Duration of Ancef (Cefazolin) for MSSA Foot Infection
For an MSSA foot infection without bone involvement, treat with cefazolin for 1-2 weeks, extending only if clinical signs of infection have not resolved by that time. 1
Treatment Duration Based on Infection Severity
Soft Tissue Infection Only (No Osteomyelitis)
- 1-2 weeks of antibiotic therapy is sufficient for most mild to moderate diabetic foot infections 1
- Extend treatment by an additional 1-2 weeks only if the infection has not adequately improved within the initial treatment period 1
- Discontinue antibiotics once clinical signs and symptoms of infection have resolved—do not continue therapy until wound healing is complete 1
If Osteomyelitis is Present
- Minimum 4-6 weeks of therapy is required for bone involvement 1
- Shorter duration is acceptable if all infected bone is surgically removed 1
- Longer duration may be needed if infected bone remains after debridement 1
Key Clinical Principles
Avoid Fixed-Duration Prescribing
The 2012 IDSA diabetic foot infection guidelines explicitly warn against routinely prescribing antibiotics for a predetermined fixed duration, as this often results in unnecessarily prolonged courses that increase costs, adverse events, and antibiotic resistance 1
Clinical Response Should Guide Duration
- Base treatment duration on resolution of infection signs (erythema, warmth, purulence, pain) rather than wound closure 1
- There is no evidence supporting continuation of antibiotics until wound healing to accelerate closure or prevent subsequent infection 1
For Non-Diabetic Cellulitis
If this is a simple cellulitis rather than a diabetic foot infection, the 2014 IDSA skin and soft tissue infection guidelines recommend 5 days of antimicrobial therapy, extending only if the infection has not improved within this timeframe 1
Important Caveats
Ensure Adequate Source Control
- Surgical debridement of necrotic tissue and drainage of abscesses is crucial for treatment success 1
- Off-loading pressure from the affected foot is essential 1
- Address underlying vascular insufficiency if present 1
Cefazolin is Appropriate for MSSA
Cefazolin (or nafcillin/oxacillin) represents first-line therapy for proven MSSA infections and demonstrates superior outcomes compared to vancomycin 2, 3