Subcutaneous Mycoses - Infections of Subcutaneous Layer | Mycology Notes

SUBCUTANEOUS MYCOSES – INFECTION OF SUBCUTANEOUS LAYER

INTRODUCTION TO SUBCUTANEOUS MYCOSES – 

Subcutaneous mycosis is principally found in tropical and subtropical regions. The fungi causing such subcutaneous mycoses are either normally present in the soil or are pathogens of plants. the various types of subcutaneous mycoses include –

  • Mycotic Mycetoma
  • Sporotrichosis
  • Rhinosporidiosis
  • Chromomycosis
  • Subcutaneous phycomycosis

MYCETOMA

Mycetoma is a chronic, granulomatous, post-traumatic infections of the subcutaneous tissue, usually affects the foot and rarely the other parts of the body

It is commonly known as Madura foot or Maduramycosis because it was first described by Gill from Madurai, South India, and is quite common in Tamil Nadu.




⇒ Causative agents and Types of Mycetoma 

» Mycetoma have been classified into three groups as follows –

  • Eumycetoma (Maduramycosis) – Mycetoma i.e. caused by Fungi.
  • Actinomycetoma – Mycetoma i.e. caused by Filamentous bacteria.
  • Botryomycosis – Mycetoma i.e. caused by Staphylococcus aureus & other bacteria.

CAUSATIVE AGENTCOLOR OF GRANULES OR GRAINTYPE OF MYCETOMA
Acremonium falciformeWhite – yellowEumycetoma
Actinomadura maduraeWhite – yellowActinomycetoma
Actinomadura pelletieriiRedActinomycetoma
Madurella mycetomaBrown – blackEumycetoma
Madurella griseaBrown – blackEumycetoma
Streptomyces somaliensisYellowActinomycetoma
Exophiala jeanselmeiBrown – blackEumycetoma
Scedosporium apiospermumWhite – YellowEumycetoma
Nocardia asteroidesWhite – YellowActinomycetoma
Nocardia brasiliensisWhite – YellowActinomycetoma
Staphylococcus aureusBotryomycosis

actinomycotic mycetoma - mycetoma - subcutaneous mycosis - mycoses - mycosis - fungal infection
ACTINOMYCOTIC MYCETOMA OF FOOT

⇒ Laboratory diagnosis of Mycetoma–

  • Diagnosis is made from examination of granules or grains. Granules are microcolonies of the causative agents.
  • The color and consistency of the granules vary with the different agents causing the disease.
  • In Actinomycotic mycetoma, the granules are composed of very thin (<1mm in diameter) filaments
  • In Mycotic lesions, granules are broader and often show septate and chlamydospores are present.

SPOROTRICHOSIS

Sporotrichosis is a chronic infection involving Subcutaneous and Lymphatic tissue, characterized by the formation of nodules and ulceration at the site of infection.

The infection is caused by thorn-pricks or some injuries.

It is more common in gardeners and farmers.

The causative agent of Sporotrichosis is a thermally dimorphic fungus Sporothrix schenckii.

⇒ Laboratory diagnosis of Sporotrichosis–

  • Specimens: the specimen collected in case of Sporotrichosis includes – aspirated fluid, Pus, Biopsy material, Skin scrapings, and Swabs.
  • Microscopy: the direct microscopic examination of KOH mounts of necrotic material or histopathological examination of tissue sections stained by Methenamine silver stain may yield a diagnosis. The characteristic feature is the asteroid body: a rounded or oval, basophilic yeast-like body 3-5 mm in diameter, with rays of an eosinophilic substance radiating from the yeast cell.
  • Culture: the fungus may not be demonstrable in pus or tissue, hence culture is done on media incubated at 25°C and 37° Sporothrix schenckii is a dimorphic fungus occurring in yeast phase in tissues and in the culture at 37°C and in mycelia phase in nature and culture at 25°C
  • Identification: In yeast phase, Sporothrix schenckii appears as cigar-shaped cells and mould form contains Hyphae carrying flower-like clusters of small conidia.



SAHIL BATRA

Hi, I'm the Founder and Developer of Paramedics World, a blog truly devoted to Paramedics. I am a Medical Lab Tech, a Web Developer and Bibliophiliac. My greatest hobby is to teach and motivate other peoples to do whatever they wanna do in life.

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