Critical care

Around 1 in 6 patients admitted to ICU with influenza will go on to develop aspergillosis, which requires treatment with antifungals

Guidelines

Biomarker diagnostics

Galactomannan

Galactomannan is a useful antigen biomarker produced by Aspergillus, Penicillium, Histoplasma, Fusarium and Talaromyces during invasive infections. Probable IA can be diagnosed when galactomannan is found in the serum (OD ≥0.5) or BAL (OD ≥0.8) of a patient with a pulmonary infection and a known risk factor. Testing CSF is also good for diagnosing CBS aspergillosis.

But be aware of the following:

  • A. flavus produces less than A. fumigatus
  • Mould-active prophylaxis reduces sensitivity
  • Sensitivity appears to be lower (~40%) in the serum of non-neutropaenic patients because neutrophils are able to clear the antigen from the blood, but testing BAL gives good sensitivity (88%)

Watch our lecture by Prof Malcolm Richardson (previous director of MRCM) explaining the performance of galactomannan testing in different sample types and patient groups, and reasons for false positives (e.g. neonates, multiple myeloma, TPN) and false negative (e.g. mould-active prophylaxis, haemolysed samples, hyperbilirubinaemia, SOT). Our YouTube channel also has video protocols for using laboratory kits made by Dynamiker, Bio-Rad (Platelia), as well as the point-of-care test made by OLM Diagnostics (AspLFD).

From our blog

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