The Cryptococcal Antigen Latex Agglutination System is a qualitative and semi-quantitative test system for the detection of capsular polysaccharide antigens of Cryptococcus neoformans.
Latex agglutination test has both diagnostic and prognostic value since progressive disease is usually accompanied by increasing antigen titers. Declining titers are usually associated with clinical improvement, with or without therapy. Inadequate therapy is indicated by stationary or rising titers on subsequent, sequential specimens. Cryptococcal antigen in the body fluids of the untreated patient indicates active infection. However, in some treated patients, titers remain positive at low levels for extended periods during which the organism can no longer be demonstrated.
Serum specimens are pre-treated with pronase and heat inactivated prior to testing.
CSF specimens are heat inactivated prior to testing.
The result is not intended to be used as the sole means for clinical diagnosis or patient management decisions.
CSF titers of 1:4 or less are presumptive evidence of central nervous system infection by C. neoformans; additional follow-up and culture are strongly recommended. CSF titers of 1:8 or greater from patients with meningitis strongly suggest infection by C. neoformans. However, diagnosis should be confirmed by identification of the organism from culture or by microscopic examination of the specimen.
A negative test does not preclude diagnosis of cryptococcosis, particularly if only a single specimen has been tested and the patient shows symptoms consistent with cryptococcosis.
A false positive reaction due to the antigen of Trichosporon beigelii which cross reacts with the C. neoformans capsular polysaccharide has been reported.
High protein levels can cause interference.
Serum: Collect serum specimens in serum separator or red top tube. Allow blood to clot for 30 minutes, then centrifuge. Pipette serum into a plastic screw cap vial.
CSF: Collect in sterile container. Centrifuge to remove white cells and particulate matter.
Minimum Specimen Requirements
Serum/CSF: 0.25 mL
Refrigerated/Frozen: 2 months
Specimen types other than serum or CSF
Ship on dry ice or frozen packs for next day service. Monday- Friday delivery
Testing is performed Monday-Friday.
Serum/CSF: Same day
*Positive results will reflex to a titer. Reportable titer up to ≥1:2048