The Leeds Teaching Hospitals NHS Trust

Pathology

Aspergillus Antigen

Aspergillus Antigen

For the following tests, please send serum (700 µl minimum) or 7 mL clotted blood in a plain tube; EDTA blood is not suitable.

BAL and CSF samples can also be tested (700 µl minimum). Send in white topped universal.

Universal container

 

 

 

 

Clotted Blood plain tube

 

 

 

 

Use(s):

Diagnosis of invasive aspergillosis usually in immunocompromised patients.

Description:

Determination of the presence of Aspergillus antigen (galactomannan) in serum or BAL by ELISA.

Please note we cannot apply this test to Brochical washings or Tracheal aspirates..

Results:

Negative; Positive with the index value (indicating the relative concentration of galactomannan)

Note:

Positive results are confirmed before reporting by re-testing the specimen submitted. To improve specificity positives should be confirmed by submission of a second specimen.

The uncertainty of measurement of this assay has been characterised in the following way, a control sample near the cutoff index of 1.0, tested over 5 months (every run performed on a single batch of kits) yielded a mean of the Optical Density of 0.637 and a standard deviation of 0.06, thus we estimate that 95% of all samples at this level will have a range of + or - 0.12 (1.96 x 0.06) in OD, which is + or - 0.24 in Index. Therefore samples with an index value of 0.26-0.49 should be considered possible false negatives and repeat tests requested. Equally samples with an index of up to 0.74 could be false positives, however all positives are restested and it is highly unlikely (<95%) that this false positive would test positive again.