Emerging Candida auris Spreading in Healthcare Outbreaks
Fungus is epidemiologically similar to a ‘superbug’ bacteria
June 1, 2017
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By Gary Evans, Medical Writer
A multidrug-resistant fungus, emerging globally, has now infected more than 60 patients in the United States, spreading more like a bacterial “superbug” than fungi, the CDC reports.
Candida auris causes high mortality, can transmit to patients on the hands of healthcare workers, persists in the environment, and can colonize people who then serve as a reservoir for outbreaks.
C. auris was an extremely rare infection in the U.S. when the CDC issued an alert1 last year that it was causing healthcare-associated outbreaks with high mortality in several countries. It has now been reported in six states.
“We have 61 cases across the U.S., with 39 of those in New York,” says Sharon Tsay, MD, an investigator in the CDC’s Epidemic Intelligence Service (EIS). “We also have identified 32 additional people who are [colonized] with C. auris.”
As has been demonstrated with multiple pathogens, the ability to persist in a colonized state means patients with no symptoms of infection could serve as a reservoir for spread to vulnerable patient populations, particularly those on IVs and other invasive devices that could seed bloodstream infections. C. auris has caused high mortality in outbreaks that involved bloodstream infections.
“They are not infected, but we are concerned that they also may be spreading it,” Tsay tells Hospital Infection Control & Prevention. “In hospitals or long-term acute care hospitals [LTACHs] they could be a source for ongoing [transmission].”
In acute care hospitals, patients with C. auris infection or colonization should be placed in single rooms under standard and contact precautions. The CDC originally recommended cleaning rooms and environmental surfaces with an antifungal agent, but has upgraded that to advise the use of a disinfectant that is EPA-approved to kill that most persistent of spore-formers — Clostridium difficile. (See CDC recommendations, in this issue.) That revision speaks volumes about both the ability of C. auris to persist in the environment and the CDC’s concern that it could gain an endemic foothold in the U.S.
“We found that it exists in the environment in very high concentrations on beds and things closest to patients,” says Paige Armstrong, MD, a CDC EIS officer. “[It’s] even in the crevices and the corners of the room, meaning that we really need to focus on cleaning with the right [disinfectants] to kill this organism.”
Armstrong and Tsay were among several CDC investigators who reported on outbreaks of C. auris recently in Atlanta at the annual EIS conference.
“It has colonized people even after they were treated with anti-fungal medications — people still have it on their skin,” Armstrong says. “This is something that we don’t usually see with a fungus. These are things that we typically see with emerging or resistant bacteria.”
In addition, C. auris has the ability to develop resistance that is “very rare” in fungi, she says.
“There are only three main classes of antifungal medication,” Armstrong says. “So once you become resistant to all three of those, there’s very little that can be done. It’s causing outbreaks in hospitals, which again, is something we typically attribute to bacteria. This is an emerging multidrug-resistant fungus that is acting like a bacterium — it’s acting like a super bug.”
Evidence of Transmission
In addition to New York, C. auris has also infected patients in five other states, including 15 in New Jersey, four cases in Illinois, and one each in Indiana, Maryland, and Massachusetts.
In a look-back study, the CDC identified the first eight fungal infections with the emerging pathogen that occurred at six health healthcare facilities in New York from May 2013 to Oct. 2016.2 The patients had multiple indwelling devices, including urinary catheters, gastrostomy tubes, tracheostomy tubes, and central venous catheters. All had been in at least three healthcare facilities in the 90 days before the infection was diagnosed. Some had overlapping stays, raising the possibility of transmission. Three (38%) died within 28 days of diagnosis.
“A lot of these cases are in the sickest of the sick,” Tsay says.
Many of the C. auris isolates were highly related by whole genome sequencing and five were resistant to two antifungal drug classes, she reported. Three of four patients sampled had C. auris colonization in multiple body sites weeks after their first positive culture. The pathogen also was found in patient rooms and colonizing ward-mates. Inadequate contact precautions adherence was found at some long-term care facilities, Tsay concluded.
Strong evidence for transmission between patients was found in a C. auris outbreak in Chicago reported at the EIS meeting. “Nearly indistinguishable” C. auris strains were isolated from patients in the same ward of an LTACH,3 investigators reported. In August 2016, the Chicago Department of Public Health was notified of two patients with C. auris infections who were treated at the same acute care hospital and LTACH. CDC investigators analyzed isolates using whole genome sequencing.
“C. auris was isolated from Patient 1’s bloodstream in May and Patient 2’s urine in July,” the CDC investigators found. “These patients had three overlapping [hospital] admissions during March–July, but wards differed. In April, three days separated their hospitalizations on the same LTACH ward. In August, we detected C. auris colonization of the index patients’ skin, nares, vagina, and rectum. C. auris was present on the mattress, bed rail, chair, table, and window ledge surfaces in Patient 1’s hospital room.”
In addition, three of 50 LTACH patients hospitalized on the same ward as both index patients were colonized with C. auris. All patient isolates were highly genetically related. Fortunately, both patients survived.
Deadly Outbreak
Evidence of the devastation possible by C. auris as a healthcare-associated infection (HAI) was demonstrated in an outbreak in several neonatal ICUs in hospitals in Colombia in 2016. Armstrong was the lead CDC investigator and reported the findings at the EIS conference.
“We’re talking about babies that have just been born, at times premature, so some of the most vulnerable patients,” Armstrong says. “When we got word of this and heard that it was very difficult to contain [and] curtail, we immediately responded and went down to Colombia.”
Working with investigators from the Instituto Nacional de Salud, Colombia’s CDC equivalent, Armstrong and colleagues visited four hospitals in three different cities. They identified 40 cases of C. auris, and more than half of them died. The in-hospital mortality rate was 56%. Forty-five percent of patients were infants. All patients had a central venous catheter, two-thirds had recent surgery, and half received parenteral nutrition during their stay, she reported.4 C. auris was isolated from 44 (14%) of 325 environmental samples, including some from rooms that had not had a case-patient present for up to six months. Of the six patients sampled, C. auris was cultured from either the groin or axilla of four.
Another troubling finding was that two nurses’ hands yielded C. auris, suggesting the route of transmission was transient colonization from other patients or equipment and environmental surfaces. Nine (23%) of 40 isolates were resistant to fluconazole and seven (18%) of 40 were resistant to amphotericin B. All isolates were highly related by whole genome sequencing.
“In Colombia, we were able to establish key fundamental pieces of information about this new emerging fungus,” Armstrong says. “Those tell us that we really need to be careful about basic things like hand hygiene, making sure people that are touching one person that might have this fungus on them aren’t going on and touching someone [else] to potentially spread it. I think there’s probably more than one reservoir within the healthcare setting.”
First reported in 2009 in Japan, C. auris has now been identified in other parts of Asia, Africa, South America, and the United Kingdom.
“This fungus has now been reported in over a dozen countries worldwide,” Armstrong says. “One [concern] is that it’s affecting vulnerable populations. So, whether that be neonates, people in long-term care facilities, ICUs, or those that are already sick and may be receiving treatment for cancer — this infection can kill at very high rates.”
Unanswered Questions
At present, there are still more unknowns than knowns about C. auris, including whether it may spread in communities.
“We have a laundry list of questions we want to answer about this particular organism,” she says. “We’re working our way through them based on what we think are of the utmost priority and those that can impact the most, and save the most lives. As far as how it came into the healthcare system, that’s really a question of, ‘Is this something that exists in the community?’ That’s a question that we’re still trying to answer. Is this something, like other multidrug-resistant organisms, that does exist in the community and we’re just seeing it when people get sick from it in the healthcare setting? We don’t have a good answer to that quite yet.”
In addition to being multidrug-resistant, the emerging pathogen also is difficult to identify with standard laboratory methods, which can result in inappropriate treatment. With healthcare outbreaks a clear threat, rapid identification of C. auris in a hospitalized patient is critical to prevent subsequent transmission, the CDC emphasizes.5 The range of infections includes bloodstream, wound, and ear. Concerning the latter, the “auris” name comes from the Latin word for “ear.”
According to the CDC, risk factors include recent surgery, diabetes, broad-spectrum antibiotic and antifungal use, and central venous catheter placement. While the sporadic outbreaks thus far certainly underscore the emergence of C. auris, a recent commentary on the new pathogen did not mince words on the ultimate threat.
“The fear is that biologic and epidemiologic factors are aligned for more extensive, worldwide emergence and/or dissemination of C. auris infections,” the authors warned.6 “…If events come together, we could witness the fungal counterpart to the worldwide expansion of carbapenem-resistant Enterobacteriaceae (CRE).”
Two scenarios — which are not necessarily mutually exclusive — could result in a major global public health problem, they explained. On the one hand, various C. auris strains, particularly those resistant to antifungal drugs, could continue to emerge independently and spread clonally, they noted. On the other, in perhaps a more concerning scenario, a single predominant strain of multidrug-resistant C. auris could emerge, which is somewhat analogous to the virulent NAP1 strain that has made C. diff so difficult to control.
“Growing cohorts of colonized and infected patients in countries with large populations and far-reaching international diasporas attest to [this] feasibility,” the authors noted. “In troubling publications from India, C. auris already accounted for [more than] 5% of candidemia in a national survey of ICUs, and as much as 30% of candidemia at individual hospitals. Other properties of C. auris may contribute to this perfect storm, including difficulties in timely and definitive identification by commonly used commercial methods, intrinsic virulence … [and] the ability to cause lengthy outbreaks and possibly persist within hospital environments.”
While the use and overuse of antifungal agents may have selected out drug-resistant C. auris strains — the classic paradigm for antibiotic resistance — something else seems to be going on, the authors concluded.
“Antifungal selection is unlikely to be the sole determinant,” the note. “It is conceivable that changes to C. auris’ ecological niches have brought the fungus into greater contact with susceptible humans.”
REFERENCES
- Centers for Disease Control and Prevention. Global Emergence of Invasive Infections Caused by the Multidrug-Resistant Yeast Candida auris. June 24, 2016:
http://www.cdc.gov/fungal/diseases/candidiasis/candida-auris-alert.html - Tsay S, Poirot E, Chow N, et al. The First Eight Reported Cases of Candida auris, an Emerging, Multidrug-Resistant Yeast — New York, 2013–2016. CDC EIS Conference. Atlanta, April 24-27, 2017.
- Kerins JL, Kemble S, Pacilli M, et al. Evidence of Health Care Transmission of Candida auris: An Investigation of 2 Cases — Chicago, Illinois, 2016. CDC EIS Conference. Atlanta, April 24-27, 2017.
- Armstrong P, Escandon DH, Caceres N. Hospital-Associated Outbreaks of Multidrug-Resistant Candida auris — Multiple Cities, Colombia, 2016. CDC EIS Conference. Atlanta, April 24-27, 2017.
- CDC. Candida auris Interim Recommendations for Healthcare Facilities and Laboratories. Updated March 16, 2017: http://bit.ly/2qPFcOj
- Clancy CJ, Nguyen MH. Emergence of Candida auris: An International Call to Arms. Clin Infect Dis 2017;64;(2):141-143.
CDC Candida auris Infection Control Measures
Infection preventionists that see a case of Candida auris, an emerging fungal infection that can be multidrug-resistant, should take the following measures, as recommended by the CDC.1
Isolation: In acute care hospitals, patients with C. auris infection or colonization should be placed in single rooms under standard and contact precautions. The optimal duration for use of infection control precautions in healthcare is unclear since the typical duration of C. auris colonization is unknown. Periodic reassessments for presence of C. auris colonization (e.g., every 1–3 months) might be needed to inform duration of infection control measures.
Assessments of colonization should involve testing of axilla and groin swabs for C. auris. Two or more assessments performed at least one week apart with negative results are needed before discontinuing infection control precautions is considered. The patient or resident should not be on antifungal medications active against C. auris at the time of these assessments.
Environmental cleaning: The fungal pathogen can persist on surfaces in healthcare environments. Healthcare facilities that have patients with C. auris infection or colonization should ensure thorough daily and terminal cleaning and disinfection of these patients’ rooms. CDC recommends the use of an Environmental Protection Agency (EPA)-registered hospital-grade disinfectant effective against Clostridium difficile spores. This is a change from the original recommendation for use of an EPA disinfectant with an antifungal claim.
Nursing homes: Residents who are colonized or infected with C. auris should be housed in single rooms when available and placed on contact precautions. Residents do not need to be restricted to their rooms, but they should perform hand hygiene before exiting their rooms. If residents colonized or infected with C. auris use shared equipment (e.g., physical therapy equipment, recreational resources), items that residents handle extensively should be cleaned and disinfected after use.
Highly functional nursing home residents without wounds or indwelling medical devices (e.g., urinary and intravenous catheters and gastrostomy tubes) who can perform hand hygiene might be at lower risk of transmitting C. auris. Facilities may consider relaxing the requirement for contact precautions for these residents. However, in these instances, healthcare personnel should still use gowns and gloves when performing tasks that put them at higher risk of contaminating their hands or clothing. These tasks include changing wound dressings and linens, and assisting with bathing, toileting, and dressing in the morning and evening.
Transfer: When patients are transferred to other healthcare facilities, receiving facilities should receive notification of C. auris infection or colonization and the level of precautions recommended. In addition, state or local health authorities and CDC should be consulted about the need for additional interventions to prevent transmission.
REFERENCE
- CDC. Candida auris Interim Recommendations for Healthcare Facilities and Laboratories. Updated March 16, 2017: http://bit.ly/2qPFcOj
Candida auris causes high mortality, can transmit to patients on the hands of healthcare workers, persists in the environment, and can colonize people who then serve as a reservoir for outbreaks.
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