The seemingly inexorable rise and spread of drug-resistant Candida auris continues in the United States, with the fungus establishing an endemic presence in some areas, accompanied by an increase in pan-resistant isolates. Concerningly, it has spread to 17 new states since 2019. The Centers for Disease Control and Prevention (CDC) reported that clinical infections increased 59% in 2020, then nearly doubled in 2021 with a 95% jump.1
Even though half of states have not had a reported case, C. auris is taking on an inevitability that suggests it might become endemic in the United States.
“I think it’s still to be determined,” says Megan Lyman, MD, the lead author of the CDC paper and a medical officer in the agency’s mycotic diseases branch. “There are definitely areas where it is much more common, but I think there’s still a lot to do to prevent spread. Even if you’re not able to eliminate it, you want to decrease the number of cases as much as possible, because each one of those patients who becomes colonized could develop an infection or spread to somebody else.”
In the CDC study, Lyman and colleagues found “ongoing transmission within and across healthcare facilities connected via patient transfers. Healthcare transmission is responsible for most, if not all, cases.”
Although there have been outbreaks in acute care hospitals, most of the C. auris cases are in high-acuity post-acute care facilities, specifically long-term acute care (LTAC) hospitals and ventilator-capable skilled-nursing facilities.
“C. auris cases tend to occur in patients who have multiple or prolonged healthcare encounters or indwelling devices, including those receiving mechanical ventilation,” the CDC noted. The disruption of the COVID-19 pandemic certainly can be credited with some, if not most, of the increase, but there also is the expectation that there were C. auris cases going unreported during the chaos of 2020 and 2021. In other words, C. auris is continuing to spread, and the increasing cases likely represent an undercount.
“Focus on COVID-19 precautions seems to have occurred in some facilities at the expense of proper implementation of standard and contact precautions and environmental disinfection needed to reduce transmission of C. auris and other MDROs (multidrug-resistant organisms),” the CDC reported.
Again, hospitals have transmission and outbreaks of C. auris, but they seem much less likely to become de facto reservoirs of the fungal pathogen like post-acute and long-term care sites. For example, an outbreak at a Central Mississippi LTAC that started in November 2022 spread out to other healthcare facilities.
“Ongoing transmission among residents within a central Mississippi LTAC is occurring, accounting for four cases of invasive infection of C. auris, with two deaths, and 28 cases of C. auris colonization,” the Mississippi State Department of Health (MSDH) reported.2 “This is a rapidly expanding and serious situation; additional cases of invasive infection and colonization may be identified. The MSDH continues to work with impacted facilities to provide infection control guidance and support surveillance and contact screening.”
A request for an update on the outbreak had not resulted in a response by the MSDH as this report was filed.
Focus on Long-Term Care
Interventions against C. auris should be prioritized in long-term care and post-acute settings, says Pat Jackson, RN, BSN, CIC, president of the Association for Professionals in Infection Control and Epidemiology (APIC)
“There really have not been major outbreaks in acute care, so I think the focus needs to be in these long-term care settings,” she says. “They haven’t been given the infection control resources that they need. This seems to be a common issue that keeps rising up — we are concerned about long-term care. During the pandemic, 40% of the COVID deaths were in long-term care.”
Although federal requirements call for a part-time infection preventionist in long-term care, these positions may be diluted by other duties, let alone all the other infections that must be dealt with, Jackson says.
“APIC continues to recommend dedicated, full-time, trained infection preventionists in long-term care,” she says.
Acute care hospitals must be vigilant about C. auris introductions, and they are the facilities best positioned on the healthcare continuum to pick up community and long-term care cases, Lyman says.
“Acute care hospitals have an important role in detecting what’s happening in their community because so many patients are being directed to them,” she says. “They see what’s going on in the community and they may detect nursing home outbreaks. If they’re seeing a lot of cases that are picked up that are coming from specific facilities, that may point to an outbreak that nobody knows is occurring."
C. auris became a nationally notifiable condition in 2019 and infections should be reported to the state or local health department and to the CDC at [email protected]. Jackson recommends getting the Centers for Medicare and Medicaid Services (CMS) involved to mandate reporting and to get the attention of the C-suite. The public health reporting probably only reflects the tip of the iceberg, she says.
The primary challenge for hospitals is identifying C. auris cases as soon as possible to get patients into isolation and prevent transmission. The fungus can be misidentified as other Candida species without high-level lab capabilities.
“If you are in a smaller community hospital like me, your automated systems might not be able to identify this or it might identify it incorrectly,” Jackson says. “If we get any species of Candida that can misidentified as C. auris, we send it out for verification."
Some hospitals have put in protocols calling for colonization screening on all patients being admitted from nursing homes, she adds. The turnaround time for colonization results is somewhat resource- and laboratory-access dependent, but one study reported colonization results within 48 hours of polymerase chain reaction testing.3 In any case, suspected C. auris cases should be put in empiric isolation with contact precautions until the results of testing are known.
First U.S. Infection in 2013
Initially identified in Japan in 2009, the first case of
C. auris occurred in the United States in 2013 and was described in a CDC report of the first seven cases in the country.
4
The fungus can cause a variety of healthcare-associated infections (HAIs), with mortality rates in the 30% to 60% range. Some have pointed out that the mortality rate is in line with other multidrug-resistant bacteria, suggesting that the
C. auris threat has been overstated.
5
But there are good reasons why C. auris is the first fungus to be rated an “urgent threat” — the CDC’s highest-level warning for pathogenic microbes. In the threat report, with a mix of wonder and horror, the CDC recalled the moment it realized what it was dealing with: “It seemed hard to believe. CDC fungal experts had never received a report describing a Candida infection resistant to all antifungal medications, let alone Candida that spreads easily between patients.”6
Likewise, the World Health Organization gave C. auris its highest threat rating of “critical” in a list of fungal priority pathogens, saying it can cause “serious nosocomial infections that especially affect critically ill and immunocompromised patients, such as cancer or bone marrow and organ transplant patients.”7
This is the result, in part, of increasing resistance to the few fungal drugs available, and an asymptomatic colonization state that still requires patient isolation because C. auris is transmissible from the skin of these carriers. There is no established decolonization protocol, though some infection preventionists have tried daily chlorhexidine baths to reduce skin shedding.
In that regard, C. auris can persist in the environment for prolonged periods in the absence of strong disinfectants, spreads on fomites, and sheds from the skin of colonized patients. Since typical hospital disinfectants may be ineffective, the Environmental Protection Agency (EPA) has a list of products that will kill C. auris, including hydrogen peroxide and peracetic acid.8
“Because C. auris colonizes the skin and patients shed into their environment, we’re seeing a lot — especially on bed rails, but also on surfaces that are not high-touch surfaces,” Lyman says. “We’ve often found it on mobile equipment, and we think that is one of the ways that it spreads so easily, because it can persist on surfaces for weeks. We have found that it’s not just roommates who get it; everyone in an entire unit is at risk. Part of the reason is because of shared medical equipment or staff. We have found it on glucometers, Hoyer lifts, and vitals monitors.”
Multidrug Resistance
In the CDC paper, Lyman and colleagues found that 3,270 clinical cases and 7,413 colonizations of C. auris were reported in the United States through 2019 to the end of 2021.
The percentage increase in clinical cases grew each year, and the number of C. auris cases that were pan-resistant to echinocandins in 2021 was about three times that in each of the previous two years.
With echinocandins the bulwark drug against C. auris, resistance to it compounds the problems seen in the other two main antifungal agents. Most C. auris is resistant to fluconazole, and amphotericin B has a lot of side effects and toxicity, Lyman says.
Isolates that are resistant to all three antifungal classes are considered to be pan-resistant.
“Before 2020, four patients with pan-resistant isolates and six others with echinocandin-resistant isolates had been reported in the United States, but it appeared they developed resistance during echinocandin treatment and had no epidemiologic links to other resistant cases,” the CDC reported.9
However, outbreaks in 2021 revealed cases of pan resistance and echinocandin resistance acquired through transmission. This dashed any hope that pan-resistant strains would not spread as easily, since bacterial pathogens sometimes acquire resistance at the expense of transmissibility.
“We thought that maybe these resistant strains were not as transmissible,” Lyman says. “Then, when we saw these cultures, we saw that resistant strains could be acquired by people who had never been on echinocandins. It opens up a whole population of people who are susceptible to getting these difficult-to-treat infections.”
Fortunately, more antifungals are in the pipeline, and fungi in general are having a pop culture moment, increasing public interest, and possibly generating more research funding. (See “Fungi: Pop Culture Darling a Future Pandemic Threat.”)
Although the actual numbers are relatively small in the COVID-19 era — about 10,500 cases and colonized patients from 2019-2021 — there is so much fear about C. auris getting into healthcare facilities that some are reportedly not admitting transferred patients infected or colonized with the fungus. An infection preventionist who described a C. auris outbreak at the 2022 APIC conference used a bright yellow transfer sheet to make the process more transparent.
“Once you have
C. auris colonization, it’s going to be difficult to discharge that patient,” says
Claudia Skinner, DNP, RN, CIC, a senior infection preventionist at Jude Medical Center in Yorba Linda, CA. “Many facilities are extremely hesitant to take patients who require this long-term isolation. Any time they’re readmitted to a facility, they should be placed back into contact isolation.” (
See Hospital Infection Control & Prevention, August 2022.)
The CDC is aware of this trend and stresses that admitting a C. auris case does not an outbreak make.
“Facilities should be able to care for a patient who has C. auris,” Lyman says. “The same precautions are used for other MDROs and C. diff. If you can take of patients with those, you can take care of a patient with C. auris. It is a little frustrating to hear that, but there are lots of facilities thinking it’s inevitable if they accept a patient that there’s going to be spread and an outbreak. But there are lots of facilities that have had a case and not had any spread.”
REFERENCES
- Lyman M, Forsberg K, Sexton JD, et al. Worsening spread of Candida auris in the United States, 2019 to 2021. Ann Intern Med 2023;Mar 21. doi:10.7326/M22-3469. [Online ahead of print].
- Mississippi State Health Department. Mississippi Candida auris Update, January 11, 2023. https://msdh.ms.gov/page/resources/19564.pdf
- de St. Maurice A, Parti U, Anikst VE, et al. Clinical, microbiological, and genomic characteristics of clade-III Candida auris colonization and infection in southern California, 2019-2022. Infect Control Hosp Epidemiol 2022;Sep 2:1-9. doi: 10.1017/ice.2022.204. [Online ahead of print].
- Vallabhaneni S, Kallen A, Tsay S, et al. Investigation of the first seven reported cases of Candida auris, a globally emerging invasive, multidrug-resistant fungus — United States, May 2013-August 2016. MMWR Morb Mortal Wkly Rep 2016;65:1234-1237.
- Chen J, Tian S, Han X, et al. Is the superbug fungus really so scary? A systematic review and meta-analysis of global epidemiology and mortality of Candida auris. BMC Infect Dis 2020;20:827.
- Centers for Disease Control and Prevention. Antibiotic resistance threats in the United States 2019. Revised December 2019. https://www.cdc.gov/drugresistance/pdf/threats-report/2019-ar-threats-report-508.pdf
- World Health Organization. WHO fungal priority pathogens list to guide research, development and public health action. Published Oct. 25, 2022. https://www.who.int/publications/i/item/9789240060241
- United States Environmental Protection Agency. List P: Antimicrobial products registered with EPA for claims against Candida auris. Updated Feb. 2, 2023. https://www.epa.gov/pesticide-registration/list-p-antimicrobial-products-registered-epa-claims-against-candida-auris
- Lyman M, Forsberg K, Reuben J, et al. Notes from the field: Transmission of pan-resistant and echinocandin-resistant Candida auris in health care facilities – Texas and the District of Columbia, January-April 2021. MMWR Morb Mortal Wkly Rep 2021;70:1022-1023.
