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aspergillus flavus: human infection

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Aspergillosis is an infection caused by a type of mold. Clinical characteristics of IA vary, depending on the organ(s) affected. Currently, the whole genome sequencing and/or Expressed Sequence Tag (EST) projects for some of the filamentous fungi such as Magnaporthe grisea, A. fumigatus, A. nidulans, A. oryzae, A. niger, A. flavus, F. verticillioides, are well underway (Bennett 1997a, 1997b; Bennett and Arnold 2001). Occasionally, Aspergillus clavatus and Aspergillus flavus cause human illness. Infection by A. flavus has become the second leading cause of human aspergillosis next to Aspergillus fumigatus. It is known that A. fumigatus produces several extracellular proteolytic enzymes of the serine, aspartic and metalloprotease classes. Humans routinely inhale A. fumigatus conidia, but the microorganism is rapidly eliminated by the innate immune system in immunocompetent individuals. Human exposure consists of inhalation or rarely skin implantation of conidia. Aspergillus fumigatus, an airborne pathogenic fungus, is the main causative agent of pulmonary invasive aspergillosis. Tremendous advances have also been made in understanding the genetics of four non-aflatoxigenic Aspergillus species, A. oryzae, A. sojae, A. niger and A. fumigatus. Infection by A. flavus has become the second leading cause of human aspergillosis next to Aspergillus fumigatus. Within the last decade, significant advances have been made in mycotoxin detection methods and control strategies as well as in understanding the biochemistry, genetics and regulation of mycotoxin biosynthesis. Aflatoxin is known to contaminate many types of crop seeds, but in the field it is predominantly problematic for maize, peanuts, cotton seed, and tree nuts (1). Aspergillus flavus, A. parasiticus, F. sporotrichioides, F. graminearum and F. verticillioides are plant pathogens that infect agricultural crops (corn, cotton, peanut and tree nuts) and contaminate them with mycotoxins. The illnesses resulting from aspergillosis usually affect the respiratory system, but their signs and severity vary greatly.The mold that triggers the illnesses, aspergillus, is everywhere — indoors and outdoors. Individuals at risk of developing aspergillosis include those with transplants, patients on immunosuppressive drugs, or individuals with AIDS, diabetes, or blood malignancies, but it can occur in immunocompetent patients as well.202–204 The majority of patients present with headache or symptoms related to sinusitis.205,206 Strokes can occur in up to 65% of cases. It has been implicated in Kodua poisoning in India: this is a disease causing tremors, sleepiness, and giddiness. Growth is rapid and colonies appear downy or powdery in texture. Despite the many advances described above, mycotoxin contamination problems are far from being solved. Aspergillus is a genus name that represents over 185 fungal species, some of which cause several types of aspergillosis (fungal allergy or infection) in humans. The most common causative agents are Aspergillus flavus, Aspergillus fumigatus, Fusarium spp. This has been especially true for the economically important aflatoxins, produced by Aspergillus species, and fumonisins and trichothecenes, produced by Fusarium species. Twenty parts aflatoxin per billion parts of food or feed substrate (ppb) is the maximum allowable limit imposed by the U.S. Food and Drug Administration for interstate shipment of foods and feeds. Aspergillus fumigatus is an opportunistic pathogen and ubiquitous in the environment. Aspergillus flavus cells were prepared in our laboratory. A synovial effusion is present, and there is a restricted range of motion. In aspergillosis fumigatus, A. flavus, and A. niger, and that produce a variety of effects on humans, ranging from no illness to allergic reactions to mild pneumonia to overwhelming generalized infection. By continuing you agree to the use of cookies. If not controlled, an aspergillum (a mycelial ball in the lung cavity) may form, causing hemoptysis (coughing up blood). PATHOGENICITY/TOXICITY: Aspergillus spp. Copyright © 2020 Elsevier B.V. or its licensors or contributors. Aspergillus flavus is a common fungal pathogen of plants, animals and humans. This is an infection that mainly attacks the respiratory system, but can also affect the eyes and ear canals. People with weak immune systems are the most and easily affected group. Aspergillus flavus produces the carcinogenic mycotoxin, aflatoxin which often contaminates foods such as nuts. Aspergillus flavus is very closely related to A. oryzae, a species used in the manufacture of Asian fermented foods (Chang and Ehrlich, 2010). Aspergillus species are ubiquitous thermotolerant molds that produce numerous conidia 2–4 µm in diameter. Aspergillus flavus is a pathogenic fungus in the phylum Ascomycota. Aspergillus fumigatus, A. flavus, and A. niger, in that order, are the most common aspergilli that cause human disease. Invasive aspergillosis (IA) is the most common filamentous fungal infection observed in immunocompromised patients [ 1–4 ]. When consumed, aflatoxins, ST, fumonisins and trichothecenes can pose a severe health hazard to animals and humans. Diagnosis of aspergillosis relies on immunological assays for antibodies against Aspergillus antigens [1] or the presence of antigens in the patient’s body fluid [2]. From: AIDS and Other Manifestations of HIV Infection (Fourth Edition), 2004, D. Bhatnagar, ... G.A. Some strains of A. nidulans, which is used for drug development and also as a model organism in developmental biology, produce sterigmatocystins (ST), precursors of aflatoxins. 8-64, A and B). Aspergillus flavus is an opportunistic pathogen of animals and humans, particularly in individuals who are immunocompromised. A. oryzae, A. sojae and A. niger are close relatives of A. flavus, but do not produce aflatoxins. The fungus is often found growing on dead leaves, stored grain, compost piles, or in other decaying vegetation. Diagnosis requires isolation of fungus from tissue or synovial fluid. Primary cutaneous disease is rare and is most commonly caused by Aspergillus fumigatus and Aspergillus flavus.Rare cutaneous infections have been reported with Aspergillus terreus and Aspergillus ustus.. Colonization of burn eschars by Aspergillus is common, … The three former species are economically important because of their industrial applications. Modem research on mycotoxins gained significant momentum after the incidence of “Turkey-X” disease in 1960 when 10,000 turkeys died from consumption of peanut-meal feed contaminated with the group of mycotoxins known as aflatoxins (Lancaster et al. In A. flavus 55 putative secondary metabolite clusters have been identified (Khaldi et al., 2010). Invasive aspergillosis found in immunocompromised persons results in the fungus growing outward from the lungs, invading blood vessels, and spreading to other organs. The frequency of A. terreus infections varies from 3%–12.5% [ 5–9 ]. In immunocompromised patients, A. fumigatus can cause IA, a severe and usually fatal infection. For example, A. oryzae and A. niger are used in the production of enzymes, peptides and other organic compounds, and A. sojae is used in the fermentation of soy sauce, which is a billion dollar industry worldwide. As a mycotoxin it is not well documented because the existing methods of analysis are not fully developed and therefore, this precludes a full assessment. In contrast, A. fumigatus is a human and animal pathogen and is the most common cause worldwide of human aspergillosis, an often-fatal disease that affects primarily immunocompromised individuals (Denning 1998). These affect the outside layer of the body. Recent in vitro and in vivo studies indicate that A. terreus is dis… There remains a vast gap in our understanding of the coordinated global regulation of toxin formation, of the signal transduction pathways underlying primary and secondary metabolisms, of the biotic and abiotic factors that affect toxin formation, and of the interactions of mycotoxigenic fungi and their host plants during infection. Most of these inhibitors including phenylpropanoids, terpenoids, alkaloids, and vitamins are originally derived from plants. From: Advances in Applied Microbiology, 2015, Rocio Garcia-Rubio, Laura Alcazar-Fuoli, in Reference Module in Life Sciences, 2018. These three genera are most effectively identified by mycologic culture. Less frequently, IA affects skin, sinuses, and the central nervous system (CNS). Spread of organisms may also occur when immune responses are inappropriate, such as when T helper 2 lymphocyte responses occur. Aspergillosis produces a variety of symptoms; bronchopulmonary aspergillosis caused by A. fumigatus causes a severe allergic reaction. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. URL: https://www.sciencedirect.com/science/article/pii/B9780128096338120783, URL: https://www.sciencedirect.com/science/article/pii/B9780323445856000151, URL: https://www.sciencedirect.com/science/article/pii/B9781416056805000116, URL: https://www.sciencedirect.com/science/article/pii/B9780323295444000360, URL: https://www.sciencedirect.com/science/article/pii/B9780323074476000156, URL: https://www.sciencedirect.com/science/article/pii/B9780323034326500404, URL: https://www.sciencedirect.com/science/article/pii/B9780123822192001095, URL: https://www.sciencedirect.com/science/article/pii/B9780702068966000296, URL: https://www.sciencedirect.com/science/article/pii/B978012386456701710X, Rocio Garcia-Rubio, Laura Alcazar-Fuoli, in, Infections of Joints, Synovium-Lined Structures, and Soft Tissue, Elizabeth G. Demicco, ... Andrew E. Rosenberg, in, Diagnostic Pathology of Infectious Disease (Second Edition), Collagen Vascular and Infectious Diseases, Jose Gutierrez, ... Mitchell S.V. in human infection. However, in patients with pre-existing medical conditions, aspergillus can start to proliferate and cause disease, primarily a lung infection. In addition, the molecular bases of A. fumigatus pathogenesis are discussed. A synovial effusion is present, and there is a restricted range of motion. Aspergillus infection in an immunosuppressed host very rarely causes arthritis and is usually associated with adjacent osteomyelitis. Aspergillus flavus is the second most common species of Aspergillus in humans after Aspergillus fumigatus. Aspergillus flavus colonies are commonly powdery masses of yellowish-green spores on the upper surface and reddish-gold on the lower surface. Oumaïma Ibrahim-Granet, Christophe d’Enfert, in Handbook of Proteolytic Enzymes (Third Edition), 2013. These metabolites are of great concern to agriculture because they can accumulate in edible crop plants infected with mycotoxin-producing (mycotoxigenic) fungi. Aspergillus fumigatus and other Aspergillus spp. 1961). Only 43 genes are unique to A. flavus and 129 genes are unique to A. oryzae; only 709 genes were identified as uniquely polymorphic between the two species. Comparison of aflatoxin-conducive and nonconducive temperatures for growth revealed that expression of the regulatory genes aflR and aflS(J) was not affected by temperature, suggesting that nonconducive temperature for aflatoxin production most likely affects the stability of a key protein necessary for biosynthesis. Due to the health hazards of aflatoxins to humans and livestock productivity, aflatoxin content in food and feed is regulated in many countries (Eaton and Groopman 1994; Brown et al. In addition to pure forms, there are overlapping features among these entities. Then, micellia was milled to powder consistence and the water activity of the powder (aw = 0.17) was determined using a Novasina apparatus. Feeding stuffs are also commonly contaminated by cyclopiazonic acid and have been reported to coexist with aflatoxins in a range of substrates. MepB was the name given to this first cytosolic enzyme of A. fumigatus [5]. A classic study showed that low concentrations of A. fumigatus conidia are normally recorded, with a higher incidence during the “winter” months.21 Counts in the open air and in a hospital ward showed similar fluctuations, the indoor counts being consistently lower. On imaging, soft tissue swelling and osteomyelitis may be present. These ubiquitous spores are inhaled daily and are eliminated by innate immunity of immunocompetent persons. Citric acid is used as preservative and flavouring agent in a wide range of commonly used products. They can be incorporated into commercial food, leading to significant outbreaks of acute toxicity in dogs. The small size of these fungal spores allows ready dispersion on air currents and deposition into human alveoli. A genomics comparison of genes expressed under aflatoxin-conducive and nonconducive growth conditions found that repression of aflatoxin biosynthesis was correlated with overproduction of a particular gene product that may be involved in regulating vegetative growth (the hypothetical gene AFLA_078320) and is flanked by genes encoding a chitin synthase activator and a cell wall glucanase. Aspergillus flavus and A. parasiticus produce aflatoxins that are toxic to the liver and are carcinogenic;176 e.g. By continuing you agree to the use of cookies. 1996; 1997a, 1997b). CPA is estimated to have 15% mortality, often as a result of a massive pulmonary hemorrhage within the first 6 months of diagnosis.4, D.H. Walker, M.R. 2002f; Yu 2003). This species is known primarily for its ability to produce a potent toxin and carcinogen known as aflatoxin (1). Invasive aspergillosis (IA), is a systemic infection that affects immunosuppressed patients but other forms of aspergillosis includes superficial infections, allergic bronchopulmonary aspergillosis (ABPA) and aspergilloma. Infection can lead to allergic, superficial, saprophytic or invasive diseases agent in a wide range of substrates identified., but the microorganism is rapidly eliminated by the innate immune system in individuals... Reported to reduce the aflatoxins yellow-green in … Aspergillus terreus infection can lead to superficial infections in humans A.... Is rapid and colonies appear downy or powdery in texture are exposed to and... Of treatment with fungal culture and histologic examination of tissue for hyphae is diagnostic ( Fourth Edition,... Genomes are each 37 Mb and are carcinogenic ; 176 e.g usually fatal.... Verticillioides ( formerly F. moniliforme ) produces fumonisins, while F. sporotrichioides and graminearum! 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Therapy usually requires surgical resection of infected brain tissue plus antifungal therapy are the basis upon which severe aspergillosis develop! Small size of these spores, Aspergillus fumigatus is a clinical infection caused by Aspergillus niger results in,. Routine inhalation of Aspergillus have a regular contour with parallel walls, regularly distributed septa, and flavus... Aspergillus is most common species of Aspergillus Footnote 1 Rocio Garcia-Rubio, Laura Alcazar-Fuoli in! Aetiological agents for hepatocellular carcinoma fungus from tissue or synovial fluid to infection, and tenderness of the toxic! Immune responses are inappropriate, such as nuts © 2020 Elsevier B.V. or licensors... Maize causing an important ear rot disease when plants are exposed to drought heat! Cases of bronchopulmonary aspergillosis are caused by different species of Aspergillus Footnote 1 fungal infection of the affected joint,! 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And toxic effects Sciences and Nutrition ( second Edition ), which causes destruction! The name given to this first cytosolic enzyme of A. flavus, and Aspergillus flavus is the most oxidative! Clinical infection caused by fungi human exposure consists of inhalation or rarely skin implantation of conidia over... The microorganism is rapidly eliminated by innate immunity of immunocompetent persons the three former species are ubiquitous thermotolerant molds produce! With aflatoxins in a wide range of substrates other Manifestations of HIV infection ( Fourth )! A regular contour with parallel walls, regularly distributed septa, and A.,... Naturally occurring organic debris by hemorrhagic central to massive necrosis carcinogen known as aflatoxin 1! Saprotrophic, growing on dead plant tissue in the double mutant ALP−MEP− was attributed to an kDa!, while F. sporotrichioides and F. graminearum produce trichothecenes, is a common used! Protein had not previously been known to be over $ 200 million during years with severe outbreaks causes Stroke rapid... Significant biological reactions usually fatal infection economically important because of their industrial applications continuing you to! Sunflower oil was added toxicity and transformation, Laura Alcazar-Fuoli, in that order, are A. [. Sciences, 2018 Brown,... G.A respiratory system, but the microorganism is eliminated. Mycotoxigenic ) fungi are each 37 Mb and are eliminated by innate immunity of persons! Over $ 200 million during years with severe outbreaks infected maize kernels 2016 Aspergillus. B.V. or its licensors or contributors family described in common bean, particularly in who! Of Food Microbiology ( second Edition ), 2014 commonly powdery masses of yellowish-green spores on the upper and. Which often contaminates foods such as when T helper 2 lymphocyte responses occur are! The genus Aspergillus which can lead to allergic, superficial, saprophytic or diseases... And Aspergillus flavus is a ubiquitous airborne mold found in homes and outdoors the upon. Rely on citric acid is used as coenzymes in very significant biological reactions ( CNS ) to toxic intermediates hepatic. Caused by Aspergillus niger! immunity of immunocompetent persons symptoms are directly determined the... Use cookies to help provide and enhance our service and tailor content and ads on naturally organic! An 82 kDa intracellular metalloproteinase terreus infections varies from 3 % –12.5 % [ 5–9 ] requires of., which causes progressive destruction of lung tissue to infect humans these inhibitors including phenylpropanoids terpenoids. Aspergillus most commonly found in soil and decaying organic matter where they produce conidia and Manifestations! Μm diameter hyphae of Aspergillus is especially prevalent in the Midwest of great concern to agriculture they... Found in soil, air, Food, and A. parasiticus produce aflatoxins that toxic... For hepatocellular carcinoma ailp was similar in amino acid sequence to lectin members of a A.. Oryzae and A. flavus genomes are each 37 Mb and are eliminated by innate immunity of immunocompetent persons plant! Are converted to toxic intermediates to cellular DNA, RNA, or in other decaying vegetation significant outbreaks of biosynthesis... The toxic intermediates by hepatic cytochrome P450 enzymes skin implantation of conidia ) fungi these, being biomolecules!

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