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Candida auris is difficult to identify with standard laboratory methods. It can be misidentified in labs without specific technology, which can lead to mismanagement.
In a study of 596 patients with coronavirus disease 2019 (COVID-19) who were admitted to an intensive care unit (ICU) in New Delhi earlier this year, 15 (2.5%) had bloodstream infections caused by the drug-resistant “superbug” Candida.1In 10 patients the predominant agent was Candida auris, while3 were infected with C. albicans, 1with C. tropicalis, and1with C. krusei. Two of the patients had hospital-acquired COVID-19.
Eight of the patients with candidemia died. That’s a death rate of 53%. Among those with C. auris, the death rate was 60%. “Of note,” the researchers say: 4patients who died experienced persistent fungemia and despite 5days of micafungin therapy, C. auris again grew in blood culture.
Data like those are why the US Centers for Disease Control and Prevention (CDC) calls Candida a “serious global health threat.” In a 2017 interview with STAT, Anne Schuchat, MD, then acting director of the CDC, called C. auris a “catastrophic threat” to society.2 At that point at least 61 patients had been diagnosed with C. auris infection; the count was soon to rise to 98.
Kevin Kavanagh, MD, a member of Infection Control Today®’s Editorial Advisory Board, says that drug resistant C. Auris is a dangerous pathogen, it first came to attention back in 2015. “Presently, it is known to be highly infectious and can cause dangerous co-infections,” says Kavanagh.”C. Auris co-infections do occur in COVID-19 patients and if present the case-fatality-rate is 60%.3C. Auris is a fungus not a bacteria and unfortunately there are few treatment options, with some strains becoming resistant to all of them.1
C. auris has been diagnosed in 40 countries since the first report about it in 2009, when clinicians found a single isolate from the discharge of the external ear canal of a 70-year-old inpatient at Tokyo Metropolitan Geriatric Hospital. By 2016, 13 cases had been identified in the United States, leading the CDC to issue interim recommendations, as well as a clinical alert, requesting laboratories to report cases and send samples to state and local health departments and the CDC.3
Cause for Concern
The CDC cites 3main reasons for concern about C. auris:
First is that it’s difficult to identify it with standard laboratory methods. It can be misidentified in labs without specific technology, which can lead to mismanagement.
Secondly, C. auris is often resistant to antifungal drugs used to treat Candida infections.
Third, importantly, it can cause outbreaks in hospital settings. C. auris outbreaks have resulted in mortality rates as high as 72%.4 Although C. albicans is the main agent of hospital-acquired fungal infections, C. auris in particular attacks patients with weakened immune systems, making it an even more serious concern when 8% to 9% of roughly 530,000 ICU patients in the United States have COVID-19.5
The CDC updates case counts monthly; the count as of this writing is 1272 clinical cases,5 based on cultures or culture-independent diagnostic testing from specimens collected during the course of clinical care. A targeted screening conducted as part of an effort to control the spread of C. auris turned up another 2493 patients found to be colonized with C. auris (patients may be carrying the fungus but not necessarily be sick with the infection).6
The problem has been on the rise and is complicated by the coincident pandemic. The California Department of Public Health (CDPH), for instance, issued a health advisory in August alerting healthcare providers to the increasing number of C. auris cases reported in southern California: The number of newly identified C. auris cases more than doubled from May to June. July cases (73) exceeded the combined total for April, May and June (59). According to the CDPH, personal protective equipment (PPE) conservation strategies and other containment practices on the basis of COVID-19 status alone “might be contributing to this resurgence.”7
In a study published in June, Chowdhary and Sharma3 point out that COVID-19 patients who are pre-colonized with C. auris and who require indwelling catheters have higher risks of C. auris–related bloodstream and urinary tract infections. It’s also important to emphasize, they say, that COVID-19 patients in the ICU tend to share risk factors, medications, and underlying comorbidities with C. auris infections, such as diabetes, chronic kidney disease, intubation, and administration of broad-spectrum antibiotics.4
Strains of C. auris in the United States have been linked to other parts of the world, the CDC says, “a result of inadvertent introduction.” Limited diagnostic capabilities in developing countries may mean under-recognition of fungal coinfections in patients with COVID-19. Chowdhary and Sharma called C. auris a “lurking scourge.” They warned the global medical community about the potential of C. auris as a confounding factor in COVID-19. They suggested that COVID-19 patient mortality might already have contributions from C. auris or other coinfections. A follow-up study, published in October, bore out their prediction.
Chowdhary et al1 say the patients in that study were probably infected while hospitalized, highlighting the fact that C. auris can be transmitted in healthcare settings just like other multidrug-resistant organisms (MDROs), such as methicillin-resistant Staphylococcus aureus (4patients also had bacteremia caused by Enterobacter cloacae and S. haemolyticus).
Despite upgraded infection control measures, they say, the pandemic may provide “ideal conditions” for outbreaks of C. auris in hospital ICUs. They point out that both C. auris and SARS-CoV-2 have been found on hospital surfaces, including air conditioner ducts, windows, and hospital floors. C. auris can survive on a wide range of surfaces, both dry and moist, for up to 14 days. Disinfectants with sporicidal activity and hydrogen peroxide-based products are the most successful, so far, at reducing C. auris colony-forming units, and chlorine-based detergents, ultraviolet light, and hydrogen peroxide vapor have been effective in environmental decontamination. But Coriegiani et al say the persistence of C. auris in the hospital environment despite disinfection procedures suggests “an involvement of the interaction between the pathogen and surfaces and the length of exposure to disinfectants.”8
Those researchers also cite evidence that C. auris is spread through exposure to contaminated facilities and transmission from healthcare personnel. Persistent outbreaks, they note, have been associated with hand transmission and contamination of surfaces. Positive samples have been collected even from surfaces with little to no patient contact and infrequent healthcare workers contact, such as door handles and alcohol gel dispensers. Thus, these researchers say, once C. auris is introduced in the hospital setting, environmental contamination “evolves well beyond the patient bedside.”
Candida is not only a health threat—it’s an economic one. Each case of candidemia results in an additional 3 to 13 days of hospitalization and costs between $6,000 and$29,000, according to the CDC.9 So until a more effective treatment for multidrug-resistant C. auris can be found, the best offense is a good defense.
One of the most remarkable features of C. auris is its sheer tough persistence. Patients and residents in healthcare facilities often remain colonized with C. auris for many months—“perhaps indefinitely,” the CDC says bleakly—even after acute infection has been treated and resolves. It can be shed into the environment and linger there for weeks, which makes infection control both an immediate and an ongoing issue.
To try to corral the fungus before it reaches vulnerable patients; the CDC recommends placing high-risk patients on preemptive contact precautions while awaiting screening results. The CDC says healthcare providers don’t need to be tested for C. auris unless they’re identified as a possible source of transmission to patients.
With regard to PPE, the CDC advises against reusing or extending use of gloves or gowns between patients with different or unknown C. auris or other MDROs and COVID-19. If PPE is in short supply, prioritize gown use for high-contact care activities and extend use of gowns only when patients are known to have the same infectious status and when those patients are housed in the same room. Healthcare providers should not continue to wear their gloves and gowns in the same hallway or other common areas—even in the designated COVID-19 unit.
Other means for keeping the counts down include putting patients in single rooms if possible; if not possible, a patient with both COVID-19 and C. auris should only be placed in the same room as another patient with COVID-19 and C. auris. Multiple patients with the same conditions can be placed together in 1wing or unit to reduce the direct movement of healthcare personnel and equipment from those colonized or infected with C. auris to those who are not.
To keep C. auris from turning into a nosocomial nightmare, stringent measures are called for, but sometimes even those aren’t enough. Infection control specialists at London’s Royal Brompton Hospital were thwarted by C. auris,which was on the rampage for 16 months in the ICU. Enhanced cleaning didn’t stop the spread, nor did segregating infected patients. In a last-ditch effort, the hospital temporarily shut the ICU. The outbreak finally ended—after 22 of 50 patients developed possible or proven C. auris infection, and9developed candidemia.9
In that study, colonization with C. auris was detected in <1% of healthcare personnel.
Colonization was transient on the hands and in the nostrils. However, the researchers learned some hard lessons about the fungus’ “innate resilience” during the outbreak. Despite the recommended daily chlorhexidine washes, they say, “patients continue to be colonized.” They cite other studies showing that hands can be key vectors in the transmission of Candida species via direct contact with patients or indirect contact with contaminated environment or equipment.
The Royal Brompton Hospital outbreak, in 2015-2016, was the first experience with the baffling “globally emerging” C. auris in a European hospital. Since then, epidemiologists and infection preventionists have learned more but, all in all, still don’t know enough about what promotes C. auris transmission to stop it. A variety of treatments are being posited, such as antimicrobial peptides. Until those candidates get past the first research stages, though, C. auris will remain a formidable foe.
JAN DYER is a writer and editor specializing in clinical topics. She lives in Suffern, New York.
JAN DYER is a writer and editor specializing in clinical topics. She lives in Suffern, New York.