Dimorphic Fungi

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Basics

  • All dimorphic fungi initially cause infection via inhalation except Sporothrix schenckii which goes via skin

Bugs

Sporothrix schenckii

  • usually hands, forearms REMEMBER THIS ONE
  • Causes ropey lymphadenopathy, especially inside of forearm
  • Diagnosis without culture can be made if someone has 1-2 lesions like so with an history of gardening (especially if old rose bushes)
  • General practitioners see these not uncommonly
  • The spore is hardier and gets through a different route.

Coccidiodes immitis

  • Most infectious and invasive of ALL FUNGI!
  • Causes San Joaquin Valley Fever (SVF)
  • It is a kind of yeast form (arthroconidia)
  • blown around in desert winds
  • In Phoenix, many San Joaquin Valley Fever (SVF) cases seen after a windy weekend.
  • Don't need many to get infected
  • San Joaquin Valley Fever (SVF) - Endemic in the U.S., found in Africa and prevalent in Southwestern Ontario, especially London
  • Usually thrown off by immunocompetent people
  • Therefore, usually asymptomatic in most of the population.

Diagnosis

  • Immunodiffusion concept
  • take bio fluid for analysis with antigen in it
  • carefully overlay plates with fluid that can contain antibodies
  • find the optimal concentration at which they form immune complexes

Diseases

Histoplasmosis

  • endemic in Mississippi, Ohio, and the Great Lakes basin
  • Resembles TB lesions (important note)

Resources

  • Dimorphic fungi handout (DOC | PDF)