Question

A patient presents with itching in the axilla. On microscopic examination of the skin scrapings, a red pigment-producing fungus with pencil – shaped macroconidia is seen. Which of the following is the most likely organism?

• A. Trichophyton violaceum
• B. Trichophyton rubrum
• C. Trichophyton tonsurans
• D. Trichophyton schoenleinii

Answer 1

The Correct Option is B

To determine the organism responsible for the symptoms described, we need to analyze the key characteristics mentioned in the problem:

• Location: Itching in the axilla (armpit) suggests a superficial fungal infection, commonly caused by dermatophytes.
• Microscopic findings: A red pigment-producing fungus with pencil-shaped macroconidia.

Now, let's compare these features against the given options:

1. Trichophyton violaceum: Known for black or violet colonies, lacking the red pigment.
2. Trichophyton rubrum: Produces a distinctive red pigment and is a common dermatophyte. It also produces alopecia (hair loss) lesions, often with pencil-shaped macroconidia.
3. Trichophyton tonsurans: Usually infects hair, forms microconidia predominantly, and does not typically produce a red pigment.
4. Trichophyton schoenleinii: Associated with favus, a complex scalp infection, and does not produce red pigment.

The distinctive characteristics of Trichophyton rubrum, especially its ability to produce red pigment and pencil-shaped macroconidia, directly match the description.

Conclusion: The most likely organism causing the symptoms is Trichophyton rubrum.