The Mortality Attributable to Candidemia in C. auris Is Higher than That in Other Candida Species: Myth or Reality?

Candidemia chronicles: Retrospective analysis of candidemia epidemiology, species distribution, and antifungal susceptibility patterns in Bahrain

BACKGROUND

Invasive fungal infections, particularly candidemia, pose significant clinical challenges globally. Understanding local epidemiology, species distribution, and antifungal susceptibility patterns is crucial for effective management despite regional variations.

AIM

To investigate the epidemiology, species distribution, antifungal susceptibility patterns, and associated risk factors of candidemia among patients in Bahrain from 2021 to 2023.

METHODS

This retrospective study analyzed demographic data, Candida species distribution, antifungal susceptibility profiles, and risk factors among candidemia patients treated at a tertiary care hospital in Bahrain over three years. Data was collected from medical records and analyzed using descriptive statistics.

RESULTS

A total of 430 candidemia cases were identified. The mean age of patients was 65.7 years, with a mortality rate of 85.5%. Candida albicans (C. albicans) was the most common species, followed by Candida parapsilosis, Candida tropicalis (C. tropicalis), and emerging multidrug-resistant Candida auris (C. auris). Antifungal susceptibility varied across species, with declining susceptibility to azoles observed, particularly among C. albicans and C. tropicalis. Major risk factors included central venous catheters, broad-spectrum antibiotics, and surgical procedures.

CONCLUSION

This study highlights the substantial burden of candidemia among older adults in Bahrain, characterized by diverse Candida species. It also concerns levels of antifungal resistance, notably in C. auris. The findings underscore the importance of local epidemiological surveillance and tailored treatment strategies to improve outcomes and mitigate the spread of multidrug-resistant Candida species. Future research should focus on molecular resistance mechanisms and optimizing therapeutic approaches to address this growing public health concern.

Candida auris MIC testing by EUCAST and CLSI broth microdilution, and gradient diffusion strips; to be or not to be amphotericin B resistant?

OBJECTIVES

Reported amphotericin B resistance rates for Candida auris vary considerably. This may reflect clinically relevant differences in susceptibility, technical issues with testing or adoption of a clinical breakpoint (BP) that bisects the wild-type population. We compared reference methods and two gradient diffusion strips using a shared C. auris strain collection.

METHODS

Forty C. auris strains from nine US states and ≥3 clades were included. Fourteen MIC data sets were generated using EUCAST E.Def 7.4, CLSI M27Ed4, Etest and MTS (Liofilchem) strip MICs. MICs ≤1 mg/L were classified as susceptible.

RESULTS

EUCAST and CLSI amphotericin B MIC testing were robust across included method variables. The modal MIC was 1 mg/L, distributions unimodal and narrow with similar GM-MICs (0.745-1.072); however, susceptibility classification varied (0-28% resistance). Gradient diffusion strip testing resulted in wider and bimodal distributions for 8/9 data sets. If adopting, per manufacturer's protocol, double inoculation for the Etest method, the modal MIC increased to 2-4 mg/L and resistance rates to 45-63% versus 25-30% with the single inoculation. The EUCAST, CLSI, Etest and MTS strip MICs correlated to the OD of drug-free control EUCAST wells suggesting that some isolates grew better than others and that this was associated with MIC.

CONCLUSIONS

The EUCAST and CLSI MIC results were in close agreement, whereas the strip test showed wider and bimodal distributions with reader to reader and centre to centre variation. Our study adds to the concern for commercial MIC testing of amphotericin B against C. auris and suggest the current breakpoint leads to random susceptibility classification.

First imported case of Candida auris infection in Milan, Italy: genomic characterisation

PURPOSE

Candida auris, an emerging multidrug-resistant yeast, has been reported worldwide. In Italy, the first case was reported in 2019. We describe the first case of C. auris, imported from Greece, in Milan, using whole genome sequencing to characterise mutations associated with antifungal resistance.

CASE PRESENTATION

On October 2022 an 80-year-old Italian man was hospitalised in Greece. In the absence of clinical improvement, the patient was transferred to our hospital, in Italy, where blood culture resulted positive for C. auris. Despite therapy, the patient died of septic shock. In a phylogenetic analysis the genome was assigned to Clade I with strains from Kenya, United Arab Emirates and India. D1/D2 region resulted identical to a Greek strain, as for many other strains from different World regions, highlighting the diffusion of this strain.

CONCLUSION

Importation of C. auris from abroad has been previously described. We report the first case of C. auris imported into Italy from Greece, according to phylogenetic analysis. This case reinforces the need for monitoring critically ill hospitalised patients also for fungi and addresses the need for the standardisation of susceptibility testing and strategies for diagnosis and therapy.

Insights from Three Pan-European Multicentre Studies on Invasive Candida Infections and Outlook to ECMM Candida IV

Invasive candidiasis and candidemia remain a significant public health concern. The European Confederation of Medical Mycology (ECMM) conducted three pan-European multicentre studies from 1997 to 2022 to investigate various aspects of invasive Candida infections. These studies revealed shifting trends in Candida species distribution, with an increase of non-albicans Candida species as causative pathogens, increasing rates of antifungal resistance, and persistently high mortality rates. Despite advancements in antifungal treatment, the persistently high mortality rate and increasing drug resistance, as well as limited drug access in low-income countries, underscore the need for continued research and development in the treatment of Candida infections. This review aims to summarize the findings of the three completed ECMM Candida studies and emphasize the importance of continued research efforts. Additionally, it introduces the upcoming ECMM Candida IV study, which will focus on assessing candidemia caused by non-albicans Candida species, including Candida auris, investigating antifungal resistance and tolerance, and evaluating novel treatment modalities on a global scale.

Clinical and microbiological characteristics of a hospital outbreak of Candida auris in a referral hospital in Lima, Peru

BACKGROUND

Candida auris, a multidrug-resistant fungal pathogen, has received considerable attention owing to its recent surge, especially in South America, which coincides with the ongoing global COVID-19 pandemic. Understanding the clinical and microbiological characteristics of outbreaks is crucial for their effective management and control.

OBJECTIVE

This retrospective observational study aimed to characterize a C. auris outbreak at a Peruvian referral hospital between January 2021 and July 2023.

METHODS

Data were collected from hospitalized patients with positive C. auris culture results. Microbiological data and antifungal susceptibility test results were analysed. Additionally, infection prevention and control measures have been described. Statistical analysis was used to compare the characteristics between the infected and colonized patients.

RESULTS

Thirty-three patients were identified, mostly male (66.7%), with a median age of 53 years. Among them, 18 (54.5%) were colonized, and 15 (45.5%) were infected. Fungemia was the predominant presentation (80%), with notable cases of fungemia in tuberculosis patients with long-stay devices for parenteral anti-tuberculosis therapy. Seventy-five percent of the isolates exhibited fluconazole resistance. Echinocandins were the primary treatment, preventing fungemia recurrence within 30 days. Infected patients had significantly longer hospital stays than colonized patients (100 vs. 45 days; p = .023). Hospital mortality rates were 46.7% and 25% in the infected and fungemia patients, respectively. Simultaneous outbreaks of multidrug-resistant bacteria were documented.

CONCLUSIONS

This study underscores the severity of a C. auris outbreak at a referral hospital in Peru, highlighting its significant impact on patient outcomes and healthcare resources. The high prevalence of fluconazole-resistant isolates, leading to prolonged hospital stay and high mortality rates, particularly in cases of fungemia, underscores the critical need for effective infection prevention and control strategies.

Chitosan and Chitooligosaccharides: Antifungal Potential and Structural Insights

Chitosan is a cationic polysaccharide derived from chitin deacetylation. This polysaccharide and its oligosaccharides have many biological activities and can be used in several fields due to their favorable characteristics, such as biodegradability, biocompatibility, and nontoxicity. This review aims to explore the antifungal potential of chitosan and chitooligosaccharides along with the conditions used for the activity and mechanisms of action they use to kill fungal cells. The sources, chemical properties, and applications of chitosan and chitooligosaccharides are discussed in this review. It also addresses the threat fungi pose to human health and crop production and how these saccharides have proven to be effective against these microorganisms. The cellular processes triggered by chitosan and chitooligosaccharides in fungal cells, and prospects for their use as potential antifungal agents are also examined.

Transcriptional Reprogramming of Candida tropicalis in Response to Isoespintanol Treatment

Candida tropicalis, an opportunistic pathogen, ranks among the primary culprits of invasive candidiasis, a condition notorious for its resistance to conventional antifungal drugs. The urgency to combat these drug-resistant infections has spurred the quest for novel therapeutic compounds, with a particular focus on those of natural origin. In this study, we set out to evaluate the impact of isoespintanol (ISO), a monoterpene derived from Oxandra xylopioides, on the transcriptome of C. tropicalis. Leveraging transcriptomics, our research aimed to unravel the intricate transcriptional changes induced by ISO within this pathogen. Our differential gene expression analysis unveiled 186 differentially expressed genes (DEGs) in response to ISO, with a striking 85% of these genes experiencing upregulation. These findings shed light on the multifaceted nature of ISO's influence on C. tropicalis, spanning a spectrum of physiological, structural, and metabolic adaptations. The upregulated DEGs predominantly pertained to crucial processes, including ergosterol biosynthesis, protein folding, response to DNA damage, cell wall integrity, mitochondrial activity modulation, and cellular responses to organic compounds. Simultaneously, 27 genes were observed to be repressed, affecting functions such as cytoplasmic translation, DNA damage checkpoints, membrane proteins, and metabolic pathways like trans-methylation, trans-sulfuration, and trans-propylamine. These results underscore the complexity of ISO's antifungal mechanism, suggesting that it targets multiple vital pathways within C. tropicalis. Such complexity potentially reduces the likelihood of the pathogen developing rapid resistance to ISO, making it an attractive candidate for further exploration as a therapeutic agent. In conclusion, our study provides a comprehensive overview of the transcriptional responses of C. tropicalis to ISO exposure. The identified molecular targets and pathways offer promising avenues for future research and the development of innovative antifungal therapies to combat infections caused by this pathogenic yeast.

Candida auris from colonisation to candidemia: A four-year study

BACKGROUND

Candida auris has become a worrisome multi-drug resistant healthcare-associated pathogen due to its capacity to colonise patients and surfaces and to cause outbreaks of invasive infections in critically ill patients.

OBJECTIVES

This study evaluated the outbreak in our setting in a 4-year period, reporting the risk factors for developing candidemia in previously colonised patients, the therapeutic measures for candidemia and the outcome of candidemia and colonisation cases among all C. auris isolates and their susceptibility to antifungals.

METHODS

Data were retrospectively collected from patients admitted to Consorcio Hospital General Universitario de Valencia (Spain) from September 2017 to September 2021. A retrospective case-control study was designed to identify risk factors for developing C. auris candidemia in previously colonised patients.

RESULTS

C. auris affected 550 patients, of which 210 (38.2%) had some clinical sample positive. Isolates were uniformly resistant to fluconazole, 20 isolates were resistant to echinocandins (2.8%) and four isolates were resistant to ampfotericin B (0.6%). There were 86 candidemia cases. APACHE II, digestive disease and catheter isolate were proven to be independent risk factors for developing candidemia in previously colonised patients. Thirty-day mortality rate for C. auris candidemia cases was 32.6%, while for colonisation cases was 33.7%.

CONCLUSIONS

Candidemia was one of the most frequent and severe infections caused by C. auris. The risk factors identified in this study should help to detect patients who are at more risk of developing candidemia, as long as an adequate surveillance of C. auris colonisation is performed.

Candida auris: the new fungal threat

Candida auris is an emergent fungal pathogen of particular concern. Since its first identification in Japan in 2009, it rapidly spread all over the world, including Italy. The main concern related to the diffusion of this fungus is its antifungal resistance. It is speculated that about 90% of isolates are resistant to fluconazole, 30% to amphotericin B and 5% to echinocandins; furthermore, some cases of pan-antifungal resistance have been described. Critically ill patients are particularly at risk of being colonized by this yeast and person-to-person transmission may generate hospital outbreaks. In fact, C. auris can survive on inanimate surfaces for a long time and commonly used disinfectants are not effective. Additionally, devices such as central venous catheters (CVCs) or urinary catheters are particularly at risk of being colonized, representing a possible source for the development of bloodstream infections caused by C. auris, which carries a high mortality rate. Given its capability to spread in the hospital setting and the limited therapeutic options it is of outmost importance to promptly identify C. auris. However, commonly used biochemical tests frequently misidentify C. auris as other Candida species; currently the best identification techniques are MALDI-TOF and molecular methods, such as PCR of the ITS and D1/D2 regions of the 28s ribosomal DNA. Whole genome sequencing remains the gold standard for the phylogenetic investigation of outbreaks. The majority of cases of colonization by C. albicans will not cause bloodstream infections and contact precautions and surveillance of contacts will be sufficient. When invasive fungal infections occur, echinocandins still represent the first therapeutic choice. A combination therapy or the use of novel antifungals (such as ibrexafungerp or fosmanogepix) would be required for echinocandin resistant strains. In conclusion, C. auris represents a growing threat because of its antifungal resistance characteristics, its difficult identification and its easy spread from person to person. The aim of this mini-review is to summarize the main aspects concerning this pathogen.

Candida auris: a global pathogen that has taken root in Colombia

Candida auris has been recognized as an emerging multidrug-resistant pathogen with a significant public health burden, causing cases of invasive infection and colonization due to its persistence on inanimate surfaces, ability to colonize skin of some patients, and high transmissibility in healthcare settings. The first sporadic report of the isolation of this species from the ear canal of a patient in Asia was in 2009 and reports from other regions of the world soon followed. However, it was not until 2015 that global epidemiological alerts were communicated as a result of an increasing number of reports of invasive infections caused by C. auris in several countries. Colombia was soon added to this list in 2016 after an unusual increase in the number of C. haemulonii isolates was reported, later confirmed as C. auris. Since the issuing of a national alert by the Colombian National Institute of Health together with the Ministry of Health in 2016, the number of cases reported reached over 2,000 by 2022. Colombian isolates have not shown pan resistance to available antifungals, unlike C. auris strains reported in other regions of the world, which leaves patients in Colombia with therapeutic options for these infections. However, increasing fluconazole resistance is being observed. Whole-genome sequencing of Colombian C. auris isolates has enhanced molecular epidemiological data, grouping Colombian isolates in clade IV together with other South American isolates.

Mortality Caused by Candida auris Bloodstream Infections in Comparison with Other Candida Species, a Multicentre Retrospective Cohort

Candida auris is an emerging pathogen considered to be critical in the World Health Organization fungal organisms list. The study aims to determine the mortality and hospital stays attributed to Candida auris (C. auris) compared to other Candida species in adult patients with candidemia. A retrospective cohort of adults with candidemia was examined from seven centres in Colombia between 2016 and 2021. The primary outcome was 30-day mortality, and the secondary outcome was the length of hospital stay among survivors. Adjustment of the confounding variables was performed using inverse probability weights of exposure propensity score (candidemia by C. auris), survival regression models (Weibull distribution), and a counting model (negative binomial distribution). A value of 244 (47.6%) of the 512 patients with candidemia died within the first 30 days. The crude mortality in C. auris was 38.1% vs. 51.1% in Candida non-auris (CNA). In the Weibull model, mortality in the C. auris group was lower (adjusted HR: aHR- 0.69, 95% CI: 0.53-0.90). Antifungal treatment also decreased mortality, with an aHR of 0.36 (95% CI 0.27-0.47), while the presence of septic shock on patient progression increased it, with an aHR of 1.73 (95% CI 1.41-2.13). Among the patients who survived, no differences in the length of hospital stay were observed between the C. auris and the CNA groups, with an incidence rate ratio of 0.92 (95% CI: 0.68-1.22). Mortality in patients with C. auris bloodstream infections appears lower when adjusted for numerous confounding variables regarding treatment and the presence of septic shock in patient progression. We identified no significant effect of C. auris on the length of hospital stay in surviving patients.

Enablers of Candida auris persistence on medical devices and their mode of eradication

Candida auris is an emerging pathogen predominantly isolated from immunocompromised patients, hospitalized for a long time. It inhabits the skin surfaces of patients causing ear, wound, and systemic infections; if not treated properly, it could lead to severe mortality. Apart from being a skin pathogen, C. auris colonizes the surfaces of medical devices. Medical devices are hospital tools and components often utilized for the diagnosis and treatment of diseases associated with human skin. The mechanism of survival and persistence of C. auris on medical devices has remained unclear and is a serious concern for clinicians. The persistence of C. auris on medical devices has deterred its effective elimination, hindered the treatment of infections, and increased its antifungal resistance. Evidence has shown that a few surface molecules on the cell wall of C. auris and the extracellular matrix of the biofilm are responsible for its persistence and exist as enablers. Due to the increased cases of ear, skin, and systemic infections as well as death resulting from the spread of C. auris in hospitals, there is a need to study these enablers. This review focused on the identification of the enablers and aimed to evaluate them in relation to their ability to induce persistence in C. auris. In order to reduce the spread of or completely eliminate C. auris and its enablers in hospitals, the efficacy of disinfection and sterilization methods were compared.