Auris Infection Research Articles

Single-cell transcriptomics unveils skin cell specific antifungal immune responses and IL-1Ra- IL-1R immune evasion strategies of emerging fungal pathogen Candida auris.

Candida auris is an emerging multidrug-resistant fungal pathogen that preferentially colonizes and persists in skin tissue, yet the host immune factors that regulate the skin colonization of C. auris in vivo are unknown. In this study, we employed unbiased single-cell transcriptomics of murine skin infected with C. auris to understand the cell type-specific immune response to C. auris. C. auris skin infection results in the accumulation of immune cells such as neutrophils, inflammatory monocytes, macrophages, dendritic cells, T cells, and NK cells at the site of infection. We identified fibroblasts as a major non-immune cell accumulated in the C. auris infected skin tissue. The comprehensive single-cell profiling revealed the transcriptomic signatures in cytokines, chemokines, host receptors (TLRs, C-type lectin receptors, NOD receptors), antimicrobial peptides, and immune signaling pathways in individual immune and non-immune cells during C. auris skin infection. Our analysis revealed that C. auris infection upregulates the expression of the IL-1RN gene (encoding IL-1R antagonist protein) in different cell types. We found IL-1Ra produced by macrophages during C. auris skin infection decreases the killing activity of neutrophils. Furthermore, C. auris uses a unique cell wall mannan outer layer to evade IL-1R-signaling mediated host defense. Collectively, our single-cell RNA seq profiling identified the transcriptomic signatures in immune and non-immune cells during C. auris skin infection. Our results demonstrate the IL-1Ra and IL-1R-mediated immune evasion mechanisms employed by C. auris to persist in the skin. These results enhance our understanding of host defense and immune evasion mechanisms during C. auris skin infection and identify potential targets for novel antifungal therapeutics.

The Candida auris Infection After the COVID-19 Pandemic Seems to be an Urgent Public Health Emergency: A Call to Attention.

Inconsequential diseases can sometimes become extremely dangerous through mutation. Antifungal resistance has increased by 24%, and resistance only due to Candida auris (C. auris) species have increased by 60%. Here, we aimed to assess the knowledge of antifungal treatment and preventative measures to mitigate the consequences of infections caused by C. auris. We performed a comprehensive literature search and gathered information for this review from publicly available published articles. We used C. auris, C. auris infection, mycoses, and antifungal resistance as search terms in Google Scholar, PubMed, and Scopus. We extracted the relevant information from the available article after careful evaluation. The genus C. auris was especially difficult to diagnose, as it was often mistaken for other types of yeast and led to incorrect treatment. The only effective method for diagnosing C. auris is through blood culture testing in laboratories and PCR tests. Because of its mutation, C. auris has grown increasingly resistant to all three classes of antifungals, with almost all strains resistant to fluconazole. These resistances were traced back to multiple-point mutations in certain genes, such as ERG11 in the case of fluconazole and amphotericin B. In addition, C. auris is phylogenetically related to C. haemulonii, an emerging pathogen notably resistant to antifungals. So, it may be an evolutionary resistance that occurred earlier but has only begun to spread now. Echinoderm, a reliable treatment for C. auris infections showed ineffectively against FKS1 and ERG3 gene mutated Candida strains. Newly developed antifungal agents, like Ibrexafungerp, showed promising results against echinocandin-resistant strains in clinical trials. Without vaccines and effective treatment, its capacity to mutate and spread has detrimental effects on humans. Therefore, extensive research on drug development, quick, reliable diagnosis, and effective strategies for disease prevention and treatment are required to mitigate the health impact of C. auris.

Application of Raman spectroscopy and machine learning for Candida auris identification and characterization.

Currently, combating Candida auris infections and transmission is challenging due to the lack of efficient identification and characterization methods for this species. To address these challenges, our study presents a novel approach that utilizes Raman spectroscopy and artificial intelligence to achieve precise identification and characterization of C. auris at the singe-cell level. It can accurately identify a single cell from the four C. auris clades. Additionally, we developed machine learning models designed to detect antifungal resistance in C. auris cells and differentiate between two distinct phenotypes based on the single-cell Raman spectrum. We also constructed prediction models for detecting aggregating and filamentous cells in C. auris, both of which are closely linked to its virulence. These results underscore the merits of Raman spectroscopy in the identification and characterization of C. auris, promising improved outcomes in the battle against C. auris infections and transmission.

Single-Cell Transcriptomics Unveils Skin Cell Specific Antifungal Immune Responses and IL-1Ra- IL-1R Immune Evasion Strategies of Emerging Fungal Pathogen Candida auris.

Candida auris is an emerging multidrug-resistant fungal pathogen that preferentially colonizes and persists in skin tissue, yet the host immune factors that regulate the skin colonization of C. auris in vivo are unknown. In this study, we employed unbiased single-cell transcriptomics of murine skin infected with C. auris to understand the cell type-specific immune response to C. auris. C. auris skin infection results in the accumulation of immune cells such as neutrophils, inflammatory monocytes, macrophages, dendritic cells, T cells, and NK cells at the site of infection. We identified fibroblasts as a major non-immune cell accumulated in the C. auris infected skin tissue. The comprehensive single-cell profiling revealed the transcriptomic signatures in cytokines, chemokines, host receptors (TLRs, C-type lectin receptors, NOD receptors), antimicrobial peptides, and immune signaling pathways in individual immune and non-immune cells during C. auris skin infection. Our analysis revealed that C. auris infection upregulates the expression of the IL-1RN gene (encoding IL-1R antagonist protein) in different cell types. We found IL-1Ra produced by macrophages during C. auris skin infection decreases the killing activity of neutrophils. Furthermore, C. auris uses a unique cell wall mannan outer layer to evade IL-1R-signaling mediated host defense. Collectively, our single-cell RNA seq profiling identified the transcriptomic signatures in immune and non-immune cells during C. auris skin infection. Our results demonstrate the IL-1Ra and IL-1R-mediated immune evasion mechanisms employed by C. auris to persist in the skin. These results enhance our understanding of host defense and immune evasion mechanisms during C. auris skin infection and identify potential targets for novel antifungal therapeutics.

Do morphogenetic switching and intraspecies variation enhance virulence of Candida auris?

Intraspecies variations that affect pathogenicity and antifungal resistance traits pose a serious obstacle to efficient therapy of Candida auris infections. Recent reports indicate that mutations determine drug susceptibility and virulence. However, mutations alone cannot fully explain a bewildering variety of phenotypes in clinical isolates from known C. auris clades, suggesting an unprecedented complexity underlying virulence traits and antifungal resistance. Hence, we wish to discuss how phenotypic plasticity promotes morphogenetic switching and how that contributes to intraspecies variations in the human fungal pathogen C. auris. Further, we will also discuss how intraspecies variations and morphogenetic events can impact the progress in molecular mycology research that aims to find better treatments for C. auris infections. Finally, we will present our opinion as to the most relevant questions to be addressed when trying to better understand the pathophysiology of C. auris.

Molecular and Microbiological Characterization of Candida auris Strains Isolated from Colonized and Infected Patients in a New York City Tertiary Care Center

Abstract Candida auris is a multidrug resistant pathogen that causes healthcare associated invasive infections and outbreaks with high mortality rates, often involving intensive care units (ICU). High rates of C. auris colonization among patients in ICUs are associated with increased risk of subsequent C. auris hospital-acquired infections. In this study, microbiological characteristics, and antifungal susceptibility patterns of C. auris isolates collected between January and December 2023 were investigated. Whole-genome sequencing was used to examine the genetic variation and molecular epidemiological characteristics. During the study period, a total of 20 patients were found to be colonized with C. auris by three site skin swab and eight of these patients subsequently developed invasive infection with C. auris. Among patients with both colonization and infection, all invasive isolates were closely related genetically to colonizing isolates and belonged to clade I. Candidemia was the most common infection identified in 4/8 (50%) patients. All isolates were resistant to fluconazole and thirteen isolates from six patients were resistant to amphotericin B. Paired isolates from patients with both colonization and invasive infection showed the same antifungal resistance patterns. All isolates had the ERG11 p.K143R mutation known to cause fluconazole resistance. Three isolates from one patient with a FKS1 hotspot region 3 p.M690I mutation were resistant to caspofungin and two isolates from one patient with a FKS1 hotspot region 2 p.R1354H mutation were resistant to caspofungin, anidulafungin and micafungin. Our study demonstrates that colonization with C. auris is associated with increased risk of infection by the same strain amongst critical ill patients. C. auris screening and implementation of adequate infection control measures are urgently needed to prevent the dissemination of C. auris infections.

Overcoming amphotericin B resistance in Candida auris using the antiemetic drug rolapitant.

The emergence of Candida auris poses a significant health challenge that has led to a new era of multidrug-resistant fungal infections. Invasive infections caused by C. auris are usually associated with remarkable morbidity and mortality. For many years, amphotericin B (AmB) remained the most efficient and the last line of treatment against most hard-to-treat fungal infections. However, strains of C. auris possess extraordinary resistance to most antifungal agents, including AmB. In this study, we screened ~2,600 FDA-approved drugs and clinical compounds to identify the antiemetic drug rolapitant as a promising enhancer to AmB against C. auris. Rolapitant exhibited potent synergistic interactions with AmB against all tested (29/29) C. auris isolates. In a time-kill assay, rolapitant restored the fungicidal activity of AmB within 4 h. Additionally, the synergistic relationship between rolapitant and AmB was observed against other medically crucial Candida, Cryptococcus, and Aspergillus species. A transcriptomic study revealed that exposure to rolapitant affects oxidation reduction processes, ion transporters, and ATP production. Rolapitant triggers an elevation in cytosolic and mitochondrial calcium levels and induces oxidative stress within fungal cells. An ATP luminescence assay confirmed that rolapitant, at sub-inhibitory concentrations, significantly interfered with ATP production in C. auris. Moreover, rolapitant enhanced the in vivo activity of AmB in a mouse model of disseminated C. auris infection, as the combination reduced the fungal burden in murine kidneys by ~1 log (~90%) colony forming units. Our findings warrant further investigation of using rolapitant to overcome AmB resistance in C. auris and other fungal species.

Azole Combinations and Multi-Targeting Drugs That Synergistically Inhibit Candidozyma auris.

Limited antifungal treatment options and drug resistance require innovative approaches to effectively combat fungal infections. Combination therapy is a promising strategy that addresses these pressing issues by concurrently targeting multiple cellular sites. The drug targets usually selected for combination therapy are from different cellular pathways with the goals of increasing treatment options and reducing development of resistance. However, some circumstances can prevent the implementation of combination therapy in clinical practice. These could include the increased risk of adverse effects, drug interactions, and even the promotion of drug resistance. Furthermore, robust clinical evidence supporting the superiority of combination therapy over monotherapy is limited and underscores the need for further research. Despite these challenges, synergies detected with different antifungal classes, such as the azoles and echinocandins, suggest that treatment strategies can be optimized by better understanding the underlying mechanisms. This review provides an overview of multi-targeting combination strategies with a primary focus on Candidozyma auris infections.

Alkaloids solenopsins from fire ants display in vitro and in vivo activity against the yeast Candida auris

ABSTRACT The urgency surrounding Candida auris as a public health threat is highlighted by both the Center for Disease Control (CDC) and World Health Organization (WHO) that categorized this species as a priority fungal pathogen. Given the current limitations of antifungal therapy for C. auris, particularly due to its multiple resistance to the current antifungals, the identification of new drugs is of paramount importance. Some alkaloids abundant in the venom of the red invasive fire ant (Solenopsis invicta), known as solenopsins, have garnered attention as potent inhibitors of bacterial biofilms, and there are no studies demonstrating such effects against fungal pathogens. Thus, we herein investigated the antibiotic efficacy of solenopsin alkaloids against C. auris biofilms and planktonic cells. Both natural and synthetic solenopsins inhibited the growth of C. auris strains from different clades, including fluconazole and amphotericin B-resistant isolates. Such alkaloids also inhibited matrix deposition and altered cellular metabolic activity of C. auris in biofilm conditions. Mechanistically, the alkaloids compromised membrane integrity as measured by propidium iodide uptake in exposed planktonic cells. Additionally, combining the alkaloids with AMB yielded an additive antifungal effect, even against AMB-resistant strains. Finally, both extracted solenopsins and the synthetic analogues demonstrated protective effect in vivo against C. auris infection in the invertebrate model Galleria mellonella. These findings underscore the potent antifungal activities of solenopsins against C. auris and suggest their inclusion in future drug development. Furthermore, exploring derivatives of solenopsins could reveal novel compounds with therapeutic promise.

Prevalence and Outcomes of Candida auris Infections in a Tertiary Hospital in the United Arab Emirates (UAE).

Background Candida auris (C. auris) is an emerging serious threat to healthcare settings, with an average mortality of 45% in cases of bloodstream infections. This study aimed to determine the prevalence of C. auris in a single center in the UAEduring the year 2022 and understand risk factors related to poor outcomes. Methods This retrospective cohort chart review at Al-Qassimi Hospital encompassed all confirmed Candida infections, including C. auris, from January to December 2022. The study involved male and female patients aged 13 years and older, using comprehensive data extracted from the hospital's electronic healthcare records. The analysis included clinical, laboratory, and epidemiological data. Adhering to the 2011 Declaration of Helsinki and Good Pharmacoepidemiology Practices, the study received Institutional Review Board approval, with informed consent waived due to its retrospective design. Data were summarized using appropriate statistical methods, including the unpaired t-test, Mann-Whitney U test, Chi-square test, and Fisher exact test. A significance level of 95% (p<0.05) was maintained throughout the statistical analyses. Results Of the 75 confirmed Candidainfections, 53 (70.7%) were C. auris-positive cases.About 23 (43.4%) of the C. auris group were above 65 years old. Most cases of C. auris group were hospital-acquired (49, 92.5%). The highest number of positive cases were found in urine samples. The demographic and clinical profiles of the C. auris and non-auris groups candidemia were largely similar, except for differences in antifungal use history and ICU requirements. Notably, the C. auris group had a significantly lower history of antifungal use and a lower ICU requirement compared to the non-auris group. The study also highlighted the higher mortality rate associated with candidemia. While mortality was higher in the non-auris group, the difference was not statistically significant. Conclusions The findings of the study suggest that while C. auris poses a serious threat, particularly in hospital settings; the clinical and demographic factors influencing its spread and impact are complex and warrant further investigation. Understanding these factors is crucial for developing effective strategies to prevent and manage C. auris infections, particularly in vulnerable patient populations.

Mortality and Associated Risk Factors in Patients With Candida auris: Insights From a Tertiary Care Hospital in Bahrain.

Introduction Candida auris poses a significant healthcare challenge due to its high mortality rates, difficulties in identification, and resistance to antifungal treatment. This study aims to identify risk factors associated with 30-day mortality in patients with either invasive Candida auris infection or colonization. Methods We conducted a prospective study at Salmaniya Medical Complex, a tertiary care hospital in Bahrain, from September 2023 to February 2024. The study included 59 patients infected or colonized by Candida auris. Data were systematically collected from patient records, including demographics, clinical characteristics, and outcomes. Risk factors for 30-day mortality were analyzed using both univariate and multivariate statistical methods. Results Among the 59 patients studied, the mean age was 63.9 years, and the cohort was predominantly male (74.6%). Key findings include a high prevalence of multiple indwelling catheters (44.2%) and recent intubation (42.4%). Candida auris was most frequently isolated from the groin (33.9%) and urine (25.4%), with a notable presence in the axillary regions (23.7%). The mortality rate was 44.1%. Univariate and multivariate analyses revealed that age (≥65 years), multiple indwelling catheters, ICU admission for over 24 hours, and recent intubation were significant risk factors for mortality while chronic kidney disease did not retain its significance in the multivariate model. Conclusion The study underscores the critical need for focused infection control and strong antimicrobial stewardship to address the high mortality associated with Candida auris infections. Emphasizing the importance of early detection and a multidisciplinary approach, these strategies are essential for managing and mitigating the impact of Candida auris in healthcare settings.

Baicalein induces apoptosis by targeting ribosomes in Candida auris.

The emergence of the "super fungus" Candida auris poses a significant threat to human health, given its multidrug resistance and high mortality rates. Therefore, developing a new antifungal strategy is necessary. Our previous research showed that Baicalein (BE), a key bioactive compound from the dried root of the perennial herb Scutellaria baicalensis Georgi, has strong fungistatic properties against C. auris. Nevertheless, the antifungal activity of BE against C. auris and its mechanism of action requires further investigation. In this study, we explored how BE affects this fungus using various techniques, including scanning electron microscopy (SEM), Annexin V-FITC apoptosis detection, CaspACE FITC-VAD-FMK In Situ Marker, reactive oxygen species (ROS) assay, singlet oxygen sensor green (SOSG) fluorescent probe, enhanced mitochondrial membrane potential (MMP) assay with JC-1, DAPI staining, TUNEL assay and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Our findings revealed that BE induced several apoptotic features, including phosphatidylserine (PS) externalization, metacaspase activation, nuclear condensation and DNA fragmentation. BE also increased intracellular ROS levels and altered mitochondrial functions. Additionally, transcriptomic analysis and RT-qPCR validation indicated that BE may induce apoptosis in C. auris by affecting ribosome-related pathways, suggesting that ribosomes could be new targets for antifungal agents, in addition to cell walls, membranes, and DNA. This study emphasizes the antifungal activity and mechanism of BE against C. auris, offering a promising treatment strategy for C. auris infection.

Analogues of the anti-malaria drug mefloquine have broad spectrum antifungal activity and are efficacious in a model of disseminated Candida auris infection.

Only three classes of antifungal drugs are currently in clinical use. Here, we report that derivatives of the malarial drug mefloquine have broad spectrum antifungal activity including difficult to treat molds and endemic fungi. Pharmacokinetic and efficacy studies of NSC-4377 indicate it penetrates the central nervous system and is active against Candida auris in vivo. These data strongly support the further development of mefloquine analogs as a potentially new class of antifungal molecules.

Candida auris: Understanding the dynamics of C. auris infection versus colonization.

Candida auris is a pathogen of growing public health concern worldwide. However, risk factors contributing to C. auris infection in patients colonized with C. auris remain unclear. Understanding these risk factors is crucial to prevent colonization-to-infection transition and devise effective preventive strategies. This study aimed to investigate risk factors associated with C. auris infection compared to colonization. The study included 97 patients who acquired laboratory-confirmed C. auris in either matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry or VITEK 2 system from October 2019 to June 2023. Baseline demographics and known risk factors associated with C. auris infection were collected from electronic medical records. The infection group had C. auris from a sterile site or non-sterile site with evidence of infection. The colonization group was followed up for a median of 30 days for any signs of infection. Associations between relevant variables and C. auris infection were assessed using multivariable logistic regression. The infection group (n=31) was more likely to be bedbound, with longer hospital stays and more arterial catheters. Chronic kidney disease (odds ratio [OR] 45.070), carriage of multidrug-resistant organisms (OR 64.612), and vasopressor use for > 20 days (OR 68.994) were associated with C. auris infection, after adjusting for sex, age, and prior colonization with C. auris. Chronic kidney disease, carriage of multidrug-resistant organisms, and prolonged vasopressor use emerged as significant risk factors for C. auris infection compared to colonization. They could be used to predict C. auris infection early in patients colonized with C. auris.

Antifungal Activity of the Dichloromethane Extract of CaoHuangGuiXiang Formula Against Candida auris by in vitro and in vivo Evaluation.

CaoHuangGuiXiang (CHGX) formula is a traditional Chinese medicine for the treatment of Candida-related infection. However, its antifungal mechanisms against the emerging fungal pathogen Candida auris remain unclear. This study aimed to evaluate the antifungal activity of the dichloromethane extract of CHGX (CHGX-DME) and clarified its antifungal mechanims against C. auris. The major components of CHGX-DME were identified by ultra-performance liquid chromatography tandem mass spectrometry. Then, the minimal inhibitory concentration (MIC) assay and the time-kill kinetic assay were performed to investigate the in vitro antifungal activity of CHGX-DME against C. auris, including 8 isolates of 4 discrete clades and 2 special phenotypes (filamentous and aggregative). Furthermore, the effect of CHGX-DME on biofilm development was examined. In addition, the in vivo toxicity and efficacy of CHGX-DME were evaluated in a Galleria mellonella infection model. First, 20 major compounds in CHGX-DME were detected and characterized. The MIC50% and MIC90% of CHGX-DME against C. auris isolates ranged from 50-200 mg/L and 100-400 mg/L, respectively. At 400 mg/L, CHGX-DME was able to efficiently kill more than 70% and 90% of C. auris cells after 3 hours and 6 hours of treatment, respectively. This notable antifungal activity exhibited a dosage- and time-dependent manner. Moreover, CHGX-DME not only played a critical role in inhibiting the proliferation of filamentous and aggregative cells, but also showed restricting effect on biofilm development in C. auris. Importantly, it significantly improved the survival rate and reduced the fungal burden in G. mellonella infection models, suggesting a remarkable treatment effect against C. auris infection. CHGX-DME exhibited potent antifungal activity against C. auris and significantly ameliorated this fungal infection in the G. mellonella model, confirming that it would be a promising antifungal drug for the troublesome and emerging fungal pathogen C. auris.

Yeast and filamentous Candida auris stimulate distinct immune responses in the skin.

Candida auris, an emerging multidrug-resistant fungal pathogen, predominately colonizes the human skin long term leading to subsequent life-threatening invasive infections. Fungal morphology is believed to play a critical role in modulating mucocutaneous antifungal immunity. In this study, we used an intradermal mouse model of C. auris infection to examine fungal colonization and the associated innate and adaptive immune response to yeast and filamentous C. auris strains. Our results indicate that mice infected with a filamentous C. auris had significantly decreased fungal load compared to mice infected with the yeast form. Mice infected with yeast and filamentous forms of C. auris stimulated distinct innate immune responses. Phagocytic cells (CD11b+Ly6G+ neutrophils, CD11b+Ly6Chi inflammatory monocytes, and CD11b+MHCII+CD64+ macrophages) were differentially recruited to mouse skin tissue infected with yeast and filamentous C. auris. The percentage and absolute number of interleukin 17 (IL-17) producing innate lymphoid cells, TCRγδ+, and CD4+ T cells in the skin tissue of mice infected with filamentous C. auris were significantly increased compared to the wild-type of yeast strain. Furthermore, complementation of filamentous mutant strain of C. auris (Δelm1 + ELM1) strain exhibited wild-type yeast morphology in vivo and induced comparable level of skin immune responses similar to mice infected with yeast strain. Collectively, our findings indicate that yeast and filamentous C. auris induce distinct local immune responses in the skin. The decreased fungal load observed in mouse skin infected with filamentous C. auris is associated with a potent IL-17 immune response induced by this morphotype.IMPORTANCECandida auris is a globally emerging fungal pathogen that transmits among individuals in hospitals and nursing home residents. Unlike other Candida species, C. auris predominantly colonizes and persists in skin tissue resulting in outbreaks of systemic infections. Understanding the factors that regulate C. auris skin colonization and host immune response is critical to develop novel preventive and therapeutic approaches against this emerging pathogen. We identified that yeast and filamentous forms of C. auris induce distinct skin immune responses in the skin. These findings may help explain the differential colonization and persistence of C. auris morphotypes in skin tissue. Understanding the skin immune responses induced by yeast and filamentous C. auris is important to develop novel vaccine strategies to combat this emerging fungal pathogen.

A single gene mutation underpins metabolic adaptation and acquisition of filamentous competence in the emerging fungal pathogen Candida auris.

Filamentous cell growth is a vital property of fungal pathogens. The mechanisms of filamentation in the emerging multidrug-resistant fungal pathogen Candida auris are poorly understood. Here, we show that exposure of C. auris to glycerol triggers a rod-like filamentation-competent (RL-FC) phenotype, which forms elongated filamentous cells after a prolonged culture period. Whole-genome sequencing analysis reveals that all RL-FC isolates harbor a mutation in the C2H2 zinc finger transcription factor-encoding gene GFC1 (Gfc1 variants). Deletion of GFC1 leads to an RL-FC phenotype similar to that observed in Gfc1 variants. We further demonstrate that GFC1 mutation causes enhanced fatty acid β-oxidation metabolism and thereby promotes RL-FC/filamentous growth. This regulation is achieved through a Multiple Carbon source Utilizer (Mcu1)-dependent mechanism. Interestingly, both the evolved RL-FC isolates and the gfc1Δ mutant exhibit an enhanced ability to colonize the skin. Our results reveal that glycerol-mediated GFC1 mutations are beneficial during C. auris skin colonization and infection.

Evolutionary accumulation of FKS1 mutations from clinical echinocandin-resistant Candida auris

Introduction: Drug resistance to echinocandins, first-line drugs used to treat Candida auris infection, is rapidly emerging. However, the accumulation of mutations in genes other than FKS1 (before an isolate develops to resistance via FKS1 mutations), remains poorly understood. Methods Four clinical cases and 29 isolates associated with the incremental process of echinocandin resistance were collected and analyzed using antifungal drug susceptibility testing and genome sequencing to assess the evolution of echinocandin resistance. Findings: Six echinocandin minimum inhibitory concentration (MIC)-elevated C. auris strains and seven resistant strains were isolated from the urinary system of patients receiving echinocandin treatment. Meanwhile, phylogenetic analyses illustrated that the echinocandin-resistant strains were closely related to other strains in the same patient. Genomic data revealed that the echinocandin-resistant strains had FKS1 mutations. Furthermore, three categories (ECN-S/E/R) of non-synonymous mutant SNP genes (such as RBR3, IFF6, MKC1, MPH1, RAD2, and MYO1) in C. auris appeared to be associated with the three-stage-evolutionary model of echinocandin resistance in C. glabrata: cell wall stress, drug adaptation, and genetic escape (FKS mutation). Interpretation: Echinocandin-resistant C. auris undergoes spatial and temporal phase changes closely related to echinocandin exposure, particularly in the urinary system. These findings suggest that FKS1 mutations mediate an evolutionary accumulation of echinocandin resistance followed by modulation of chromosome remodeling and DNA repair processes that ultimately lead to FKS1 hot spot mutations and the development of drug resistance. This study provides an in-depth exploration of the molecular pathways involved in the evolution of Candida auris echinocandin resistance.

Alteration of β-glucan in the emerging fungal pathogen Candida auris leads to immune evasion and increased virulence

Candida auris is an emerging pathogenic yeast that has been categorized as a global public health threat and a critical priority among fungal pathogens. Despite this, the immune response against C. auris infection is still not well understood. Hosts fight Candida infections through the immune system that recognizes pathogen-associated molecular patterns such as β-glucan, mannan, and chitin on the fungal cell wall. In this study, levels of β-glucan and mannan exposures in C. auris grown under different physiologically relevant stimuli were quantified by flow cytometry-based analysis. Lactate, hypoxia, and sublethal concentration of fluconazole trigger a decrease in surface β-glucan while low pH triggers an increase in β-glucan. There is no inverse pattern between exposure levels of β-glucan and mannan in the cell wall architecture among the three clades. To determine the effect of cell wall remodeling on the immune response, a phagocytosis assay was performed, followed by quantification of released cytokines by ELISA. Lactate-induced decrease in β-glucan leads to reduced uptake of C. auris by PMA-differentiated THP-1 and RAW 264.7 macrophages. Furthermore, reduced production of CCL3/MIP-1⍺ but not TNF-⍺ and IL-10 were observed. An in vivo infection analysis using silkworms reveals that a reduction in β-glucan triggers an increase in the virulence of C. auris. This study demonstrates that β-glucan alteration occurs in C. auris and serves as an escape mechanism from immune cells leading to increased virulence.

Candida auris cluster in a center with no previous infections associated with a single organ donor

Background: Candida auris is an opportunistic pathogen reported in the US since 2016. C. auris infections (CAI) are frequently healthcare-associated, but only one case of donor-derived CAI in a lung transplant recipient has been reported (PMID 28520901). We describe a cluster of two CAIs at a single center in South Carolina occurring in 2 different recipients from the same solid organ transplant donor. Methods: We describe two cases of invasive CAIs occurring in an academic medical center without prior CAI in Charleston, SC in October 2023. C. auris was identified using Bruker MALDI-TOF and confirmed by the state health department. Results: Patient 1: 40-49 year-old male underwent heart transplantation on day 19 from admission complicated by growth of C. auris on post-op day #15 from a drain. He was readmitted post-op days 22-63 with positive blood cultures for C. auris and underwent re-operation with debridement and hardware removal. C. auris pericarditis required multiple returns to the OR (Figure). He was discharged on micafungin/posaconazole with plans for long-term antifungal therapy. Patient 2: 50-59 year-old male underwent liver and kidney transplantation on day 25 from admission from the same donor as Patient 1 in a separate hospital complex. His course was complicated by possible infected biloma not amendable to drainage and C. auris/C. glabrata fungemia, which was further complicated by abdominal wall collection cultures growing C. auris on post-operative day 35 on washout. He was managed with dual micafungin/posaconazole however, he died of unrelated causes at 93 days after transplant (Figure). Investigation: The donor for both recipients was a 10-19 year-old male who suffered brain death after trauma and was hospitalized for 56 days prior to procurement in Atlanta, GA without known CAI. Airway cultures at the time of organ procurement were positive for rare Pseudomonas and light unidentified yeast of multiple morphologies; urine cultures also grew 40,000 cfu/ml un-identified yeast. Screening of 35 and 4 inpatients in units exposed to patients 1 &amp; 2, respectively, with axilla/groin PCR was negative (Figure). A third organ recipient for this donor (kidney) at our center was identified and had negative urine fungus cultures. Conclusions: Despite no definitive link to a known donor infection, this cluster of CAI occurring simultaneously in 2 patients in separate hospitals/units at a single center with no known prior cases represents likely donor-derived CAI. Our experience suggests that organ procurement organizations should consider improved screening techniques for C. auris in donor cultures.Disclosure: Scott Curry: Consultant- Ferring; Abbott Diagnostics- Speaker honorarium