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SUBCUTANEOUS MYCOSIS

SUBCUTANEOUS MYCOSIS. III MBBS. INTRODUCTION. Usually follow trauma. Lesions develop at the site of implantation of the etiological agent in the subcutaneous tissue. Includes – Mycetoma - Sporotrichosis - Rhinosporidiosis

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SUBCUTANEOUS MYCOSIS

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  1. SUBCUTANEOUSMYCOSIS III MBBS Dr Ekta, Microbiology

  2. INTRODUCTION • Usually follow trauma. • Lesions develop at the site of implantation of the etiological agent in the subcutaneous tissue. • Includes – Mycetoma - Sporotrichosis - Rhinosporidiosis - Chromoblastomycosis - Phaeohyphomycosis - Lobomycosis Dr Ekta, Microbiology

  3. MYCETOMA • Chronic, slowly progressive granulomatous infection of skin & subcutaneous tissues with the involvement of underlying fasciae & bones commonly affecting the extremities. • Reported by Gill from Madurai, S.India. • Maduramycosis or Madura foot. • Tropical & subtropical countries of Asia , Africa, Central & S.America. Dr Ekta, Microbiology

  4. Classification of Mycetoma • Based on the causative agent Fungi – Eumycetoma Bacteria (actinomycetes) - Actinomycetoma • Based on the colour of grains Bacterial agents – white to yellow grains except Actinomadura pelletieri (red or pink) Fungal agents – black as well as white grains. Dr Ekta, Microbiology

  5. Colour of grains in Mycetoma of various etiology Dr Ekta, Microbiology

  6. Epidemiology • More prevalent in developing countries, especially in the rural areas. • Young men 20 to 40 yrs of age • Field workers, farmers – prone to thorn prick injury & trauma. • Prevalence in world : Eumycetoma (40%) Actinomycetoma (60%) Dr Ekta, Microbiology

  7. Pathogenesis & Pathology • Causative agent present in soil • Accidental trauma by thorns or splinter injury • Minor trauma & skin abrasions • Mycetoma of ear – use of wicks for removal of earwax. • Mycetoma of back – carrying goods like wood, grain bags, stons, etc • Mycetoma of the head & neck – bundles of wood Dr Ekta, Microbiology

  8. Pathogenesis & Pathology • Lesion begins as a small subcutaneous swelling of the foot, which enlarges burrowing into the deeper tissues & tracking to the surface as multiple sinuses discharging viscid, seropurulent fluid containing granules or grains which are microcolonies of the causative agent. Dr Ekta, Microbiology

  9. Clinical features • Characterised by a triad of clinical features irrespective of the causative agent: • Tumefaction – tumor like swelling • Multiple draining sinuses • Presence of grains or granules in sinuses. Dr Ekta, Microbiology

  10. Dr Ekta, Microbiology

  11. Diagnosis • Radiodiagnosis – Xray, CT, MRI. • Laboratory diagnosis - Proper h/o patient - Gross examination of lesion by a microbiologist Specimen – grains or granules - pus / exudates or biopsy Lesions cleaned with antiseptics & the grains collected by pressing the sinus from the periphery. Gross examination of grains – size, shape, texture, colour Dr Ekta, Microbiology

  12. Direct Examination • KOH mount – grains Eumycetoma : 2-6µ, wide interwoven hyphae with large, swollen cells (chlamydospores) at the margin of the lesion. Actinomycetoma : filaments with a diameter of 0.5 - 1µ, coccoid to bacillary forms. If hyphae seen on KOH mount, use special stains. Dr Ekta, Microbiology

  13. Direct Examination • Gram stain – gram +ve branching filamentous bacteria embedded in the grain material. • Modified Acid fast staining with 1% sulphuric acid – pink colored filamentous bacteria i.e. Nocardia Sps whereas other actinomycetes are non- acid fast. Dr Ekta, Microbiology

  14. Culture • Different sets of media – both possibilities of fungi & bacteria . • When Actinomycetoma is suspected on directexamination - wash grains several times with NS & then inoculate on SDA without antibiotics, BA, LJ & BHIA. • When Eumycetoma is suspected – wash grains several times in NS with antibiotics(Pn) & inoculate it on SDA with antibiotics. - actidione not added. - incubated at 25° & 37°C Dr Ekta, Microbiology

  15. Treatment & prophylaxis • Eumycetoma – Oral Ketoconazole & Itraconazole AMB for Madurella & Fusarium species. • Actinomycetoma – Sulfonamides, Tetracyclines, Streptomycin, Amoxycillin, Clavunate & Amikacin • Protracted case – Surgery (debridement with skin graft) Dr Ekta, Microbiology

  16. Botryomycosis • Similar condition caused by bacteria like S.aureus, P.aeruginosa, CONS, E.coli. Pr.vulgaris etc. • 2 types : cutaneous visceral – ill debilitated pts Dr Ekta, Microbiology

  17. SPOROTRICHOSIS • Caused by Sporothrix schenckii, a dimorphic fungus. • Most common in USA. • Found on plant, thorns & timber • Infection is acquired through thorn pricks or other minor injuries Dr Ekta, Microbiology

  18. Pathogenesis & pathology • Spreads from primary site to the regional LNs through lymphatics • Mostly involves upper limbs • Pyogranulomatous reaction • Clinical features - Nodules on the skin, subcutaneous tissue and in the LNs which later soften & ulcerate. Lymphocutaneous sporotrichosis Dr Ekta, Microbiology

  19. Laboratory Diagnosis • Specimens – pus, exudate & aspirate from nodules. - curettage or swabs from open lesions. Direct Examination • Gram’s stain – gram+ve, irregularly stained yeast cells. • CFW – very useful. Dr Ekta, Microbiology

  20. Direct examination • Tissues – organisms appear as cigar shaped bodies (yeast cells)3-5µ in diameter. • “Asteroid bodies” in the lesion – central fungus cell surrounded by a refractile eosinophilic halo, called “ Splendore-Hoeppli” phenomenon : due to immune complex deposition around the organism. Dr Ekta, Microbiology

  21. Culture • Inoculated on 2 sets of SDA, BHIA • Incubated at 25°& 37°C. Dr Ekta, Microbiology

  22. Smear from Culture • septate hyphae - very thin & carry flower like clusters of small conidia on delicate sterigmata. Dr Ekta, Microbiology

  23. Treatment & Prophylaxis • Saturated solution of KI – drug of choice • Oral Ketoconazole or Itraconazole • AMB – disseminated & CNS disease. Dr Ekta, Microbiology

  24. RHINOSPORIDIOSIS • Caused by a hydrophilic protist, Rhinosporidium seeberi • 1st identified in Argentina, but majority of cases occur in India and Sri lanka. • High incidence among people who frequently bath along with domestic animals in ponds, tanks, lakes Dr Ekta, Microbiology

  25. Clinical Features • Chronic granulomatous disease of mucous membrane. • Characterised by the development of friable polyps in the nose, mouth or eye. • Miscellaneous forms – Buccal cavity,vagina, vulva, penis, urethra or rectum Dr Ekta, Microbiology

  26. Laboratory Diagnosis • Cannot be cultured Direct Examination • FNAC, Biopsy of lesion, Nasal washing - Contains sporangia filled with thousands of sporangiospores(6-9µ) embedded in a stroma of connective tissue & capillaries Dr Ekta, Microbiology

  27. Treatment & Prophylaxis • Radical Surgery:- Excision/ Electrocautery • Medical therapy :- not useful DDS (widely used) • Recurrence common Dr Ekta, Microbiology

  28. CHROMO BLASTOMYCOSIS • Caused by dematiaceous (pigmented) fungi • Commonest fungi - Fonsecaea Species Phialophora verrucosa Cladosporium carrionii • Also called as Verrucous dermatitis Dr Ekta, Microbiology

  29. Clinical features • Soil saprobes enter the skin by traumatic implantation and lesions develop slowly around the site of implantation • Warty cutaneous nodules which resembles flouts of cauliflower - Verrucous dermatitis • Frequently ulcerate • Confined to the subcutaneous tissue of the feet and lower legs Dr Ekta, Microbiology

  30. Laboratory Diagnosis Direct Examination Dry crusty material from the surface of the lesions • KOH w/m – dark brown, multicellular structures, 5-12μ in diameter that divide by transverse septation. -Called sclerotic bodies, medlar bodies,copper-pennies bodies or muriform cells Dr Ekta, Microbiology

  31. Sclerotic bodies - KOH Sclerotic bodies - tissues Dr Ekta, Microbiology

  32. Direct examination Medlar bodies - characteristic tissue form - facilitates survival of organism in host tissues. • Tissue Stains - for Biopsy specimens HE, Giemsa & Fontana- Masson - Sclerotic bodies very well seen Fungal culture - SDA with actidione and antibiotics Dr Ekta, Microbiology

  33. Treatment & Prophylaxis • Responds poorly to available therapies. • Cryotherapy, Thermotherapy, Laser therapy,Chemotherapy and Surgery. • Flucytosine (commonly used drug) • Itraconazole, Fluconazole, Terbinafine *Relapses are frequently seen Dr Ekta, Microbiology

  34. PHAEOHYPHOMYCOSIS • Seen in debilitated & immunodeficient hosts. • Causes subcutaneous & systemic infection. • Caused by dematiaceous fungi. Commonest genera involved - Alternaria, Bipolaris, Curvularia, Exophiala, Phialophora, etc. Dr Ekta, Microbiology

  35. Clinical Features • Clinical types: • Brain abscess caused by Cladosporium • Subcutaneous or intramuscular lesions withabscess or cysts - single circumscribed lesion with a central cavity filled with pus and surrounded by a fibrous wall • Cutaneous lesions Dr Ekta, Microbiology

  36. Laboratory Diagnosis Specimen • Aspirates from cysts • Curreting from plaques, nodules and drained abscess Direct Examination KOH mount - Pigmented hyphae 3-4µ in dia. Dr Ekta, Microbiology

  37. Fungal Culture • SDA with actidione at 25º & 37ºC. Treatment & Prophylaxis • Local excision for subcutaneous forms • Invasive infections – I.V. AMB + Oral Flucytosine. Dr Ekta, Microbiology

  38. LOBOMYCOSIS • Caused by Lacazia loboi (Hydrophilic fungus) : exists only as yeast cells. • Involves exposed parts • Presence of macule, papule, keloid, verrucous, nodular lesions or plaques & tumors. • Lesions are painless with slight pruritis Dr Ekta, Microbiology

  39. Laboratory Diagnosis • Direct Examination of curettage / biopsy -crushed a. KOH w / m b. CFW - spheroid, yeast - like cells, 5 -12µ - thick - walled & multinucleate. - form chain with cells joined by bridges. c. HE – may show ‘asteroid bodies’ • Culture – cannot be cultured Dr Ekta, Microbiology

  40. Fontana Masson stain Dr Ekta, Microbiology

  41. Treatment & prophylaxis • No effective medical treatment • Complete excision • Cryosurgery. Dr Ekta, Microbiology

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