Fungal ‘superbug’ drug-resistant Candida auris has been identified by the Centres for Disease Control and Prevention (CDC) as a ‘serious threat to global health’ following a startling increase in the number of infection cases that do not respond to treatment over recent years.
Candida is most notably associated with thrush, which although not life-threatening, affects at least 135 million individuals world-wide1. The infection can however be lethal to people with immature or compromised immune systems, including new-borns and the elderly, smokers, diabetics and people with autoimmune disorders. This invasive C.auris infection can infect the bloodstream, where it manifests as sepsis, the central nervous system and internal organs.
For decades now, public health experts have warned of the overuse of antibiotics, but lately there has been an increase in the number fungal ‘superbugs’ that are resistant to antifungal treatments. It is understood that these C.auris strains are almost universally resistant to fluconazole, with 30% resistant to two or more of the four main classes of existing antifungals.2 There is concern that doctors may even be promoting development of resistance when prescribing antifungals as a preventative measure for patients who have received an organ transplant or are undergoing chemotherapy.
The first case of C.auris infection was noted in Japan in 2009 and since this time, at least 1100 incidences have been confirmed across more than twenty countries including the US, Spain, India and the UK. Despite these numbers however, it is thought that the prevalence of the infection has in fact been underestimated due to difficulties in identifying the fungus.
Misidentification is just one of the reasons why C.auris infection is a widespread problem. The fungus mimics other common fungi of the Candida genus, meaning that the patients’ symptoms are often managed inapproprately or that proper diagnosis is significantly delayed.3
In addition, unlike most other fungal pathogens which die once outside the human body, C.auris is able to survive beyond the death of its host on a range of surfaces such as those in hospitals and long-term care facilities for a number of days. Such intractable spread was demonstrated in 2016 when The Royal Brompton Hospital, UK was forced to close its ICU for two weeks following an outbreak of fifty C.auris cases. Thirteen of the patients were actually infected with the fungus, some of whom presented with candidaemia. Three out of the thirteen infected patients died due to multi-organ failure, though it was impossible to prove whether the infection contributed to the deaths. Environmental tests on the ICU following the outbreak demonstrated persistent presence of the fungus in the air, floors, beds, equipment monitors, trollies, radiators and window sills, despite normal cleaning procedures.4
Around this time last year, following the death of an infected patient at the Brooklyn branch of Mount Sinai Hospital, environmental tests showed presence of the fungus everywhere in the patient’s room, which required special cleaning equipment and even removal of some of the ceiling and floor tiles in order to eradicate it.5 It is believed that prolonged outbreak of the infection is likely to be due to low level environmental contamination and that high strength chlorine based agents and hydrogen peroxide vaporisation are required for reducing the presence of C.auris in the surrounding environment.
In order to control the rising impacts of resistant fungal infections clinicians will need to maintain vigilance, and significant investment will need to be made into better methods for early and more cost effective detection, new anti-fungal treatments and coordinated infection control measures. Widespread efforts to curb the emergence of new resistant strains including the judicious use of antifungals both in human health and agriculture, similar to those used for antibiotics, must be adopted.
1. The Fungal Infection Trust. How common are fungal diseases? Fungal Research Trust 20th Anniversary meeting. London June 18th 2011, updated August 2017.
2. Alfouzan, W. Dhar, R. Albarrag, A. Al-Abdely, H. The emerging pathogen Candida auris: A focus on the Middle-Eastern countries. Journal of Infection and Public Health. [Epub ahead of print] 2019. Available from: https://doi.org/10.1016/j.jiph.2019.03.009
3. Bidaud, A.L. Chowdhary, A. Dannaoui, E. Candida auris: An emerging drug resistant yeast – A mini-review. Journal de Mycologie Médicale. 2018;28(3): 568-573. Available from: https://doi.org/10.1016/j.mycmed.2018.06.007
4. Schelenz, S. Hagen, F. Rhodes, J.L. Abdolrasouli, A. Chowdhary, A. Hall, A. Ryan, L. Shackleton, J. Trimlett, R. Meis, J.F. Armstrong-James, D. Fisher, M.C. First hospital outbreak of the globally emerging Candida auris in a European hospital. Antimicrobial Resistance & Infection Control. 2016;5: 35. Available from: https://doi.org/10.1186/s13756-016-0132-5
5. The New York Times. A Mysterious Infection, Spanning the Globe in a Climate of Secrecy. Available from: https://www.nytimes.com/2019/04/06/health/drug-resistant-candida-auris.html [Accessed 02/05/2019]