6.SUBCUTANEOUS MYCOSES BY DR. RAZAQ MOMOH.pptx

SUBCUTANEOUS MYCOSES BY DR. RAZAQ MOMOH • Implicated fungi are habitats of soil and vegetation • Infections are usually by traumatic inoculation with contaminated materials • Lesions from trauma sites become granulomatous, expanding slowing from implantation foci • Extension via draining lymphatic...

SUBCUTANEOUS MYCOSES BY DR. RAZAQ MOMOH • Implicated fungi are habitats of soil and vegetation • Infections are usually by traumatic inoculation with contaminated materials • Lesions from trauma sites become granulomatous, expanding slowing from implantation foci • Extension via draining lymphatics is slow except in sporotrichosis • SPOROTRICHOSIS • Causative agent is Sporothrix schenckii • Thermally dimorphic fungus whose habitat is vegetation • Ambient temperature sees the fungus grow as mold, with branching septate hyphae conidia • In tissues or in vitro at 35-37ᵒC, it appears as a small budding yeast. • Traumatic inoculation by a contaminated material, allows Sporothrix schenckii to be introduced into the body leading to sporotrichosis • Sporotrichosis is a chronic granulomatous infection, which has a secondary spread involving draining lymphatics and lymph nodes • Morphology and Identification • At room temperature, the young colonies appear blackish and shinny, later becoming wrinkled and fuzzy as it age. • There is a variation in pigmentation from black to gray to white • The organism produces branching septate hyphae and small distinctive conidia (3-5ųm) • These conidia delicately cluster at the tip of tapering conidiospores • Larger conidia may be formed directly from hyphae • Since the fungus is thermally dimorphic, at 35ᵒC, it grows as a multiplying budding yeast cells • Antigenic Structure: Heat killed saline suspensions of cultures or carbohydrate fractions (Sporotrichin) will elicit a positive delayed skin tests in infected humans or animals. • Pathogenesis and Clinical Findings • Inoculation is via trauma • Initial lesions are usually at the extremities but can be seen elsewhere • 75% of cases are lyphocutaneous, wherein, initial cases develops as a granulomatous nodule that may progress to form necrotic or • Draining lymphatics become thickened and cord-like • Multiple subcutaneous nodules and abscesses occur along the lymphatics • NB: Fixed sporotrichosis , a non Lymphangitic nodule is seen in endemic areas such as Mexico, where there is high level of exposure and immunity in the local population • Fixed sporotrichosis is limited and less progressive • Usually, little systemic illness is associated with fixed sporotrichosis though dissemination could occur • Rarely, primary pulmonary sporotrichosis results from inhalation of the conidia. • PPS mimics cavitary tuberculosis and usually occur in debilitated patients with impaired cell mediated immunity. • However, clinically, it is safe to say • Most cases occur in the upper limb • Extremities are the usual sites of infection, but children may present with facial lesions • Sporotrichosis is characterized by development of nodules on the skin, subcutaneous tissues and lymph nodes which then softens and break to form indolent ulcers. • Types of Sporotrichosis • a. Plaque sporotrichosis: Non-tender lesion confined to the inoculation site • b. Lymphangitis sporotrichosis: MC manifestation in which secondary lesions are seen along the lymphatic channels. The small painless nodules may ulcerate and exudate pus • c. Extracutaneous sporotrichosis: Predilection for the lungs, which is noted as the primary portal. • Pulmonary sporotrichosis is usually presentas single chronic cavitary upper lobe lesion • Diagnosis: • Culture: pus, joint fluid, sputum or skin biopsy in which septate hyphae carrying flower like clusters of small conidia is seen. Note: culture is most reliable • In tissue, fungus is seen as a “cigar shaped yeast” without mycelia • At times, Asteroid Bodies can be seen, which is formed due to antigen-antibody reaction. • Treatment: • Cutaneous sporotrichosis- DOC itraconazole • Alternative therapy- Potassium iodide • Extracutaneous sporotrichosis: DOC iv Amphotericin • Alternative therapy- itraconazole • MYCETOMA • Is a painless localized woody induration without systemic symptoms caused by either a bacteria( Actinomycotic mycetoma) or a fungi(Eumycotic mycetoma) • Thus, mycetoma can be said to be a granulomatous involvement of subcutaneous and deeper tissues induced by traumatic inoculation of saprophytic fungi or bacteria. • Features of Mycetoma • MC site-foot: presents as tumour with multiple discharging sinus (discharging sulphur granules) called MADURA FOOT • MC cause is fungi called (eumycotic mycetoma,/Maduromycosis/Madura foot): black granules and stout filaments are seen on microscopy • Aetiologic agents of eumycotic mycetoma: Pseudallescheria boydii, Exophiala jeanselmei, Madurella mycetomatis, Acremonium falciforme and Madurella grisea • Actinomycotic mycetoma are caused by species of Actinomyces, Nocardia, Streptomyces and Nocardiopsis • Staphylococcus aureus can cause mycetoma like lesions called botryomycosis • In actinomycotic mycetoma, granules are white to yellow and thin filaments are seen on microscopy • Treatment : • Actinomycetoma- DOC Streptomycin+Dapsone or Cotrimoxazole • Eumycotic mycetoma of Madurella mycetoma-DOC Ketoconazole/Itraconazole • NB: Other Eumycetoma rarely respond to chemotherapy • CHROMOBLASTOMYCOSIS • Otherwise called Chromomycosis • Has five(5) common aetiologic agents including • - Phialophora verrucosa • - Fonsecaea pedrosoi • - Fonsecaea compacta • - Rhinocladiella aquaspersa • - Cladophialophora caririonii • These subcutaneous infection is caused by traumatic inoculation by any of the listed fungi spp • The listed fungi spp reside in soil and vegetation • All are dematiaceous fungi with melaninized cell walls • Chromoblastomycosis is a chronic infection characterized by a slow progressive granulomatous lesion, which invariably induce hyperplasia of the epidermal tissue • Morphology and Identification • These dematiaceous fungi are similar in their pigmentation, antigenic structure, morphology and physiologic properties. • Colonies are compact, with brown to black coloration, also developing a velvety wrinkled surface. • All agents are identified by their conidiations• -appearing in tissues as spherical brown cells(4-12ųm in diameter) termed muriform or sclerotic bodies. • These sclerotic bodies divide by transverse septation • NB: Septation in different planes with delayed separation gives rise to a cluster of 4-8 cells • NB:cells within superficial crusts or exudates may germinate into septate, branching hyphae • Cultural characteristics of aetiologic agents • a) P. verrucosa: conidia are produced by flask-shaped phialides with cup-shaped collarettes • b) F. pedrosoi: it is polymorphic. Most strains of F. pedrosoi for short branching chains of blastoconidia seen in Cladosporium as well as sympodial conidia seen in Rhinocladiella conidiation • c) F. compacta: Blastoconidia produced by this species are virtually spherical, with a broad base connecting the conidia,very similar to those of F. pedrosoi • d) R. aquaspersa: Produces lateral or terminal conidia from a lengthening conidiogenous cell, more like a sympodialprocess. These conidia are elleptical to clavate • e) C. carrionii: produces branching chains of conidia by acropetalous (distal) budding, wherein, the terminal conidium o a chain gives rise to the next conidium by budding • C. carrionii produces elongated conidiophores with long, branching chains of oval conidia. • Pathogenesis and Clinical Findings: • Over months to years, initial primary lesions becomes verrucous and wart-like with extension along the draining lymphatics. • Cauliflower-like nodules with crusting abscesses eventually coverthe area • Small ulcerations or black dots of hemopurulent materials are presenton the warty surface • Rarely, elephantiasis may result from secondary infection, obstruction and fibrosis of the lymph channels • Dissemination of the condition is rare • Satellite lesions may occur due to local lymphatic spread or due to autoinoculation • Histologically, lesions are granulomatous and dark sclerotic bodies may be seen within leukocytes or giant cells • Diagnosis : • Culture on SDA inculcated with antibiotics • There are several saprophytic dematiaceous molds. They differ from the pathogenic species in their inability to grow at 37◦C and being able to digest gelatin. • Treatment • Surgical excision for smaller lesions, with wide margin excision around the the lesion • Flucytosine and itraconazole for larger lesions • Local heat application • Relapse is rather common