Mycology – Candida auris

Consistent with O. Reg. 671/92 of the French Language Services Act, laboratory testing information on this page is only available in English because it is scientific or technical in nature and is for use only by qualified health care providers and not by members of the public.

This page provides reference identification and susceptibility testing information for Candida auris (C. auris) at Public Health Ontario (PHO).

Prompt and accurate identification of C. auris is a crucial step for controlling the spread of this emerging fungal pathogen. This test information sheet is intended to provide guidance to clinical laboratories on the current limitations to the identification of C. auris and communicate the support services that PHO can provide.

C. auris is an emerging pathogen, which is significant in that, it:

has been identified from many countries within a short period of time¹
effectively colonizes patients (skin and other body sites), contaminates healthcare settings and equipment, and has caused several large healthcare-associated outbreaks^2,3,4
causes invasive disease associated with high mortality⁵
is often resistant to fluconazole and is commonly resistant to multiple classes of antifungal drugs¹
is tolerant to many commonly used disinfectants (e.g., quaternary ammonia-based disinfectants)⁴
is challenging to identify using many common commercial yeast identification systems^6,7

Additional information for healthcare facilities on how to prevent the transmission of C. auris in Ontario healthcare facilities is available in the following document, available on the Public Health Ontario (PHO) website at: Ontario Agency for Health Protection and Promotion (Public Health Ontario) Interim Guide for Infection Prevention and Control of C. auris.

For information regarding other Mycology testing options, refer to the following webpages:

Updates

This is a new test information sheet containing information from LAB-SD-131 Candida auris reference identification and susceptibility testing. There are no changes on the guidelines for submission.

*Uncontrolled print copy. Valid only on day of print: 25 March 2025.

Testing Indications

For laboratorians and health care providers requiring reference identification and susceptibility testing of C. auris isolates, refer to this test information sheet.

PHO encourages all laboratories that have identified, or are querying, C. auris in clinical specimens or environmental samples linked to confirmed patient cases to submit those isolates to PHO. Isolates will be tested for confirmation and as appropriate, antifungal susceptibility testing, as it is an emerging pathogen of clinical and public health concern.

Submission of C. auris isolates from all new cases (colonizations and infections) to PHO is recommended as part of provincial and national surveillance of emerging infectious diseases.

Acceptance/Rejection Criteria

PHO will not accept primary screening/surveillance swabs for C. auris testing. Only isolated colonies of yeast (culture) suspected of being C. auris will be accepted for identification and susceptibility testing from patient screens. Primary clinical specimens will continue to be processed as outlined in Mycology - Fungal Culture – Superficial, Dermatophytes and Mycology – Fungal Culture – Systemic.
Susceptibility Testing on Isolates from Non-Sterile Human Body Sites: Typically, PHO does not perform antifungal susceptibility testing on yeast from non-sterile sites unless there is a particular clinical indication (e.g. an immunocompromised patient). However, since C. auris is often drug resistant, there are limited classes of antifungal drugs available, and this organism has a propensity for nosocomial spread, PHO will perform susceptibility testing on the first isolate from a newly identified colonized patient. In cases such as nosocomial outbreaks, not all screening/surveillance isolates will have susceptibility testing performed. Consultation with a Microbiologist prior to submission of such isolates will be required to determine the appropriate number of susceptibility tests to be performed and over what period.
Environmental Isolates- Susceptibility Testing: susceptibility testing for C. auris isolated from environmental sites will not be performed. See below in special instructions for more details regarding environmental isolates.

Typing and National Surveillance

All confirmed C. auris isolates will be forwarded to the National Microbiology Laboratory for typing by next generation sequencing as part of a national effort to better understand the epidemiology of this emerging pathogen in Canada. To expedite this process, information on any risk factors for acquisition of C. auris (e.g. hospitalization outside of Canada, or at an institution known to have cases of C. auris) must be included on the requisition to be submitted to PHO.

Specimen Collection and Handling

Specimen Requirements

Test Requested	Required Requisition(s)	Specimen Type	Minimum Volume	Collection Kit
C. auris – confirmation/Identification and/or susceptibility testing	Reference Bacteriology Requisition	Pure culture of yeast isolate	N/A	Appropriate culture media for growth (slant or plate) or Swab from pure culture.

Submission and Collection Notes

Complete all fields of the requisition form, and specify:

test(s) requests and indications for testing
information on type of specimen/rationale for testing (eg. clinical/diagnostic, surveillance or environmental), source
presumptive identification and method used for identification
whether this is part of an outbreak investigation (ensure the outbreak or investigation number is included)
any known risk factors for C. auris (e.g. direct contact with a C. auris case, admission to a health care facility with known C. auris cases, hospitalization outside of Canada within the last 12 months, location of travel, etc.)
whether isolate is from an active infection or colonization

Label the culture container(s) with the patient’s first and last name, date of collection, and one other unique identifier such as the patient’s date of birth or Health Card Number. For additional information see: Criteria for Acceptance of Patient Specimens. Failure to provide this information may result in rejection or testing delay.

Isolates must be submitted in pure state.

Limitations

PHO does not offer any identification services for yeast and filamentous fungi that have been isolated from environmental sources. Exceptions may be made for C. auris if there is an epidemiological link to a confirmed clinical case. See below in ‘Special Instructions’ for more details.

Identification Challenges:
C. auris is a relatively newly described organism which was first identified in 2009. Not all commercial yeast identification systems can confidently or reliably identify C. auris. Inability to identify or misidentifications are possible depending on the system in-use. New versions of MALDI-ToF MS databases include C. auris and these systems are quite good at identification. It is very important for laboratorians to be familiar with the capabilities and limitations of the specific identification systems and database versions in use in their laboratories and create strategies which will ensure the accurate identification of this pathogen of clinical, infection prevention and control, and public health interest.

Below in Table 1 is a list of common yeast identification systems as well as the organisms that C. auris may possibly be misidentified as^6,7. It is important to also remember that “no identification” or identification with low confidence, could also potentially be C. auris.

Note, this list is a guide and is not comprehensive and information may change as identification systems are updated. Laboratorians should be aware of the performance of yeast identification systems they use with respect to C. auris identification.

Table 1. Possible misidentifications of C. auris by commercial yeast identification systems (Note: performance characteristics of each system may change overtime with updates)

Yeast Identification System	Possible C. auris Misidentifications
RapID YEAST PLUS	Candida parapsilosis
API 20C	Rhodoturula glutinis, Candida sake
MicroScan	Candida famata, Candida guilliermondii, Candida lusitaniae, Candida parapsilosis
BD Phoenix yeast identification system	Candida haemulonii, Candida catenulata
VITEK 2 YST (version 8.01 and older)	Candida haemulonii, Candida duobushaemuloniie
bioMérieux VITEK MS, IVD (versions earlier than 3.2)	Candida haemulonii
bioMérieux VITEK MS, RUO Saramis Ver 4.14 and Saccharomycetaceae update	C. auris is able to be identified
Bruker MALDI Biotyper, FDA-approved CA system (version claim 4)	C. auris is able to be identified
Bruker MALDI Biotyper, RUO libraries version 2014 [5627] and beyond	C. auris is able to be identified

Storage and Transport

Culture or isolate container should be placed in a biohazard bag, sealed and stored at room temperature or 28°C following isolation and shipped to PHO as soon as possible. All clinical specimens must be shipped in accordance to the Transportation of Dangerous Good Act.

Special Instructions

Submission to PHO for Reference Identification and/or Confirmation:

Patient Isolates – As C. auris is an emerging pathogen and little is known about its prevalence and public health impact in Canada, all sterile and non-sterile clinical and patient screening isolates suspected of being C. auris should be sent to PHO for confirmation of identification and as a part of provincial and national surveillance programs.
While this is not a mandatory program, it is strongly recommended that all laboratories participate for the detection and epidemiology of this emerging threat be understood. The site of isolation and whether the yeast was isolated from a clinical sample or from a screening/surveillance program must be indicated on the requisition as well as active infection or colonization.

Environmental Isolates – C. auris is known to colonize, or remain viable, in healthcare environments and be a source of nosocomial outbreaks. Testing environmental isolates requires prior approval by a PHO microbiologist. Contact PHO Customer Service Centre prior to submission. Testing to confirm the identification of yeast suspected to be C. auris from an environmental source will be considered if there is an epidemiological link to a confirmed clinical case. Only isolated colonies of yeast suspected of being C. auris will be accepted for identification and no susceptibility testing will be performed on these isolates.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

C. auris reference identification and susceptibility testing is performed daily Monday to Friday, at PHO, Toronto Location.

Turnaround Time:

Confirmation/identification: typically, 3 business days (up to 5 business days) from date of receipt at PHO.
Susceptibility testing: within 5 working days or receipt at PHO.

Results are reported to the ordering physician or health care provider as indicated on the requisition.

Test Methods

Yeast presumed to be C. auris will be identified using a MALDI-ToF MS system which has been validated for the identification of C. auris, and/or through Polymerase Chain Reaction (PCR) and sequencing.

Susceptibility testing for C. auris isolated from sterile sites will be performed by broth microdilution assay (according to CLSI M27) and MICs (minimal inhibitory concentration) will be reported as there are currently no interpretations available. Susceptibility testing can be performed on isolates repeatedly isolated from the same patient up to one time per week.

Interpretation

All isolates submitted for confirmation/identification will be reported to genus/species level.

C. auris isolated from:	Susceptibility Testing
C. auris isolated from:	Performed?	Drugs Tested	Notes
Patient, sterile body site	Yes, routinely on all isolates	Amphotericin B Echinocandins (anidulafungin, micafungin and caspofungin) Azoles (fluconazole, itraconazole, posaconazole and voriconazole) 5-Flucytosine	There are currently no CLSI interpretations for Candida auris and any drugs¹
Patient screening /colonization	Yes, but only on first isolate from a newly identified colonized patient.	Amphotericin B Echinocandins (anidulafungin, micafungin and caspofungin) Azoles (fluconazole, itraconazole, posaconazole and voriconazole) 5-Flucytosine	There are currently no CLSI interpretations for Candida auris and any drugs¹ In cases such as nosocomial outbreaks not all screening/surveillance isolates will have susceptibility testing performed. Consultation with a Microbiologist prior to submission of such isolates will be required to determine the appropriate number of susceptibility tests to be performed and over what period.
Environment	No	None	None

¹There are currently no established C. auris-specific susceptibility breakpoints. The U.S. Centers for Disease Control and Prevention has published tentative breakpoints based on other species and expert opinion; correlation between these breakpoints and clinical outcomes is currently unknown. Antifungal Susceptibility Testing for C. auris

Reporting

Results are reported to the physician, authorized health care provider (General O. Reg 45/22, s.18) or submitter as indicated on the requisition.

As of January 1, 2025, C. auris is now a Disease of Public Health Significance. Confirmed C. auris first isolated from a patient as a cause of an active infection is reported to the Medical Officer of Health as per the Ontario Health Protection and Promotion Act.

References

Lockhart SR, Etienne KA, Vallabhaneni S, Farooqi J, Chowdhary A, Govender NP, et al. Simultaneous emergence of multidrug-resistant Candida auris on 3 continents confirmed by whole-genome sequencing and epidemiological analyses. Clin Infect Dis. 2017;64(2):134-40. Available from: https://academic.oup.com/cid/article/64/2/134/2706620
Schelenz S, Hagen F, Rhodes JL, Abdolrasouli A, Chowdhary A, Hall A, et al. First hospital outbreak of the globally emerging Candida auris in a European hospital. Antimicrob Resist Infect Control. 2016;5:35. Available from: https://aricjournal.biomedcentral.com/articles/10.1186/s13756-016-0132-5
Eyre DW, Sheppard AE, Madder H, Moir A, Moroney R, et al. A Candida auris outbreak and its control in an intensive care setting. N Engl J Med. 2018; 379:1322-31. Available from: https://www.nejm.org/doi/full/10.1056/NEJMoa1714373
Welsh RM, Bentz ML, Shams A, Houston H, Lyons A, Houston H, et al. Survival, persistence, and isolation of the emerging multidrug-resistant pathogenic yeast Candida auris on a plastic healthcare surface. J Clin Microbiol. 2017;55(10):2996-3005. Available from: https://journals.asm.org/doi/full/10.1128/jcm.00921-17
Osei Sekyre J. Candida auris: A systematic review and meta-analysis of current updates on an emerging multidrug-resistant pathogen. MicrobiologyOpen. 2018; 7(4):e00578. Available from: https://onlinelibrary.wiley.com/doi/10.1002/mbo3.578
Mizusawa M, Miller H, Green R, Lee R, Durante M, Perkins R, et al. Can multidrug-resistant Candida auris be reliably identified in clinical microbiology laboratories? J Clin Microbiol. 2017;55(2):638-40. Available from: https://journals.asm.org/doi/full/10.1128/jcm.02202-16
Centers for Disease Control and Prevention. Recommendations for Identification of Candida auris [Internet]. Atlanta, GA: Centers for Disease Control and Prevention; 2024 June 27. Available from: https://www.cdc.gov/candida-auris/hcp/laboratories/identification-of-c-auris.html
Ontario Agency for Health Protection and Promotion (Public Health Ontario) Interim Guide for Infection Prevention and Control of Candida auris. Toronto, ON : Queen’s Printer for Ontario; 2019. Available from: Public Health Ontario Interim Guide for Infection Prevention and Control of Candida auris
CLSI. Reference Method for Broth Dilution Antifungal Susceptibility Testing of Yeasts. 4th ed. CLSI Standard M27. Wayne, PA: Clinical and Laboratory Standards Institute; 2017.
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