Priority Fungal PathogensCandida auris: A Priority Pathogen on the March

Multi-drug-resistant bacterial strains are responsible for 1.27 million deaths annually and are estimated to indirectly contribute to 4.95 million deaths. Considerable resources have been directed towards the research into, and management of, these infective pathogens.^{5 (p. vii)}

Recently, however, the World Health Organisation (WHO) and other infectious disease watchdogs have noted, with concern, the alarming global increase in cases of multi-resistant infectious fungal diseases, or IFDs.

Unlike bacterial infections, IFDs have to date received very little attention. To address this, in 2022 the WHO released the first fungal priority pathogens list — the WHO FPPL. The report lists 19 fungal pathogens as priority pathogens and differentiates between those with a critical, medium and high risk (see Figure 1).

Against this background, alarm bells have been sounded regarding the rapid increase of Candida auris (C. auris), an emerging fungal infective listed in the critical group in the FPPL. In the US alone, cases of C. auris have risen by almost 200% since 2019.² While global data is scanty, it is thought that this situation is playing out in countries across the globe, including here in South Africa.

Figure 1 · WHO Fungal Priority Pathogens List

C. auris produces invasive candidiasis of the blood (candidaemia), internal organs, cardiovascular, central nervous and urinary tract systems. It also is known to cause infections of the bone and eye.^{5 (p. 16)}

Patients most at risk are hospitalised patients — particularly those in critical care situations — and immunocompromised patients, including those with underlying severe diseases such as diabetes, TB, in particular those with previous mycosis infections, HIV patients and patients with haematologic malignancies.^{5 (p. 16)}

Drug Resistance Profile

The pathogen is intrinsically resistant to most available antifungal medications, and some strains are pan-resistant. A 2019 paper published in JAMA indicates the pathogen is:

Mortality and Morbidity

There is a high mortality rate in cases of C. auris infections, ranging from 29% to 53%.^{5 (p. 16)} According to the WHO:

Furthermore, they indicate that whilst the actual rate of global infection is difficult to determine due to a lack of studies:

Therapeutic Controls and Management

C. auris has a high person-to-person transferral rate, particularly within hospitals and care facilities. Its ability to form biofilms and adhere to polymeric surfaces means that normal bio-cleaning agents are frequently ineffective. The pathogen may persist on shared equipment and other surfaces if care is not taken.^{4, 3 (p. 2036)}

This means the potential for outbreaks is high, and eradicating the pathogen is extremely difficult. The implications for hospitals, clinics and nursing homes are significant, as eradication may require shutting down wards and facilities.^{5 (p. 1)}

C. auris is difficult to detect in a resource-constrained environment, difficult to treat due to its properties and antimicrobial resistance profile, and extremely difficult to eradicate from hospitals, clinics and care facilities once it has become endemic.

As it reshapes the candidaemia profile, this priority pathogen poses a significant threat.

Given the rapid rise in cases, prefaced against the ongoing battle with antimicrobial overprescribing, poor prescribing practices, and inadequate infection control practices, the question arises: will we be able to stem the march of this priority pathogen before it becomes yet another lethal endemic resident in our hospitals and communities?

1. Bradley, S. F. (2019). What is known about Candida auris. JAMA, 322(15), 1510–1511. https://doi.org/10.1001/jama.2019.13843
2. Centers for Disease Control and Prevention. (2022). Candida auris. https://www.cdc.gov/fungal/candida-auris/index.html
3. Govender, N. P., Magobo, R. E., Mpembe, R., Mhlanga, M., Matlapeng, P., Corcoran, C., Govind, C., Lowman, W., Senekal, M., & Thomas, J. (2018). Candida auris in South Africa, 2012–2016. Emerging Infectious Diseases, 24(11), 2036–2040. https://doi.org/10.3201/eid2411.180368
4. van Schalkwyk, E., Mpembe, R. S., Thomas, J., Shuping, L., Ismail, H., Lowman, W., Karstaedt, A. S., Chibabhai, V., Wadula, J., Avenant, T., Messina, A., Govind, C. N., Moodley, K., Dawood, H., Ramjathan, P., Govender, N. P., & GERMS-SA. (2019). Epidemiologic shift in candidemia driven by Candida auris, South Africa, 2016–2017. Emerging Infectious Diseases, 25(9), 1698–1707. https://doi.org/10.3201/eid2509.190040
5. World Health Organization. (2022). WHO fungal priority pathogens list to guide research, development and public health action. World Health Organization. https://www.who.int/publications/i/item/9789240060241