Biology of FUNgi. Lecture 21 The Ugly - localized disease-causing fungi

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1 Biology of FUNgi Lecture 21 The Ugly - localized disease-causing fungi Flashback - fungitoxins Toxins you should know about The deadly Amanita phalloides Galerina autumnalis Group I: Amatoxin and phyllotoxin (cyclic peptides) containing species. Group II: Orellanin (cyclic peptides) containing species. Group III: Gyromitrin (monomethyl hydrazine - MMH) containing species. Cortinarius alboviolaceous Gyromitra esculenta Gyromitra caroliniana 1

2 Flashback - fungitoxins Toxins you should know about Silly heads Amanita muscaria Group IV: Muscarine containing species. Group V: Ibotenic acid and muscimol (mycoatropines) containing species. Group VI: Psilocin and psilocybin (indole derivatives) containing species. Tummy aches Many of the above Amanita pantherina Amanita muscaria Group VII: Mixed bag of GI-irritants Psilocybe cyanescens Psilocybe cubensis Last time... Inhaled fungitoxins - Stachybotrys. Allergens - various indoor fungi. Ingested fungitoxins - aflatoxin, trichothecenes Poisonous mushrooms. 2

3 Fungus of the day - Ajellomyces capsulatus Taxonomy: Phylum (subphylum) Ascomycota Order - Onygenales (Cleistothecial) Family - Onygenaceae Ajellomyces capsulatus is better known for its anamorph Histoplasma capsulatum. Histoplasma capsulatum macroand microconidia. A. capsulatus is the causal agent of histoplasmosis. Dimorphic fungus, which is filamentous on solid substrates and unicellular in liquid substrates. Temperature has an impact on the growth form as well. Histoplasma capsulatum unicellular yeast growth. Fungus of the day - Ajellomyces capsulatus Histoplasma capsulatum infection is pulmonary, but systemic infections may involve cutanous symptoms. Pulmonary infection is often a result of inhalation of spores. Fungus is soil-borne but inhalation risk is greater if you are exposed to bird and/or bat droppings. The pulmonary infection can result in systemic infection as Histoplasma spores are disseminated through the bloodstream. 3

4 Fungus of the day - Ajellomyces capsulatus Histoplasma capsulatum infection is often benign and asymptomatic. Pulmonary symptoms include dry cough, chest pains, fever and fatigue. The chronic infection is similar to tuberculosis with bloody cough. Symptoms may vary widely. Systemic (throughout the body) infection symptoms include enlarged liver and spleen, mouth and gastrointestinal sores, possibly also death. Lesion Necrotic lesions in the lung x-ray and biopsy. Lesions indicate individual Histoplasma colonies. Histoplasma colonies Lesion Fungus of the day - Ajellomyces capsulatus Although initially pulmonary, systemic histoplasmosis involves lesions in almost every possible organ in the body and includes cutanous infections. Fortunately, 95% of the cases are benign and subclinical. The 5% become chronic infecting cutaneous tissues and/or lungs and may rapidly turn into fatal systemic infections. Cutanous histoplasmosis lesions Pulmonary histoplasmosis 4

5 Fungus of the day - Ajellomyces capsulatus How common is histoplasmosis? Almost 90% of the people living in the Mississippi, Missouri and Kansas River valleys have a chronic pulmonary Histoplasma infection. This equals 40,000,000 americans testing positive for histoplasmosis. These are mainly benign infections, causing only lesions in the lungs and no acute symptoms. Histoplasma capsulatum, conidial stage of the etiologic agent. Histoplasma distribution based on the home of nearly 300,000 navy recruits. Fungus of the day - Ajellomyces capsulatus Histoplasmosis was brought to the spot lights when Bob Dylan contracted pulmonary histoplasmosis, which then turned systemic. In benign cases, no treatment is necessary. Rest is recommended. Acute, severe cases, like Dylan s, require extended treatments with systemic fungicides. Bob Dylan introduced histoplasmosis to the greater audiences. 5

6 Topics of the day... Localized mycoses of the skin Superficial Cutanous Subcutanous The Ugly - disease-causing fungi Fungal diseases may not be particularly diverse, but they are ubiquitous. In addition to true disease-causing fungi, there is a whole number of common indoor and outdoor fungi which are opportunistic colonizers of immunocompromized patients or organ transplant recipients. 6

7 The Ugly - disease-causing fungi For convenience and clarity we will divide the fungal diseases into five different groups: 1) Superficial mycoses 2) True dermatophytoses 3) Subcutanous mycoses 4) True systemic mycoses And, 5) opportunistic fungal infections. The Ugly - superficial mycoses Primarily cause just cosmetic effects. Otomycosis - symptoms include itching and deposits of epithelial debris (+masses of bacteria and fungi) on ears. Piedra - fungal infection of hair. Piedraia hortai - black piedra on hair and in pure culture Black piedra: The piedra symptoms include small stony nodules on hair. Black piedra appears exclusive to scalp, i.e., not in the pubic hair or beard. 7

8 The Ugly - superficial mycoses White piedra: Like black piedra, small stony nodules on hair. As opposed to black piedra, white piedra appears exclusive to the hair of beard and mustache. Both piedras occur world-wide. Trichosporon beigelii - white piedra on hair and in pure culture The fungi can easily be brought into pure culture from colonized hair. Convenient! The Ugly - dermatophytoses Infection of keratinous tissues (nail, skin) in various parts of the body. The diseases are known as tineas: Tinea capitis (head), Tinea manuum (hand), Tinea pedis (foot), Tinea corporis (body). The common name for tineas is ringworm. Various anamorphic species: e.g. Microsporum, Trichophyton. Microsporum audoninii - colony and phragmosporic conidia 8

9 The Ugly - dermatophytoses Microsporum spp: Anamorphic genus with a number of species infecting animals and humans. Microsporum spp. can be found in any part of the body: scalp, beard (or face), or body. Microsporum may be among the most common soil isolated keratin-utilizing fungi. Tinea capitis, the ring worm. Fungal colonies form concentric rings from the infection point outwards. The Ugly - dermatophytoses Trichophyton spp: Another anamorphic genus with a number of species infecting skin, hair and nails of especially feet and toes. Infection may result in a variety of symptoms including lumpy colonies in the infected areas. Like Microsporum, Trichophyton is often isolated from soil. Trichophyton, too, can be baited with keratinized tissues from soil Trichophyton tonsurans - a causal agent of many tineas. Tinea pedis caused by Trichophyton sp. 9

10 The Ugly - subcutanous mycoses Subcutanous infections are most commonly associated with traumatic implantation into the skin. Usually the infection remains localized or slowly spread from the site of implantation. Some of these infections may spread through the lymphatic channels to other parts of the body (e.g. Sporothrix; Ophiostomatales). Typical mode of entry for the subcutanous mycoses. Systemic Exophiala infection in an immonocompromized child. True systemic infections most frequently enter the body through the pulmonary route. The Ugly - subcutanous mycoses Mycetoma: Mycetoma is a chronic granular infection of, most often, feet. The disease is best characterized warty outgrowths enlargement, deformity and bone destruction. Several etiological agents may be involved, both fungal and actinomycetous. Depending on the etiological agent the granule color may be black or white. Mycetoma of the foot. Lumps are usually clusters of fungal sclerotia (resting structures), the granules. Cross section of tissue containing black granules 10

11 The Ugly - subcutanous mycoses To provide a few examples of fungi causing mycetomas and to gain appreciation for their diversity, Acremonium sp., Fusarium sp. and Pseudallescheria sp. produce white granules. Fusarium sp. conidiophore. Pseudallescheria boydii cleistothecium White sclerotia in mycetomatous foot tissue The Ugly - subcutanous mycoses Others produce black granules. Examples of those include Curvularia sp., Exophiala sp. and Leptosphaeria sp. Curvularia verruculosa conidiophore. Black sclerotia in mycetomatous foot tissue 11

12 The Ugly - subcutanous mycoses Chromoblastomycosis: Fairly common subcutanous fungal infection. Chromoblastomycoses are typically localized, chronic skin and subcutaneous tissue infections. These differ from mycetomas by more often producing ulcerating warty or tumor-like lesions. Chromoblastomycosis on foot, note the ulcerating lesions. Fungal cells in chromoblastomycotic lesion tissue. The Ugly - subcutanous mycoses Chromoblastomycosis: Like mycetomas, chromoblastomycoses mainly infect the lower extremities but may also occur in face or neck area. Chromoblastomycosis on foot, note the ulcerating lesions. 12

13 The Ugly - subcutanous mycoses Chromoblastomycosis: There are five main etiological agents for chromoblastomycosis: Fonsacea pedrosi, F. compacta, Phialophora verrucosa, Cladosporium carrionii, Rhinocladiella aquaspersa. All these have global distribution and are fairly common Fonsacea pedrosi melanized, anamorphic causal agent of chromoblastomycosis These are dematiaceous (dark colored, melanin pigments in the cell wall) and occur commonly in soil. They are introduced, typically to subcutaneous infections, by splinters or skin abrasion. Phialophora verrucosa also a melanized anamorph The Ugly - subcutanous mycoses Sporotrichosis: Sporotrichosis is manifested as nodular lesions and ulcers in the lymphatic system, skin, or as subcutanous tissues. Sporotrichosis may also involve primary pulmonary infection. Sporotrichosis primary lesion after trauma. Although mostly known to occur as localized lesions following a trauma in hands arms or legs, disseminated infection may involve also bones, joints and central nervous system. The dissemination occurs through bloodstream. Sporotrichosis nodular lesions 13

14 The Ugly - subcutanous mycoses Sporotrichosis: The etiological agent Sporothrix schenkii, an anamorph of a perithecial ascomycete (member of Ophiostomatales). Sporothrix schenkii commonly occurs in soil, wood or vegetation. It can be injected through wounds from infected splinters, or the can be conidia inhaled causing a subcutanous infection in the lungs. Sporothrix schenkii culture and conidia. Summary Fungal infections of skin Superficial infections (Piedras) Cutanous infections (Tineas) Subcutanous infections (Sporotrichosis, Mycetomas, and Chromoblastomycoses) 14