Module 13: Intro to Dermatophytes

Module 13.3: Three Most Common Veterinary Dermatophytes Observed on DTM

The three most common veterinary dermatophytes observed on DTM

In the laboratory you will be asked to identify the 3 most common dermatophytes commonly cultured on DTM; Microsporum canis, Microsporum gypseum, and a Trichophyton sp. Below are descriptions and images of those fungi.

Microsporum canis

The macroconidia are multicellular (5-15 cells), spindle-shaped with rough, thick-walled.  The macroconidia have a terminal knob.  They produce fewer macroconidia than M. gypseum.

Microsporum canis
Microsporum canis

Microsporum gypseum

The macroconidia are numerous, multicellular (4-6 cells), symmetrical, ellipsoidal, with thin walls.  The ends of the macroconidia differ in shape.  The distal end is rounded where the proximal end can be truncated from where it attached to hyphae.

Microsporum gypseum
Microsporum gypseum

Trichophyton sp.

The microconidia are single-celled, spherical in shape, and numerous.  The macroconidia are cigar-shaped, multicellular (2-5 cells), thin-walled, and are rarely seen. These can be differentiated from M. canis as they have 6 compartments formed by the septae.

Trichophyton sp.
Trichophyton sp.

Knowledge check


Key Takeaways

  • Dermatophytes are common cutaneous fungal pathogens in all species
  • Microsporum and Trichophyton are the 2 most common genera in veterinary medicine
  • On DTM, the dermatophyte fungal colonies are buff in color and accompany a color change to red on the agar
  • Saphyrophytic or contaminant fungi will grow on DTM, but do not routinely cause a color change and the colonies are not buff
  • Microscopic evaluation of the colonies is an important step in the diagnosis and may influence the control steps based on the species of dermatophyte observed (i.e. geophilic vs. zoophilic)
You have now reached the end of Module 13. If you are enrolled in CVM 6925, please go to the Canvas page and take the quiz: “Module 13: Dermatophyte quiz.” There is an assignment that accompanies the in-person laboratory for this module.

License

Share This Book