Small, crater-like depressions appearing on the soles of the feet after water exposure are the characteristic sign of Pitted Keratolysis (PK). This condition is a superficial bacterial skin infection affecting the outermost layer of the skin. PK is generally considered non-serious and is treatable, developing due to an overgrowth of bacteria thriving in moist conditions.
Identifying Pitted Keratolysis
The most noticeable sign of this condition is the presence of numerous circular, “punched-out” pits on the soles of the feet. These small depressions typically range in size from 1 to 3 millimeters. They often cluster together, especially on the weight-bearing areas like the heels and the balls of the feet. The pits become significantly more pronounced and visible when the affected skin is wet or waterlogged.
The skin may also appear white or somewhat wrinkled due to the saturation of the outer layer. A strong, foul odor, known as bromodosis, is almost universally associated with pitted keratolysis and is often the primary reason people seek treatment. While the condition is frequently asymptomatic, some individuals report mild irritation, itching, or a burning sensation when walking.
The Bacterial Cause of Foot Pitting
Pitted keratolysis is caused by an infection involving specific types of bacteria, primarily species from the Corynebacterium family. Other bacteria involved include Kytococcus sedentarius and Dermatophilus congolensis. These bacteria flourish in environments that are warm, dark, and excessively moist, such as feet enclosed in non-breathable footwear for long periods. Excessive sweating, known as hyperhidrosis, is a significant factor that contributes to the necessary high-moisture environment.
The bacteria produce proteinase enzymes that actively break down the keratin found in the stratum corneum, the tough, outermost layer of the skin. This dissolution of the skin’s surface layer creates the characteristic microscopic tunnels and pits. The strong, unpleasant smell results from the bacteria metabolizing sulfur compounds on the foot, producing volatile by-products like thiols and sulfides.
Addressing the Current Infection
Treatment for an active case of Pitted Keratolysis focuses on eliminating the bacterial overgrowth and reducing the foot’s moisture level. Healthcare providers commonly prescribe topical antibiotics, which are applied directly to the affected areas of the feet. Effective options include solutions or gels containing clindamycin, erythromycin, or mupirocin.
The standard regimen usually involves applying the topical medication twice daily for a period of two to three weeks until the infection clears. Dermatologists also recommend using drying agents to reduce the moisture that supports the bacteria. Antiperspirants containing aluminum chloride are particularly helpful, as they reduce the excessive sweating that provides the bacteria with their ideal habitat. In rare instances of severe or resistant infection, a short course of oral antibiotics may be considered.
Preventing Recurrence
After the active infection has been treated, long-term management focuses on maintaining a dry foot environment to prevent the bacteria from returning. Strict attention to foot hygiene is important, which includes washing the feet daily and ensuring they are thoroughly dried afterward, paying close attention to the spaces between the toes.
Wearing socks made of moisture-wicking materials like synthetic blends or wool can help pull sweat away from the skin, and they should be changed immediately if they become damp. It is helpful to avoid wearing occlusive footwear, such as rubber boots, for extended periods. Rotating shoes is also a highly effective practice, allowing each pair twenty-four hours to completely air out and dry before being worn again. Prophylactic measures include the regular use of foot powders or over-the-counter antiperspirants on the soles to keep the skin dry and inhospitable to the moisture-loving bacteria.