Mixed Candida species growing on ChromID Candida 2 Agar - detail. Photo by Nathan Reading on Flickr (CC BY-NC-ND 2.0)

Candida auris and superbugs in Aotearoa – Expert Reaction

The antifungal-resistant yeast Candida auris has been detected in New Zealand, adding to the list of germs that can resist treatment by our currently available medications.

The World Health Organisation lists antimicrobial resistance as one of the top 10 public health threats facing humanity.

The SMC asked experts to comment on Candida auris and how it fits in the wider picture of antimicrobial resistance in NZ. 

Associate Professor Brent Seale, Food Science & Microbiology, AUT, comments:

“Antimicrobial resistance around the world is increasing. What’s alarming is that Candida auris is one of the first antifungal resistant fungi that have drawn attention in recent times. There’s a chance for it to be resistant to all three main classes of anti-fungals. So the World Health Organization and the CDC have moved this yeast up to their critical list of pathogens that they’re worried about.

“Antimicrobial-resistant micro-organisms are not new. Bacteria such as MRSA, methicillin resistant Staphylococcus aureus, which has been around for many years in both hospitals and in the community. A more recent example is extended-spectrum beta-lactamase producing E. coli, which is becoming more alarming. We are starting to see these bacteria leaving healthcare settings and showing up in the community around the world and in New Zealand. Currently we are only seeing Candida auris in hospital settings, but there’s a chance if it isn’t controlled that it could spread out into the wider community too. And so it’s being closely watched and precautions put in place to try to prevent that from happening.

“In general, we are not producing enough new antibiotics now to keep up with the rate of antimicrobial resistance. One of the reasons for that is because there’s not enough funding available around the world, let alone New Zealand to do the research. The drug companies don’t see it as an immediate moneymaker as well. There are many researchers around the world and in NZ trying to find new strategies to combat antibiotic resistance – for example trying to make some of the old antibiotics work again or finding new classes of antibiotics. But there needs to be a lot more research because in another 50 years time, these diseases that we’re hearing about now will become more common, and we will have even fewer antibiotics to fight them.”

No conflict of interest declared.

Dr Sally Roberts, Infectious Diseases Physician/Microbiologist at Auckland City Hospital, comments:

Candida auris is unique as it survives happily in the hospital environment, tolerates higher temperatures and it is not killed by some of the commonly used hospital grade disinfectants. It is also resistant to some of the antifungal agents used to treat these infections with. Its emergence does not appear to have been driven by excessive antifungal use. Most antifungal agent use in New Zealand is topical antifungals. The use of intravenous or oral treatment is limited to unwell patients in hospital. There is limited knowledge of antifungal use in the New Zealand horticultural industry. Use in this industry is reported to be associated with triazole resistance in other fungi but not linked to the emergence of C. auris.

“The trouble with Candida auris is that it’s highly adapted to the hospital environment, and survives very well on hard, dry surfaces. So if you’re a patient colonised with C. auris, wearing a hospital gown or touching the hard surfaces in your bed space with your hands, can transfer it from your skin to these hard surfaces. It’s not effectively killed by the usual hospital grade disinfectants. Hospitals have moved away from using bleach due to health and safety reasons, but they may have to bring it back out to combat this pathogen. There are other options, including peracetic acid wipes and vaporized hydrogen peroxide systems that are also very effective at killing C. auris. C. auris is one of those tedious pathogens, that if you don’t thoroughly clean the clinical environment, such as patients rooms, in the hospital, it can transfer from patient to patient very effectively.

“It’s different from other multi-antibiotic resistant germs, such as multi-drug resistant E. coli, which a greater cross section of the community may be exposed to, but we still have effective treatment options available. There is no known natural reservoir for C. auris and because it survives well in the hospital environment, it poses a significant risk for highly vulnerable patients in our hospital. Our skin is the one of our best defences against infection and if you breach the skin barrier by inserting a medical device, then pathogens can enter the body and cause disease. If C. auris invades the bloodstream, the risk of dying from that infection is very high. We want to avoid transmission of C. auris in haematology and oncology wards where central lines are in use for long periods of time. Neonatal units are another highly vulnerable patient group, and so are intensive care settings where patients might require multiple medical interventions and have long stays.

“Antimicrobial use drives resistance. However, most antimicrobial resistant pathogens of high concern are imported into New Zealand. They form part of the microbial flora of people who have travelled from, or to countries, where there are high rates of multi-drug resistant germs in the community. These bacteria reside happily on the person’s skin or in their gut and because the person is healthy they cause them no harm. This includes New Zealanders who have gone overseas for a holiday, or to visit friends and family, or for a medical procedure, or who have become unwell overseas and have spent time in a local hospital. They return to New Zealand colonised or infected with a multi-resistant bacteria. Over time they typically are replaced by less resistant bacteria. If you’re traveling overseas, hand hygiene is really important because a lot of the multi-antibiotic resistant germs are transmitted through eating contaminated food. Clean your hands regularly when travelling and importantly, before you eat.”

No conflict of interest declared.

Professor Kurt Krause, Infectious Diseases Physician; Professor of Biochemistry, University of Otago, comments:

“Candida auris, a medically significant yeast, was first identified in 2009 and is causing concern around the world for four reasons – 1) it causes serious infections – in fact, invasive infections involving the bloodstream, heart and brain have a mortality more than 30%, 2) it is commonly resistant to normal anti-fungal treatments with some strains highly resistant to all anti-fungals i.e. treatment can be challenging, 3) it is easy to mis-identify from cultures unless hospital laboratories are forewarned and 4) numbers, at least in the USA are booming – from a few hundred in years past to almost 6000 cases last year.

“The good news, if there is any good news about this tenacious and dangerous organism, is that is does not target healthy people and instead is a risk to those that are unfortunately quite ill, hospitalized, often in intensive care units (ICU) and long-term nursing facilities (LTNH). Therefore, it is very unlikely to cause a pandemic as fans of the streaming series, The Last of Us, have been wondering.

“The main risk to New Zealand seems to be if it becomes embedded in our ICUs and LTNH facilities. This risk is real because the yeast loves to live on human skin, particularly in sweat. It sheds prodigiously onto surfaces rapidly contaminating bed railings, window sills, doorknobs etc. and is easily transmitted from patient to patient. Once colonized it has proven difficult to decolonize people even long after they leave the hospital!

“Disinfecting rooms is something we know a lot about in the post-COVID-19 era but we may need to learn more. Turns out that some disinfectants e.g. chlorhexidine may be less effective versus C. auris while others – alcohol based, peroxide based – work well.

“The combination of easy colonization of people’s skin, difficult room decontamination, long term shedding of yeast even after discharge from the hospital can complicate elimination strategies. As a result, best practice emerging from overseas highlights the need to put a multi-disciplinary plan in place before C. auris is found at your hospital and that the team needs to include physicians, nurses, clinical microbiologists, infection control personnel and hospital decontamination personnel.”

No conflict of interest declared.