Mycology

Cryptococcal Antigen Latex Agglutination Test

Hi! I'm posted to mycology for this week and i''ll share with you guys the test that i get a hands on with.

Cryptococcal Antigen Latex Agglutination Test is a qualitative and quantitative test. The test is used to detect capsular polysaccharide antigens of Cryptococcus neoformans in patient’s serum and cerebrospinal fluid. It is done using commercial latex particles coated with anticryptococcal globulin (detection latex). In the presence of capsular polysaccharide antigen in the patient's serum or CSF, the latex particles coated with anticryptococcal globulin will react with the antigen and form a visible agglutination. Latex particles coated with normal globulin acts as the control (control latex).

This is the kit that is used CALAS®.

http://www.cardinalhealth.com/us/en/distributedproducts/ASP/140100.asp?cat=laboratoy

Procedure

1. First, when the blood sample is received it is centrifuged at 1000 rpm for 15 minutes.

2.Then, Transfer 100ul of patient’s serum to a test tube with 100ul of pronase.Pronase is an enzyme which degrades non specific macro globulin.

3. Incubate the serum-pronase solution in a water bath for 15 minutes at 56°C.

4. Immediately boil the solution for a full five minutes to terminate the enzymatic digestion.

5. Allow the solution to cool to room temperature.

6.Then remove enough cards (see the pic above) to run the test and label one ring as detection latex with the patient's lab number (DL) and another as control latex (CL).

7. Pipette 25ul of patient serum to both CL and DL rings.

8. Holding the detection latex bottle in a vertical position, squeeze one free-falling drop of reagent to the DL ring. Do the same for the control latex bottle and drop one free-falling drop of reagent to the CL ring.

9. Place card on a rotator and rotate at 125 rpm for 5 minutes.

10. Read the result immediately.

For CSF, it does not require steps 1-3. It begins by transfering about 0.5 ml of CSF to a test tube and boiling it for a full 5 mins. The subsequence steps are the same as the blood.

Result Interpretation

Negative: No visible clumping
1+: Fine granulation against a milky background
2+: Small but definite clumps against a slightly cloudy background.
3+: Large and small clumps against a clear background.
4+: Large clumps against a very clear background.

Shameema :) 0700486D