Tinea is a fancy name for fungus. There have been shown to be more than
80 different strains of fungus on the average person's foot with the highest concentrations being on the heel. These fungi live in a balance that isn't a problem until that balance is disturbed. People at risk for fungal infections include those with:
- Compromised immune systems (HIV, Diabetes, Oral Steroid use)
- Advanced age
- History of trauma to the toenail.
- Poor blood flow in their toes.
- Frequent use public/locker room showers (thus the term athlete's foot).
- Poor pedal hygiene (improved hygiene has even shown to cure 35% of existing fungal skin infections).
- Genetically prone.
ANATOMY INVOLVED
While tinea can get into the blood and cause systemic infections it most commonly affects the most superficial layer of skin, the epidermis, and the nail plates. The areas that are most resistant to treatment are the plantar foot and the nail plates due to the high amount of keratin which makes it difficult for topical medications to penetrate the structure.
THE EXAM AND DIAGNOSIS
Signs of a fungal infection of the skin, also known as athlete's foot or tinea pedia can include:
- redness (erythema)
- itchiness (pruritus)
- foul odor
- macerated (white over-hydrated skin) or hyperkaratotic (dry callused skin) scaling
- fissures (cracking)
They present in three main patterns; interdigital, moccasin, and vestibulobullous(fluid filled blisters). Interdigital infections are usually more macerated while the moccasin pattern in more hyperkaratotic.
Research has shown that the most common fungal strains resulting in tinea pedis are
Trichophyton rubrum and
Trichophyton mentagrophytes (more aggressive strain).
T. mentagrophytes has been shown to be more common in the younger healthier individual.
Signs of a fungal infection of the toenails, also known as onychomycosis, include:
- nail discoloration; yellow, orange or brown patches or streaks.
- nail detachment from nail bed (onycholysis).
- subungual (under the nail plate) debris.
- nail thickening
- nail crumbling
The "gold standard" method for diagnosis of pedal fungal infections is microscopic examination of skin subungual (skin under the nail plate) scrapings prepared in potassium hydroxide (KOH). The examiner can see hyphae. Today's podiatrists send these scrapings to a lab where they are read in a lab.
TREATMENT
Treatments for fungal infections include topical powders and creams for less severe infections and oral medications for more sever or resistant infections. Due to the resistive nature of onychomycosis (toenail fungus) the most effective treatments are oral medications. The downside of oral antimicrobial medications are that many have been shown to cause liver damage to a very small percentage of individuals. The internet is full of many home remedies and other remedies for treatment of toenail fungus (Vick's Vapor Rub, Colloidal Silver, Tea Tree Oil....). Due to the high number of these types of treatments and the low level of effectiveness I am not going to discuss all of them. The below list of medications that have been proven with varying degrees of effectiveness which I have put in order of effectiveness.
Topical Treatments:
- 2% Miconazole Nitrate Powder - Available Over the Counter
- 1% Clotrimazole Cream- Available Over the Counter
- 1% Clotrimazole Solution (better penetration into nail plate).
- 1% Terbinafine Cream (Lamisil)
- 1% Terbinafine Gel
- 0.77% Ciclopirox Cream/Gel
- 8% Ciclopirox Solution (Penlac Nail Lacquer)
- 20% Urea Cream*
- 40% Urea Cream*
- Salycilic Acid*
*can be used with topical medications to soften the nail plate and callused skin improving penetration of medication.
Oral Medications:
- 250mg Terbinafine (Lamisil); liver enzymes from a blood test are also monitored while this medication is given to ensure that there is not irreparable damage occurring.
Other Treatment Options
- Cleaning feet daily has shown to cure about 35% of cases.
- Laser Treatment (for onychomycosis) is available and is very expensive. Its efficacy is still being investigated.
- Toenail Avulsion (removal of toenail). In sever cases the complete removal either permanently or temporarily, is always an option. This options will prevent spread to other toes and is a sure cure. Toenails serve no real purpose beyond their aesthetic appeal.
PREVENTION
The best option is to take proper precautions to prevent fungal infections from getting out of control in the first place. Most toenail infections begin as athlete's foot that has been neglected and the fungus gets into the nail. Once in the nail it is extremely difficult to cure and the fungus can damage the cells that cause the nail to grow making the nail thick and disfigured. Once a nail has become thick and disfigured the chances of being able to return to nail to its appearance prior to the infection if very low. Here are some suggestions as for prevention:
- Wash your feet daily with soap. Fungal spores are EVERYWHERE and washing them will decrease the amount on your feet and will remove the dirt and grim that harbors colonies.
- Alternate shoes to allow them to dry out. The environment in your shoes (moist, dark, warm) is prefect for fungus to thrive so allowing your shoes to dry out will inhibit growth.
- Wear well ventilated shoes, synthetic socks and use shoe powders occasionally to keep feet dry.
- Treat fungal skin infections early on to prevent them from getting out of control and into the tissue that is more difficult to get to with medication like callused skin and toenails.
- Avoid going barefoot in public area such as showers and pools. Fungal spores and live on for months to years.
Hsu AR, Hsu J. Topical Review: Skin Infections in the Foot and Ankle Patient. Foot & Ankle International. 33(7):612-619, 2012
