Microsporum

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Microsporum

• Colonies of M. canis are often cottony or
  wooly and usually is lemon-yellow around the
  growing periphery or the underside of the colony
• Colonies of M. gypseum are off-yellow, tan, or
  cinnamon in color and have the chalky texture of
  gypsum

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M. canis Colony on SDA
Front
Back
3
M. gypseum Colony on SDA
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Microsporum

• Colonies of M. audouini are cream to light tan
  with very short aerial hyphae
• The fact that M. audouini grows very poorly on
  non-fortified rice grains whereas most other
  Microsporum species grow well on this medium is
  a good point of differentiation

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M. audouinii Colony on SDA
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Growth Comparison on Sterile Polished Rice Grain
M. audouinii
Other Microsporum sp.
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Microsporum

• Microscopically Microsporum species usually
  produce abundant macroconidia that are
• Echinulate
• Fusiform
• Thick-walled
• Multiseptate (as Macroconidia are)

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Microsporum

• Microscopic
• The production of microconidia is variable
• Most species produce a few to moderate pyriform
  to globose microconidia arranged along the hyphae
  (en thyrse birds on a fence)

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Typical Conidia of Microsporum
Microconidia?
M. canis
M. gypseum
M. namum
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Microsporum

• Most isolates of Microsporum audouinii fail to
  produce macroconidia or microconidia
• These isolates must be identified on clinical
  grounds and in vitro growth characteristics (e.g.
  colony morphology and failure to grow on sterile
  polished rice grains)