Pittted keratolysis is a bacterial infection that causes stinky feet and whitish, macerated skin with pits or indentations. It occurs most often on the soles of your feet but can also affect the palms of your hands.
The bacteria that cause it grow in warm, moist environments like your feet. They break down keratin proteins in your skin, which creates small holes and produces the foul odor.
Causes
Pitted keratolysis is triggered by prolonged exposure to moisture. This occurs when shoes and socks trap sweat on the feet, allowing bacteria to thrive. The bacteria produce protease enzymes that destroy the top layer of skin, creating pits or craters. These are often accompanied by a foul odor, due to the sulfur compounds (thiols and thioesters) produced by the bacteria. This condition is most common in people who spend long hours on their feet and in warm climates. People with hyperhidrosis and those who wear occlusive footwear are also at increased risk of developing this infection.
Pittted keratolysis is usually easy to diagnose, thanks to its distinctive appearance and malodour. It is often found on pressure-bearing areas of the foot, but can occur on the palms as well. It can be seen in association with other Corynebacterium infections, such as erythrasma and trichomycosis axillaris.
The most important step to prevent pitted keratolysis is to ensure that the feet are kept clean and dry at all times. This includes taking off shoes and socks frequently, wearing breathable footwear and washing and drying the feet thoroughly after showering or bathing. It is also important to avoid the use of over-the-counter antifungal creams, as these are likely to make pitted keratolysis worse. Instead, consult with a podiatrist to discuss your symptoms and develop an effective treatment plan.
Symptoms
Pitted keratolysis occurs due to an overgrowth of bacteria, particularly Corynebacterium species, in warm and moist conditions. The bacteria produce proteases enzymes that break down the outer layers of skin, resulting in small holes or “craters” and an unpleasant odor. It usually affects the soles of the feet, but can also occur on the web spaces between toes and on the palms of hands. It is most common in individuals who sweat excessively, wear tight shoes and socks, or have poor immune systems. It is also more common in males, and patients with hyperhidrosis are at increased risk of developing the condition.
Symptoms are typically self-limiting, and the odor improves with treatment. Often, the infection clears up in one to eight weeks. However, patients with severe symptoms may need to continue clindamycin gel therapy for up to six weeks.
To prevent recurrence, practice good foot hygiene by washing your feet daily with antibacterial soap and drying them thoroughly. Wearing breathable footwear and rotating your shoes to allow each pair to air out can help reduce moisture buildup as well. A healthcare provider can perform a culture test or scrape a tiny sample of skin from the affected area to identify the bacteria and confirm your diagnosis. They can also assess your compliance with foot care and hyperhidrosis treatment to ensure that the infection doesn’t recur.
Diagnosis
Symptoms of pitted keratolysis include small indentations (pits) that resemble craters and an unpleasant odor. The odor is caused by bacteria that break down the outer layer of skin, called the stratum corneum, to release stinky sulfur compounds. The infection typically appears on the pressure points of your feet, such as the heels, toe pads, and balls. It may also affect the palms of your hands, but this is rare.
Corynebacterium species, including the types that cause pitted keratolysis, thrive in warm and humid conditions, especially in areas of your foot covered by shoes or socks that limit airflow. When the bacteria get into these areas, they produce protease enzymes that destroy layers of dead skin cells that continuously shed, resulting in the formation of pits. The pits then coalesce to form a whitish lesion on your skin. Pitted keratolysis is more common in men than women, and it tends to affect people who sweat excessively, wear tight shoes and socks, or work in occupations where the feet are often wet, such as rice paddy farmers.
If you have pitted keratolysis, your doctor will diagnose the condition by reviewing your medical history and performing a physical exam. Your doctor may also order a bacterial culture to find out which type of Corynebacterium is responsible for the infections in your foot. The bacterium that causes pitted keratolysis is not contagious, so you can’t infect other people.
Treatment
Pitted keratolysis is triggered by prolonged exposure of the skin to moisture and it is more common in people who live in tropical climates, work in wet environments or wear shoes that prevent their feet from breathing. It also is more prevalent in men than in women.
The bacterial infection that causes the condition is mainly caused by Corynebacterium species and some Streptomyces species. These are gram positive, diphtheroid bacteria that are normally present in the human skin flora. They cause the symptoms by producing an enzyme that destroys the top layer of skin on the top of the foot, called the stratum corneum or horney layer. This leads to a crater-like appearance with pits and an unpleasant odor.
It is important to diagnose pitted keratolysis because it can be mistaken for athlete’s foot, which is caused by a contagious fungal infection. Your doctor will examine your feet for the condition and may use a dermatoscope, which is a handheld tool that lets your doctor see a closer look at your skin.
Your doctor can recommend treatments that will help reduce the bacterium on your feet. These include antiseptic soaps and gels, such as clindamycin and erythromycin, and drying agents. Your doctor can also prescribe antifungal drugs if a fungus is causing the pitted keratolysis. The doctor may also suggest treatment for excessive sweating (hyperhidrosis) to help prevent the pitted keratolysis from recurring.