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Lab Manual for UCSF Clinical Laboratories

Lab Manual for SFGH

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Item Value
Available Stat? No
Test code CRAG (Serum)/CRAC (CSF)
Performed by? Microbiology
Sendout? no
Price range $$$-$$$$ depending if + or not
In House Availability CRAG (Serum): Mon. - Fri., 8 am - 4 pm
CRAC (CSF): Qualitative test done 24 hours/7 days
Titers done Mon. - Fri., 8 am - 4 pm
Principle The cryptococcal antigen detection test utilizes latex particles coated with anticryptococcal immunoglobulin. The sensitized latex particles react with the cryptococcal polysaccharide antigen causing a visible agglutination. Titers are performed on all positive specimens.
Interpretation Cryptococcal antigen in the CSF or serum of untreated patients indicates active disease. Declining titers indicate a positive response to chemotherapy in the treated patient. Failure of titers to decline indicates inadequate therapy. Occasionally, however, low titers may persist for an indefinite period in the presence of nonviable fungus.

A negative test result does not exclude a diagnosis of cryptococcosis, particularly if only a single specimen has been tested and the patient shows symptoms consistent with cryptococcosis.

One false positive reaction due to an antigen of Trichosporon beigelii which crossreacts with the Cryptococcus neoformans capsular polysaccharide has been reported. The reaction occurred in a serum specimen from a patient with disseminated Trichosporon infection.
Container type Blood in gold gel; CSF in sterile tube
Amount to Collect 3 mL blood; 0.5 mL CSF
Sample type Clotted Blood; CSF
Normal range Negative.
Stability 3 days at 4°C
Additional information REQUISITION: Blood/Serum - Main Laboratory (for blood) or Microbiology (for CSF).
References 1. Chuck SL, and Sande MA. 1989. Infections with Cryptococcus neoformans in the acquired immunodeficiency syndrome. N. Engl. J. Med., 321:794-799.

2. Hamilton JR, Noble A, Denning DW, Stevens DA. 1991. Performance of cryptococcus antigen latex agglutination kits on serum and cerebrospinal fluid specimens of AIDS patients before and after pronase treatment. J. Clin. Microbiol., 29:333-339.

3. Frank U, Nishimura SL, Li NC, Sugai K, Yajko DM, Hadley WK, Ng VL. 1993. Evaluation of an enzyme immunoassay for detection of cryptococcal capsular polysaccharide antigen in serum and cerebrospinal fluid. J. Clin. Microbiol., 31:97-101
CPT coding 86403
Last Updated 1/30/2009 10:46:04 AM
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