SUBCUTANEOUS MYCOSES - RHINOSPORIDOSIS - FUNGAL INFECTION - SKIN HAIR NAILS

SUBCUTANEOUS MYCOSES

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

⇒ 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 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: 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 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 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.



Leave a Reply

Your email address will not be published. Required fields are marked *

Scroll to top
0 Shares
Share
Pin
Tweet
+1
Share
Stumble