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SUBCUTANEOUS MYCOSIS

SUBCUTANEOUS MYCOSIS. Phase II MBBS. INTRODUCTION. Usually follow trauma or any kind of injury In field workers Lesions develop at the site of implantation of the etiological agent in the subcutaneous tissue. Includes – Mycetoma - Sporotrichosis

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SUBCUTANEOUS MYCOSIS

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  1. SUBCUTANEOUSMYCOSIS Phase II MBBS Dr Ekta, Microbiology

  2. INTRODUCTION • Usually follow trauma or any kind of injury • In field workers • Lesions develop at the site of implantation of the etiological agent in the subcutaneous tissue. • Includes – Mycetoma - Sporotrichosis - Rhinosporidiosis - Chromoblastomycosis chromomycosis - 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. 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 • Entry of pathogen into the injured site, mostly foot. • Lesion begins as a small subcutaneous swelling of the injured site • Enlargement of the lesion & burrowing into deeper tissues • Formation of multiple sinuses on the surface discharging viscid, seropurulent fluid containing granules or grains which are microcolonies of the causative agent. Dr Ekta, Microbiology

  8. Other types of Mycetoma • Mycetoma of ear – use of wicks for removal of earwax. • Mycetoma of back – carrying goods like wood, grain bags, stones, etc • Mycetoma of the head & neck – bundles of wood 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 – X-Ray, CT scan, 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 – after crushing the 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 (sun ray appearance) • 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 • Cause - thorn pricks or other minor injuries • Mostly involves upper limbs Dr Ekta, Microbiology

  18. Pathogenesis & pathology • Spreads from primary site to the regional LNs through lymphatics • 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. 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 • Smear from Culture • septate hyphae - very thin & carry flower like clusters of small conidia on delicate sterigmata Dr Ekta, Microbiology

  22. 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

  23. Clinical Features • Chronic, recurrent 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

  24. 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

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

  26. CHROMO BLASTOMYCOSIS • Caused by dematiaceous (pigmented) fungi • Confined to subcutaneous tissue of the feet & lower legs • Commonly seen in barefoot agricultural workers & wood cutters. • Commonest fungi - Phialophora verrucosa Cladosporium sp. • Also called as Verrucous dermatitis - Warty cutaneous nodules which resembles flouts of cauliflower • Frequently ulcerates Dr Ekta, Microbiology

  27. Laboratory Diagnosis Direct Examination Specimen - 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

  28. Direct examination Histopathology • Specimen - Tissue biopsy • Stains - HE, Giemsa & Fontana- Masson • Sclerotic bodies very well seen Sclerotic/ Medlar bodies - characteristic tissue form facilitates survival of organism in host tissues. Dr Ekta, Microbiology

  29. Treatment & Prophylaxis • Poor response to available therapies. • Cryotherapy, Thermotherapy, Laser therapy, Chemotherapy and Surgery. • Flucytosine (commonly used drug) *Relapses are frequently seen Dr Ekta, Microbiology

  30. PHAEOHYPHOMYCOSIS • Also caused by dematiaceous (pigmented) fungi • Causes infection mainly in debilitated & immunodeficient hosts. • Can cause cutaneous, subcutaneous as well as deep infections • Clinical types: • Brain abscess • Subcutaneous or intramuscular lesions - abscess or cysts • Cutaneous lesions • Diagnosis : KOH mount of cyst aspirates/ abscess – pigmented hyphae • Treatment - Local excision , I.V. AMB + Oral Flucytosine. Dr Ekta, Microbiology

  31. 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 • Treatment – excision/ cryosurgery Dr Ekta, Microbiology

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

  33. Eid Mubarak to you all! Dr Ekta, Microbiology

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