MSGERC Grand Rounds Webinar Series

Q & A Section for C auris Webinar

Below are answers to questions submitted during the webinar.

1. Can we rely on YeastOne for AFST for C auris?

Dr. Meghan Lyman: Yes.

2. For the patients who developed pan-resistance while on therapy, how long were they treated prior to developing resistance? Were they all treated with echinocandins alone?

Dr. Meghan Lyman: There is not great data on this and often patients were not being tested routinely to identify when resistance developed. But hopefully, we will start to learn more about the development of echinocandin resistance in patients on treatment.

More details about the first three cases can be found here: https://www.cdc.gov/mmwr/volumes/69/wr/mm6901a2.htm

3. Are there cases of long-term C auris infections?

Dr. Meghan Lyman: Patients can remain colonized for a very long time, even years. But we don’t have great information/data about patient outcomes for infections of C auris.

4. Why does C auris occur more frequently in patients treated with antibiotics?

Dr. Meghan Lyman: We don’t know for sure, but antibiotics could affect their microbiome and kill bacteria (and maybe other microbes like fungi), allowing a clean slate for C auris to grow and take over.

5. Is there any notable difference in the pathogenicity between clades circulating in the US?

Dr. Meghan Lyman: There is no national outcome data or data comparing outcomes between clades, so we don’t know, but no signals that we’ve noted so far.

6. Do you have any epidemiological information about C auris from Europe?

Dr. Meghan Lyman: Here is a recent report about the increase in cases/outbreaks in Europe:

https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2022.27.46.2200846

7. As some hospitals use urine samples for screening of patients going into ICUs, do colonized patients shed C auris in urine?

Dr. Meghan Lyman: C auris can be found in urine, but we don’t know how sensitive or specific urine samples are for identifying colonized patients (compared to axilla/groin skin swabs).

8. Are there any multi-institutional epidemiological surveillance studies? I expect that the prevalence should be higher in highly immunosuppressed cancer patients with altered microbiomes, but we don’t have a surveillance policy yet despite many of our patients are international.

Dr. Meghan Lyman: C auris is nationally notifiable although there is not great surveillance data provided to CDC about risk factors. However, anecdotally, we do not hear about C auris cases or outbreaks being more common among patients with typical immunocompromising conditions, like transplant, malignancy, or chemo. However, patients with C auris often are very ill and have different underlying conditions/risk factors (like invasive medical devices, broad spectrum antimicrobials, etc) that may impact their immune system and microbiome.

9. What breakpoint is considered for C auris AFT for MIC values?

Dr. Meghan Lyman: There are currently no established C auris-specific susceptibility breakpoints. Therefore, tentative breakpoints have been defined based on those established for closely related Candida species and on expert opinion. The correlation between microbiologic breakpoints and clinical outcomes is not known at this time.

You can find the tentative breakpoints here:  https://www.cdc.gov/fungal/candida-auris/c-auris-antifungal.html

10. For screening purposes, which site of collection is better, axilla/groin or rectal swab?

Dr. Meghan Lyman: CDC currently recommends screening for C auris colonization using a composite swab of the patient’s bilateral axilla and groin. Available data suggest that these sites are the most common and consistent sites of colonization, but C auris can colonize other body sites and research continues to evaluate other body sites for use in screening.

11. Should organ procurement sites screen for C auris in potential donors?

Dr. Meghan Lyman: A donor-derived infection caused by C auris has been reported related to a lung transplant: https://academic.oup.com/cid/article/65/6/1040/3830200. However, there are no official recommendations at this time and it might depend on the local prevalence and risk factors of the donor.

12. Does C auris look like Candida albicans? How does it differ morphologically?

Dr. Meghan Lyman: They cannot be distinguished from one another morphologically. CHROMagar can be used to identify the phenotypic differences between the species. Candida albicans can also be distinguished from C auris using the germ tube test.

13. What is the hit rate of invasive disease versus colonization?

Dr. Meghan Lyman: Our surveillance shows that 5-10% of colonized individuals have a positive clinical specimen and about half of those are from invasive specimens. But these estimates can vary based on the amount of screening conducted and amount of screening cases detected.

14. What is the mechanism of echinocandin resistance in C auris? Does it relate to epigenetics or are there any mutations between resistant and non-resistant strains? Also, which clade is the resistant strain more likely from?

Dr. Meghan Lyman: Mutation in the FKS gene is the most common mutation associated with echinocandin resistance. Echinocandin resistance has been identified among multiple clades, including all three of the major clades circulating in the US.

15. Does C auris disseminate in organs other than kidneys?

Dr. Meghan Lyman: Bloodstream infections are the most common cause of invasive infection, but infection of other invasive sites or organs is possible.

Speakers