Emergence of Clonally-Related South Asian Clade I Clinical Isolates of Candida auris in a Greek COVID-19 Intensive Care Unit

Comparative analyses of the biological characteristics, fluconazole resistance, and heat adaptation mechanisms of Candida auris and members of the Candida haemulonii complex

Candida auris and the emerging fungal pathogens comprising the Candida haemulonii complex (C. haemulonii and C. duobushaemulonii) are phylogenetically closely related. Notably, each can cause serious nosocomial infection and acquire multidrug resistance. We isolated various strains of C. auris and C. haemulonii complex from patient specimens. The results of growth curve analysis and the spot assay showed that C. auris was the most tolerant to high temperatures, while differences were found among the five strains of the C. haemulonii complex. We selected a representative strain from each of the three types of fungi that exhibit differences in heat resistance for further research. In addition, three strains were resistant to fluconazole, whereas sensitivity to common antifungal agents differed, as determined by the micro liquid-based dilution method. Moreover, C. auris was more virulent in Galleria mellonella than members of the C. haemulonii complex. In addition, there were notable differences in biofilm formation, hydrophobicity, adhesion, and enzyme activity among the three Candida strains. The results of transcriptomics, real-time quantitative PCR, and biochemical analyses showed that C. auris was most tolerant to heat stress due to the expression of genes in regulating pyruvate consumption and the accumulation of intracellular pyruvate. These results provide valuable references for further studies of the biological characteristics, pathogenesis, and treatment of Candida infection.

IMPORTANCE

Candida auris and the Candida haemulonii complex are multidrug-resistant fungi that have emerged in recent years, posing a significant threat to human health. The biological characteristics of two strains of the Candida haemulonii complex and one strain of C. auris isolated from clinical patient samples were analyzed. Our primary focus was to compare the heat resistance between C. auris and the C. haemulonii complex, with a particular emphasis on understanding the differences in the heat resistance mechanisms. The main distinction between environmental and pathogenic fungi is that the latter can survive at human body temperature. Despite their close phylogenetic relationship, the C. haemulonii complex and C. auris exhibit significant differences in heat resistance. Studying these heat resistance mechanisms may aid in our understanding of the evolutionary process of environmental fungi transforming into pathogenic fungi.

The multidrug-resistant Candida auris, Candida haemulonii complex and phylogenetic related species: Insights into antifungal resistance mechanisms

The rise of multidrug-resistant (MDR) fungal pathogens poses a serious global threat to human health. Of particular concern are Candida auris, the Candida haemulonii complex (which includes C. haemulonii sensu stricto, C. duobushaemulonii and C. haemulonii var. vulnera), and phylogenetically related species, including C. pseudohaemulonii and C. vulturna. These emerging, widespread, and opportunistic pathogens have drawn significant attention due to their reduced susceptibility to commonly used antifungal agents, particularly azoles and polyenes, and, in some cases, therapy-induced resistance to echinocandins. Notably, C. auris is classified in the critical priority group on the World Health Organization's fungal priority pathogens list, which highlights fungal species capable of causing systemic infections with significant mortality and morbidity risks as well as the challenges posed by their MDR profiles, limited treatment and management options. The mechanisms underlying antifungal resistance within these emerging fungal species is still being explored, but some advances have been achieved in the past few years. In this review, we compile current literature on the distribution of susceptible and resistant clinical strains of C. auris, C. haemulonii complex, C. pseudohaemulonii and C. vulturna across various antifungal classes, including azoles (fluconazole, voriconazole, itraconazole), polyenes (amphotericin B), echinocandins (caspofungin, micafungin, anidulafungin), and pyrimidine analogues (flucytosine). We also outline the main antifungal resistance mechanisms identified in planktonic cells of these yeast species. Finally, we explore the impact of biofilm formation, a classical virulence attribute of fungi, on antifungal resistance, highlighting the resistance mechanisms associated with this complex microbial structure that have been uncovered to date.

Factors Associated With Poor Clinical and Microbiologic Outcomes in Candida auris Bloodstream Infection: A Multicenter Retrospective Cohort Study

BACKGROUND

Candida auris has become a growing concern worldwide because of increases in incidence of colonization and reports of invasive infections. There are limited data on clinical factors associated with poor outcomes in patients with C. auris bloodstream infection (BSI).

METHODS

We assembled a multicenter retrospective cohort of patients with C. auris BSI from 2 geographics areas in US healthcare settings. We collected data on demographic, clinical, and microbiologic characteristics to describe the cohort and constructed multivariate logistic regression models to understand risk factors for 2 clinical outcomes, all-cause mortality during facility admission, and blood culture clearance.

RESULTS

Our cohort consisted of 187 patients with C. auris BSI (56.1% male, 55.6% age >65 years); 54.6% died by facility discharge and 66.9% (of 142 with available data) experienced blood culture clearance. Pitt bacteremia score at infection onset was associated with mortality (odds ratio [95% confidence interval]: 1.19 [1.01-1.40] per 1-point increase). Hemodialysis was associated with a reduced odds of microbiologic clearance (0.15 [0.05-0.43]) and with mortality (3.08 [1.27-7.50]).

CONCLUSIONS

The Pitt bacteremia score at the onset of C. auris BSI may be a useful tool in identifying patients at risk for mortality. Targeted infection prevention practices in patients receiving hemodialysis may be useful to limit poor outcomes.

Candida auris fungaemia outbreak in a tertiary care academic hospital and emergence of a pan-echinocandin resistant isolate, Greece, 2021 to 2023

After the start of the COVID-19 pandemic, a rapid rise in reported numbers and wide geographic spread of Candida auris-related invasive infections has been observed globally. However, the contemporary epidemiology of C. auris fungaemias in Greece remains unknown. An outbreak of C. auris bloodstream infections has been ongoing for almost 3 years in a Greek tertiary care academic hospital, with 89 C. auris-driven episodes appearing in five waves every 6-7 months following peaks in colonisation rates by 3-4 months. All isolates clustered in clade I and were genetically related, 84% were fluconazole-resistant and all were non-resistant to amphotericin B and echinocandins, except one pan-echinocandin-resistant isolate (FKS1S639F mutant) recovered from a patient on empiric therapy with anidulafungin. Notably, C. auris was in 2023 the most prevalent (34%) cause of candidaemia in our hospital. The accelerated and long-term transmission dynamics of C. auris fungaemia underscore the need for rigorous infection control measures, while antifungal stewardship is warranted to contain the selection of echinocandin-resistant isolates.

Global Epidemiology of Invasive Infections by Uncommon Candida Species: A Systematic Review

Emerging and uncommon Candida species have been reported as an increasing cause of invasive Candida infections (ICI). We aim to systematize the global epidemiology associated with emergent uncommon Candida species responsible for invasive infections in adult patients. A systematic review (from 1 January 2001 to 28 February 2023) regarding epidemiological, clinical, and microbiological data associated to invasive Candida infections by uncommon Candida spp. were collected. In total, 1567 publications were identified, and 36 were selected according to inclusion criteria (45 cases). The chosen studies covered: C. auris (n = 21), C. haemulonii (n = 6), C. fermentati (n = 4), C. kefyr (n = 4), C. norvegensis (n = 3), C. nivariensis (n = 3), C. bracarensis (n = 1), C. duobushaemulonii (n = 1), C. blankii (n = 1), and C. khanbhai (n = 1). Over the recent years, there has been an increase in the number of invasive infections caused by uncommon Candida spp. Asia and Europe are the continents with the most reported cases. The challenges in strain identification and antifungal susceptibility interpretation were significant. The absence of clinical breakpoints for the susceptibility profile determination for uncommon Candida spp. makes interpretation and treatment options a clinical challenge. It is crucial that we focus on new and accessible microbiology techniques to make fast and accurate diagnostics and treatments.

Candida auris: Outbreak, surveillance and epidemiological monitoring in Northern Greece

Candida auris is an emerging fungal pathogen associated with multi-drug resistance rates and widespread outbreaks in hospitals and healthcare units worldwide. Sequencing studies have revealed that different clonal lineages of the fungus seem to be prevalent among distinct geographical sites. The first case of C. auris in Northern Greece was reported in Thessaloniki in October 2022, almost 2 years after the first isolation in Greece (Athens 2019). The Mycology Laboratory of the Medical School of Aristotle University of Thessaloniki stands as the reference laboratory for fungal diseases in Northern Greece and a meticulous search for the yeast, in plenty of suspicious samples, has been run since 2019 in the Lab as well as a retrospective analysis of all its yeasts' collection, back to 2008, with negative results for the presence of C. auris. Here, are presented the findings concerning the outbreak and surveillance of C. auris in Northern Greece, mainly the region of Thessaloniki and the broader area of Macedonia, from October 2022 until August 2023. The isolates from Northern Greece continue to fall in Clade I and present with an almost equal and stable sensitivity profile until now.

Increase in candidemia cases and emergence of fluconazole-resistant Candida parapsilosis and C. auris isolates in a tertiary care academic hospital during the COVID-19 pandemic, Greece, 2020 to 2023

BackgroundThe COVID-19 pandemic and the emergence of Candida auris have changed the epidemiological landscape of candidaemia worldwide.AimWe compared the epidemiological trends of candidaemia in a Greek tertiary academic hospital before (2009-2018) and during the early COVID-19 (2020-2021) and late COVID-19/early post-pandemic (2022-2023) era.MethodsIncidence rates, species distribution, antifungal susceptibility profile and antifungal consumption were recorded, and one-way ANOVA or Fisher's exact test performed. Species were identified by MALDI-ToF MS, and in vitro susceptibility determined with CLSI M27-Ed4 for C. auris and the EUCAST-E.DEF 7.3.2 for other Candida spp.ResultsIn total, 370 candidaemia episodes were recorded during the COVID-19 pandemic. Infection incidence (2.0 episodes/10,000 hospital bed days before, 3.9 during the early and 5.1 during the late COVID-19 era, p < 0.0001), C. auris (0%, 9% and 33%, p < 0.0001) and fluconazole-resistant C. parapsilosis species complex (SC) (20%, 24% and 33%, p = 0.06) infections increased over time, with the latter not associated with increase in fluconazole/voriconazole consumption. A significant increase over time was observed in fluconazole-resistant isolates regardless of species (8%, 17% and 41%, p < 0.0001). Resistance to amphotericin B or echinocandins was not recorded, with the exception of a single pan-echinocandin-resistant C. auris strain.ConclusionCandidaemia incidence nearly tripled during the COVID-19 era, with C. auris among the major causative agents and increasing fluconazole resistance in C. parapsilosis SC. Almost half of Candida isolates were fluconazole-resistant, underscoring the need for increased awareness and strict implementation of infection control measures.

Candida auris in Greek healthcare facilities: Active surveillance results on first cases and outbreaks from eleven hospitals within Attica region

BACKGROUND

Candida auris was sporadically detected in Greece until 2019. Thereupon, there has been an increase in isolations among inpatients of healthcare facilities.

AIM

We aim to report active surveillance data on MALDI-TOF confirmed Candida auris cases and outbreaks, from November 2019 to September 2021.

METHODS

A retrospective study on hospital-based Candida auris data, over a 23-month period was conducted, involving 11 hospitals within Attica region. Antifungal susceptibility testing and genotyping were conducted. Case mortality and fatality rates were calculated and p-values less than 0.05 were considered statistically significant. Infection control measures were enforced and enhanced.

RESULTS

Twenty cases with invasive infection and 25 colonized were identified (median age: 72 years), all admitted to hospitals for reasons other than fungal infections. Median hospitalisation time until diagnosis was 26 days. Common risk factors among cases were the presence of indwelling devices (91.1 %), concurrent bacterial infections during hospitalisation (60.0 %), multiple antimicrobial drug treatment courses prior to hospitalisation (57.8 %), and admission in the ICU (44.4 %). Overall mortality rate was 53 %, after a median of 41.5 hospitalisation days. Resistance to fluconazole and amphotericin B was identified in 100 % and 3 % of tested clinical isolates, respectively. All isolates belonged to South Asian clade I. Outbreaks were identified in six hospitals, while remaining hospitals detected sporadic C. auris cases.

CONCLUSION

Candida auris has proven its ability to rapidly spread and persist among inpatients and environment of healthcare facilities. Surveillance focused on the presence of risk factors and local epidemiology, and implementation of strict infection control measures remain the most useful interventions.

Potential Environmental Reservoirs of Candida auris: A Systematic Review

Candida auris, a multidrug-resistant yeast, poses significant challenges in healthcare settings worldwide. Understanding its environmental reservoirs is crucial for effective control strategies. This systematic review aimed to review the literature regarding the natural and environmental reservoirs of C. auris. Following the PRISMA guidelines, published studies until October 2023 were searched in three databases: PubMed, Web of Science, and Scopus. Information regarding the origin, sampling procedure, methods for laboratory identification, and antifungal susceptibility was collected and analyzed. Thirty-three studies published between 2016 and 2023 in 15 countries were included and analyzed. C. auris was detected in various environments, including wastewater treatment plants, hospital patient care surfaces, and natural environments such as salt marshes, sand, seawater, estuaries, apples, and dogs. Detection methods varied, with molecular techniques often used alongside culture. Susceptibility profiles revealed resistance patterns. Phylogenetic studies highlight the potential of environmental strains to influence clinical infections. Despite methodological heterogeneity, this review provides valuable information for future research and highlights the need for standardized sampling and detection protocols to mitigate C. auris transmission.

Candida auris Outbreaks: Current Status and Future Perspectives

Candida auris has been identified by the World Health Organization (WHO) as a critical priority pathogen on its latest list of fungi. C. auris infections are reported in the bloodstream and less commonly in the cerebrospinal fluid and abdomen, with mortality rates that range between 30% and 72%. However, no large-scale epidemiology studies have been reported until now. The diagnosis of C. auris infections can be challenging, particularly when employing conventional techniques. This can impede the early detection of outbreaks and the implementation of appropriate control measures. The yeast can easily spread between patients and in healthcare settings through contaminated environments or equipment, where it can survive for extended periods. Therefore, it would be desirable to screen patients for C. auris colonisation. This would allow facilities to identify patients with the disease and take appropriate prevention and control measures. It is frequently unsusceptible to drugs, with varying patterns of resistance observed among clades and geographical regions. This review provides updates on C. auris, including epidemiology, clinical characteristics, genomic analysis, evolution, colonisation, infection, identification, resistance profiles, therapeutic options, prevention, and control.

Comparing the virulence of four major clades of Candida auris strains using a silkworm infection model: Clade IV isolates had higher virulence than the other clades

Candida auris is an emerging fungal pathogen that is feared to spread of infection because of its propensity for multidrug resistance and high mortality rate. This pathogenic yeast is classified into four major clades by phylogenetic analyses, which are referred to the South Asia clade (clade I), East Asia clade (clade II), South Africa clade (clade III), and South America clade (clade IV), based on the location of the initial isolate. In this study, we evaluated the virulence of C. auris strains belonging to four major clades and the therapeutic effects of micafungin in a silkworm infection model. The highest mortality rate at 21 h after C. auris inoculation was observed for strains from clade IV (80% or more). In contrast, it was 20% or less in those from other clades. Antifungal susceptibility tests indicated resistance to fluconazole and sensitivity to echinocandins in the blood-derived strains. Micafungin prolonged the survival of blood-derived C. auris infected silkworms. These results suggest that the silkworm infection model is useful for evaluating the virulence of C. auris and determining its therapeutic effects.

Use of antibiotics in hospitalized patients with COVID-19: evolving concepts in a highly dynamic antimicrobial stewardship scenario

INTRODUCTION

Excessive use of antibiotics has been frequently reported in hospitalized patients with COVID-19 worldwide, compared to the actual number of bacterial co-infections or super-infections.

AREAS COVERED

In this perspective, we discuss the current literature on the use of antibiotics and antimicrobial stewardship interventions in hospitalized patients with COVID-19. A search was conducted in PubMed up to March 2023.

EXPERT OPINION

The COVID-19 pandemic has witnessed an excessive use of antibiotics in hospitals worldwide, especially before the advent of COVID-19 vaccination, although according to the most recent data there is still an important disproportion between the prevalence of antibiotic use and that of proven bacterial coinfection or superinfections. An important reduction in the prevalence of antibiotic use in COVID-19 patients reported in the literature, from 70-100% to 50-60%, has been observed after successful vaccination campaigns, likely related to the reduced median disease severity of hospitalized COVID-19 patients and some successful interventions of antimicrobial and diagnostic stewardship. However, the disproportion between antibiotic use and the prevalence of bacterial infections (4-6%) is still uncomfortable from an antimicrobial stewardship perspective and requires further attention.