Fungus Culture – Susceptibility Testing
Susceptibility testing for yeast will be performed from sterile-sites; exceptions can be made for isolates from non-sterile sites from patients that are immune compromised or in the ICU (please ensure this information is clearly indicated on the requisition).
Susceptibility testing for filamentous fungi must be discussed and approved by the PHO Microbiologist that oversees Mycology.
|Test Requested||Required Requisition(s)||Specimen Type||Minimum Volume||Collection Kit|
Submit isolates on plain fungal media that supports the growth of the isolate.
Submission and Collection Notes
Include the Identification of the fungus and request susceptibility testing on the General Test Requisition Form.
Requests for susceptibility testing on dimorphic fungi will be rejected.
Clearly indicate if the patient is immune compromised or in the ICU on the General Test Requisition Form. Susceptibility test requests for yeast from non-sterile site will be rejected unless the patient belongs to a high risk group (e.g. immunocompromised, transplant, ICU etc). Contact PHO laboratory for special requests that require approval by a microbiologist.
Preparation Prior to Transport
Label the specimen container with the patient’s full name, date of collection and one other unique identifier such as the patient’s date of birth or Health Card Number. Failure to provide this information may result in rejection or testing delay.
Place specimen in a biohazard bag and seal. Store isolate on fungal media at room temperature or 28°C until submitted. Specimens should be shipped to the laboratory ASAP.
Test Frequency and Turnaround Time (TAT)
The Fungus culture susceptibility test is done daily Monday to Friday.
Turn-around time for susceptibility testing of pure culture organisms, after receipt by the PHO – Toronto laboratory is:
- Candida spp.: within 5 working days
- Cryptococcus neoformans and other yeast: within 7 working days
- Aspergillus spp.: within 7 working days
Other filamentous fungi variable turnaround time.
Results are reported to the ordering physician or health care provider as indicated on the requisition.
Fungus cultures are tested for Susceptibility by MIC (modified CLSI broth microdilution method).
Susceptibility testing for Candida species will be performed by broth microdilution assay (Sensititre™ YeastOne™) according to CLSI guidelines. MICs (minimal inhibitory concentration) will be reported with interpretation where available.
Susceptibility testing for Aspergillus species will be performed by broth microdilution assay on request after approval by the PHO Microbiologist that oversees Mycology. Results will be reported as MICs (or equivalent) without interpretation.
Susceptibility for other filamentous fungi may need referral to an outside laboratory.
NB: This is not a routine test for all pathogens.