Pitted keratolysis is a common skin condition affecting the feet, characterized by small, crater-like indentations on the soles. Also known as keratolysis plantare sulcatum, it is harmless, though the “little holes” can be bothersome and cause discomfort.
What Causes These Little Holes?
Specific bacteria cause these pits. Common culprits include Corynebacterium species, Kytococcus sedentarius, Dermatophilus congolensis, Actinomyces, and Streptomyces. These microorganisms thrive in moist, warm environments on the feet.
Bacteria produce proteinase enzymes that break down keratin, the outer layer of skin, creating pits. They also generate sulfur compounds (thiols, sulfides, thioesters) which cause a foul odor.
Factors creating an ideal environment for these bacteria include: Excessive sweating (hyperhidrosis) increases foot moisture. Occlusive footwear, like tight shoes or boots, traps moisture and heat. Poor foot hygiene contributes to bacterial buildup.
Recognizing the Signs
Pitted keratolysis is most noticeable by small, shallow pits on the soles. These pits measure 1 to 3 millimeters and often appear clustered. Multiple pits may merge, forming larger, irregular lesions or grooves.
Pits are common on pressure-bearing areas like the heels and balls. They can also appear between the toes. Affected skin may appear whitish or macerated, and pits can become more pronounced or brownish when wet.
A strong, unpleasant odor is another symptom. This odor results from sulfur compounds produced by bacteria breaking down skin keratin. While often asymptomatic, some may experience mild itching or a burning sensation.
Effective Treatment Approaches
Treatment involves self-care and medical interventions. Keep feet clean and dry. Wash feet regularly, ideally twice daily, with antibacterial soap, drying thoroughly, especially between the toes.
Effective topical antibacterial medications include creams or solutions with clindamycin, erythromycin, fusidic acid, or mupirocin, which reduce skin bacteria. Over-the-counter benzoyl peroxide is also effective due to its antimicrobial properties. Apply treatments as directed to clear the infection.
For excessive sweating, antiperspirants with aluminum chloride can control foot moisture. If self-care and over-the-counter treatments fail or symptoms are severe, consult a healthcare professional. They can diagnose and prescribe stronger topical treatments or, in rare severe cases, oral antibiotics.
Preventing Future Occurrences
Preventing recurrence involves consistent foot hygiene and modifying daily habits. Maintain dry feet by regularly washing with antibacterial soap and thoroughly drying them.
Choose appropriate footwear. Opt for breathable materials like leather or canvas, avoiding tight, occlusive footwear that traps moisture. Rotating shoes daily allows each pair to air out and dry completely, preventing bacterial growth.
Wear moisture-wicking socks (cotton or wool) to draw sweat away. Change socks frequently, especially if damp, to reduce moisture. Apply foot powders or antiperspirants to manage sweat and create a less hospitable environment for bacteria. Wash socks at 60ºC to eliminate bacteria.