Candida auris: An emerging fungal threat?
Written by Emily Fucarino
Edited by Michelle Wong
July 31st 2021
Edited by Michelle Wong
July 31st 2021
When you think of the microbes that cause infectious diseases, what do you think of? Viruses? Bacteria? While both of these groups are highly relevant in public health, they aren’t the only culprits. Fungi also have the capacity to be pathogenic—that is, to cause disease—and although they are less prolific, they are no less capable.
New pathogens are constantly emerging and posing novel threats to public health, including Candida auris, a member of the notorious Candida fungal family (Du et al., 2020). As a whole, Candida species are responsible for the majority of fungal infections acquired in a hospital setting, and can cause fatal infections in the bloodstream (Brown et al., 2020). C. auris is a relatively new species and was only identified for the first time in 2009 (Du et al., 2020) but it is already causing scientists to worry.
In particular, the rise of C. auris is concerning due to its “rapid emergence worldwide and multidrug resistance properties,” and the high rate at which C. auris infections are associated with death (Du et al., 2020). C. auris is especially problematic due to its wide geographical range, which is hinted at by its emergence; genetic evidence supports the theory that unique strains arose at the same time in different places. While C. auris was only recently discovered in 2009, re-examined studies show evidence that it has been around since at least the 1990s (Oh et al., 2011). However, the scarcity of recorded C. auris infections prior to 2009 implies that C. auris only recently evolved into a human pathogen (Du et al., 2020) and existed before, under the radar, as a nonpathogenic species.
As recently as 2016, the Centers for Disease Control raised concern about “the international emergence of C. auris infections with high mortality rates” (Du et al., 2020). Hospital-acquired infections like those caused by C. auris are often dangerous because many exposed people are patients who have underlying conditions that make it more difficult to combat infection, which can contribute to a high mortality rate. Risk factors for C. auris infection include a weakened immune system, broad-spectrum antibiotic use, recent antifungal courses, long-term kidney disease, as well as time spent in the ICU as a patient (Sardi et al., 2018).
Unlike other prolific Candida species, C. auris is thought to establish infection on the skin, rather than in the gut, urinary, or reproductive organs. Hospital-acquired C. auris infections, though, are primarily infections of the bloodstream which occur at a higher rate in ICU patients (Spivak & Hanson, 2018) and which have mortality rates that range from 30% to 60% around the world (Arensman et al., 2020).
Concerningly for hospitals, C. auris is characterized by its heightened ability to withstand hostile environments compared to other fungal species that infect humans, and its ability to endure for weeks on “skin and [other] surfaces”. C. auris is also naturally resistant to certain antifungals, which can complicate treatment options once patients are diagnosed (Du et al., 2020).
Many questions remain concerning C. auris and its sudden appearance as a pathogen, its durability and resistance to antifungals, and the factors that enable it to cause disease. A more thorough understanding is needed in order to properly address the public health concern that it poses (Du et al., 2020) and going forward scientists will be looking for more answers.
Work Cited
Arensman, K., Miller, J. L., Chiang, A., Mai, N., Levato, J., LaChance, E., Anderson, M., Beganovic, M., & Dela Pena, J. (2020). Clinical Outcomes of Patients Treated for Candida auris Infections in a Multisite Health System, Illinois, USA. Emerging infectious diseases, 26(5), 876–880. https://doi.org/10.3201/eid2605.191588
Brown, G. D., Denning, D. W., Gow, N. A., Levitz, S. M., Netea, M. G., & White, T. C. (2012). Hidden killers: human fungal infections. Science translational medicine, 4(165), 165rv13. https://doi.org/10.1126/scitranslmed.3004404
Du, H., Bing, J., Hu, T., Ennis, C. L., Nobile, C. J., & Huang, G. (2020). Candida auris: Epidemiology, biology, antifungal resistance, and virulence. PLoS pathogens, 16(10), e1008921. https://doi.org/10.1371/journal.ppat.1008921
Oh, B. J., Shin, J. H., Kim, M. N., Sung, H., Lee, K., Joo, M. Y., & Ryang, D. W. (2011). Biofilm formation and genotyping of Candida haemulonii, Candida pseudohaemulonii, and a proposed new species (Candida auris) isolates from Korea. Medical Mycology, 49(1), 98-102. https://doi.org/10.3109/13693786.2010.493563
Sardi, J. D. C. O., Silva, D. R., Mendes-Giannini, M. J. S., & Rosalen, P. L. (2018). Candida auris: epidemiology, risk factors, virulence, resistance, and therapeutic options. Microbial pathogenesis, 125, 116-121. https://doi.org/10.1016/j.micpath.2018.09.014
Spivak, E. S., & Hanson, K. E. (2018). Candida auris: an emerging fungal pathogen. Journal of clinical microbiology, 56(2). e01588-17. https://doi.org/10.1128/JCM.01588-17