Multidrug-resistant Candida auris: an epidemiological review

Beyond the usual suspects: A case report of multi-etiological and multidrug-resistant Candida onychomycosis

This is a rare case of Candida onychomycosis caused by three Candida species that were resistant to several antifungal drugs. A 56-year-old Iranian woman with no previous medical or injury history experienced discoloration and lifting of her left thumbnail for six months. Laboratory tests identified yeast and pseudohyphae consistent with Candida onychomycosis. Conventional and molecular techniques confirmed that onychomycosis was caused by three different Candida species. All strains were resistant to various antifungal drugs. Therapeutic failure, in addition to multi-drug resistance, may be due to the presence of multiple etiological agents.

Key Factors to Consider for Candida auris Screening in Healthcare Settings: A Systematic Review

BACKGROUND

Candida auris is an emerging fungal pathogen that is often multidrug-resistant. It can persist on skin and in hospital environments, leading to outbreaks and severe infections for patients at risk. Several countries and institutions are working on establishing guidelines and recommendations for prevention. This review aims to assess the evidence on factors associated with C. auris colonisation or infection, the duration of such colonisation, possible colonisation sites, and the risk of secondary cases to inform screening recommendations.

METHODS

We systematically searched five databases for primary studies and systematic reviews of our four outcomes. We excluded studies on treatment, management, laboratory methods, drug resistance, and environmental screening. From each paper, we extracted relevant data and summarised them in tables. Main findings were described narratively.

FINDINGS

We selected 117 studies for inclusion. Most of the studies were observational studies. Without taking the method of testing into account, the duration of C. auris colonisation varied, with up to and beyond a year being common. The predominant sites of colonisation were the axillae and groin, with the nares and rectum being less common sites. The risk of secondary cases saw considerable variation across the studies, and the secondary cases primarily involved patients and not healthcare workers. Critical care settings, invasive medical devices, recent antimicrobial use, and comorbidities were often associated with C. auris colonisation and infection.

CONCLUSION

Our review highlights that, despite relevant findings on factors influencing C. auris colonisation and infection, substantial gaps remain in the evidence supporting screening practices. Most studies were conducted reactively, in outbreak settings, and lack systematic protocols. Given these limitations, screening guidelines are likely to be more successful if grounded in medical theory and yeast microbiology rather than relying solely on current studies. Rigorous, well-designed research is urgently needed to inform future C. auris screening and control efforts.

Decoding host cell interaction- and fluconazole-induced metabolic alterations and drug resistance in Candida auris

Candida auris is an emerging drug-resistant pathogen associated with high mortality rates. This study aimed to explore the metabolic alterations and associated pathogenesis and drug resistance in fluconazole-treated Candida auris-host cell interaction. Compared with controls, secreted metabolites from fluconazole-treated C. auris and fluconazole-treated C. auris-host cell co-culture demonstrated notable anti-Candida activity. Fluconazole caused significant reductions in C. auris cell numbers and aggregated phenotype. Metabolites produced by C. auris with potential fungal colonization, invasion, and host immune evasion effects were identified. Metabolites known to enhance biofilm formation produced during C. auris-host cell interaction were inhibited by fluconazole. Fluconazole enhanced the production of metabolites with biofilm inhibition activity, including behenyl alcohol and decanoic acid. Metabolites with potential Candida growth inhibition activity such as 2-palmitoyl glycerol, 1-tetradecanol, and 1-nonadecene were activated by fluconazole. Different patterns of proinflammatory cytokine expression presented due to fluconazole concentration and host cell type (fibroblasts versus macrophages). This highlights the immune response's complexity, emphasizing the necessity for additional research to comprehend cell-type-specific responses to antifungal therapies. Both host cell interaction and fluconazole treatment increased the expression of CDR1 and ERG11 genes, both associated with drug resistance. This study provides insights into pathogenesis in C. auris due to host cell interaction and fluconazole treatment. Understanding these interactions is crucial for enhancing fluconazole sensitivity and effectively combating C. auris.

Sensitivity Analysis of C. auris, S. cerevisiae, and C. cladosporioides by Irradiation with Far-UVC, UVC, and UVB

Background

The World Health Organization has published a list of pathogenic fungi with prior-itizing groups and calls for research and development of antifungal measures, with Candida auris belonging to the group with high priority.

Methods

The photosensitivity towards short wavelength ultraviolet irradiation (Far-UVC, UVC, and UVB) was investigated and compared to other yeasts (Saccharomyces cerevisiae) and a mold (Cladosporium cladosporioides). The observed 1-log reduction doses were compared to literature values of other representatives of the genus Candida, but also with S. cerevisiae, Aspergillus niger, and A. fumigatus.

Results

For the determined 1-log reduction doses, an increase with higher wavelengths was observed. A 1-log reduction dose of 4.3 mJ/cm2 was determined for C. auris when irradiated at 222 nm, a dose of 6.1 mJ/cm2 at 254 nm and a 1-log reduction dose of 51.3 mJ/cm2 was required when irradiated with UVB.

Conclusions

It was observed that S. cerevisiae is a possible surrogate for C. auris for irradiation with Far-UVC and UVB due to close 1-log reduction doses. No surrogate suitability was verified for C. cladosporioides in relation to A. niger and A. fumigatus for irradiation with a wavelength of 254 nm and for A. niger at 222 nm.

Metabolic Patterns of Fluconazole Resistant and Susceptible Candida auris Clade V and I

Candida auris, an emerging non-albicans multidrug-resistant yeast, has become a significant cause of invasive candidiasis in healthcare settings. So far, data on the metabolites of C. auris in different clades are minimal, and no studies have focused on clade V metabolites. Therefore, Gas chromatography-mass spectrometry (GC-MS) was used for the metabolomic profiling of clade I C. auris compared with fluconazole-resistant and susceptible C. auris in clade V strains. GC-MS chromatography revealed 28, 22, and 30 compounds in methanolic extracts of the fluconazole-susceptible and fluconazole-resistant C. auris clade V and C. auris clade I strain, respectively. Some compounds, such as acetamide and metaraminol, were found in fluconazole-susceptible and resistant C. auris clade V and clade I. N-methyl-ethanamine and bis(2-ethylhexyl) phthalate metabolites were found in both fluconazole -susceptible and resistant C. auris clade V, as well as 3-methyl-4-isopropylphenol, 3,5-bis(1,1-dimethyl)-1,2-benzenediol, and diisostyl phthalate metabolites in both fluconazole resistant C. auris clade V and I. Identifying these metabolites contributes to understanding the morphogenesis and pathogenesis of C. auris, highlighting their potential role in antifungal drug resistance and the control of fungal growth. However, further experiments are warranted to fully comprehend the identified metabolites' regulatory responses, and there may be potential challenges in translating these findings into clinical applications.

In silico bioprospecting of receptors associated with the mechanism of action of Rondonin, an antifungal peptide from spider Acanthoscurria rondoniae haemolymph

Multiple drug-resistant fungal species are associated with the development of diseases. Thus, more efficient drugs for the treatment of these aetiological agents are needed. Rondonin is a peptide isolated from the haemolymph of the spider Acanthoscurria rondoniae. Previous studies have shown that this peptide has antifungal activity against Candida sp. and Trichosporon sp. strains, acting on their genetic material. However, the molecular targets involved in its biological activity have not yet been described. Bioinformatics tools were used to determine the possible targets involved in the biological activity of Rondonin. The PharmMapper server was used to search for microorganismal targets of Rondonin. The PatchDock server was used to perform the molecular docking. UCSF Chimera software was used to evaluate these intermolecular interactions. In addition, the I-TASSER server was used to predict the target ligand sites. Then, these predictions were contrasted with the sites previously described in the literature. Molecular dynamics simulations were conducted for two promising complexes identified from the docking analysis. Rondonin demonstrated consistency with the ligand sites of the following targets: outer membrane proteins F (id: 1MPF) and A (id: 1QJP), which are responsible for facilitating the passage of small molecules through the plasma membrane; the subunit of the flavoprotein fumarate reductase (id: 1D4E), which is involved in the metabolism of nitrogenous bases; and the ATP-dependent Holliday DNA helicase junction (id: 1IN4), which is associated with histone proteins that package genetic material. Additionally, the molecular dynamics results indicated the stability of the interaction of Rondonin with 1MPF and 1IN4 during a 10 ns simulation. These interactions corroborate with previous in vitro studies on Rondonin, which acts on fungal genetic material without causing plasma membrane rupture. Therefore, the bioprospecting methods used in this research were considered satisfactory since they were consistent with previous results obtained via in vitro experimentation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-024-00224-1.

Photoinactivation by UVA radiation and visible light of Candida auris compared to other fungi

In addition to the rising number of patients affected by viruses and bacteria, the number of fungal infections has also been rising over the years. Due to the increase in resistance to various antimycotics, investigations into further disinfection options are important. In this study, two yeasts (Candida auris and Saccharomyces cerevisiae) and a mold (Cladosporium cladosporioides) were irradiated at 365, 400, and 450 nm individually. The resulting log 1 reduction doses were determined and compared with other studies. Furthermore, fluorescence measurements of C. auris were performed to detect possible involved photosensitizers. A roughly exponential photoinactivation was observed for all three fungi and all irradiation wavelengths with higher D90 doses for longer wavelengths. The determined log 1 reduction doses of C. auris and S. cerevisiae converged with increasing wavelength. However, S. cerevisiae was more photosensitive than C. auris for all irradiation wavelengths and is therefore not a suitable C. auris surrogate for photoinactivation experiments. For the mold C. cladosporioides, much higher D90 doses were determined than for both yeasts. Concerning potential photosensitizers, flavins and various porphyrins were detected by fluorescence measurements. By excitation at 365 nm, another, so far unreported fluorophore and potential photosensitizer was also observed. Based on its fluorescence spectrum, we assume it to be thiamine.Graphic abstract.

An evaluation of Rezafungin: the latest treatment option for adults with candidemia and invasive candidiasis

INTRODUCTION

Invasive fungal infections, especially candidemia and invasive candidiasis, continue to cause substantial morbidity and mortality. In addition, the emergence of drug-resistant Candida species, notably C. glabrata and C. auris, along with limitations in available treatments, highlights the urgent need for novel, effective antifungal agents.

AREAS COVERED

This review discusses the results of in vitro studies evaluating the spectrum and highlights the pharmacokinetic/pharmacodynamic properties. It also includes discussions on two key clinical studies that assess safety, tolerability, and efficacy.

EXPERT OPINION

Rezafungin has demonstrated comparable efficacy to other echinocandins in two clinical studies and exhibits in vitro activity against a broad range of Candida species and Aspergillus spp. It has a favorable safety profile with minimal side effects, and no drug interactions or effects on QT intervals. In contrast to other echinocandins, it demonstrates dose-dependent killing, a prolonged half-life, and low clearance make it suitable for once-weekly dosing, which is supported by clinical trials confirming its efficacy. Rezafungin offers a promising option for the outpatient management of difficult to treat fungal infections. It has become a valuable addition to the antifungal arsenal, with the potential to reduce hospital length of stay and hospitalization costs and combat drug-resistant Candida species.

Anticandidal effectiveness of greenly synthesized zinc oxide nanoparticles against candidal pathogens

Drug resistance of pathogenic candidal strains to conventional antifungal agents represents a significant health issue contributing to high morbidity worldwide. Hence, the aim of the current study focused on evaluating the antifungal and synergistic activities of the green synthesized zinc oxide nanoparticles formulated using Laurus nobilis leaf extract. The biogenic ZnONPs were hexagonal in shape with average particle size diameter of 37.98 nm and pure crystalline structure as detected by XRD data. The highest antifungal activity of biogenic ZnONPs was detected against Candida parapsilosis strain demonstrating relative inhibitory zone diameters of 17.13 ± 0.74 and 25.78 ± 0.47 mm, at the concentrations of 100 and 200 µg/disk, respectively. Moreover, the biogenic ZnONPs demonstrated the highest synergistic activity with clotrimazole antifungal agent against Candida glabrata followed by Candida auris strains. MTT assay revealed that the biogenic ZnONPs showed low toxicity demonstrating relative IC50 value of 774.45 µg/mL against normal lung fibroblast cells which further affirmed their biosafety for application. In conclusion, the bioinspired ZnONPs could be utilized for the formulation of effective antifungal agents against drug resistant candidal strains and also could be combined with antifungal agents to boost their antifungal efficiency.

Upc2-mediated mechanisms of azole resistance in Candida auris

Candida auris is an emerging yeast pathogen of major concern because of its ability to cause hospital outbreaks of invasive candidiasis and to develop resistance to antifungal drugs. A majority of C. auris isolates are resistant to fluconazole, an azole drug used for the treatment of invasive candidiasis. Mechanisms of azole resistance are multiple, including mutations in the target gene ERG11 and activation of the transcription factors Tac1b and Mrr1, which control the drug transporters Cdr1 and Mdr1, respectively. We investigated the role of the transcription factor Upc2, which is known to regulate the ergosterol biosynthesis pathway and azole resistance in other Candida spp. Genetic deletion and hyperactivation of Upc2 by epitope tagging in C. auris resulted in drastic increases and decreases in susceptibility to azoles, respectively. This effect was conserved in strains with genetic hyperactivation of Tac1b or Mrr1. Reverse transcription PCR analyses showed that Upc2 regulates ERG11 expression and also activates the Mrr1/Mdr1 pathway. We showed that upregulation of MDR1 by Upc2 could occur independently from Mrr1. The impact of UPC2 deletion on MDR1 expression and azole susceptibility in a hyperactive Mrr1 background was stronger than that of MRR1 deletion in a hyperactive Upc2 background. While Upc2 hyperactivation resulted in a significant increase in the expression of TAC1b, CDR1 expression remained unchanged. Taken together, our results showed that Upc2 is crucial for azole resistance in C. auris, via regulation of the ergosterol biosynthesis pathway and activation of the Mrr1/Mdr1 pathway. Notably, Upc2 is a very potent and direct activator of Mdr1.IMPORTANCECandida auris is a yeast of major medical importance causing nosocomial outbreaks of invasive candidiasis. Its ability to develop resistance to antifungal drugs, in particular to azoles (e.g., fluconazole), is concerning. Understanding the mechanisms of azole resistance in C. auris is important and may help in identifying novel antifungal targets. This study shows the key role of the transcription factor Upc2 in azole resistance of C. auris and shows that this effect is mediated via different pathways, including the regulation of ergosterol biosynthesis and also the direct upregulation of the drug transporter Mdr1.

The Gordian Knot of C. auris: If You Cannot Cut It, Prevent It

Since its first description in 2009, Candida auris has, so far, resulted in large hospital outbreaks worldwide and is considered an emerging global public health threat. Exceptionally for yeast, it is gifted with a profoundly worrying invasive potential and high inter-patient transmissibility. At the same time, it is capable of colonizing and persisting in both patients and hospital settings for prolonged periods of time, thus creating a vicious cycle of acquisition, spreading, and infection. It exhibits various virulence qualities and thermotolerance, osmotolerance, filamentation, biofilm formation and hydrolytic enzyme production, which are mainly implicated in its pathogenesis. Owing to its unfavorable profile of resistance to diverse antifungal agents and the lack of effective treatment options, the implementation of robust infection prevention and control (IPC) practices is crucial for controlling and minimizing intra-hospital transmission of C. auris. Rapid and accurate microbiological identification, adherence to hand hygiene, use of adequate personal protective equipment (PPE), proper handling of catheters and implantable devices, contact isolation, periodical environmental decontamination, targeted screening, implementation of antimicrobial stewardship (AMS) programs and communication between healthcare facilities about residents' C. auris colonization status are recognized as coherent strategies for preventing its spread. Current knowledge on C. auris epidemiology, clinical characteristics, and its mechanisms of pathogenicity are summarized in the present review and a comprehensive overview of IPC practices ensuring yeast prevention is also provided.

Antifungal therapy of Candida biofilms: Past, present and future

Virtually all Candida species linked to clinical candidiasis are capable of forming highly resistant biofilms on different types of surfaces, which poses an additional significant threat and further complicates therapy of these infections. There is a scarcity of antifungal agents, and their effectiveness, particularly against biofilms, is limited. Here we provide a historical perspective on antifungal agents and therapy of Candida biofilms. As we reflect upon the past, consider the present, and look towards the future of antifungal therapy of Candida biofilms, we believe that there are reasons to remain optimistic, and that the major challenges of Candida biofilm therapy can be conquered within a reasonable timeframe.

The rapid emergence of antifungal-resistant human-pathogenic fungi

During recent decades, the emergence of pathogenic fungi has posed an increasing public health threat, particularly given the limited number of antifungal drugs available to treat invasive infections. In this Review, we discuss the global emergence and spread of three emerging antifungal-resistant fungi: Candida auris, driven by global health-care transmission and possibly facilitated by climate change; azole-resistant Aspergillus fumigatus, driven by the selection facilitated by azole fungicide use in agricultural and other settings; and Trichophyton indotineae, driven by the under-regulated use of over-the-counter high-potency corticosteroid-containing antifungal creams. The diversity of the fungi themselves and the drivers of their emergence make it clear that we cannot predict what might emerge next. Therefore, vigilance is critical to monitoring fungal emergence, as well as the rise in overall antifungal resistance.

Metabarcoding approach to identify bacterial community profiling related to nosocomial infection and bacterial trafficking-routes in hospital environments

Nosocomial infections (NIs) appear in patients under medical care in the hospital. The surveillance of the bacterial communities employing high-resolution 16S rRNA profiling, known as metabarcoding, represents a reliable method to establish factors that may influence the composition of the bacterial population during NIs. The present study aimed to utilize high-resolution 16S rRNA profiling to identify high bacterial diversity by analyzing 11 inside and 10 outside environments from the General Hospital of Ribeirão Preto Medical School, Brazil. Our results identified a high bacterial diversity, and among these, the most abundant bacterial genera linked to NIs were Cutibacterium, Streptococcus, Staphylococcus, and Corynebacterium. A Acinetobacter was detected in cafeterias, bus stops, and adult and pediatric intensive care units (ICUs). Data suggest an association between transport and alimentation areas proximal to the hospital ICU environment. Interestingly, the correlation and clusterization analysis showed the potential of the external areas to directly influence the ICU pediatric department microbial community, including the outpatient's clinic, visitor halls, patient reception, and the closest cafeterias. Our results demonstrate that high-resolution 16S rRNA profiling is a robust and reliable tool for bacterial genomic surveillance. In addition, the metabarcoding approach might help elaborate decontamination policies, and consequently reduce NIs.

Screening the medicine for malaria venture's Pandemic Response Box to identify novel inhibitors of Candida albicans and Candida auris biofilm formation

Candida spp. are opportunistic yeasts capable of forming biofilms, which contribute to resistance, increasing the urgency for new effective antifungal therapies. Repurposing existing drugs could significantly accelerate the development of novel therapies against candidiasis. We screened the Pandemic Response Box containing 400 diverse drug-like molecules active against bacteria, viruses or fungi, for inhibitors of Candida albicans and Candida auris biofilm formation. Initial hits were identified based on the demonstration of >70% inhibitory activity. Dose-response assays were used to confirm the antifungal activity of initial hits and establish their potency. The spectrum of antifungal activity of the leading compounds was determined against a panel of medically important fungi, and the in vivo activity of the leading repositionable agent was evaluated in murine models of C. albicans and C. auris systemic candidiasis. The primary screening identified 20 hit compounds, and their antifungal activity and potency against C. albicans and C. auris were validated using dose-response measurements. From these experiments, the rapalog everolimus, emerged as the leading repositionable candidate. Everolimus displayed potent antifungal activity against different Candida spp., but more moderate levels of activity against filamentous fungi. Treatment with everolimus increased survival of mice infected with C. albicans, but not those with C. auris. The screening of the Pandemic Response Box resulted in the identification of several drugs with novel antifungal activity, with everolimus emerging as the main repositionable candidate. Further in vitro and in vivo studies are needed to confirm its potential therapeutic use.

Enhancing the antimicrobial activity of silver nanoparticles against ESKAPE bacteria and emerging fungal pathogens by using tea extracts

The sale of antibiotics and antifungals has skyrocketed since 2020. The increasing threat of pathogens like ESKAPE bacteria (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.), which are effective in evading existing antibiotics, and yeasts like Candida auris or Cryptococcus neoformans is pressing to develop efficient antimicrobial alternatives. Nanoparticles, especially silver nanoparticles (AgNPs), are believed to be promising candidates to supplement or even replace antibiotics in some applications. Here, we propose a way to increase the antimicrobial efficiency of silver nanoparticles by using tea extracts (black, green, or red) for their synthesis. This allows for using lower concentrations of nanoparticles and obtaining the antimicrobial effect in a short time. We found that AgNPs synthesized using green tea extract (G-TeaNPs) are the most effective, causing approximately 80% bacterial cell death in Gram-negative bacteria within only 3 hours at a concentration of 0.1 mg mL-1, which is better than antibiotics. Ampicillin at the same concentration (0.1 mg mL-1) and within the same duration (3 h) causes only up to 40% decrease in the number of S. aureus and E. cloacae cells (non-resistant strains). The tested silver nanoparticles also have antifungal properties and are effective against C. auris and C. neoformans, which are difficult to eradicate using other means. We established that silver nanoparticles synthesized with tea extracts have higher antibacterial properties than silver nanoparticles alone. Such formulations using inexpensive tea extracts and lower concentrations of silver nanoparticles show a promising solution to fight various pathogens.

Improving health literacy of antifungal use-Comparison of the readability of antifungal medicines information from Australia, EU, UK, and US of 16 antifungal agents across 5 classes (allylamines, azoles, echinocandins, polyenes, and others)

Adherence to antifungals is poor in high endemic regions where antifungal resistance is high. Poor readability of prescription/over-the-counter (OTC) antifungals may contribute to poor adherence, due to the patient not fully understanding the purpose, importance, and dosage of their antifungal medicine. As there are no reports on the readability of antifungals, this study examined the readability of patient-facing antifungal information. Antifungals (n = 16; five classes [allylamines, azoles, echinocandins, polyenes, and others-flucytosine and griseofulvin]) were selected. Readability of four sources of information, (i) summary of product characteristics, (ii) patient information leaflets (PILs), (iii) OTC patient information, and (iv) patient web-based information, was calculated using Readable software, to obtain readability scores [(i) Flesch Reading Ease [FRE], (ii) Flesch-Kinkaid Grade Level [FKGL], (iii) Gunning Fog Index, and (iv) Simple Measure of Gobbledygook (SMOG) Index) and text metrics [word count, sentence count, words/sentence, and syllables/word]. PILs, web-based resources, and OTC patient information had good readability (FRE mean ± sd = 52.8 ± 6.7, 58.6 ± 6.9, and 57.3 ± 7.4, respectively), just falling short of the ≥ 60 target. For FKGL (target ≤ 8.0), PILs, web-based resources, and OTC patient information also had good readability (mean ± sd = 8.5 ± 1.0, 7.2 ± 0.86, and 7.8 ± 0.1, respectively). Improved readability scores observed correlate with reduced words, words/sentence and syllables/word. Improving readability may lead to improved patient health literacy. Healthcare professionals, academics, and publishers preparing written materials regarding antifungals for the lay/patient community are encouraged to employ readability calculators to check the readability of their work, so that the final material is within recommended readability reference parameters, to support the health literacy of their patients/readers.

High-Throughput Screening of the Repurposing Hub Library to Identify Drugs with Novel Inhibitory Activity against Candida albicans and Candida auris Biofilms

Candidiasis is one of the most frequent nosocomial infections affecting an increasing number of at-risk patients. Candida albicans remains the most frequent causative agent of candidiasis, but, in the last decade, C. auris has emerged as a formidable multi-drug-resistant pathogen. Both species are fully capable of forming biofilms, which contribute to resistance, increasing the urgency for new effective antifungal therapies. Repurposing existing drugs could significantly accelerate the development of novel therapies against candidiasis. Here, we have screened the Repurposing Hub library from the Broad Institute, containing over 6000 compounds, in search for inhibitors of C. albicans and C. auris biofilm formation. The primary screen identified 57 initial hits against C. albicans and 33 against C. auris. Confirmatory concentration-dependent assays were used to validate the activity of the initial hits and, at the same time, establish their anti-biofilm potency. Based on these results, ebselen, temsirolimus, and compound BAY 11-7082 emerged as the leading repositionable compounds. Subsequent experiments established their spectrum of antifungal activity against yeasts and filamentous fungi. In addition, their in vivo activity was examined in the murine models of hematogenously disseminated C. albicans and C. auris infections. Although promising, further in vitro and in vivo studies are needed to confirm their potential use for the therapy of candidiasis and possibly other fungal infections.

Emerging Role of Sphingolipids in Amphotericin B Drug Resistance

Invasive fungal infections in humans are common in people with compromised immune systems and are difficult to treat, resulting in high mortality. Amphotericin B (AmB) is one of the main antifungal drugs available to treat these infections. AmB binds with plasma membrane ergosterol, causing leakage of cellular ions and promoting cell death. The increasing use of available antifungal drugs to combat pathogenic fungal infections has led to the development of drug resistance. AmB resistance is not very common and is usually caused by changes in the amount or type of ergosterol or changes in the cell wall. Intrinsic AmB resistance occurs in the absence of AmB exposure, whereas acquired AmB resistance can develop during treatment. However, clinical resistance arises due to treatment failure with AmB and depends on multiple factors such as the pharmacokinetics of AmB, infectious fungal species, and host immune status. Candida albicans is a common opportunistic pathogen that can cause superficial infections of the skin and mucosal surfaces, thrush, to life-threatening systemic or invasive infections. In addition, immunocompromised individuals are more susceptible to systemic infections caused by Candida, Aspergillus, and Cryptococcus. Several antifungal drugs with different modes of action are used to treat systemic to invasive fungal infections and are approved for clinical use in the treatment of fungal diseases. However, C. albicans can develop a variety of defenses against antifungal medications. In fungi, plasma membrane sphingolipid molecules could interact with ergosterol, which can lead to the alteration of drug susceptibilities such as AmB. In this review, we mainly summarize the role of sphingolipid molecules and their regulators in AmB resistance.

Rapid preparation of Candida genomic DNA: combined use of enzymatic digestion and thermal disruption

Nucleic acid based molecular technologies are the most promising tools for the early diagnosis of Candida infection. A simple and effective DNA preparation method is of critical for standardizing and applying molecular diagnostics in clinic laboratories. The goal of this study was to develop a Candida DNA preparation method that was quick to do, easy to perform, and bio-safe. Snailase and lyticase were screened and combined in this work to enhance the lysis of Candida cells. The lysis solution composition and metal bath were optimized to boost amplification efficiency and biosafety. A duplex real-time PCR was established to evaluate the sensitivity and specificity of the preparation method. Using the supernatant from the rapid preparation method as templates, the duplex PCR sensitivities for five common Candida species were determined to be as low as 10⁰ CFUs. When compared to conventional preparation methods, the samples prepared by our method showed higher PCR detection sensitivity. PCR identification and ITS sequencing were 100% consistent, which was better than biochemical identification. This study demonstrates a rapid method for Candida DNA preparation that has the potential to be used in clinical laboratories. Meanwhile, the practical application of the method for clinical samples needs to be proven in future investigations.

Metal Complexes as Antifungals? From a Crowd-Sourced Compound Library to the First In Vivo Experiments

There are currently fewer than 10 antifungal drugs in clinical development, but new fungal strains that are resistant to most current antifungals are spreading rapidly across the world. To prevent a second resistance crisis, new classes of antifungal drugs are urgently needed. Metal complexes have proven to be promising candidates for novel antibiotics, but so far, few compounds have been explored for their potential application as antifungal agents. In this work, we report the evaluation of 1039 metal-containing compounds that were screened by the Community for Open Antimicrobial Drug Discovery (CO-ADD). We show that 20.9% of all metal compounds tested have antimicrobial activity against two representative Candida and Cryptococcus strains compared with only 1.1% of the >300,000 purely organic molecules tested through CO-ADD. We identified 90 metal compounds (8.7%) that show antifungal activity while not displaying any cytotoxicity against mammalian cell lines or hemolytic properties at similar concentrations. The structures of 21 metal complexes that display high antifungal activity (MIC ≤1.25 μM) are discussed and evaluated further against a broad panel of yeasts. Most of these have not been previously tested for antifungal activity. Eleven of these metal complexes were tested for toxicity in the Galleria mellonella moth larva model, revealing that only one compound showed signs of toxicity at the highest injected concentration. Lastly, we demonstrated that the organo-Pt(II) cyclooctadiene complex Pt1 significantly reduces fungal load in an in vivo G. mellonella infection model. These findings showcase that the structural and chemical diversity of metal-based compounds can be an invaluable tool in the development of new drugs against infectious diseases.

Antimicrobial, Antivirulence, and Antiparasitic Potential of Capsicum chinense Jacq. Extracts and Their Isolated Compound Capsaicin

Bacterial, fungal, and parasitic infections increase morbimortality rates and hospital costs. This study aimed to assess the antimicrobial and antiparasitic activities of the crude extract from the seeds and peel of the pepper Capsicum chinense Jacq. and of the isolated compound capsaicin and to evaluate their ability to inhibit biofilm formation, eradicate biofilm, and reduce hemolysin production by Candida species. The crude ethanolic and hexane extracts were obtained by maceration at room temperature, and their chemical compositions were analyzed by liquid chromatography coupled to mass spectrometry (LC–MS). The antimicrobial activity of the samples was evaluated by determining the minimum inhibitory concentration. Inhibition of biofilm formation and biofilm eradication by the samples were evaluated based on biomass and cell viability. Reduction of Candida spp. hemolytic activity by the samples was determined on sheep blood agar plates. The antiparasitic action of the samples was evaluated by determining their ability to inhibit Toxoplasma gondii intracellular proliferation. LC–MS-ESI analyses helped to identify organic and phenolic acids, flavonoids, capsaicinoids, and fatty acids in the ethanolic extracts, as well as capsaicinoids and fatty acids in the hexane extracts. Antifungal action was more evident against C. glabrata and C. tropicalis. The samples inhibited biofilm formation and eradicated the biofilm formed by C. tropicalis more effectively. Sub-inhibitory concentrations of the samples significantly reduced the C. glabrata and C. tropicalis hemolytic activity. The samples only altered host cell viability when tested at higher concentrations; however, at non-toxic concentrations, they reduced T. gondii growth. In association with gold standard drugs used to treat toxoplasmosis, capsaicin improved their antiparasitic activity. These results are unprecedented and encouraging, indicating the Capsicum chinense Jacq. peel and seed extracts and capsaicin display antifungal and antiparasitic activities.

COVID-19-Associated Fungal Infections: An Urgent Need for Alternative Therapeutic Approach?

Secondary fungal infections may complicate the clinical course of patients affected by viral respiratory diseases, especially those admitted to intensive care unit. Hospitalized COVID-19 patients are at increased risk of fungal co-infections exacerbating the prognosis of disease due to misdiagnosis that often result in treatment failure and high mortality rate. COVID-19-associated fungal infections caused by predominantly Aspergillus and Candida species, and fungi of the order Mucorales have been reported from several countries to become significant challenge for healthcare system. Early diagnosis and adequate antifungal therapy is essential to improve clinical outcomes, however, drug resistance shows a rising trend highlighting the need for alternative therapeutic agents. The purpose of this review is to summarize the current knowledge on COVID-19-associated mycoses, treatment strategies and the most recent advancements in antifungal drug development focusing on peptides with antifungal activity.

Emergence of Candida auris in intensive care units in Algeria

Background

Currently, Candida auris is among the most serious emerging pathogens that can be associated with nosocomial infections and outbreaks in intensive care units. Clinicians must be able to identify and manage it quickly.

Objective

Here, we report for the first time in Algeria seven cases of C. auris infection or colonisation.

Methods and Results

The strains were isolated from clinical sites including bronchial aspirates (n = 4), wound swabs (n = 1), urine sample (n = 1) and peritoneal fluid (n = 1), in patients admitted to the intensive care unit. Candida auris was identified both by MALDI‐TOF and by sequencing the ITS region and the D1/D2 domain. Antifungal susceptibility testing was performed using the E‐test method. Non‐wildtype susceptibility was observed for five strains against fluconazole, itraconazole, voriconazole and caspofungin. Genotyping showed the presence of four clades (I–IV) in one hospital.

Conclusions

Appropriate antifungal treatments with rapid and accurate microbial identification are the cornerstone for the management and control of C. auris infections.

The effect of antifungal resistance development on the virulence of Candida species

In recent years, the relevance of diseases associated with fungal pathogens increased worldwide. Members of the Candida genus are responsible for the greatest number of fungal bloodstream infections every year. Epidemiological data consistently indicate a modest shift toward non-albicans species, albeit Candidaalbicans is still the most recognizable species within the genus. As a result, the number of clinically relevant pathogens has increased, and, despite their distinct pathogenicity features, the applicable antifungal agents remained the same. For bloodstream infections, only three classes of drugs are routinely used, namely polyenes, azoles and echinocandins. Antifungal resistance toward all three antifungal drug classes frequently occurs in clinical settings. Compared with the broad range of literature on virulence and antifungal resistance of Candida species separately, only a small portion of studies examined the effect of resistance on virulence. These studies found that resistance to polyenes and echinocandins concluded in significant decrease in the virulence in different Candida species. Meanwhile, in some cases, resistance to azole type antifungals resulted in increased virulence depending on the species and isolates. These findings underline the importance of studies aiming to dissect the connections of virulence and resistance in Candida species.

Antifungal Properties of Zataria multiflora on Candida species: A Systematic Review

BACKGROUND AND PURPOSE

Candida infections have increased significantly in the antimicrobial resistance era, and synthetic antifungal drugs have limitations. The present work aimed to review the antifungal properties of Zataria multiflora (Z. multiflora) as an herbal remedy.

METHOD

PubMed, Scopus, ScienceDirect, Web of Science, SID, Civilica, and Magiran databases were searched for the antifungal activity on in vitro, in vivo, dental biofilm, and clinical studies of Z. multiflora on Candida species.

RESULTS

Overall, 33 articles evaluated the effect of Z. multiflora on Candida species and classified them into four groups, as follows in vitro (23), dental biofilm (6), in vivo (2), and clinical studies (3). All studies considered Z. multiflora effective in reducing or even inhibiting the growth of Candida species. NoMFC significant differences were seen in the effect of Z. multiflora on susceptible Candida compared to the resistant groups of Candida in the studies. It was also influential in inhibiting C. parapsilosis, C. glabrata, C. krusei, C. kefyer, and C. zeylanoides.

CONCLUSION

Considering the side effects and resistance of current antifungal drugs as well as the benefits of using herbal medicines, such as lower cost, less likely to develop drug resistance, the absence of side effects, and toxicity compared with chemical ones, it is possible as a powerful alternative to replace or combine with the current antifungal for Candida infection therapy along with other therapies.

Laboratory-based surveillance of Candida auris in Colombia, 2016-2020

BACKGROUND

Since the first report of Candida auris in 2016, the Colombian Instituto Nacional de Salud (INS) has implemented a national surveillance of the emerging multidrug-resistant fungus.

OBJECTIVES

This report summarises the findings of this laboratory-based surveillance from March 2016 to December 2020.

RESULTS

A total of 1720 C. auris cases were identified, including 393 (23%) colonisation cases and 1327 (77%) clinical cases. Cases were reported in 20 of 32 (62%) departments of Colombia and involved hospitals from 33 cities. The median age of patients was 34 years; 317 (18%) cases were children under 16 years, 54% were male. The peak number of cases was observed in 2019 (n = 541). In 2020, 379 (94%) of 404 cases reported were clinical cases, including 225 bloodstream infections (BSI) and 154 non-BSI. Among the 404 cases reported in 2020, severe COVID-19 was reported in 122 (30%). Antifungal susceptibility was tested in 379 isolates. Using CDC tentative breakpoints for resistance, 35% of isolates were fluconazole resistant, 33% were amphotericin B resistant, and 0.3% isolates were anidulafungin resistant, 12% were multidrug resistant, and no pan-resistant isolates were identified.

CONCLUSION

For five years of surveillance, we observed an increase in the number and geographic spread of clinical cases and an increase in fluconazole resistance. These observations emphasise the need for improved measures to mitigate spread.

Impact of SARS-CoV-2 Epidemic on Antimicrobial Resistance: A Literature Review

Antimicrobial resistance is an urgent threat to public health and global development; in this scenario, the SARS-CoV2 pandemic has caused a major disruption of healthcare systems and practices. A narrative review was conducted on articles focusing on the impact of COVID-19 on multidrug-resistant gram-negative, gram-positive bacteria, and fungi. We found that, worldwide, multiple studies reported an unexpected high incidence of infections due to methicillin-resistant S. aureus, carbapenem-resistant A. baumannii, carbapenem-resistant Enterobacteriaceae, and C. auris among COVID-19 patients admitted to the intensive care unit. In this setting, inappropriate antimicrobial exposure, environmental contamination, and discontinuation of infection control measures may have driven selection and diffusion of drug-resistant pathogens.

Photodynamic Therapy Is Effective Against Candida auris Biofilms

Fungal infections are increasing in prevalence worldwide. The paucity of available antifungal drug classes, combined with the increased occurrence of multidrug resistance in fungi, has led to new clinical challenges in the treatment of fungal infections. Candida auris is a recently emerged multidrug resistant human fungal pathogen that has become a worldwide public health threat. C. auris clinical isolates are often resistant to one or more antifungal drug classes, and thus, there is a high unmet medical need for the development of new therapeutic strategies effective against C. auris. Additionally, C. auris possesses several virulence traits, including the ability to form biofilms, further contributing to its drug resistance, and complicating the treatment of C. auris infections. Here we assessed red, green, and blue visible lights alone and in combination with photosensitizing compounds for their efficacies against C. auris biofilms. We found that (1) blue light inhibited and disrupted C. auris biofilms on its own and that the addition of photosensitizing compounds improved its antibiofilm potential; (2) red light inhibited and disrupted C. auris biofilms, but only in combination with photosensitizing compounds; and (3) green light inhibited C. auris biofilms in combination with photosensitizing compounds, but had no effects on disrupting C. auris biofilms. Taken together, our findings suggest that photodynamic therapy could be an effective non-drug therapeutic strategy against multidrug resistant C. auris biofilm infections.

In Vitro Antifungal Activity of Luliconazole, Efinaconazole, and Nine Comparators Against Aspergillus and Candida Strains Isolated from Otomycosis

Background: Aspergillus and Candida species are the most commonly identified fungal pathogens in otomycosis. However, we usually encounter some difficulties in its treatment because many patients show resistance to antifungal agents and present a high recurrence rate. Objectives: The current research was conducted to compare the in vitro activities of luliconazole (LUL), and efinaconazole (EFN) and the nine comparators on Aspergillus and Candida strains isolated from otomycosis. Methods: The in vitro activities of nine common antifungal drugs (amphotericin B (AMB), voriconazole (VRC), fluconazole (FLU), itraconazole (ITC), ketoconazole (KTO), clotrimazole (CLO), nystatin (NYS), terbinafine (TRB), and caspofungin (CAS)) and two novel new azoles (LUL and EFN) against 108 clinical isolates of Aspergillus and Candida species obtained from otomycosis were assessed according to the CLSI broth microdilution document. Results: The LUL and EFN had the geometric mean minimum inhibitory concentrations (GM MICs) of 0.098 and 0.109 μg/mL against all Aspergillus strains, respectively. Furthermore, the GM MICs of all Candida isolates for LUL, EFN, CAS, CLO, VRC, AMB, ITC, KTO, FLU, NYS, and TRB were calculated to be 0.133, 0.144, 0.194, 0.219, 0.475, 0.537, 0.655, 1.277, 4.905, 9.372, and 13.592 μg/mL, respectively. Additionally, 6 (35.29%), 2 (11.7%), and 1 (5.88%) Candida isolates were resistant to FLU, CAS, and VRC, respectively. Conclusions: As the findings indicated, LUL and EFN showed the lowest GM MIC values against the examined species. Accordingly, these novel imidazole and triazole antifungal agents can be regarded as proper candidates for the treatment of otomycosis caused by Aspergillus and Candida strains.

Axillary Digital Thermometers uplifted a multidrug-susceptible Candida auris outbreak among COVID-19 patients in Brazil

Objectives

To describe the first outbreak of Candidaauris in Brazil, including epidemiological, clinical and microbiological data.

Methods

After the first Candidaauris‐colonised patient was diagnosed in a COVID‐19 ICU at a hospital in Salvador, Brazil, a multidisciplinary team conducted a local C. auris prevalence investigation. Screening cultures for C. auris were collected from patients, healthcare workers and inanimate surfaces. Risk factors for C. auris colonisation were evaluated, and the fungemia episodes that occurred after the investigation were also analysed and described. Antifungal susceptibility of the C. auris isolates was determined, and they were genotyped with microsatellite analysis.

Results

Among body swabs collected from 47 patients, eight (n = 8/47, 17%) samples from the axillae were positive for C. auris. Among samples collected from inanimate surfaces, digital thermometers had the highest rate of positive cultures (n = 8/47, 17%). Antifungal susceptibility testing showed MICs of 0.5 to 1 mg/L for AMB, 0.03 to 0.06 mg/L for voriconazole, 2 to 4 mg/L for fluconazole and 0.03 to 0.06 mg/L for anidulafungin. Microsatellite analysis revealed that all C. auris isolates belong to the South Asian clade (Clade I) and had different genotypes. In multivariate analysis, having a colonised digital thermometer was the only independent risk factor associated with C. auris colonisation. Three episodes of C. auris fungemia occurred after the investigation, with 30‐day attributable mortality of 33.3%.

Conclusions

Emergence of C. auris in Salvador, Brazil, may be related to local C. auris clade I closely related genotypes. Contaminated axillary monitoring thermometers may facilitate the dissemination of C. auris reinforcing the concept that these reusable devices should be carefully cleaned with an effective disinfectant or replaced by other temperature monitoring methods.

Fungaemia due to rare yeasts in paediatric intensive care units: A prospective study

BACKGROUND

Considering the emergence of fungaemia due to rare yeasts at our centre, we performed a systematic epidemiologic study on fungaemia due to rare yeasts.

OBJECTIVES

We undertook the present prospective observational study to explore the epidemiological features and clinical characteristics of fungaemia due to rare yeasts in paediatric ICUs at our centre.

METHODS

The successive yeasts isolated from blood at our PICUs during December 2017 through March 2019 were identified by molecular methods. Fungaemia due to yeasts other than C. albicans, C. tropicalis, C. glabrata, C. krusei and C. parapsilosis was categorised as rare yeast fungaemia. Antifungal susceptibility testing of the yeast isolates was performed as per clinical and laboratory standards institute (CLSI) guidelines. We also compared different clinical parameters of fungaemia due to common versus rare yeasts, and rare yeasts in neonates versus non-neonates.

RESULTS

During the study period, 212 yeast isolates were obtained from 159 patients at PICUs of our hospital, and 127 isolates from 98 patients (61.6%) were categorised as rare yeasts. Neonates acquired fungaemia significantly earlier after ICU admission than non-neonates (median: 4 vs 6 days; p = .005). of rare yeast fungaemia, Wickerhamomyces anomalus (43.8%) and Candida utilis (40.8%) were common isolates; surgical intervention and gastrointestinal disease were significantly associated; overall, azole, echinocandin and amphotericin B resistance was at 9.1%, 1.02% and 1.02%, respectively; overall mortality was 65.3%.

CONCLUSIONS

The emergence of rare yeasts especially W. anomalus and C. utilis causing fungaemia in our children demands urgent attention to control the spread.

Promising Drug Candidates and New Strategies for Fighting against the Emerging Superbug Candida auris

Invasive fungal infections represent an expanding threat to public health. During the past decade, a paradigm shift of candidiasis from Candida albicans to non-albicans Candida species has fundamentally increased with the advent of Candida auris. C. auris was identified in 2009 and is now recognized as an emerging species of concern and underscores the urgent need for novel drug development strategies. In this review, we discuss the genomic epidemiology and the main virulence factors of C. auris. We also focus on the different new strategies and results obtained during the past decade in the field of antifungal design against this emerging C. auris pathogen yeast, based on a medicinal chemist point of view. Critical analyses of chemical features and physicochemical descriptors will be carried out along with the description of reported strategies.

Nontoxic Cobalt(III) Schiff Base Complexes with Broad-Spectrum Antifungal Activity

Resistance to currently available antifungal drugs has quietly been on the rise but overshadowed by the alarming spread of antibacterial resistance. There is a striking lack of attention to the threat of drug-resistant fungal infections, with only a handful of new drugs currently in development. Given that metal complexes have proven to be useful new chemotypes in the fight against diseases such as cancer, malaria, and bacterial infections, it is reasonable to explore their possible utility in treating fungal infections. Herein we report a series of cobalt(III) Schiff base complexes with broad-spectrum antifungal activity. Some of these complexes show minimum inhibitory concentrations (MIC) in the low micro- to nanomolar range against a series of Candida and Cryptococcus yeasts. Additionally, we demonstrate that these compounds show no cytotoxicity against both bacterial and human cells. Finally, we report the first in vivo toxicity data on these compounds in Galleria mellonella, showing that doses as high as 266 mg kg-1 are tolerated without adverse effects, paving the way for further in vivo studies of these complexes.

The Postbiotic Activity of Lactobacillus paracasei 28.4 Against Candida auris

Candida auris has emerged as a medically important pathogen with considerable resistance to antifungal agents. The ability to produce biofilms is an important pathogenicity feature of this species that aids escape of host immune responses and antimicrobial agents. The objective of this study was to verify antifungal action using in vitro and in vivo models of the Lactobacillus paracasei 28.4 probiotic cells and postbiotic activity of crude extract (LPCE) and fraction 1 (LPF1), derived from L. paracasei 28.4 supernatant. Both live cells and cells free supernatant of L. paracasei 28.4 inhibited C. auris suggesting probiotic and postbiotic effects. The minimum inhibitory concentration (MIC) for LPCE was 15 mg/mL and ranges from 3.75 to 7.5 mg/mL for LPF1. Killing kinetics determined that after 24 h treatment with LPCE or LPF1 there was a complete reduction of viable C. auris cells compared to fluconazole, which decreased the initial inoculum by 1-logCFU during the same time period. LPCE and LPF1 significantly reduced the biomass (p = 0.0001) and the metabolic activity (p = 0.0001) of C. auris biofilm. There was also a total reduction (~10⁸ CFU/mL) in viability of persister C. auris cells after treatment with postbiotic elements (p < 0.0001). In an in vivo study, injection of LPCE and LPF1 into G. mellonella larvae infected with C. auris prolonged survival of these insects compared to a control group (p < 0.05) and elicited immune responses by increasing the number of circulating hemocytes and gene expression of antimicrobial peptide galiomicin. We concluded that the L. paracasei 28.4 cells and postbiotic elements (LPCE and LPF1) have antifungal activity against planktonic cells, biofilms, and persister cells of C. auris. Postbiotic supplementation derived from L. paracasei 28.4 protected G. mellonella infected with C. auris and enhanced its immune status indicating a dual function in modulating a host immune response.

International Society for Human and Animal Mycology (ISHAM)-New Initiatives

Fungal infections have emerged as major threat to human beings. The world is not ready to face this formidable challenge due to limited awareness, insufficient laboratories, and difficulty in managing mycoses especially in developing countries. The International Society for Human and Animal Mycology (ISHAM) has undertaken several new initiatives to overcome these gaps, including a global outreach program with national affiliated mycology societies and other regional groups. ISHAM is working closely with the European Confederation of Medical Mycology (ECMM) and Global Action Fund for Fungal Infections (GAFFI) to enhance these efforts. The society has launched laboratory e-courses and is in the process of the development of clinical e-courses. ISHAM has partnered with regional conferences in South America and Asia by sponsoring international experts and young delegates. The society also supports young people from less developed countries to undergo training in laboratories of excellence. ISHAM facilitated the formation of the INFOCUSLatin American Clinical Mycology Working Group (LATAM) and the Pan-African Mycology Working Group. The society appointed country ambassadors to facilitate coordination with national societies. Still, the task is enormous and ISHAM calls for strong advocacy and more coordinated activities to attract the attention of people from all disciplines to this neglected field.