One of the most disturbing features of C auris is that, in its relatively short life, it has rapidly developed resistance to the few available treatment options.
What’s the most important thing to know about Candida auris today? Mainly that it’s a clear present and future danger. The Centers for Disease Control and Prevention (CDC) classifies
C auris as an “urgent threat”—the highest level of concern.1 C auris is 1 of only 5 pathogens to fall into that category, and it is the first fungal pathogen.2
“C auris is a public health concern due to high rates of antifungal resistance and a unique ability to spread easily and cause outbreaks in health care settings, especially long-term care facilities,” said Joe Sexton, acting laboratory team lead at the CDC’s mycotic diseases branch, in an interview with Infection Control Today®. “It’s a high priority not only for our group but also at the agency as a whole.”
According to the CDC’s tracking, the cumulative number of C auris cases so far this year is 161. In 2020, the cumulative total was 178, so it’s likely that 2021 will surpass that number.3 The number of clinical cases may seem small, but add to that the nearly 3000 people who have been identified through screening as colonized with the extremely transmissible fungus.4
C auris was first reported in 2009, although retrospective review suggests earlier strains date to 1996. One of the most disturbing features of C auris is that, in its relatively short life, it has rapidly developed resistance to the few available treatment options. Approximately 85% of C auris isolates in the US are resistant to azoles, 33% to amphotericin B, and 1% to echinocandins—making echinocandins critical.5 But since 2019, cases of “pan-resistance” have been appearing; that is, patients for whom echinocandins don’t work. CDC investigators reported on 5 cases (3 in Washington, DC, and 2 in Texas). All 5 were clustered within facilities. Perplexingly, none of the patients had been treated with antifungal drugs prior to the diagnosis, which is a first, according to the investigators.5
Worrisome as it is, C auris incidence has taken a back seat to the COVID-19 pandemic, like many health care concerns. “News about C auris outbreaks has been overshadowed over the past year and a half by coverage of COVID-19,” said Cornelius (Neil) Clancy, MD, an associate professor of medicine and director of the mycology program at the University of Pittsburgh. “However, it hasn’t gone away, and the threat it poses worldwide to health care systems, long-term care facilities, and the public health has not diminished.”
Clancy said it’s hard to know precisely how the pandemic has affected the incidence of C auris infections. “What is clear, however, is that outbreaks of infections, including C auris outbreaks and increased incidence of health care-acquired infections, in general, are major features of the pandemic,” he said.
The pandemic has essentially put a match to a combustible situation. “We tend to see transmission and see cases among patients who are in these high-acuity, long-term care facilities…that have very sick patients, like ones who are on ventilators or have tracheostomy or other invasive medical devices,” said Meghan Lyman, MD, a medical officer in the CDC’s mycotic diseases branch and lead author on the study of pan-resistance, in an interview with STAT. “Getting COVID-19 and having these complications puts them at higher risk for acquiring C auris.”6
The synergy of COVID-19 plus C auris infections has added pressure to what health care facilities are dealing with. The infection prevention challenges likely stem from pressures the pandemic placed on infection preventionists (IPs) and health care resources and personnel, Clancy said. “Even under the best of circumstances, IP teams typically operate at the extremes of their capacity. When an unprecedented public health challenge like COVID-19 emerges, there is limited overflow capacity, and attention and resources normally given to routine IP practices run the risk of being diverted. Moreover, staff become overwhelmed and fatigued, which makes adherence to strict IP practices more difficult to sustain,” he said.
Not only that, “many COVID-19 patients, particularly those who are hospitalized, are at increased risk for secondary infections due to risk factors like [intravenous] lines, urinary catheters, and mechanical ventilation. With this background, facilities are vulnerable to C auris and other outbreaks,” Clancy said.
If it does arrive in a facility, it’s toward the top of the danger list, given the bad outcomes among infected patients, Clancy warned. Death is 1 of those possible outcomes. A systematic review of nearly 5000 cases worldwide reported an overall crude mortality rate of 39%.2 Among the patients with pan-resistance detailed in the CDC report, 30-day mortality in both outbreaks combined was 30%, although the relative contribution of C auris was unknown.5
Combating a C auris outbreak takes its toll throughout the facility. Eradicating, or simply controlling, outbreaks commands “massive and sustained IP efforts,” Clancy said. “Clearly, devoting these efforts is much more difficult with COVID-19 and the IP challenges imposed by the pandemic.”
“Unfortunately, we have seen increased spread of C auris during the pandemic. Typically, it’s most problematic in long-term care settings, which have also been heavily burdened by the pandemic. However, during the pandemic, we’ve seen outbreaks in COVID-19 specialty care units, ICUs, and other acute care settings where we typically don’t see spread of C auris,” Sexton said. He cites a case reported in the CDC’s Morbidity and Mortality Weekly Report: In July 2020, the Florida Department of Health was alerted to 3 C auris bloodstream infections and 1 urinary tract infection in 4 patients with COVID-19, who received care in the same dedicated COVID-19 unit of an acute care hospital.7
“We’ve also seen unusual cases pop up without epidemiologic links to other cases,” Sexton said. “Which tells us there is additional undetected transmission happening. The reasons for increased spread during the pandemic are not fully clear but may be related to changes in routine infection control practices.”
Donning and Doffing
In the CDC study of pan-resistance, the investigators observed multiple opportunities for contamination of the base layer of gowns and gloves during doffing and through direct contact with the patient care environment or potentially contaminated surfaces, such as mobile computers. Mobile computers and medical equipment were not always disinfected between uses, and medical supplies (eg, oxygen tubing and gauze) were stored in open bins in hallways and accessed by health care providers wearing the base personal protective equipment (PPE) layer. The investigators also observed missed opportunities for performing hand hygiene.
Those lapses likely contributed to widespread C auris transmission, the investigators concluded. After the hospital removed supplies from hallways, enhanced cleaning and disinfection practices, and ceased base PPE layer practices, the investigators detected no further C auris transmission on subsequent surveys.
Can we get a handle on C auris? At the moment, the answer is…possibly. “Our ability to respond to C auris has improved substantially,” Sexton said. “Due to enhanced diagnostic capacity, improved understanding of risk factors, and advancements in disinfectant and infection prevention and control [IPC] guidance.” And of course, increased awareness and adherence to essential IPC practices are also critical to improved control.
But the fact that the fungus continues to spread within and between facilities, as demonstrated by an increase in the number and geographic spread of cases in recent years, means “we need to improve our understanding of how colonization relates to environmental contamination, and how to disrupt transmission pathways,” Sexton said. Shedding from colonized patients’ skin into the health care environment (calculated to occur at a rate of a million microbes per hour) creates an environmental reservoir and source of ongoing nosocomial transmission, said the research team (including Sexton), who studied residents of a skilled nursing facility (SNF) with endemic C auris.
Investigators are coming up with a variety of plans of attack. At the CDC, Sexton’s group is actively engaged in numerous applied scientific studies, including collaborations with external partners and other government agencies, to improve public health guidance for C auris.
Twenty-five New Disinfectants
“In the beginning of 2019, there were still no hospital disinfectants approved for C auris, leaving a gap in practical guidance for health care facilities. We generated data in our laboratory, which reinforced concerns that many common disinfectants could not kill C auris. However, we also found several chemistries that worked quite well. We worked with the Environmental Protection Agency [EPA] to improve temporary guidance based on this data, which helped pave the way for the private sector to get engaged,” Sexton said. “Now, just 2 years later, over 25 hospital disinfectants have been approved specifically for C auris, giving health care facilities a wide selection of products they can be confident are effective.” The EPA has organized these approved products into an easy-to-use reference, “List P,” which is regularly updated.8
When people are colonized with C auris, they can spread the fungus to others while not getting an active infection. However, about 5% to 10% of those carrying C auris will go on to have invasive infections later, according to the CDC investigators. The CDC is actively pursuing studies that add to the understanding of colonization patterns and the positive relationship between skin colonization burden and environmental contamination. For instance, data from the SNF study suggest “highly personalized patterns” of C auris skin colonization.2 The site-to-site variability in colonization limits infection control strategies predicated on targeting only patients known to be colonized, the investigators said. Facility or unit-wide infection control approaches may be more effective.
At the University of Pittsburgh, Clancy said, “We are not researching C auris per se in the lab, but we do a lot of work on antifungal resistance among Candida species. Of course, antifungal resistance is a hallmark feature of C auris. Antifungal resistance, poor outcomes among infected patients, capacity for nosocomial spread, and environmental persistence are the constellation of features that make C auris a major threat. We also do whole genome sequencing of Candida clinical strains from our health care system, so we are confident we will identify any strains, should they arrive, and that we have not missed any strains in the past.”
Much to Learn
Both Clancy and Sexton stress we still have a lot to learn about how C auris spreads and how to stop transmission. “Raising awareness about C auris is critical because early detection is key to control,” Sexton said. He also noted that the CDC made resources publicly available on its website that provide useful information and guidance for patients, health care providers, public health professionals, laboratorians, and more.
“If C auris has not arrived, then there is potential for danger if it does arrive. Facilities need to have detailed plans in place to detect and respond promptly, and IP programs, the clinical microbiology lab, and other services need to maintain vigilance,” Clancy said.
“We’re really encouraging health departments and facilities to be more proactive instead of reactive to identifying Candida auris in general,” Lyman told STAT. “We’ve found that controlling the situation and containing spread is easiest when it’s identified early before there’s widespread transmission.”
Jan Dyer is a writer and editor, specializing in clinical topics. She lives in Suffern, New York.