Trichophyton rubrum is a fungus that colonizes the outer layers of dead skin and is a frequent cause of common skin infections. This organism is a dermatophyte, meaning it requires the protein keratin for growth. Keratin is a primary component of skin, hair, and nails, which is why these areas are most affected by the fungus. T. rubrum is classified as an anthropophilic fungus because it primarily infects and spreads among humans, making it one of the most widespread causes of fungal infections globally.
Common Infections Caused by Trichophyton Rubrum
Trichophyton rubrum is responsible for a variety of fungal infections, which are generally superficial. The specific names of the infections often relate to the part of the body affected.
- Tinea pedis (athlete’s foot): This condition begins with itching, stinging, and burning between the toes or on the soles of the feet. It can also present as chronic dryness and scaling on the soles in a “moccasin” pattern. The skin may crack, peel, or blister in affected areas.
- Tinea cruris (jock itch): Affecting the groin and inner thighs, this infection results in an itchy, red, and often ring-shaped rash. The rash may have a border that is slightly raised and more distinctly red. While more common in men, it can affect anyone, particularly in warm, humid conditions.
- Tinea corporis (ringworm): This can appear nearly anywhere on the body, including the arms, legs, and trunk. It is characterized by a circular rash that is red and itchy, with a raised, scaly border that resembles a worm. The center of the rash may appear clear or have less scaling.
- Onychomycosis: When the fungus infects the nails, the condition is called onychomycosis. This infection causes the nails to become thick, brittle, and discolored, often turning yellow or white. The nail may also become distorted in shape and can separate from the nail bed.
How The Fungus Spreads
Trichophyton rubrum is primarily transmitted from one person to another through direct, skin-to-skin contact with an individual who has an active infection. The fungus also spreads indirectly through contact with contaminated surfaces like public shower floors, locker room benches, and pool decks. Shared personal items such as towels, bedding, and clothing can harbor the fungus.
Certain factors increase susceptibility to a T. rubrum infection. Excessive sweating creates a moist environment where the fungus can thrive, and wearing tight footwear that traps moisture contributes to athlete’s foot. Minor injuries to the skin or nails can provide an entry point for the fungus, and individuals with weakened immune systems are more vulnerable.
Diagnosis and Treatment Options
A healthcare provider begins the diagnostic process with a visual examination of the affected skin or nails. To confirm a fungal infection, a skin scraping or nail clipping may be taken. This sample is then examined under a microscope in a potassium hydroxide (KOH) test to reveal fungal elements. A fungal culture may also be performed to identify the specific species, though this can take several weeks for results.
Treatment for T. rubrum infections depends on the location and severity. For most skin infections like athlete’s foot and ringworm, topical antifungal creams, lotions, or powders are effective. These products, containing active ingredients such as clotrimazole or terbinafine, are available over-the-counter or by prescription.
For more widespread skin infections or for fungal infections of the nails, oral antifungal medications are necessary. Oral medications such as terbinafine and itraconazole are prescribed to eliminate the fungus systemically.
It is important to complete the full course of treatment as prescribed, even if symptoms improve. Stopping treatment early can result in the infection not being fully eradicated, leading to recurrence. For nail infections, treatment can be lengthy, sometimes requiring several months of medication.
Prevention Strategies
Keeping the skin clean and dry is a fundamental step in preventing fungal infections. This is particularly important in areas prone to moisture, such as the feet and groin. Thoroughly drying the skin after bathing or swimming creates an environment less hospitable to fungal growth.
Choosing appropriate clothing and footwear is also important. Wearing breathable footwear and socks made of moisture-wicking materials helps keep the feet dry. In hot weather, loose-fitting clothing can help reduce sweating and moisture buildup.
To avoid contact with the fungus, wear protective footwear like sandals in communal areas such as locker rooms and public showers. This creates a barrier between your feet and potentially contaminated surfaces.
Avoiding the sharing of personal items is another preventive measure. Items such as towels, clothing, and nail care tools can harbor fungal spores. Promptly treating any existing fungal infection prevents it from spreading.