1. TURST Antigen suspension  
  2. Positive Control Serum  
  3. Negative Control Serum  
  4. Disposable Plastic Cards  
  5. Disposable Plastic Droppers  
  6. Disposable Applicator Sticks  
  7. Antigen Delivery Dropper  
  8. Rubber Teats  



  1. Using disposable serum dropper, place one free falling drop of serum / plasma or control on the entire circle with the help of disposable applicator stick.  
  2. Gently shake the TRUST Antigen Suspension bottle to resuspend the particle. From the dropper dispense few drops of the reagent back into the reagent bottle itself to remove air trapped to the dropper.  
  3. Add one free falling drop of TRUST Antigen Suspension using antigen delivery dropper. Keep the delivery dropper vartical, exactly at 90o while adding antigen suspension. Do not mix.  
  4. Place the card on the mechanical rotator under humidifying cover and rotate the card for 8 minutes at 100 ±2 rpm.  
  5. After 8 minutes, immediately remove the card from the rotator, rotate and till the card gently by hand.   6) Observe the result under a high intensity lamp or strong day light.  
  6. Perform the quantitative test for specimens exhibiting any degree of flocculation or “roughness”. 



  1. Place 50μL of 0.9% saline solution on 2nd, 3rd, 4th and 5th circles of the card by using micropipette. Do not spread the saline solution.  
  2. Using micropipette, add 50μL sample to saline in 1st and 2nd circle.  
  3. Mix sample with saline in 2nd circle by drawing the mixture up and down for 8 times in the micropipette. Avoid bubble formation.  
  4. Aspirate 50μL from 2nd circle and transfer to 3rd circle. Repeat the same successively up to 5th circle.  
  5. Aspirate 50μL from the 5th circle and discard it.  
  6. Repeat step no.2-6 of qualitative test for each of diluted sample drop.    
  7. Complete test as described in qualitative test procedure. Use a clean tip for each specimen tested.  
  8. Prepare higher dilution if necessary in 1:50 nonreactive serum dilution.
  9. The end point is the highest dilution showing visible black clumps.   

Observation table of TRUST test:



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