Mycology. BioV 400. Subcutaneous Mycoses. Ecological associations. Geographic distribution World-wide

Transcription

1 BioV 400 Mycology Handout 8 Subcutaneous Mycoses Lymphocutaneous sporotrichosis Chromoblastomycosis Phaeohyphomycosis Zygomycosis Mycetoma Lymphocutaneous sporotrichosis Sporothrix schenckii Chronic infection (nodular and ulcerative lesions) Primarily a disease of the cutaneous tissue and lymph nodes Recently, pulmonary disease Portals of entry: inhalation and inoculation Ecological associations Rose thorns Sphagnum moss Timbers Soil Geographic distribution World-wide 1

2 Clinical specimens Sporothrix schenckii (PAS) positive yeast-like cells Pus Biopsy material Sputum Bronchial washings Cigar-shaped Mycology At 37 C Sporothrix white yeast round to oval forms (3-10 m) At 25º C colony is white-cream black and leathery as it ages Mycelium is branching, septate The pyriform conidia, 2-4 m a typical arrangement in radial groups at the end of a conidiophore called "daisies" 2

3 Chromoblastomycosis A chronic, localized infection of subcutaneous tissues Verrucous nodules (cauliflowerlike appearance) Caused by several species of dematiaceous (black pigmented) fungi Chromoblastomycosis The etiologic agents Fonsecaea pedrosoi Cladosporium carrionii Phialophora verrucosa Septate, mold-like, branching, darkly pigmented mycelia Diagnosis shape and formation of the conidia and biochemical tests The melanin may be a virulence factor Main features Saprobes Traumatic implantation Sub-cutaneous lesions (flat or warty) Dark-walled hyphae in tissue and culture Sclerotic bodies in tissues (Medlar bodies) Induce granulomatous reaction Produce asexual conidia 3

4 Sclerotic cells on a potassium hydroxide preparation Fonsecaea pedrosoi Etiologic agent of Chromob. Phialide and phialospores Humid regions of the world Rotting woods and soil debris Cladosporium carrionii Common cause of chromob. Arid and semi-arid areas (tropical and subtropical zones) 4

5 Phialophora verrucosa Etiologic agent of chromob. and phaeohyphomycosis Flask-shaped phialides Chromoblastomycosis World-wide distribution of fungi Clinical specimens: pus, biopsy material Therapy Excision, 5-FC, Itraconazole No serological test Phaeohyphomycosis Wangiella dermatitidis Human and animal diseases Black moulds (dark-walled septate) Xylohypha bantiana Wangiella dermatitidis Affect debilitated or immunosuppressed Chronic subcutaneous warty lesions May be systemic (brain, pulmonary) 5

6 Mycetoma Fungus tumors Chronic, subcutaneous infections Frequently invade contiguous tissue, particularly the bone Eumycotic mycetoma (tumors caused by the TRUE fungi) or eumycetoma Actinomycetoma (actinomycetes) Mycetoma Diagnosis of the etiologic agent is essential for patient management because the prognosis and therapy differs Features Tumefaction (swelling) Granules (different colors) Draining sinus tracts Agents Madurella mycetomatis Exophiala jeanselmei Pseudallescheria boydii Identification Colonial morphology Agents are filamentous fungi (7-10 days) Conidia formation Granules Color Size shape Texture Bioche mical reactions Madurella mycetomatis Black grain mycetoma: subcutaneous nodule Involves superficial layers of the skin and underlying fascia and bones Traumatic implantation of fungal pathogen 6

7 Exophiala jeanselmei Exophiala jeanselmei Conidiophores of E.j. E.j. is a human pathogen Mycetoma, subcutaneous cysts, endocarditis Cerebral involvement and disseminated infections Pseudallescheria boydii Madura foot, caused by Pseudallescheria boydii Conidiophores and conidia Human pathogen immunocompromised persons Infections in all body regions Pseudallescheriasis 7

8 Therapy Terbinefine Itraconazole Posaconazole Zygomycosis Mucormycosis and phycomycosis Acute inflammation Angiotropic disease (systemic dissemination) Disease is rapidly fatal Ubiquitous but rarely cause disease in immunocompetent host Susceptibility conditions Diabetes Severe burns Immunosuppression Rhizopus arrhizus Mucor pusillus The most common species of Rhizopus causing Zygo. Histopathology in a heart valve Fungal elements associated with Zygo. Aseptate hyphae 8

9 Absidia corymbifera Wide, non-septate, ribbon-like Features of zygo. Worldwide distribution Soil, food, organic debris Disease in uncontrolled diabetics If untreated patient dies within days Invasion of blood vessels brain Culture (rapid growth, white mold in 24-48H formation of sporangia, dark colony Treatment Debridement Amphotericin B Zygomycosis Periorbital fungal infection (mucor.) Affected regions: eye and nose Growth and destruction of periorbital tissues invasion of the brain Rapidly fatal 9

10 Characteristics of mucor infection Affinity for arterial infection Nasal or sinus infections Direct extension to the brain Rapidly fatal 10