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1.
Molecular targets for antifungals in amino acid and protein biosynthetic pathways.
Kuplińska, A, Rząd, K
Amino acids. 2021;(7):961-991
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Abstract
Fungi cause death of over 1.5 million people every year, while cutaneous mycoses are among the most common infections in the world. Mycoses vary greatly in severity, there are long-term skin (ringworm), nail or hair infections (tinea capitis), recurrent like vaginal candidiasis or severe, life-threatening systemic, multiorgan infections. In the last few years, increasing importance is attached to the health and economic problems caused by fungal pathogens. There is a growing need for improvement of the availability of antifungal drugs, decreasing their prices and reducing side effects. Searching for novel approaches in this respect, amino acid and protein biosynthesis pathways appear to be competitive. The route that leads from amino acid biosynthesis to protein folding and its activation is rich in enzymes that are descriptive of fungi. Blocking the action of those enzymes often leads to avirulence or growth inhibition. In this review, we want to trace the principal processes of fungi vitality. We present the data of genes encoding enzymes involved in amino acid and protein biosynthesis, potential molecular targets in antifungal chemotherapy, and describe the impact of inhibitors on fungal organisms.
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Mechanisms of triazole resistance in Aspergillus fumigatus.
Nywening, AV, Rybak, JM, Rogers, PD, Fortwendel, JR
Environmental microbiology. 2020;(12):4934-4952
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Abstract
The ubiquitous fungal pathogen Aspergillus fumigatus is the primary cause of opportunistic mould infections in humans. Aspergilli disseminate via asexual conidia passively travelling through air currents to germinate within a broad range of environs, wherever suitable nutrients are found. Though the average human inhales hundreds of conidia daily, A. fumigatus invasive infections primarily affect the immunocompromised. At-risk individuals can develop often fatal invasive disease for which therapeutic options are limited. Regrettably, the global insurgence of isolates resistant to the triazoles, the frontline antifungal class used in medicine and agriculture to control A. fumigatus, is complicating the treatment of patients. Triazole antifungal resistance in A. fumigatus has become recognized as a global, yet poorly comprehended, problem. Due to a multitude of factors, the magnitude of resistant infections and their contribution to treatment outcomes are likely underestimated. Current studies suggest that human drug-resistant infections can be either environmentally acquired or de novo host selected during patient therapy. While much concerning development of resistance is yet unknown, recent investigations have revealed assorted underlying mechanisms enabling triazole resistance within individual clinical and environmental isolates. This review will provide an overview of triazole resistance as it is currently understood, as well as highlight some of the prominent biological mechanisms associated with clinical and environmental resistance to triazoles in A. fumigatus.
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Adapting to survive: How Candida overcomes host-imposed constraints during human colonization.
Alves, R, Barata-Antunes, C, Casal, M, Brown, AJP, Van Dijck, P, Paiva, S
PLoS pathogens. 2020;(5):e1008478
Abstract
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.
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Comprehensive review on Caelsalpinioideae lectins: From purification to biological activities.
Cavada, BS, Pinto-Junior, VR, Osterne, VJS, Oliveira, MV, Lossio, CF, Silva, MTL, Bari, AU, Lima, LD, Souza-Filho, CHD, Nascimento, KS
International journal of biological macromolecules. 2020;:333-348
Abstract
Lectins are a class of proteins with specific and reversible carbohydrate binding properties. Plant lectins constitute the group of these proteins most studied, placing emphasis on the legume family. The Caesalpinioideae subfamily is part of Leguminosae and second only to Papilionoideae with more published works on lectins. Classically, Caesalpinioideae is formed by 171 genera and 2250 species. It presents 13 genera with reports of lectins, featuring the Bauhinia genus with the greatest number of species having purified and characterized lectins. Comparing genera, the lectins in this subfamily do not have similar physicochemical or structural properties. Collectively, however, antibacterial, antiviral, and anticancer activities have been reported, as well as applications as biosensors and biomarkers. This review aims to summarize the available data on purified lectins from species of the Caesalpinioideae subfamily, demonstrating the characteristics of these molecules and the potential for their application in future studies of new lectins, as well as of application in several areas.
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Hormographiella aspergillata: an emerging basidiomycete in the clinical setting? A case report and literature review.
Moniot, M, Lavergne, RA, Morel, T, Guieze, R, Morio, F, Poirier, P, Nourrisson, C
BMC infectious diseases. 2020;(1):945
Abstract
BACKGROUND Filamentous basidiomycetes are mainly considered to be respiratory tract colonizers but the clinical significance of their isolation in a specimen is debatable. Hormographiella aspergillata was first reported as a human pathogen in 1971. We discuss the role of this mold as a pathogen or colonizer and give an update on diagnostic tools and in vitro antifungal susceptibility. CASE PRESENTATION We identified three cases of H. aspergillata with respiratory symptoms in a short period of time. One invasive infection and two colonizations were diagnosed. Culture supernatants showed that H. aspergillata can produce galactomannan and β-D-glucan but not glucuronoxylomannan. For the first time, isavuconazole susceptibility was determined and high minimum inhibitory concentrations (MICs) were found. Liposomal amphotericin B and voriconazole have the lowest MICs. CONCLUSION To date, 22 invasive infections involving H. aspergillata have been reported. On isolation of H. aspergillata, its pathogenic potential in clinical settings can be tricky. Molecular identification and antifungal susceptibility testing are essential considering high resistance against several antifungal therapies.
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Medication association and immunomodulation: An approach in fungal diseases and in particular in the treatment of paracoccidioidomycosis.
Santos, LA, Grisolia, JC, Malaquias, LCC, Paula, FBA, Dias, ALT, Burger, E
Acta tropica. 2020;:105412
Abstract
Fungal infections have been increasing in recent decades, mainly affecting immunocompromised individuals, although certain mycoses, such as paracoccidioidomycosis (PCM), infect immunologically competent individuals. The major problems observed regarding fungal diseases are inadequate diagnosis, prolonged treatment time, the reduced number of drugs available for treatment, in addition to the fact that there are no vaccines for clinical use. Drug combination in order to immunomodulate the immune response is a new strategy used for the treatment of mycoses, since it is difficult to develop new antifungal drugs. The aim of this study is to present and analyze strategies recently suggested for the treatment of fungi of medical interest, in particular for PCM, such as the utilization of combinations of protein fractions or dead microorganisms, as vaccinal antigens, and cellular immunotherapy. We will also propose new therapeutic alternatives, such as lipids, vitamins, synthetic or natural products as well as the use of low intensity LASER therapy (LLLT) to modulate the immune response of the host, enhancing the efficiency of the existing treatments of mycoses of medical interest and in particular of PCM.
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Cushing's disease with pulmonary Cryptococcus neoformans infection in a single center in Beijing, China: A retrospective study and literature review.
Lu, L, Zhao, YY, Yang, HB, Tian, XL, Xu, ZJ, Lu, ZL
Journal of the Formosan Medical Association = Taiwan yi zhi. 2019;(1 Pt 2):285-290
Abstract
BACKGROUND Patients with Cushing's disease (CD) with hypercortisolism have an increased risk of opportunistic infection. However, most CD patients exposed to infections are diagnostic latency, leading to a poor prognosis. METHODS Six patients in our hospital and an additional six patients in the literature were included in this study. Clinical information of CD patients with pulmonary Cryptococcus neoformans are reviewed. RESULTS The average baseline total cortisol and ACTH in serum at 8 am of all the patients was 44.85 μg/dL (normal range 4.0-22.3 μg/dL) and 200.3 pg/mL (normal range 0-46 pg/mL), respectively. Lymphopenia was found in 2 out of 6 patients in our hospital. The pulmonary radiologic findings included nodules (4/12), masses with or without a cavity (5/12), infiltration (5/12), and consolidation (4/12). The diagnosis of C.neoformans was established by lung pathology results (7/12), microorganism culture (3/12), and serum cryptococcal polysaccharide antigen (4/12). Lung lobectomy was performed in two patients who had a nodule in one lung lobe. Antifungal drugs were administered, including amphotericin-B (7/12), fluconazole (4/12), flucytosine (2/12) and liposomal amphotericin (1/12). Additional therapies for CD included trans-sphenoidal pituitary adenoma surgery (9/12), adrenalectomy (1/12) and ketoconazole (2/12). Seven patients survived, and five patients died. CONCLUSION Pulmonary C.neoformans is an uncommon but fatal opportunistic infection in CD patients. Pulmonary nodules or masses should be aggressively investigated to exclude the C.neoformans among CD patients. The infiltration lesions in chest CT scan and lymphopenia are associated with poor prognosis.
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[Update in the diagnostic and therapeutic approach of invasive aspergillosis in adult population].
Rabagliati, R
Revista chilena de infectologia : organo oficial de la Sociedad Chilena de Infectologia. 2018;(5):531-544
Abstract
The invasive fungal disease produced by Aspergillus spp., is the infection by filamentous fungi most frequently reported among immunocompromised individuals and responsible for a very high mortality in this group of patients. In recent years, important advances have been made both from the diagnostic and therapeutic point of view. At present, a series of risk factors associated with its development have been identified, allowing the categorization of patients in high, intermediate and low risk of invasive aspergillosis (IA); and diagnostic criteria have also been established that consider factors of the host, traditional mycological laboratory, biomarkers such as galactomannan and 1→3-β-d-glucan, together with the better understanding and interpretation of the tomographic images that have allowed to reach a consensus on the diagnostic categories. This added to the incorporation of new antifungals and therapeutic strategies in different scenarios, have allowed decreasing the associated mortality. In this review, are updated the epidemiological aspects, the risk factors, the diagnosis, prevention and prophylaxis as well as the therapeutic confrontation, including strategies for the use of empirical, precocious and directed antifungal therapy, as well as the most relevant aspects of the first-choice and alternative antifungals for the IA management.
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The pathogenicity of Aspergillus fumigatus, drug resistance, and nanoparticle delivery.
Szalewski, DA, Hinrichs, VS, Zinniel, DK, Barletta, RG
Canadian journal of microbiology. 2018;(7):439-453
Abstract
The genus Aspergillus includes fungal species that cause major health issues of significant economic importance. These microorganisms are also the culprit for production of carcinogenic aflatoxins in grain storages, contaminating crops, and economically straining the production process. Aspergillus fumigatus is a very important pathogenic species, being responsible for high human morbidity and mortality on a global basis. The prevalence of these infections in immunosuppressed individuals is on the rise, and physicians struggle with the diagnosis of these deadly pathogens. Several virulence determinants facilitate fungal invasion and evasion of the host immune response. Metabolic functions are also important for virulence and drug resistance, since they allow fungi to obtain nutrients for their own survival and growth. Following a positive diagnostic identification, mortality rates remain high due, in part, to emerging resistance to frequently used antifungal drugs. In this review, we discuss the role of the main virulence, drug target, and drug resistance determinants. We conclude with the review of new technologies being developed to treat aspergillosis. In particular, microsphere and nanoparticle delivery systems are discussed in the context of improving drug bioavailability. Aspergillus will likely continue to cause problematic infections in immunocompromised patients, so it is imperative to improve treatment options.
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10.
Antifungal Compounds against Candida Infections from Traditional Chinese Medicine.
Liu, X, Ma, Z, Zhang, J, Yang, L
BioMed research international. 2017;:4614183
Abstract
Infections caused by Candida albicans, often refractory and with high morbidity and mortality, cause a heavy burden on the public health while the current antifungal drugs are limited and are associated with toxicity and resistance. Many plant-derived molecules including compounds isolated from traditional Chinese medicine (TCM) are reported to have antifungal activity through different targets such as cell membrane, cell wall, mitochondria, and virulence factors. Here, we review the recent progress in the anti-Candida compounds from TCM, as well as their antifungal mechanisms. Considering the diverse targets and structures, compounds from TCM might be a potential library for antifungal drug development.