Sporotrichosis and Rhinosporidiosis

SPOROTRICHOSIS Also known as Rose Gardner's disease (common in gardeners and florists) Presented as subcutaneous noduloulcerative lesions Caused by Sporothrix schenckii (thermally dimorphic fungus) PATHOGENESIS Minor trauma (thorn prick or splinter injury) + Spores of S/ schenckii introduced into skin Fungal Enzymes (like serine proteinase and aspartate proteinanse) help in local invasion S.schenckii has a tendency to spread along the lymphatics CLINICAL MANIFESTATION Five clinical types • Lymphocutaneous type Osteoarticular type Pulmonary type Disseminated sporotrichosis Fixed cutaneous type • Chronic subcutaneous pyogranulomatous disease • Incubation period - about 3 weeks • Lymphocutaneous type: most common type (80%) - Painless noduloulcerative lesions (sporotrichoid pattern) along the lymphatics - Enlarged Lymph nodes, indurated and have cord like feeling on palpation • Osteoarticular type: seen among alcoholics • Pulmonary type: following spore inhalation, seen in people with COPD • Disseminated sporotrichosis: in immunocompromised patients (AIDS) • Fixed cutaneous type: Single nodule is found, that is less progressive and does not spread by lymphatics Epidemiology: prevalent in tropical countries with high humidity LABORATORY DIAGNOSIS • Specimens - pus, aspirate from nodules, curettage or swabbing from ulcers • Direct microscopy: KOH mount or calcofluor staining → elongated yeast cells of 3-5 µm in diameter • Histopathological staining of tissue sections-cigar- shaped asteroid bodies • Asteroid body central basophilic yeast cell surrounded by radiating extensions of eosinophilic mass, composed of antigen-antibody complexes (Splendore-Hoeppli phenomenon) Asteroid bodies: Culture: It is the most definitive tool for diagnosis. Specimens are inoculated onto SDA and blood agar in duplicate and incubated at 25°C and 37°C simultaneously, because S. schenckii is a dimorphic fungus At 25°C: It produces mycelial form, consisting of slender delicate hyphae with conidia arranged in flower-like pattern (Fig. 52.118) At 37°C: It produces yeast form, characterized by moist creamy white colonies which turn brown black in 10-14 days. Yeast form (asteroid body) Mold form showing thin septate hyphae wit flower-like sporulation • Serology: Latex agglutination test detects serum antibodies in patients with extracutaneous form of the disease • Skin test: delayed type of hypersensitivity reaction against sporotrichin antigen • Treatment Sporotrichosis • Itraconazole drug of choice for all forms of sporotrichosis; except for disseminated form where amphotericin B is recommended Duration: 2-4 weeks after the lesions resolve RHINOSPORIDIOSIS Chronic granulomatous disease • Characterised by large friable polyps in the nose (most common site), conjuctive, ears, larynx Nasal Ocular Cutaneous Disseminated (rare) Potato Nose AGENT: Rhinosporidium seeberi Previously classified under fungi Now considered to be an aquatic protistan parasite SOURCE: Stagnant water. Spores are inhaled while bathing in contaminated water DISTRIBUTION: common in tropical areas especially sri lanka and india DIAGNOSIS: • Histopathology of polylps that demonstrates spherules (large sporangia up to 350microm size that contain numerous endospores) Stained better with mucicarmine stain R.seebri has not been cultivated yet. TREATMENT Radical surgery with cauterization (main) Dapsone Recurrence is common