How our tests work
Galactomannan
GM is a fungal cell wall antigen produced by Aspergillus, Histoplasma, Fusarium, Talaromyces and some other fungi. This test is commonly used to detect invasive aspergillosis or disseminated histoplasmosis. Not recommended for patients on mould-active prophylaxis.
- Mercier et al (2020) A Mortality Prediction Rule for Hematology Patients with Invasive Aspergillosis Based on Serum Galactomannan Kinetics. J Clin Med 9(2), 610
- Springer et al (2020) The screening of blood by Aspergillus PCR and galactomannan ELISA precedes BAL detection in patients with proven and probable IA. Medical Mycology, myaa007
- Lai et al (2020) Diagnostic Value of Galactomannan in Bronchoalveolar Lavage Fluid for Chronic Respiratory Disease with Pulmonary Aspergillosis J Clin Microbiol 58(3):e01308-19
- Erman-Daloglu et al (2020) Evaluation of Commercially Available Real-Time Polymerase Chain Reaction Assays for the Diagnosis of Invasive Aspergillosis in Patients with Haematological Malignancies. Mycopathologia
Beta-D-glucan
BDG is a cell wall antigen found in most pathogenic fungi (but not Mucorales), which makes the test useful for excluding invasive fungal infections as part of an antifungal stewardship programme. False positives can occur if glucans are introduced to the body from the diet (e.g. yoghurts, ice pops, seaweed) or from medical items (e.g. some surgical gauzes or dialysis membranes).
PCR
Aspergillus PCR testing on BAL/sputum can be useful in monitoring disease progression and response to treatment in CPA/ABPA cases.
- We use the Aspergillus spp ELITe MGB® Kit which is based on the Aspergillus 18S rDNA gene
Identification & sequencing
Fungi are grown on agar and then identified using molecular methods (sequencing, mass spectrometry) or traditional methods such as microscopy.
Therapeutic drug monitoring
Several antifungals require therapeutic drug monitoring, particularly for patients with hepatic or renal impairment. In particular, serum concentrations of itraconazole and voriconazole can vary substantially between patients due to variable pharmacokinetics, and require TDM in order to make the appropriate dose adjustments.