August 15, 2017

What is Candida auris? Understanding this bug, how it is spread and how to avoid it

First published 15.08.17; Edited and republished 00.00.00

Candida, which is a type of yeast, is an uncommon type of fungus that can cause a range of illnesses. Healthcare facilities in several countries have reported that a type of Candida called Candida auris has been causing severe illness in hospitalized patients.

What is Candida auris?

Candida auris is an emerging fungal pathogen – a yeast species first isolated from the external ear of a patient in Japan in 2009. Retrospective review of Candida strain collections found that the earliest known strain of C. auris dates to 1996 in South Korea.

Health authorities consider C. auris an emerging pathogen because increasing numbers of infections have been identified in multiple countries since it was recognized.

What countries have been infected?

Infections, including candidaemia, caused by C. auris have been reported from over a dozen countries, including Canada, Colombia, Germany, India, Israel, Japan, Kenya, Kuwait, Norway, Pakistan, Spain, South Africa, South Korea, the United Kingdom, and Venezuela, as well as the United States. With hospital outbreaks confirmed in 5 of these countries; C. auris appears to be unlike other pathogenic yeast species in its propensity for transmission between hospital patients.

Because identification of C. auris requires specialized laboratory methods, infections likely have occurred in other countries but have not been identified or reported.

Who is at risk for infection from C. auris?

To date, it has mainly been seen in hospital patients. Infections have been found in patients of all ages, from preterm infants to the elderly.

Limited data suggest that the risk factors for Candida auris infections are generally similar to risk factors for other types of Candida infections. These risk factors include recent surgery, diabetes, broad-spectrum antibiotic and antifungal use. People who have recently spent time in nursing homes and have lines and tubes that go into their body (such as breathing tubes, feeding tubes and central venous catheters), seem to be at highest risk for C. auris infection. Further study is needed to learn more about risk factors for C. auris infection.

How is it transmitted?

The fungus is usually picked up from surfaces or from skin.

The precise mode of transmission within the healthcare environment is not known. However, experience during previous outbreaks suggests that C. auris might substantially contaminate the environment of rooms of colonised or infected patients.

Transmission directly from fomites (such as blood pressure cuffs, stethoscopes and other equipment in contact with the patient) is a particular risk, however this does not preclude transmission via hands of healthcare workers.

What are the symptoms?

In some cases patients can have no symptoms. However, C. auris can lead to bloodstream infections, wound infections, and otitis (ear infections).

It has also been cultured from urine and the respiratory tract, although it is not known if positive cultures from these sites represent infections or colonisations.

Candida is in itself a normal fungus which can be found in various places in the body, most notably as thrush. When that happens, it’s a nuisance but it’s not life-threatening. It becomes life-threatening when it is infecting patients whose immune system is compromised.

How is C. auris infection diagnosed?

Like other Candida infections, C. auris infections are usually diagnosed by fungal culture of blood or other body fluids. However, C. auris is harder to identify from cultures than other, more common types of Candida. For example, it can be confused with other types of yeasts, particularly Candida haemulonii. Special laboratory tests are needed to identify C. auris.

Can it be treated?

Resistance to fluconazole was common in isolates internationally and in all those isolated to date from the UK. Most C. auris infections are treatable with a class of antifungal drugs called echinocandins. However, many of the fungus have shown resistance to all the three main classes of antifungal drugs (azoles, echinocandins and polyenes) making it extremely difficult to treat, and side-effects of treatment are common.

Difficulty in treating arises, not only because of resistance and the heavily toxic treatment, but also because the patients who have been infected are usually already so ill. However, like mentioned above, some patients have been treated successfully with echinocandins.

Expert advice on countering spread

As this species can evolve rapidly to develop resistance, susceptibility testing is recommended on all isolates from invasive disease and should be repeated on later isolates if infection persists despite treatment.

Also read: More articles on infectious diseases

1). Centers for Disease Control: General Information about Candida auris - Fungal diseases. Accessed 15.08.17. Available here: https://www.cdc.gov/fungal/diseases/candidiasis/candida-auris-qanda.html
2). Public Health England: Candida auris - Infectious diseases. Accessed 15.08.17. Available here: https://www.gov.uk/government/collections/candida-auris

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