Giardia Antigen, Stool (Sendout)

Reference Values: Negative

Interpretation:

A positive enzyme-linked immunosorbent assay (ELISA) indicates the presence in a fecal specimen of Giardia antigens.

As per the manufacturer, the assay has a sensitivity of 96%, specificity of 97%, and a positive predictive value of 95%.

Interpretation of results should be correlated with patient symptoms and clinical picture.

Cautions:

Small numbers of organisms residing only in the duodenum may not yield a positive test result.

Giardia antigen detection should be used as an aid in diagnosis of giardiasis. A single diagnostic assay should not be used as the only criteria to form a clinical conclusion.

Testing of at least 2 consecutive fecal specimens by enzyme-linked immunosorbent assay (ELISA) is recommended before considering the results negative.

Feces containing large amounts of leukocytes or red blood cells may give falsely positive results.

Collect 5 g of stool in a screw-capped, preservative-free plastic container.

• Also Accepted: 5 g of stool in Formalin-Meridian 10% Buffered Neutral preservative or SAF (sodium acetate formalin).

Unacceptable:

• Stool in Cary-Blair preservative.
• Duodenal, colonic wash, or small bowel aspirates are not acceptable for this test.

Outside Laboratories:

• Unpreserved Stool: Freeze sample at -20°C.
• Stool in preservative: Store and transport at ambient temperature.

Stability:

• Unpreserved Stool: Frozen (preferred): 60 days; Refrigerated: 8 hours; Ambient: 8 hours.
• Stool in Preservative: Ambient (preferred): 60 days; Frozen (not preferred): 60 days; Refrigerated: Unacceptable.

Reject Due To: Grossly bloody feces (containing no visible specimen), or very mucoid feces, specimens preserved in ECOFIX (green cap), C and S (orange cap), or methiolate formalin (MF).

• Unpreserved Stool: Freeze at -20°C.
• Stool in Preservative: Store and transport at ambient temperature.

Login Note: This test should be ordered on its own accession to prevent multiple stool tests from routing to the same container ID in Sunquest. Separate stool specimens or aliquots must be submitted for each sendout test.

• If a single unpreserved stool specimen is received for multiple tests, samples may be sent to Micro to be split prior to freezing. Include CID labels and directions for splitting (including minimum volumes). If there is insufficient sample, contact the provider to prioritize testing.

Sendouts:

• Order Mayo Test: GIAR.
• Interfaced: Yes.

Stability:

• Unpreserved Stool: Frozen (preferred): 60 days; Refrigerated: 8 hours; Ambient: 8 hours.
• Stool in Preservative: Ambient (preferred): 60 days; Frozen (not preferred): 60 days; Refrigerated: Unacceptable.

Reject Due To: Grossly bloody feces (containing no visible specimen), or very mucoid feces, specimens preserved in ECOFIX (green cap), C and S (orange cap), or methiolate formalin (MF).