Current Approach to the Laboratory Diagnosis of Invasive Fungal Infections in Haematology Units

Abstract

Recipients of haematopoietic stem cell transplant, patients with haematological malignancies and 
patients with neutropaenia are among the most vulnerable patient groups for invasive fungal infections 
(IFI). This may be due to the immunosuppressive nature of the underlying diseases, their treatment or 
both. Recent advances in the fields of stem cell transplant and haemato-oncology heighten further the 
likelihood of IFI, particularly invasive candidiasis and aspergillosis, in these patients. IFIs are associated 
with high morbidity, mortality and increased patient/hospital costs. The diagnosis of these infections is 
universally challenging because the clinical symptoms are often non-specific. A high index of suspicion 
and effective use of the laboratory is necessary to arrive at diagnosis and aid management. Laboratory 
strategies can be viewed as conventional, contemporary and cutting-edge. Conventional methods 
including culture and histopathology are not sufficiently sensitive and they often require invasive 
methods of specimen collection which may be precluded in haematology patients. Contemporary 
methods include the detection of fungal biomarkers in various specimens. They provide quick diagnosis 
and may be especially useful for excluding serious fungal infections but many exhibit varying sensitivity 
and specificity according to patient group. Combination of these biomarkers, particularly in the 
diagnosis of invasive aspergillosis, has been found to be superior in performance to the use of a single 
assay. Molecular methods such as polymerase chain reaction (PCR) represent the cutting-edge of 
diagnosis but most are not standardized and so are largely unavailable in routine clinical laboratories. 
The diversity and level of complexity encountered in these laboratory methods calls for continuous 
liaison between the haematologist and clinical microbiologist to expedite management and improve 
patient outcomes.