Final answer:
The most common organism causing tinea pedis or athlete's foot is the fungus Trichophyton rubrum, which is a dermatophyte thriving in moist conditions.
Step-by-step explanation:
The most common organism in tinea pedis, commonly known as athlete's foot, is the fungus Trichophyton rubrum. Dermatophytes such as Trichophyton rubrum are a type of fungal molds that thrive on keratin found in skin, hair, and nails, especially in moist conditions.
Tinea pedis often occurs on the feet, leading to symptoms such as itching, burning, and cracked skin between the toes. This type of infection is particularly common in environments like public showers and can proliferate in dark, moist areas like sweaty shoes and socks.
The identification of dermatophytes like Trichophyton rubrum is typically confirmed through culturing, using a medium such as Sabouraud dextrose CC agar plate where the fungus can grow and be visually identified.