Candida auris undergoes adhesin-dependent and -independent cellular aggregation.

Candida auris is a fungal pathogen of humans responsible for nosocomial infections with high mortality rates. High levels of resistance to antifungal drugs and environmental persistence mean these infections are difficult to treat and eradicate from a healthcare setting. Understanding the life cycle and the genetics of this fungus underpinning clinically relevant traits, such as antifungal resistance and virulence, is of the utmost importance to develop novel treatments and therapies. Epidemiological and genomic studies have identified five geographical clades (I-V), which display phenotypic and genomic differences. Aggregation of cells, a phenotype primarily of clade III strains, has been linked to reduced virulence in some infection models. The aggregation phenotype has thus been associated with conferring an advantage for (skin) colonisation rather than for systemic infection. However, strains with different clade affiliations were compared to infer the effects of different morphologies on virulence. This makes it difficult to distinguish morphology-dependent causes from clade-specific or even strain-specific genetic factors. Here, we identify two different types of aggregation: one induced by antifungal treatment which is a result of a cell separation defect; and a second which is controlled by growth conditions and only occurs in strains with the ability to aggregate. The latter aggregation type depends on an ALS-family adhesin which is differentially expressed during aggregation in an aggregative C. auris strain. Finally, we demonstrate that macrophages cannot clear aggregates, suggesting that aggregation might after all provide a benefit during systemic infection and could facilitate long-term persistence in the host.

Glucose-enhanced oxidative stress resistance-A protective anticipatory response that enhances the fitness of Candida albicans during systemic infection.

Most microbes have developed responses that protect them against stresses relevant to their niches. Some that inhabit reasonably predictable environments have evolved anticipatory responses that protect against impending stresses that are likely to be encountered in their niches-termed "adaptive prediction". Unlike yeasts such as Saccharomyces cerevisiae, Kluyveromyces lactis and Yarrowia lipolytica and other pathogenic Candida species we examined, the major fungal pathogen of humans, Candida albicans, activates an oxidative stress response following exposure to physiological glucose levels before an oxidative stress is even encountered. Why? Using competition assays with isogenic barcoded strains, we show that "glucose-enhanced oxidative stress resistance" phenotype enhances the fitness of C. albicans during neutrophil attack and during systemic infection in mice. This anticipatory response is dependent on glucose signalling rather than glucose metabolism. Our analysis of C. albicans signalling mutants reveals that the phenotype is not dependent on the sugar receptor repressor pathway, but is modulated by the glucose repression pathway and down-regulated by the cyclic AMP-protein kinase A pathway. Changes in catalase or glutathione levels do not correlate with the phenotype, but resistance to hydrogen peroxide is dependent on glucose-enhanced trehalose accumulation. The data suggest that the evolution of this anticipatory response has involved the recruitment of conserved signalling pathways and downstream cellular responses, and that this phenotype protects C. albicans from innate immune killing, thereby promoting the fitness of C. albicans in host niches.

C. albicans N-linked mannans potentiate the induction of trained immunity via Dectin-2.

The interaction between the Candida albicans cell wall and pattern recognition receptors is crucial for the initiation of host immune responses which, ultimately, contribute to the clearance of this pathogenic fungus. In the present study, we investigate the ability of C. albicans mannans to modulate immune response and induce innate immune memory (also termed trained immunity). Using mutants of C. albicans that are defective in, or lack mannosyl residues, we show that alterations in the mannosylation of the C. albicans cell wall affect the innate cytokine response and strongly reduce the secretion of T cell-derived cytokines. Subsequently, we demonstrate that the branching of N-linked mannan, but not O-linked mannan, is essential to potentiate the induction of trained immunity, a process mediated by Dectin-2. In conclusion, N-linked mannan is needed, in addition to ß-glucans, for an effective induction of trained immunity by C. albicans.

Review of infection and bleeding complications in excisional skin surgery.

Skin excision is the primary treatment for skin cancer. Complication rates from skin cancer excision are generally low but rates of complications may vary according to procedural complexity, site and patient factors. It is important that patients are fully informed through the consent process considering individual circumstances, the Montgomery ruling and material risks. The clinician must use an evidence-based approach to the consent process and assessment of risk. We have searched the literature and reviewed the current evidence regarding complications, and their incidence where data were available, following excisional skin surgery. This article aims to enable clinicians to better inform patients during the consent process about associated bleeding and infection risk.

Immune cells fold and damage fungal hyphae.

Innate immunity provides essential protection against life-threatening fungal infections. However, the outcomes of individual skirmishes between immune cells and fungal pathogens are not a foregone conclusion because some pathogens have evolved mechanisms to evade phagocytic recognition, engulfment, and killing. For example, Candida albicans can escape phagocytosis by activating cellular morphogenesis to form lengthy hyphae that are challenging to engulf. Through live imaging of C. albicans-macrophage interactions, we discovered that macrophages can counteract this by folding fungal hyphae. The folding of fungal hyphae is promoted by Dectin-1, ß2-integrin, VASP, actin-myosin polymerization, and cell motility. Folding facilitates the complete engulfment of long hyphae in some cases and it inhibits hyphal growth, presumably tipping the balance toward successful fungal clearance.

Heightened Efficacy of Anidulafungin When Used in Combination with Manogepix or 5-Flucytosine against Candida auris In Vitro.

Candida auris is an emerging, multidrug-resistant fungal pathogen that causes refractory colonization and life-threatening, invasive nosocomial infections. The high proportion of C. auris isolates that display antifungal resistance severely limits treatment options. Combination therapies provide a possible strategy by which to enhance antifungal efficacy and prevent the emergence of further resistance. Therefore, we examined drug combinations using antifungals that are already in clinical use or are undergoing clinical trials. Using checkerboard assays, we screened combinations of 5-flucytosine and manogepix (the active form of the novel antifungal drug fosmanogepix) with anidulafungin, amphotericin B, or voriconazole against drug resistant and susceptible C. auris isolates from clades I and III. Fractional inhibitory concentration indices (FICI values) of 0.28 to 0.75 and 0.36 to 1.02 were observed for combinations of anidulafungin with manogepix or 5-flucytosine, respectively, indicating synergistic activity. The high potency of these anidulafungin combinations was confirmed using live-cell microfluidics-assisted imaging of the fungal growth. In summary, combinations of anidulafungin with manogepix or 5-flucytosine show great potential against both resistant and susceptible C. auris isolates.

The impact of ORF19.36.1 in the pathobiology of Candida albicans.

BACKGROUND: Our previous proteomics data obtained from Candida albicans recovered after serial passage in a murine model of systemic infection revealed that Orf19.36.1 expression correlates with the virulence of the fungus. Therefore, the impact of ORF19.36.1 upon virulence was tested in this study. MATERIALS & METHODS: CRISPR-Cas9 technology was used to construct homozygous C. albicans orf19.36.1 null mutants and the phenotypes of these mutants examined in vitro (filamentation, invasion, adhesion, biofilm formation, hydrolase activities) and in vivo assays. RESULTS: The deletion of ORF19.36.1 did not significantly impact the phenotypes examined or the virulence of C. albicans in two infection models. CONCLUSION: These results suggest that, although Orf19.36.1 expression correlates with virulence, this protein is not essential for C. albicans pathobiology.

Fungal resilience and host-pathogen interactions: Future perspectives and opportunities.

We are constantly exposed to the threat of fungal infection. The outcome-clearance, commensalism or infection-depends largely on the ability of our innate immune defences to clear infecting fungal cells versus the success of the fungus in mounting compensatory adaptive responses. As each seeks to gain advantage during these skirmishes, the interactions between host and fungal pathogen are complex and dynamic. Nevertheless, simply compromising the physiological robustness of fungal pathogens reduces their ability to evade antifungal immunity, their virulence, and their tolerance against antifungal therapy. In this article I argue that this physiological robustness is based on a 'Resilience Network' which mechanistically links and controls fungal growth, metabolism, stress resistance and drug tolerance. The elasticity of this network probably underlies the phenotypic variability of fungal isolates and the heterogeneity of individual cells within clonal populations. Consequently, I suggest that the definition of the fungal Resilience Network represents an important goal for the future which offers the clear potential to reveal drug targets that compromise drug tolerance and synergise with current antifungal therapies.

Adapting to survive: How Candida overcomes host-imposed constraints during human colonization.

Successful human colonizers such as Candida pathogens have evolved distinct strategies to survive and proliferate within the human host. These include sophisticated mechanisms to evade immune surveillance and adapt to constantly changing host microenvironments where nutrient limitation, pH fluctuations, oxygen deprivation, changes in temperature, or exposure to oxidative, nitrosative, and cationic stresses may occur. Here, we review the current knowledge and recent findings highlighting the remarkable ability of medically important Candida species to overcome a broad range of host-imposed constraints and how this directly affects their physiology and pathogenicity. We also consider the impact of these adaptation mechanisms on immune recognition, biofilm formation, and antifungal drug resistance, as these pathogens often exploit specific host constraints to establish a successful infection. Recent studies of adaptive responses to physiological niches have improved our understanding of the mechanisms established by fungal pathogens to evade the immune system and colonize the host, which may facilitate the design of innovative diagnostic tests and therapeutic approaches for Candida infections.

Artificial intelligence in the detection of skin cancer.

Recent advances in artificial intelligence (AI) in dermatology have demonstrated the potential to improve the accuracy of skin cancer detection. These capabilities may augment current diagnostic processes and improve the approach to the management of skin cancer. To explain this technology, we discuss fundamental terminology, potential benefits, and limitations of AI, and commercial applications relevant to dermatologists. A clear understanding of the technology may help to reduce physician concerns about AI and promote its use in the clinical setting. Ultimately, the development and validation of AI technologies, their approval by regulatory agencies, and widespread adoption by dermatologists and other clinicians may enhance patient care. Technology-augmented detection of skin cancer has the potential to improve quality of life, reduce health care costs by reducing unnecessary procedures, and promote greater access to high-quality skin assessment. Dermatologists play a critical role in the responsible development and deployment of AI capabilities applied to skin cancer.

A review of Mohs micrographic surgery for skin cancer. Part 3: Squamous cell carcinoma.

This review presents and discusses the evidence for MMS to treat cutaneous squamous cell carcinoma (cSCC). The MEDLINE, Embase and Cochrane databases were searched; 39 papers were identified for recurrence and 2 papers for cost-effectiveness. We included all clinical trials and observational studies, including retrospective reports, and excluded editorials and systematic reviews or meta-analyses. We categorized the evidence under the following headings: tumour recurrence, specific site outcomes (ear, lip, scalp and periocular), cSCC with perineural invasion, and cost-effectiveness. Although there are many observational studies indicating the potential benefits of MMS in the management of certain cSCCs, no randomized controlled trials (RCT) were identified. The evidence from comparitor studies suggests that MMS has a lower recurrence rate than that of other treatments for cSCC, including standard excision. Many studies identified were single-armed, but did demonstrate a low to very low recurrence rate of cSCC following MMS. A single recent study suggests MMS for intermediate cSCC is highly cost-effective compared with wide local excision when all-in costs are considered. Since the overall quality of included studies was mixed and highly heterogeneous, further methodologically robust studies with comparator arms or comprehensive long-term registry data would be valuable. It would be ideal to employ a definitive multicentre RCT but given the evidence to date and multiple advantages to MMS, the lack of clinical equipoise makes this difficult to justify. Comparison with current modalities would likely not be ethical/achievable on a like-for-like basis given MMS provides 100% margin assessment, enables histological clearance prior to reconstruction, and minimizes the removal of uninvolved tissue.

A review of the evidence for Mohs micrographic surgery. Part 2: basal cell carcinoma.

Mohs micrographic surgery (MMS) is considered the gold-standard treatment for basal cell carcinoma (BCC) particularly for sites with a high-risk of incomplete excision such as the central face, for tumours with an aggressive growth pattern and consequent unpredictable subclinical extension and for recurrent tumours. However, the process is more time-consuming than for standard excision (SE), and the magnitude of benefit is uncertain. This article aims to provide a more complete picture of current evidence, including a review of cosmetic outcomes, tissue-sparing ability and cost-effectiveness of MMS. Although robust evidence is lacking, there is a large volume of observational data supporting a low recurrence rate after MMS. The risk of incomplete excision and higher recurrence rate of standard excision favours the use of MMS at high-risk sites. There is some low-certainty evidence that MMS results in a smaller defect size compared with SE, and that incomplete excision with SE results in larger defects. Larger defects may affect cosmetic outcome but there is no direct evidence that MMS improves cosmetic outcome compared with SE. There is conflicting evidence regarding the cost of MMS compared with SE, as some studies consider MMS less expensive than SE and others consider it more expensive, which may reflect the healthcare setting. A multicentre 10-year randomized controlled trial comparing MMS and SE in the treatment of high-risk BCC would be desirable, but is unlikely to be feasible or ethical. Collection of robust registry data capturing both MMS and SE outcomes would provide additional long-term outcomes.

Clinicopathological characteristics of individuals with coexisting melanoma and chronic lymphocytic leukaemia: a multicentre cohort study.

BACKGROUND: Individuals with a prior diagnosis of chronic lymphocytic leukaemia (CLL) have a higher risk of developing melanoma and exhibit poorer outcomes than patients without CLL. However, there are limited data reporting the clinicopathological features of melanoma diagnosed in patients with CLL. AIMS: To review clinicopathological characteristics of patients with coexisting diagnoses of melanoma and CLL. METHODS: A retrospective review was undertaken for patients with coexisting diagnoses of melanoma and CLL between 2005 and 2015 in 11 centres in the UK and Ireland. RESULTS: Overall, 46 cutaneous melanomas identified in 45 patients were included. In 28 (62.2%) patients, melanoma was diagnosed after an existing diagnosis of CLL. In this group, mean Breslow thickness was 2.7 mm (range 0.2-25 mm). Ten patients (35.7%) developed locoregional recurrence and 8 (28.6%) developed distant metastases. Melanoma-specific mortality was 5 of 28 (17.9%) and all-cause mortality was 13 of 28 (46.4%). In 17 patients, melanoma was diagnosed before CLL. In this group, mean BT was 2.9 mm (range 0.4-14 mm); five patients (29.4%) developed locoregional recurrence and three (17.6%) developed distant metastases. Melanoma-specific mortality was 1 of 17 (5.8%) and all-cause mortality was 5 of 17 (29.4%) in this group. CONCLUSIONS: To our knowledge, this is the first and largest cohort study to report clinicopathological data of coexisting melanoma and CLL in the UK and Ireland. Although the thickness of primary melanoma was not different before or after a CLL diagnosis, melanoma recurrence and melanoma-specific mortality appear to be more common in patients with a prior diagnosis of CLL.

The winning score.

Incision lines placed at cosmetic boundaries and/or in rhytids during surgical procedures provide ideal concealment of scars. We suggest the use of a 30-gauge, half-inch needle or alternatively the back edge of a #15 scalpel blade to superficially score the skin to provide markings, which are fine enough to lie exactly within rhytids or at exact cosmetic boundaries such as the nasolabial fold or the junction of the cutaneous and vermillion lip. We measured the average depth of these scores to demonstrate that they are shallow enough to heal without scarring.

Impact of the Environment upon the Candida albicans Cell Wall and Resultant Effects upon Immune Surveillance.

The fungal cell wall is an essential organelle that maintains cellular morphology and protects the fungus from environmental insults. For fungal pathogens such as Candida albicans, it provides a degree of protection against attack by host immune defences. However, the cell wall also presents key epitopes that trigger host immunity and attractive targets for antifungal drugs. Rather than being a rigid shield, it has become clear that the fungal cell wall is an elastic organelle that permits rapid changes in cell volume and the transit of large liposomal particles such as extracellular vesicles. The fungal cell wall is also flexible in that it adapts to local environmental inputs, thereby enhancing the fitness of the fungus in these microenvironments. Recent evidence indicates that this cell wall adaptation affects host-fungus interactions by altering the exposure of major cell wall epitopes that are recognised by innate immune cells. Therefore, we discuss the impact of environmental adaptation upon fungal cell wall structure, and how this affects immune recognition, focussing on C. albicans and drawing parallels with other fungal pathogens.

Transcriptomic and proteomic profiling revealed reprogramming of carbon metabolism in acetate-grown human pathogen Candida glabrata.

BACKGROUND: Emergence of Candida glabrata, which causes potential life-threatening invasive candidiasis, has been widely associated with high morbidity and mortality. In order to cause disease in vivo, a robust and highly efficient metabolic adaptation is crucial for the survival of this fungal pathogen in human host. In fact, reprogramming of the carbon metabolism is believed to be indispensable for phagocytosed C. glabrata within glucose deprivation condition during infection. METHODS: In this study, the metabolic responses of C. glabrata under acetate growth condition was explored using high-throughput transcriptomic and proteomic approaches. RESULTS: Collectively, a total of 1482 transcripts (26.96%) and 242 proteins (24.69%) were significantly up- or down-regulated. Both transcriptome and proteome data revealed that the regulation of alternative carbon metabolism in C. glabrata resembled other fungal pathogens such as Candida albicans and Cryptococcus neoformans, with up-regulation of many proteins and transcripts from the glyoxylate cycle and gluconeogenesis, namely isocitrate lyase (ICL1), malate synthase (MLS1), phosphoenolpyruvate carboxykinase (PCK1) and fructose 1,6-biphosphatase (FBP1). In the absence of glucose, C. glabrata shifted its metabolism from glucose catabolism to anabolism of glucose intermediates from the available carbon source. This observation essentially suggests that the glyoxylate cycle and gluconeogenesis are potentially critical for the survival of phagocytosed C. glabrata within the glucose-deficient macrophages. CONCLUSION: Here, we presented the first global metabolic responses of C. glabrata to alternative carbon source using transcriptomic and proteomic approaches. These findings implicated that reprogramming of the alternative carbon metabolism during glucose deprivation could enhance the survival and persistence of C. glabrata within the host.

The environmental stress sensitivities of pathogenic Candida species, including Candida auris, and implications for their spread in the hospital setting.

Candida auris is an emerging pathogenic yeast of significant clinical concern because of its frequent intrinsic resistance to fluconazole and often other antifungal drugs and the high mortality rates associated with systemic infections. Furthermore, C. auris has a propensity for persistence and transmission in health care environments. The reasons for this efficient transmission are not well understood, and therefore we tested whether enhanced resistance to environmental stresses might contribute to the ability of C. auris to spread in health care environments. We compared C. auris to other pathogenic Candida species with respect to their resistance to individual stresses and combinations of stresses. Stress resistance was examined using in vitro assays on laboratory media and also on hospital linen. In general, the 17 C. auris isolates examined displayed similar degrees of resistance to oxidative, nitrosative, cationic and cell wall stresses as clinical isolates of C. albicans, C. glabrata, C. tropicalis, C. parapsilosis, C. krusei, C. guilliermondii, C. lusitaniae and C. kefyr. All of the C. auris isolates examined were more sensitive to low pH (pH 2, but not pH 4) compared to C. albicans, but were more resistant to high pH (pH 13). C. auris was also sensitive to low pH, when tested on contaminated hospital linen. Most C. auris isolates were relatively thermotolerant, displaying significant growth at 47°C. Furthermore, C. auris was relatively resistant to certain combinations of combinatorial stress (e.g., pH 13 plus 47°C). Significantly, C. auris was sensitive to the stress combinations imposed by hospital laundering protocol (pH > 12 plus heat shock at >80°C), suggesting that current laundering procedures are sufficient to limit the transmission of this fungal pathogen via hospital linen.

The indigoidine synthetase BpsA provides a colorimetric ATP assay that can be adapted to quantify the substrate preferences of other NRPS enzymes.

OBJECTIVES: To develop a colorimetric assay for ATP based on the blue-pigment synthesising non-ribosomal peptide synthetase (NRPS) BpsA, and to demonstrate its utility in defining the substrate specificity of other NRPS enzymes. RESULTS: BpsA is able to convert two molecules of L-glutamine into the readily-detected blue pigment indigoidine, consuming two molecules of ATP in the process. We showed that the stoichiometry of this reaction is robust and that it can be performed in a microplate format to accurately quantify ATP concentrations to low micromolar levels in a variety of media, using a spectrophotometric plate-reader. We also demonstrated that the assay can be adapted to evaluate the amino acid substrate preferences of NRPS adenylation domains, by adding pyrophosphatase enzyme to drive consumption of ATP in the presence of the preferred substrate. CONCLUSIONS: The robust nature and simplicity of the reaction protocol offers advantages over existing methods for ATP quantification and NRPS substrate analysis.

High-Throughput Screening for Inhibitors of the SARS-CoV-2 Protease Using a FRET-Biosensor.

The global SARS-CoV-2 pandemic started late 2019 and currently continues unabated. The lag-time for developing vaccines means it is of paramount importance to be able to quickly develop and repurpose therapeutic drugs. Protein-based biosensors allow screening to be performed using routine molecular laboratory equipment without a need for expensive chemical reagents. Here we present a biosensor for the 3-chymotrypsin-like cysteine protease from SARS-CoV-2, comprising a FRET-capable pair of fluorescent proteins held in proximity by a protease cleavable linker. We demonstrate the utility of this biosensor for inhibitor discovery by screening 1280 compounds from the Library of Pharmaceutically Active Compounds collection. The screening identified 65 inhibitors, with the 20 most active exhibiting sub-micromolar inhibition of 3CLpro in follow-up EC50 assays. The top hits included several compounds not previously identified as 3CLpro inhibitors, in particular five members of a family of aporphine alkaloids that offer promise as new antiviral drug leads.

Identification of Substituted Amino Acid Hydrazides as Novel Anti-Tubercular Agents, Using a Scaffold Hopping Approach.

Discovery and development of new therapeutic options for the treatment of Mycobacterium tuberculosis (Mtb) infection, particularly drug-resistant strains, are urgently required to tackle the global burden of this disease. Herein, we reported the synthesis of a novel series of N-substituted amino acid hydrazides, utilising a scaffold hopping approach within a library of anti-tubercular agents. Efficacy and selectivity were evaluated against three strains of Mtb (wild-type, isoniazid-resistant and rifampicin-resistant), and cytotoxicity against macrophages in vitro. The antibacterial activity and therapeutic index of these molecules were significantly affected by modifications with the N-substituents. Introduction of a 3,5-dinitroaryl moiety demonstrated enhanced antibacterial activity against all three strains of Mtb. In contrast, the inclusion of an imidazo [1,2-a]pyridine-3-carboxy moiety resulted in enhanced activity towards isoniazid mono-resistant Mtb relative to wild-type Mtb. Consequently, this scaffold hopping approach showed significant promise for exemplification of novel molecules with specific activity profiles against drug-resistant tuberculosis.