Monograph on Dematiaceous Fungi

Monograph On Dematiaceous fungi A guide for description of dematiaceous fungi fungi of medical importance, diseases caused by them, diagnosis and treatment By Mohamed Refai and Heidy Abo El-Yazid Department of Microbiology, Faculty of Veterinary Medicine, Cairo University 2014 1 Preface The first time I saw cultures of dematiaceous fungi was in the laboratory of Prof. Seeliger in Bonn, 1962, when I attended a practical course on moulds for one week. Then I handled myself several cultures of black fungi, as contaminants in Mycology Laboratory of Prof. Rieth, 1963-1964, in Hamburg. When I visited Prof. DE Varies in Baarn, 1963. I was fascinated by the tremendous number of moulds in the Centraalbureau voor Schimmelcultures, Baarn, Netherlands. On the other hand, I was proud, that El-Sheikh Mahgoub, a Colleague from Sundan, wrote an internationally well-known book on mycetoma. I have never seen cases of dematiaceous fungal infections in Egypt, therefore, I was very happy, when I saw the collection of mycetoma cases reported in Egypt by the eminent Egyptian Mycologist, Prof. Dr Mohamed Taha, Zagazig University. To all these prominent mycologists I dedicate this monograph. Prof. Dr. Mohamed Refai, 1.5.2014 Heinz Seeliger Heinz Rieth Gerard de Vries, El-Sheikh Mahgoub Mohamed Taha 2 Contents 1. Introduction 4 2. 30. The genus Rhinocladiella 83 2. Description of dematiaceous 6 2. 31. The genus Scedosporium 86 fungi 2. 1. The genus Alternaria 6 2. 32. The genus Scytalidium 89 2.2. The genus Aurobasidium 11 2.33. The genus Stachybotrys 91 2.3. The genus Bipolaris 16 2. 34. The genus Stemphylium 93 2.4. The genus Cladosporium 20 2.35. The genus Ulocladium 94 2.5. The genus Cladophialophora 24 2. 36. The genus Wangiella 96 2.6. The genus Cheatomium 28 2. 37. The genus Xylohypha 98 2.7. The genus Coniothyrium 31 3. Diseases caused by 99 dematiacaeous fungi 2.8.The genusParaconiothyrium 32 3. 1. Phaeohyphomycosis 99 2.9. The genus Curvularia 33 3.1.1. Skin infections 99 2.10. The genus Epicoccum 36 3.1.2. Nail infections 103 2.11. The genus Exophiala 38 3.1.3. Eye infections 103 2.12. The genus Drechslera 44 3.1.4. Respiratory phaeohyphomycosis 106 2.13. The genus Exserohilum 45 3.1.5. Central nervous system infection 108 2.14. The genus Fonseceae 47 3.1.6. Disseminated pheohyphomycosis 111 2.15. The genus Hortaea 51 3.2. Chromomycosis 115 2.16. The genus Lasiodiplodia 53 3.3. Mycetoma 118 2.17. The genus Lecythophora 54 4. Dematiaceous fungi in Egypt 120 2.18. The genus Leptosphaeria 56 5. Mycotoxicoses 122 2.19. The genus Madurella 58 5.1. Alternariosis 122 2.20. The genus Myrothecium 61 5.2. Facial eczema (Pithomycotoxicosis) 122 2.21. The genus Nattrassia 62 5.3. Stachybotryotoxicosis 124 2.22.The genus Ochroconis 64 2.23. The genus Phialemonium 67 6. Laboratory diagnosis 125 2.24. The genus Phialophora 69 2. 25. The genus Phoma 73 7. Treatment 126 2.26. The genus Pithomyces 75 2. 27. The genus Pyrenochaeta 76 8. Contamination and deterioration by 127 dematiaceous fungi 2.28. The genus Pythium 79 2. 29. The genus Ramichloridium 81 9. References 133 3 1. Introduction The dematiaceous fungi are usually defined as those that have melanin or melanin-like pigment in the wall of the hyphae and/or spores and can cause a variety of infections in humans known as phaeohyphomycosis (phaeo is Greek for "dark"). Over 100 species and 60 genera of dematiaceous, or pigmented fungi have been implicated in human diseases. The vast majority are filamentous fungi or moulds, though a few yeast species are also important pathogens. Though they represent a very heterogeneous group of fungi, the distinguishing characteristic common to all these various species is the presence of melanin in their cell walls, which imparts the dark colour to their conidia or spores and hyphae. The colonies are typically brown to black in colour as well. Dematiaceous fungi are generally found in soil or associated with plants and distributed worldwide. Those causing the specific conditions of mycetoma and chromoblastomycosis are primarily found in tropical regions. Exposure is thought to be from inhalation or minor trauma, which may not even be noticed by the patient. The taxonomy and nomenclature of dematiaceous fungi undergo constant revision and are controversial. Thus, a single organism may be identified by a variety of names in the recent and historical literature, a circumstance that contributes to confusion for clinicians and for all but the most dedicated mycologists. This monograph does not attempt to deal definitively with the difficult questions of mycological classification and nomenclature of dematiaceous fungi, but alternative names or appropriate synonyms will be given in each case. Identification of these fungi is based mostly upon morphology. Important structures include annellides (Phaeoannellomyces, Exophiala), phialides (Phialophora, Wangiella), adelophialides (Phialemonium without collarettes, Lecythophora with collarettes), differentiation of conidiophores (Cladosporium) and conidial hilum, septation and germination (Bipolaris, Drechslera, Exserohilum). 4 A variety of infectious syndromes are attributed to dematiaceous fungi Two unique conditions, mycetoma and chromoblastomycosis, are caused by a small number of species and are usually seen in tropical regions. Mycetoma is commonly associated with chronic swelling and draining sinus tracts, usually of the lower extremities. It can be debilitating and difficult to treat. Chromoblastomycosis often presents with verrucous lesions that may occur anywhere on the body, but usually on the lower extremities. This is a chronic, slowly progressive subcutaneous mycosis. Minor trauma typically precedes the lesions. Initially, nodular lesions are present, which may progress over years to form large, verrucous plaques. Phaeohyphomycosis is a term that encompasses many clinical syndromes due to a wide variety of fungi. Conditions include superficial infections such as keratitisand subcutaneous nodules, allergic diseases, and invasive infections such as brain abscess and disseminated disease. Relatively little is known regarding the pathogenic mechanisms by which many of these fungi cause disease, particularly in immunocompetent individuals. One of the likely candidate virulence factors is the presence of melanin in the cell wall, which is common to all dematiaceous fungi. There are several mechanisms proposed by which melanin may act as a virulence factor : It is thought to confer a protective advantage by scavenging free radicals and hypochlorite that are produced by phagocytic cells in their oxidative burst that would normally kill most organisms. Melanin may bind to hydrolytic enzymes, thereby preventing their action on the plasma membrane. 5 2. Description of dematiaceous fungi of medical importance 2. 1. The genus Alternaria The genus Alternaria currently contains around 300 species. Alternaria is a wide-spread dematiaceous fungus commonly isolated from plants, soil, food, and indoor air environment.. At least 20% of agricultural spoilage is caused by Alternaria species; most severe losses may reach up to 80% of yield. Many human health disorders can be caused by these fungi, which grow on skin and mucous membranes, including on the eyeballs and within the respiratory tract. Allergies are common, but serious infections are rare, except in people with compromised immune systems. Species of Alternaria are often prolific producers of a variety of toxic compounds. The terms alternariosis and alternariatoxicosis are used for disorders in humans and animals caused by a fungus in this genus. 2.1.1. Alternaria alternata (Fr.) Keissl. (1912) Synonyms: Alternaria tenuis Nees 1917 Macrosporium fasciculatum Cooke & Ellis (1817), Torula alternata Fr. (1832), Alternaria fasciculata Jones & Grout (1897), Alternaria rugosa McAlpine (1896) Morphology Alternaria species grow rapidly producing flat, downy to woolly colonies, covered by grayish, short, aerial hyphae. The surface is greyish white at the beginning which later darkens and becomes greenish black or olive brown with a light border. Microscopically, the fungus develops septate, brown hyphae. Conidiophores are also septate and brown in colour, occasionally producing a zigzag appearance. They bear simple or branched large conidia, which have both transverse and longitudinal septations (muriform conidia). They are dark in colour, elongated and found in chains. The conidia may be observed singly or in acropetal chains and may produce germ tubes. They are ovoid to obclavate, darkly pigmented, muriform, smooth or roughened. The end of the conidium nearest the conidiophore is round while it tapers towards the apex. 6 The species can be divided into three groups according to the number of conidia on the conidiophore: Noncatenatae with single conidia; Brevicatenatae with short chains containing three to five conidia; Longicatenatae with long chains containing 10 spores or more. Alternaria alternata belongs to the last group. The microscopic differences between Alternaria species are not significant, and the character of every species varied depending on the conditions of growth. So, the identification of species is very difficult. Alternaria alternata A. tenuissima 7 A. infectoria A. triticina 8 Pathogenicity : Alternaria spp. have emerged as opportunistic pathogens particularly in patients with immunosuppression, such as the bone marrow transplant patients They are one of the causative agents of phaeohyphomycosis. Cases of onychomycosis, sinusitis, ulcerated cutaneous

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