Fungal detection

Keywords: Fungal detection microscopy and culture and NAA

Specimen:

Fresh tissue obtained at surgical biopsy is preferable to material obtained by fine needle aspiration.

Sufficient specimen should be collected to allow histologic examination as well as microbiological studies. For instance, if mucormycosis is suspected a fresh 1cmx1cmx1cm cube of tissue will be required to culture the fungus.

For fluids it is important that an adequate volume is collected eg, 5-20 mL cerebrospinal fluid.

Method:

Microscopy (wet preparation); culture on specialised fungal media with incubation for up to 4 weeks.

The usefulness of susceptibility testing depends of the identification of the organism isolated.

NAA.

Antigen detection ie galactomannan or BD glucan may also be indicated in particular clinical situations.

Application:

Diagnosis of invasive fungal infections, especially in immunocompromised patients.

Interpretation:

The significance of isolation of fungi from clinical specimens depends on the specific site and identification of the organism.

Histological evidence of invasion is a very useful adjunct to interpreting the microbiology.

Specimens from the respiratory tract and paranasal sinuses are particularly problematic since colonisation or contamination cannot be differentiated from infection.

Reference:

Sutton DA. In: Murray PR et al eds. Manual of Clinical Microbiology. 8th ed 2003. ASM Press.