Subcutaneous Fungi 10/13/2009. General Characteristics. Pathogenesis. Epidemiology. Laboratory Diagnosis. Specimens. Growth rate: 1-4 weeks

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1 General Characteristics Growth rate: 1-4 weeks Subcutaneous Fungi Clinical Laboratory Science Program Carol Larson MSEd, MT(ASCP) Dematiaceous septate hyphae Hyaline septate hyphae Branching GPR Epidemiology Found in soil and on plants Saprophytic (nonpathogenic) Pathogenesis Acquire by mechanical means trauma Elicit disease depends on: Tissue involved Immune system Amount of exposure Lesion Skin, subcutaneous tissue, others RARELY disseminates Laboratory Diagnosis Specimen collection Direct Examination Culture Specimens Skin scrapings Aspirated debris Tissue biopsy Pus/drainage from lesion Sputum, BW 1

2 Direct Examination of Specimens 10% KOH Calcofluor white stain Histological stains Methenamine silver stain Hematoxylin-eosin (HE) stain Gram stain Modified acid fast stain Specimen processing Sulfur granules Crush before culturing Tissue Grind the tissue before culturing Culture Media Select two media types Nonselective Sabouraud s agar Inhibitory mold agar Blood agar (actinomycotic) BHI Selective Mycosel agar Antibiotics may inhibit growth Culture Growth Requirements Place specimen on culture media Can streak for isolation Incubate at C in ambient (room) air Growth at 5 days to 4 weeks Examine plates frequently for 6 weeks Scotch tape preparation Tease prep Slide culture Diseases Eumycotic (Fungal) Mycetoma Actinomycotic (Bacterial) Mycetoma Sporotrichosis 2

3 Etiologic Agents Fonsecaea species Phialophora verrucosum Cladophialophora carrionii Distribution Clinical disease Chronic Involves skin and subcutaneous tissue Cauliflower-like lesion Secondary infection & ulceration Conidial structures A. Acrotheca (rhinocladiella) B. Cladosporium Fonsecaea species C. Phialophora Phialophora verrucosum Cladophialophora carrionii 3

4 Mycetoma Eumycotic Acremonium species Others Actinomycotic Nocardia species Streptomyces species Actinomyces species Mycetoma Distribution Clinical disease Chronic granulomatous infection Triad of symptoms Swelling Sinus tracts Sulfur granules Slow progression to surrounding tissue Acremonium species Nocardia species Gram stain morphology Partially acid fast positive Streptomyces species Gram stain morphology Actinomyces species Gram stain morphology Acid fast negative Acid fast negative 4

5 Sporotrichosis Etiologic agent: Sporothrix schenckii Sporotrichosis Distribution is worldwide Clinical disease Chronic subcutaneous infection Primary lesion Nodule lesions Lymphatic channels & lymph nodes Mold Sporothrix schenckii Yeast Sporothrix schenckii Microscopic morphology In Summary Diseases Mycetoma (Eumycotic, Actinomycotic) Sporotrichosis Growth rate, colony morphology, & microscopic exam What structures do you see? A. Acrotheca B. Cladosporium C. Phialophora Possible Genus? Fonsecaea (shows all three types) 5

6 Who am I? Who am I? Sabouraud's Agar Growth at 3 days Gram stain Nocardia species Acid fast stain Sabouraud s Agar Acremonium species LPAB Stain of Slide Culture Who am I? Growth at 25C Growth at 35C Sporothrix schenckii 6