A small number of fungal infections are so distinctive that the diagnosis can be made without any additional testing, although confirmation may be desirable. In most cases there are alternative plausible diagnoses possible, and sometimes a fungal infection co-exists with another infection or other diagnosis.
In addition to making or confirming the diagnosis of fungal infection, full mycological testing has several advantages:
- Knowing which fungus is involved guides appropriate antifungal choice, dose and duration of therapy. It may also guide investigations seeking the source of infection.
- Additional or dual infections can be identified (i.e. 3-5% of Candida bloodstream infections).
- The severity of infection may be revealed from the extent of involvement on skin or scans, the number or load of organisms visible on microscopy or histology or the strength of signal on antigen or PCR tests. These factors may assist in determining whether additional therapy should be added and in following response to therapy.
- Assessing whether antifungal resistance is present, and so an alternative antifungal agent is required.
Some samples are easy to take and process, blood and urine being the obvious examples. Others are harder, including fingernail or toenail clippings, tissue biopsies and respiratory samples. Additional guidance may be required beyond what is given on this website.