Working Diagnosis:
Ruptured friction blister complicated by methicillin resistant Staphylococcus aureus cellulitis which progressed to osteomyelitis by contiguous spread to the talus, navicular, cuboid, and calcaneus

Treatment:
Surgical debridement, wound vacuum-assisted closure, intravenous clindamycin and vancomycin was initiated empirically until methicillin resistant Staphylococcus aureus was cultured from surgical debridement. Ultimately, patient was discharged on 6-weeks of oral trimethoprim/sulfamethoxazole based on microbial sensitivities with close Orthopedics, Infectious Disease, and Physical Therapy follow up for wound care.

Outcome:
Patient completed a 6-week course of trimethoprim/sulfamethoxazole . He was followed by Orthopedics, Infectious Disease, and wound care. Through 6 weeks of physical therapy, he transitioned from ambulating with crutches to ambulating without an assistive device. He followed a prescribed return to play protocol for football and wrestling before returning to full participation in sports activities.

Author's Comments:
A friction blister can progress to skin infection, soft tissue infection, or osteomyelitis in athletes. Careful consideration should be given to proper gear fit, especially shoes, where skin thickness, vigorous activity, and heavy load bearing increases risk of friction injury. Complications of secondarily infected friction blisters are serious. Any increasing redness, worsening pain, or purulent drainage warrants further evaluation. Patients with clinical signs of infection should receive appropriate antibiotic therapy. If there is no improvement, a resistant organism should be suspected.

Editor's Comments:
Friction blisters are a common finding among athletes and may be seen in many as 74% of athletes. Mechanical forces cause a shearing between the stratum corneum of the epidermis and the underlying dermal stratum spinosum with accumulation of serous or serosanguinous fluid. Friction blisters occur more commonly in areas with thicker stratum corneum such as the hands and feet, higher moisture, and higher skin-textile forces of certain fabrics. Treatment of uncomplicated friction blisters include coverage, padding, as well as keeping the area clean and moist to help facilitate healing. In the event of a painful blister, evacuation of fluid via sterile techniques may be utilized for patient comfort. Deroofing the overlying stratum corneum is not recommended as it confers an increased risk of infection. Systemic antimicrobial treatment is recommended in the event of purulent drainage, erythematous streaking, lymphangitis, and fever. Empiric treatment should include coverage for the most implicated organism, Streptococcus, and my include coverage for Staphylococcus aureus. In patients with history of infection with methicillin-resistant Staphylococcus aureus or colonization, antimicrobial coverage should be expanded. Osteomyelitis commonly occurs in the lower extremity, second to the axial spine and may be spread by local or hematogenous route. Staphylococcal aureus is the most common causative bacteria. Empiric treatment is intravenous broad-spectrum antimicrobials with culture-directed treatment thereafter for at least 6 weeks. Initial X-ray is often normal, so clinical suspicion must remain high in patients with pain, erythema, and swelling. In acute osteomyelitis, pain radiography may show periosteal reaction, osseous lucency, and soft tissue swelling. Magnetic resonance imaging is largely seen as the gold standard imaging study for diagnosis. Delayed treatment often results in significant morbidity and early diagnosis and treatment remains paramount for optimal clinical outcomes.

References:
Brennan Fred H Jr DO Treatment and Prevention of Foot Friction Blisters ACSM Health and Fitness Journal
Volume 17 Issue 6 2013

ChicharroLuna et al Prevalence and risk factors associated with the formation of dermal lesions on the foot during hiking
Journal of Tissue Viability Volume 29 Issue 3 2020

DSouza et al A Brief Review on Factors Affecting the Tribological Interaction between Human Skin and Different Textile Materials
Materials Volume 15 2022

Knapik JJ Reynolds KL Duplantis KL et al Friction Blisters
Sports Medicine Volume 20 1995

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