Complex Foot Infection Following Orthopedic Surgery: Bacterial, Fungal, or Drug Hypersensitivity?
Case at a Glance
A patient developed a progressive, spreading skin condition on the foot and lower leg following K-wire pin removal after surgical repair of a fifth toe fracture-dislocation. The condition evolved from initial localized erythema to extensive blistering, weeping dermatitis with systemic spread, complicated by elevated eosinophils and clinical uncertainty regarding bacterial infection versus drug hypersensitivity reaction.
Patient's Story
The patient presented with escalating skin symptoms beginning two months after sustaining a fifth toe fracture-dislocation that required surgical fixation with K-wire placement and six weeks of non-weight bearing status. Initial symptoms appeared as localized erythema and urticarial lesions at the surgical site following bandage removal. Over a two-week period, the condition rapidly progressed to involve extensive areas of the foot, ankle, and bilateral lower extremities with blistering, serous drainage, and systemic symptoms.
Initial Assessment
Upon pin removal, patient noted small erythematous patch with urticarial appearance initially attributed to adhesive irritation. Virtual consultation led to empirical treatment with trimethoprim-sulfamethoxazole for suspected cellulitis. Progressive worsening prompted urgent care evaluation, where bacterial etiology was maintained and antibiotic therapy continued despite patient concerns about alternative diagnoses.
The Diagnostic Journey
Day 1 (Pin removal): Localized erythema with urticarial lesions noted. Day 8: Virtual consultation, trimethoprim-sulfamethoxazole initiated for suspected cellulitis. Day 9: Worsening with faint erythematous spread to ipsilateral calf. Day 10: Urgent care visit showing significant progression with blistering and serous drainage; bacterial infection diagnosis maintained. Day 11: Emergency department presentation with purulent drainage and contralateral lower extremity involvement. Laboratory studies revealed elevated eosinophils and basophils suggesting possible drug hypersensitivity. Blood cultures obtained, single dose IV vancomycin administered, switched to doxycycline therapy.
Final Diagnosis
Working diagnosis of complex dermatitis with differential including: 1) Secondary bacterial infection (possible Staphylococcus species), 2) Drug hypersensitivity reaction (supported by elevated eosinophils/basophils), 3) Allergic contact dermatitis, 4) Mixed bacterial-allergic process. Consulting dermatologist suspected allergic contact dermatitis as primary etiology.
Treatment Plan
Initial empirical antibiotic therapy with trimethoprim-sulfamethoxazole, escalated to IV vancomycin followed by oral doxycycline 100mg twice daily. Topical antifungal therapy attempted empirically. Specialist consultation recommended high-potency topical corticosteroids or systemic corticosteroids for suspected allergic contact dermatitis component. Blood culture results pending to guide targeted antimicrobial therapy.
Outcome and Follow-up
Partial improvement noted with doxycycline therapy - some blister desiccation and mild erythema reduction observed. However, continued progression to new anatomical areas and persistent pruritus raised ongoing concerns about underlying allergic or hypersensitivity mechanism. Podiatry follow-up scheduled for comprehensive evaluation and potential tissue sampling for definitive diagnosis.