Q&A: 'Good old basics of infection control' critical when C. auris emerges

Key takeaways:

• Symptoms of Candida auris can be nonspecific, making diagnosis a challenge.
• It is most common in long-term health care facilities, but PCPs still play an important role in its detection.

Primary care providers can play an important part in Candida auris detection, according to an expert.

The CDC has labeled C. auris “an emerging fungus that presents a serious global health threat.” In the most recent data available, which represent the year 2022, the CDC reported 5,754 screening cases (patients who test positive for C. auris in a screening swab) of C. auris in the United States and 2,377 clinical cases (a new case found in a clinical specimen). California saw 359 clinical cases that year — the most of any state.

The CDC’s guidance on C. auris screening recommends using one swab on both the groin and armpit areas (where current data indicate that the most common sites of colonization are). According to the CDC, the decisions about whom to screen and how often “should be based on several factors,” including patient risk factors, the local C. auris burden and epidemiology, the purpose of screening and epidemiologic linkages to other cases.

The main challenge the fungus presents is in treatment. It is frequently antimicrobial resistant, according to the CDC. In some rare cases, C. auris has even become resistant to all classes of antifungals — in other words, it becomes untreatable.

Healio spoke with Tom M. Chiller, MD, MPHTM, chief of the CDC’s Mycotic Diseases Branch, to learn more about the role primary care providers play in C. auris detection and management.

Healio: C. auris has been primarily limited to health care settings, especially hospitals . Why should primary care providers be concerned about the disease?

Chiller: It's been, really, a disease of very high-risk individuals in longer term acute-care settings or skilled nursing facilities. In longer term care where there are very sick people who have chronic health issues, that's really where we were seeing this problem evolve and really develop here in the U.S. a number of years ago. We have subsequently had challenges in larger hospital settings, especially during COVID, when we were obviously very challenged with infection control practices for lots of other reasons, and we did see more C. auris cases in hospitals. But I like to say it’s a “heavily experienced patients in health care phenomenon,” for the most part, so far in this country.

What we don't understand is the role of community transmission. So, we know there's transmission within health care settings, and we know it can get on surfaces like bed rails and windowsills, and you can find it living on environmental surfaces for long periods of time, where it may transmit to other patients. Our big question is twofold. One is, “Where is it in the community in that environment?” And secondly, “Does it as readily colonize healthy people's skin as it does colonize those who are in these health care facilities, are on different medicines and are exposed to different treatments?” That's still somewhat of an unknown. I think we're trying to actively learn more about that.

So, I think for PCPs right now, for the most part, it's not something we're concerned about. They should be aware that it is a health care associated infection that is very resistant to current antifungals, which can cause bloodstream or deeper, more invasive infections in high-risk patients who are in these health care facilities. PCPs will often see people in follow-up, or they may see people who have chronic health problems who are in these facilities, and so I think it is going to be important for them to be aware that this is one of those organisms that can colonize the skin and can cause invasive infections if these people get sick.

Healio: C. auris can present like a bacterial infection, and symptoms are often nonspecific, making its identification that much harder. How can PCPs identify it or even suspect that a patient might be infected, much less colonized?

Chiller: I think you characterized that question absolutely correctly. It has sort of the nonspecific symptoms of someone with a bloodstream infection that could either be caused by a bacteria or, in this case, a fungus, or even other causes of fever and an illness, like a virus or even other diseases. So, it's one of those diseases that, if you suspect that a patient is sick in these health care settings, you would send a culture to the laboratory. The good news is that either a blood culture or a urine culture, if it had C. auris in it, it would most likely grow. It grows readily in our hospital laboratory identification systems. So, generally, it's going to be identified if you are simply evaluating a patient for those nonspecific symptoms, who was ill in a health care setting.

Healio: Can you walk us through the testing process?

Chiller: Absolutely. I think there are two different ways to think about testing. There's the way to think about testing in terms of if it's an invasive infection — like those hospitalized patients in ICUs or who are sick and then have fevers, and these nonspecific symptoms of someone with sepsis or septicemia — generally, blood cultures are going to be the key to diagnosis, and it will grow in those blood culture systems that are in hospitals. It also could grow in urine or you could get it to grow on other specimens that are taken from a patient.

But the other way in which we are diagnosing people who are colonized with it is by doing swabs of the skin. This is something different than the classic diagnostic test. Here, you're looking for, essentially, carriers, such as people who have it colonized on their skin. They may not be sick with C. auris, but we know that they have a higher risk to become sick from this organism and have it become an invasive infection if it is on their skin. So, especially if you are in a facility that has identified C. auris in that environment, there is a role for screening people and doing skin swabs, and then again, it can readily grow or one can do a polymerase chain reaction from those swabs to identify C. auris DNA.

Healio: C. auris is one of two nationally notifiable fungal diseases, the other being coccidioidomycosis, or valley fever. What is the protocol for reporting C. auris?

Chiller: C. auris has been made a nationally notifiable disease by the Council of State and Territorial Epidemiologists — the group that represents state public health organizations. They've made it a reportable disease so states can report it to that system, which will then come to us at CDC, where we can document that it is in that particular area. Of course, states always reserve the right — I mean, they judge what they want to report. So, even though it's nationally notifiable, it's really up to the state as to whether they want to report it to us.

Healio: If PCPs discover that a patient of theirs has C. auris and has come into contact with their facility, what are their next steps, if any?

Chiller: That's going to depend on obviously the level of their facility and is this patient visiting them as an outpatient? Is the PCP, for example, taking care of a patient that's in a nursing home or a longer term care facility? And certainly if a patient is colonized or has C. auris infection or a deeper infection, then you do need to be thinking about where that patient was in that health care facility and how you can disinfect the areas where that patient was in and keep that patient isolated from other patients so that they don't spread the infection. We do know that this infection spreads into the health care environment. And once you have a colonized patient in one of these environments, it can lead to other colonized patients, in which case there’s more risk to develop a more serious infection.

This is back to the basics of infection control. It's washing the hands, disinfecting surfaces, being careful to isolate patients when they're colonized, wearing personal protective equipment when interacting with the patient and just good old basics of infection control practices can make a huge difference for C. auris, just like it does for these other bacteria that are also commonly transmitted in this way.

Healio: What is the take-home message for PCPs?

Chiller: I think the important thing for all of us to know as physicians is that this is another highly resistant, invasive infection that can infect health care-experienced patients, can be readily transmitted in these health care facilities and is hard to treat when it's in the blood and when it becomes invasive.

We have limited antifungal medicines to begin with. We really only have three classes of drugs right now, so when you have an organism that is resistant to one, two or even all three of those drugs, it becomes very hard to treat if it indeed becomes invasive. So, I think our best strategy is to try to look for it in these facilities, then, if we find it, do our best infection control practices that we have available to us and certainly isolate those patients from others. And I think it's just important for us all to be aware of the growing number of these pathogens.

I think the other message would be that we don't generally think of Candida infections acting this way, so the best way to think of C. auris is it's a yeast that's acting like a bacteria. If we think of it that way, it helps us think how this infection can take hold, how challenging it is to control and the importance of infection control.

Healio: Is there anything else you would like to add?

Chiller: This is not a pathogen that I am worried about in healthy people, but I'm still wondering how much of a risk community transmission is, and that is something that is still unknown.

References:

• Candida auris 2023 case definition. https://ndc.services.cdc.gov/case-definitions/candida-auris-2023/. Accessed March 29, 2024.
• Screening for Candida auris colonization in healthcare settings. https://www.cdc.gov/fungal/candida-auris/c-auris-screening.html. Accessed March 27, 2024.
• Tracking Candida auris. https://www.cdc.gov/fungal/candida-auris/tracking-c-auris.html. Accessed March 27, 2024.