Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1353 page)

   Special Collection and Transport Instructions

   Blood samples are collected and transported according to standard protocol. Samples are allowed to clot and serum separated for testing (minimum 0.5 mL).

   Use

   BG testing may be submitted for early evaluation of patients at risk for IFI or
Pneumocystis
pneumonia, or to monitor the effectiveness of therapy.

   Interpretation

   
Expected result:
Not detected.

   
Positive result:

   For IFI in neutropenic patients, BG levels ≥80 pg/mL are consistent with emerging or active infection (sensitivity approximately 65%; specificity approximately 95%).

   For
Pneumocystis
pneumonia, a higher cutoff value (≥100 pg/mL) has been recommended, yielding sensitivity approximately 95% with approximately 99% specificity.

   
Indeterminate result:
Detectable BD levels below cutoff values do not establish or reject a diagnosis. Repeat testing is recommended.

   
Negative result:
Fungal infection or
Pneumocystis
pneumonia is unlikely, but infection with
Cryptococcus
species or Zygomycetes is not ruled out.

   Limitations

   The BG assay is not specific for any specific fungal pathogen. Additional testing is required for identification of the infecting species. Evaluation of patients at risk for IFI or
Pneumocystis
pneumonia should not be evaluated by BD as the sole diagnostic testing. Fungal culture, wet mount, imaging studies, histopathology and other relevant diagnostic evaluations should be performed as relevant.