Randomized Study Comparing Different Durations of Antibiotic Treatment for Diabetic Foot Infections

Diabetic foot infections (DFI) are frequent and are associated with a high burden of morbidity, costs, recurrence risk or new episodes of infections. About two-third of recurrent DFI may reveal other microorganisms than in the previous period, suggesting new episodes of infection due to the underlying problem, and/or selection by prior antimicrobial therapy. Osteomyelitis in the diabetic toe is almost always established by contiguous spread of infection from a chronic ulcer. It occurs in up to 15% of patients with a diabetic foot ulcer and about 20% of all DFI (and over half of severe infections) involve bone at presentation. The severity of a diabetic foot infection is based on the local and systemic signs and symptoms of infection and has been categorically defined in the Infectious Disease Society of America guidelines for the "Diagnosis and Treatment of Diabetic Foot Infections" (IDSA guidelines).

Knowing the potential for poor outcomes, many clinicians have tended to treat DFIs with a long duration of antibiotic therapy, with many side effects, development and spreading of antibiotic resistance, and associated costs. Data from recent comparative trials has shown that 1-2 weeks is sufficient for most soft tissue infections, and 4 to 6 weeks appears adequate in those with (unresected) infected bone. Retrospective reviews over the past two decades have demonstrated that about two-thirds of selected patients with diabetic foot osteomyelitis can achieve remission with antibiotic therapy alone (i.e., without bone resection). One recent randomized trial found that treatment with only antibiotic therapy (given for 90 days) gave similar clinical outcomes to treatment with conservative surgery (removal only of the infected bone) along with just a short course of antibiotic therapy. Another randomized trial compared a 6-week against 12-week course of antibiotic therapy, without concomitant surgery, for diabetic foot osteomyelitis and also found similar outcomes.

Likewise, the optimal antibiotic duration for any skin and soft tissue infection is unknown. According to some databases of University of Geneva Hospitals, among 378 skin and soft tissue infections in 346, overall cure was achieved in 330 episodes (87%) after a median antibiotic administration of 15 days. In multivariate Cox regression analysis, duration of antibiotic therapy (HR 1.0, 95%CI 0.96-1.02) did not influence treatment failure among patients with positive MRSA carriage.

Our study intends to optimize the duration of antibiotic therapy in DFI; for skin and soft tissue infections as well as for diabetic toe osteomyelitis that is not amputated.