# P-1944. Previously Unrecognized Candida auris Gut Colonization in Critically Ill Patients

## TL;DR

This study finds that the drug-resistant fungus Candida auris can colonize the gut of ICU patients and may survive better in the gut environment than other Candida species.

## Contribution

The study identifies previously unrecognized gut colonization by Candida auris in ICU patients and reveals its resistance to bile acids, suggesting gut adaptation.

## Key findings

- Candida auris was detected in the gut of 2% of ICU patients and showed resistance to fluconazole.
- C. auris isolates from the gut were less inhibited by deoxycholic acid compared to C. albicans isolates.
- Genomic analysis showed the C. auris isolates were clonal and belonged to Clade III.

## Abstract

Candida auris is a drug-resistant fungus that poses a growing risk in healthcare environments, particularly among intensive care unit (ICU) patients. While other Candida species routinely colonize the gut, it is unknown if the gastrointestinal (GI) tract is a niche for C. auris. We aimed to determine the presence of C. auris in the gut of ICU patients and evaluate whether these isolates exhibit phenotypic traits that support intestinal colonization.Figure 1.Abbreviations: DCA, deoxycholic acid; ICU, intensive care unit; MALDI-ToF, matrix-assisted laser desorption/ionization-time of flight; WGS, whole genome sequencing.Figure 2.C. auris gut colonization and clinical detection in intensive care unit (ICU) patients.

Abbreviations: DCA, deoxycholic acid; ICU, intensive care unit; MALDI-ToF, matrix-assisted laser desorption/ionization-time of flight; WGS, whole genome sequencing.

C. auris gut colonization and clinical detection in intensive care unit (ICU) patients.

We assessed C. auris gut colonization in ICU patients by collecting stool samples and demographic/clinical information from enrolled patients from 01/2021-06/2024 (Figure 1). Stool samples were cultured on Candida selective media, isolates were identified using MALDI-ToF and their genomes were sequenced. To evaluate bile acid resistance, representative stool isolates of C. auris and C. albicans were exposed to increasing concentrations of the secondary bile acid deoxycholic acid (DCA), and growth was measured over time. Antifungal minimum inhibitory concentrations (MICs) were determined by broth microdilution.Figure 3.Phylogenetic tree of C. auris isolates (Clade III), collected in triplicate from each patient on different days from stool and clinical cultures.Figure 4.Growth of C. auris vs. C. albicans gut colonizing isolates in deoxycholic acid (DCA).

Phylogenetic tree of C. auris isolates (Clade III), collected in triplicate from each patient on different days from stool and clinical cultures.

Growth of C. auris vs. C. albicans gut colonizing isolates in deoxycholic acid (DCA).

Of 150 ICU patients enrolled, the mean age was 60.8 ± 15.6 years, 83 (56%) were male, and 24% were Hispanic/Latino. Mean Charlson Comorbidity Index was 4.9 ± 3.0; 34 patients (23%) were solid organ transplant recipients, and 54 (36%) were in shock on ICU admission. C. auris was detected in stool cultures of three patients (2%), of which two had colonization at other body sites (Figure 2). Genomic analysis showed that these isolates were highly clonal and belonged to Clade III (Figure 3). All C. auris isolates were resistant to fluconazole and susceptible to micafungin. When exposed to DCA, C. auris stool isolates exhibited significantly less growth inhibition compared to C. albicans stool isolates. At high (0.3%) DCA concentrations, the mean inhibition rates were 17% for C. auris stool isolates and 66% for C. albicans stool isolates (Figure 4).

These findings provide evidence of C. auris GI colonization in ICU patients. Moreover, the demonstrated resistance of C. auris stool isolates to DCA highlights its potential adaptive mechanisms for survival in the gut. These findings indicate that the GI tract may be a persistent reservoir for C. auris with implications for transmission and infection control.

All Authors: No reported disclosures