Which microorganism is the etiologic agent of ringworm?

Which microorganism is the etiologic agent of ringworm?

• A. Microsporum sp.
• B. Mycobacterium sp.
• C. Micrococcus sp.
• D. Moraxella sp.

Answer: (A)

Ringworm is a superficial fungal infection caused by dermatophytes that invade keratinized tissues like skin, hair, and nails. The fungi most commonly responsible belong to Microsporum, Trichophyton, and Epidermophyton; among these, Microsporum species are classic etiologic agents of ringworm, especially in animal-associated cases, so Microsporum sp. is the best answer. The other organisms listed are bacteria—Mycobacterium sp. are the bacteria that cause tuberculosis and related diseases, Micrococcus sp. are Gram-positive cocci, and Moraxella sp. are Gram-negative diplococci—and they do not cause ringworm.

Ringworm is a superficial fungal infection caused by dermatophytes that invade keratinized tissues like skin, hair, and nails. The fungi most commonly responsible belong to Microsporum, Trichophyton, and Epidermophyton; among these, Microsporum species are classic etiologic agents of ringworm, especially in animal-associated cases, so Microsporum sp. is the best answer. The other organisms listed are bacteria—Mycobacterium sp. are the bacteria that cause tuberculosis and related diseases, Micrococcus sp. are Gram-positive cocci, and Moraxella sp. are Gram-negative diplococci—and they do not cause ringworm.