Letter to the Editor
Background: Candidozyma auris (C. auris) is an emerging human fungal pathogen that was first discovered from a human external ear specimen from Japan in 2009 (Satoh et al. 2009 and Lockhart et al. 2023). However, a subsequent retrospective study found infections with C. auris as early as 1996 in South Korea initially misidentified as Candidozyma haemuli (Lee et al. 2011). The fungus has rapidly spread across six continents (Ahmad & Asadzadeh, 2023; World Health Organization [WHO], 2022). Extensive transmission has occurred in South Asia, South America, South Africa, and United States with some areas considered endemic (Jackson et al. 2019; Geremia et al. 2023; Reiner-McAfee et al. 2021; WHO, 2022).
Erica Susky, MSc, CIC1*
1 Associate Editor, Canadian Journal of Infection Control
*Corresponding author
Erica Susky
Infection Control Practitioner
Unity Health Toronto
Saint Michael’s Hospital
Toronto, ON, Canada
Article history:
Received 14 October 2025
Received in revised form 3 December 2025
Accepted 16 December 2025
Background
Candidozyma auris (C. auris) is an emerging human fungal pathogen that was first discovered from a human external ear specimen from Japan in 2009 (Satoh et al. 2009 and Lockhart et al. 2023). However, a subsequent retrospective study found infections with C. auris as early as 1996 in South Korea initially misidentified as Candidozyma haemuli (Lee et al. 2011). The fungus has rapidly spread across six continents (Ahmad & Asadzadeh, 2023; World Health Organization [WHO], 2022). Extensive transmission has occurred in South Asia, South America, South Africa, and United States with some areas considered endemic (Jackson et al. 2019; Geremia et al. 2023; Reiner-McAfee et al. 2021; WHO, 2022). Analyses of genetic divergence between C. auris clades suggest that the pathogen likely emerged simultaneously in multiple locations globally (Akinbobola et al. 2023; Lockhart et al. 2017). Considering its thermotolerance (it can be cultured at temperatures as high as 42°C), climate change may have played a role in the evolution of C. auris as a human pathogen. (Ahmad & Asadzadeh, 2023; Jackson et al. 2019; WHO, 2022). Another factor in its emergence is the widespread use of antifungals in agriculture exerting a selective pressure on environmental yeasts (Akinbobola et al. 2023; WHO, 2022; WHO, 2025).
In fact, C. auris is frequently multidrug resistant, with increasing resistance to one or more antifungal drug classes (azole, polyene, and echinocandin), including pan-resistant isolates resistant to all three drug classes. (Lyman et al. 2021; Lyman et al. 2023; WHO, 2025). This limits current available treatments as there are currently few antifungal drug classes in development (WHO, 2025). Invasive C. auris infections also have a high mortality (Geremia et al. 2023) and are increasing worldwide (Akinbobola et al. 2023). Also, the fungus is increasingly causing outbreaks in healthcare facilities worldwide (Ahmad & Asadzadeh, 2023), and is resistant to some disinfectants (Public Health Agency of Canada, 2024). For these reasons, the World Health Organization in 2022 classified C. auris as a fungal pathogen of critical priority and the Centers for Disease Control (CDC) named C. auris as an urgent antimicrobial threat (WHO, 2022; CDC, 2019).
Although neighbouring United States has seen exponential growth in C. auris colonisations and infections (Public Health Ontario [PHO], 2024), C. auris prevalence in Canada remains low, with only 64 cases reported between 2012 and March 2025, although case counts are increasing (A. Bharat, personal communication, March 10, 2025). The potential for C. auris transmission in Canadian healthcare facilities remains high whether through importation from international healthcare settings or within Canadian healthcare facilities (Eckbo et al. 2021; Garcia-Jeldes et al. 2020; Schwartz & Hammond, 2017; Townsend et al. 2021). This risk is further compounded when laboratory testing is not done and transmission occurs undetected (Ahmad & Asadzadeh, 2023; PHO, 2024; WHO, 2022).
Recommendations
The Public Health Agency of Canada (PHAC) recommends that screening programs for C. auris be in place for Canadian healthcare facilities, including long-term care facilities (PHAC, 2024). Those admitted to healthcare facilities with the following risk factors require microbiological testing (including axilla and groin swabs for colonization); admission to healthcare facility or long-term care facility outside of Canada within the past twelve months and those transferred from facilities with ongoing C. auris transmission (PHAC, 2024). Currently, healthcare facilities in Canada are not universally screening patients or residents for C. auris. In addition, not all healthcare laboratories have the ability to identify C. auris from routine clinical and surveillance specimens (PHO, 2024; PHO, 2024). Although there are advancements in microbiological identification of C. auris, misidentification still occurs (Ahmad & Asadzadeh, 2023) and laboratories incur a cost in order to have these diagnostic capabilities (PHO, 2024). Discussions are ongoing among public health and Infection Prevention and Control (IPAC) communities regarding the need for screening and laboratory surveillance for C. auris (PHO, 2024).
Some of the reasons brought forward for not initiating a screening program include a facility not yet having a case of C. auris, competing priorities, and insufficient resources (PHO, 2024). In my opinion, if consistent screening guidelines are not applied universally in Canada, undetected instances will likely occur when only few patients or residents are screened (PHO, 2024). For example, one retrospective study found C. auris in Canada preceding the first known introduction of a multidrug-resistant case as far back as 2014 in Ontario (Ahmad & Asadzadeh, 2023; Hota et al. 2020; Schwartz & Hammond, 2017) and inadvertent cases of C. auris occurred that did not have the above risk factors for C. auris screening (Eckbo et al. 2021; PHO, 2024). It's even more concerning as outbreaks can be fast and protracted (Adams et al. 2018; Eckbo et al, 2021; Geremia et al, 2023). If C. auris can proliferate before detection, the cost to Canadian healthcare facilities will increase both in resources and in patient and resident outcomes (PHO, 2024).
The value of screening
As determined by Lapointe-Shaw et al. (2017), universal microbiological testing for carbapenemase-producing Enterobacterales (CPE) of all hospital inpatients on admission was cost-effective when the prevalence in a population was above 0.3%. Unfortunately, there is yet no prevalence threshold for C. auris to justify the cost of universal testing, but cases are increasing in Canada (A. Bharat, personal communication, March 10, 2025). However, early identification of C. auris would facilitate the implementation of appropriate infection prevention methods such as contact precautions (having the affected patient or resident in a single room with dedicated toileting facilities and the use of glove and gowns for all contact with the individual), dedicating equipment, and the use of recommended sporicidal disinfectants for environmental and shared equipment cleaning and disinfection (PHAC, 2024).
Although screening programs incur a cost, laboratories and IPAC programs across Canada should prepare and reassess on a regular basis the need to initiate screening programs. If currently not feasible, both departments should become familiar with the requirements of laboratories and IPAC programs to shift priorities in the event of changing regional epidemiology. A key factor will be the wide aggregation of Canadian surveillance data. Though the Canadian Nosocomial Surveillance Program (CNISP) reports C. auris numbers in Canada, participation in this surveillance program is voluntary (Ettles et al. 2024) and obtaining accurate data is a challenge as
C. auris is only reportable in British Columbia, Alberta and Ontario (PHO, 2024; Ettles et al. 2024; Ontario Ministry of Health, 2025). Determining when to adopt a screening program may depend on knowing the prevalence in a province or region, yet the prevalence will remain unknown until more healthcare facilities test and report cases to national programs like CNISP. Those accessing Canadian healthcare are at risk from this pathogen, and likely, there will be more transmission in the coming years.
REFERENCES
Adams, E., Quinn, M., Tsay, S., Poirot, E., Chaturvedi, S., Southwick, K., Greenko, J., Fernandez, R., Kallen, A., Vallabhaneni, S., Haley, V., Hutton, B., Blog, D., Lutterloh, E., Zucker, H., & Candida auris Investigation Workgroup. (2018). Candida auris in healthcare facilities, New York, USA, 2013–2017. Emerging Infectious Diseases, 24(10), 1816–1824. https://doi.org/10.3201/eid2410.180649
Ahmad, S., & Asadzadeh, M. (2023). Strategies to prevent transmission of Candida auris in healthcare settings. Current Fungal Infection Reports, 17, 36–48.
https://doi.org/10.1007/s12281-023-00451-7
Akinbobola, A. B., Kean, R., Hanifi, S. M. A., & Quilliam, R. S. (2023). Environmental reservoirs of the drug-resistant pathogenic yeast Candida auris. PLoS Pathogens, 19(4), e1011268. https://doi.org/10.1371/journal.ppat.1011268
Centers for Disease Control and Prevention. (2019). Antibiotic resistance threats in the United States, 2019.
https://doi.org/10.15620/cdc:82532
Eckbo, E. J., Wong, T., Bharat, A., Cameron-Lane, M., Hoang, L., Dawar, M., & Charles, M. (2021). First reported outbreak of the emerging pathogen Candida auris in Canada. American Journal of Infection Control, 49, 804–807.
https://doi.org/10.1016/j.ajic.2021.01.013
Ettles, S., Wellon, T., Hardy, H., Graham, A., & Prematurge, C. (2024). Candida auris: What literature exists to inform control of outbreaks in healthcare settings? Canadian Journal of Infection Control, 39(3), 153–164.
Garcia-Jeldes, H. F., Mitchell, R., McGeer, A., Rudnick, W., Amaratunga, K., Vallabhaneni, S., Lockhart, S. R., Bharat, A., & CNISP Candida auris Interest Group. (2020). Prevalence of Candida auris in Canadian acute care hospitals among at-risk patients, 2018. Antimicrobial Resistance & Infection Control, 9(1), 82.
https://doi.org/10.1186/s13756-020-00752-3
Geremia, N., Brugnaro, P., Solinas, M., Scarparo, C., &
Panese, S. (2023). Candida auris as an emergent public health problem: A current update on European outbreaks and
cases. Healthcare, 11(3), 425.
https://doi.org/10.3390/healthcare11030425
Hota, S., Gade, L., Forsberg, K., Susky, E., Poutanen, S., Katz, K., Leis, J., Nadarajah, J., Amirov, C., & Nankoosingh, V. (2020). WGS reveals a potential novel sub-clade of pan-susceptible Candida auris in Ontario, Canada. Infection Control & Hospital Epidemiology, 41(Suppl. 1), S57–S58.
https://doi.org/10.1017/ice.2020.542
Jackson, B. R., Chow, N., Forsberg, K., Litvintseva, A. P., Lockhart, S. R., Welsh, R., Vallabhaneni, S., & Chiller, T. (2019). On the origins of a species: What might explain the rise of Candida auris? Journal of Fungi, 5(3), 58.
https://doi.org/10.3390/jof5030058
Lapointe-Shaw, L., Voruganti, T., Kohler, P., Thein, H.-H., Sander, B., & McGeer, A. (2017). Cost-effectiveness analysis of universal screening for carbapenemase-producing Enterobacteriaceae in hospital inpatients. European Journal of Clinical Microbiology & Infectious Diseases, 36, 1047–1055. https://doi.org/10.1007/s10096-016-2890-7
Lee, W. G., Shin, J. H., Uh, Y., Kang, M. G., Kim, S. H., Park, K. H., & Jang, H. C. (2011). First three reported cases of nosocomial fungemia caused by Candida auris. Journal of Clinical Microbiology, 49(9), 3139–3142.
https://doi.org/10.1128/JCM.00319-11
Lockhart, S. R., Chowdhary, A., & Gold, J. A. W. (2023). The rapid emergence of antifungal-resistant human-pathogenic fungi. Nature Reviews Microbiology, 21, 818–832.
https://doi.org/10.1038/s41579-023-00960-9
Lockhart, S. R., Etienne, K. A., Vallabhaneni, S., Farooqi, J., Chowdhary, A., Govender, N. P., Colombo, A. L., Calvo, B., Cuomo, C. A., Desjardins, C. A., Berkow, E. L.,
Castanheira, M., Magobo, R. E., Jabeen, K., Asghar, R. J., Meis, J. F., Jackson, B. R., Chiller, T., & Litvintseva, A. P. (2017). Simultaneous emergence of multidrug-resistant Candida auris on three continents confirmed by whole-genome sequencing and epidemiological analyses. Clinical Infectious Diseases, 64(2), 134–140.
https://doi.org/10.1093/cid/ciw691
Lyman, M., Forsberg, K., Reuben, J., Dang, T., Free, R.,
Seagle, E. E., Sexton, D. J., Soda, E., Jones, H.,
Hawkins, D., Anderson, A., Bassett, J., Lockhart, S. R., Merengwa, E., Iyengar, P., Jackson, B. R., & Chiller, T. (2021). Notes from the field: Transmission of pan-resistant and echinocandin-resistant Candida auris in healthcare
facilities — Texas and the District of Columbia, January–April 2021. MMWR Morbidity and Mortality Weekly Report, 70(29), 1022–1023.
https://doi.org/10.15585/mmwr.mm7029a2
Lyman, M., Forsberg, K., Sexton, D. J., Chow, N. A., Lockhart, S. R., Jackson, B. R., & Chiller, T. (2023). Worsening spread of Candida auris in the United States, 2019 to 2021. Annals of Internal Medicine, 176(4), 489–495.
https://doi.org/10.7326/M22-3469
Ontario Ministry of Health. (2025). Ontario public health standards: Infectious diseases protocol, appendix 1 –
Candida auris. https://www.ontario.ca
Osbourne Townsend, J., Morillo, A., Kariko Braithwaite, L., Boodosingh, S., Neil, A., Widle, J., & Farshait, N. (2021). Identification of Candida auris in a foreign repatriated patient to Ontario, Canada and infection control strategies to prevent transmission. Canadian Journal of Infection Control, 36(4), 184–187.
Public Health Agency of Canada. (2024, December 23). Candida auris: Infection prevention and control in
Canadian healthcare settings. https://www.canada.ca
Public Health Ontario. (2025). Antimicrobial resistance in common hospital pathogens in Ontario: Annual laboratory and hospital survey report 2023.
https://www.publichealthontario.ca
Public Health Ontario. (2025, February 11). PHO rounds: Candida auris – Management of this highly transmissible fungal pathogen. https://www.publichealthontario.ca
Reimer-McAtee, M., Corsi, G., Reed, E., Boston, K. M., Yalamanchili, H., Burnazian, G., Bassett, S., Butler, J., McGinnis-Cole, T., Chavez, V., Wanger, A., & Ostrosky-Zeichner, L. (2021). Successful implementation of the CDC recommendations during the care of two patients with Candida auris in inpatient rehabilitation and intensive care settings. American Journal of Infection Control, 49(4), 525–527. https://doi.org/10.1016/j.ajic.2020.08.027
Satoh, K., Makimura, K., Hasumi, Y., Nishiyama, Y., Uchida, K., & Yamaguchi, H. (2009). Candida auris sp. nov., a novel ascomycetous yeast isolated from the external ear canal of an inpatient in a Japanese hospital. Microbiology and Immunology, 53(1), 41–44.
https://doi.org/10.1111/j.1348-0421.2008.00083.x
Schwartz, I. S., & Hammond, G. W. (2017). First reported case of multidrug-resistant Candida auris in Canada. Canada Communicable Disease Report, 43(7–8), 150–153.
https://doi.org/10.14745/ccdr.v43i78a02
World Health Organization. (2022, October 25). WHO fungal priority pathogens list to guide research, development and public health action. https://www.who.int
World Health Organization. (2025). Antifungal agents in clinical and preclinical development: Overview and analysis.
https://www.who.int