Subcutaneous Mycoses

Subcutaneous Mycoses wide rang of fungal infections  Characterized by lesion  Usually associated with trauma  Sporotrichosis  Chromoblastomycosis  Mycetoma  Rhinosporidiosis  Labiomycosis 

Common future Trauma at site of infection  Thorn, splinter  Infection occur at site prone to trauma  Hand, arm  Organisms usually found in soil  Infections mimic subcutaneous bacterial  Excision and amputation is frequently employed 

Etiology and clinical syndroms Heterogeneous groups of fungi  Low pathogenic potential  found in soil  Disease interplay between organism and host response  No underlying immunological defect 

Lymphocutaneous sporotrichosis         

Chronic infection Nodular and ulcerative lesions Drain at site of inoculation Causative agent Sporothrix schenkii

Thermally dimorphic Natural habitat soil 37°C: Round/cigar-shaped yeast cells 25°C: Septate hyphae, rosette-like clusters of conidia at the tips of the conidiophores

Pathogenesis & Clinical Findings  Skin:

Follows minor trauma Nodule  ulcer necrosis Skin/subcutaneous tissue lymphatic channels lymph nodes  Systemic dissemination: Bones, joints, meninges  Primary pulmonary: Chronic alcoholics

Laboratory Diagnosis Samples: Aspiration fluid, pus, biopsy I. Micro. Direct microscopic examination (KOH), histopathological examination (methenamine silver stain) Yeast cells, asteroid body II.Culture III.Serology Yeast agglutination test IV. Sporotrichin skin test (?)

Treatment  Spontaneous

healing is possible.  Cutaneous infection  Potassium iodide (Topical/oral)  Disseminated infection  Amphotericin B

Eumycotic MYCETOMA (=Maduromycosis=Madura foot) General futures  Posttraumatic chronic inf. of subcutaneous tissue  Common in tropical climates  Causative agents  Saprophytic fungi (Eumycetoma)  Actinomyces (Actinomycetoma) 

MYCETOMA Causative agents  Madurella

mycetomatis  Pseudallescheria boydii  Acremonium  Exophiala jeanselmei  Leptosphaeria  Aspergillus  Actinomyces

Clinical findings  Site's  Feet,

lower extremities, hands  Findings:  Abscess formation, draining  sinuses containing granules  Deformities  Dissemination  Muscles and bones

Laboratory Diagnosis  Clinical

findings are non-specific  Identification of the infecting fungus is difficult  Characteristics of the granule, colony morphology, and physiological tests are used for identification

Treatment  Surgery

 Antifungal

therapy  Amphotericin B  Flucytosine  Topical nystatin  Topical potassium iodide  choice of treatment varies according to the infecting fungus

CHROMOBLASTOMYCOSIS 

General features

Posttraumatic chronic inf. of subcutaneous tissue  Papules verrucous cauliflowerlike lesions on lower extremities  Systemic invasion is very rare 

Causative agents Fonsecaea 2. Phialophora 1.

3.  

Cladosporium Pigmented (dematiaceous) fungi in soil Arrangement and shape of the spores vary from one genus to other

Laboratory diagnosis Direct microscopic examination (KOH)  Sclerotic body  Culture  Sabouraud dextrose agar, 4-6 weeks, 37°C 

TREATMENT Surgery  Antifungal therapy (susceptibility varies depending on the genus)  Amphotericin B  Flucytosine  Ketaconazole  Heat 