What is the best oral antibiotic for cellulitis on a diabetic foot?

From the Guidelines

For diabetic foot cellulitis, the best oral antibiotic is typically amoxicillin-clavulanate (Augmentin) at a dose of 875/125 mg twice daily for 7-14 days. This recommendation is based on the most recent and highest quality study available, which suggests that amoxicillin-clavulanate provides adequate coverage against the most common pathogens involved in diabetic foot infections, including Staphylococcus aureus and Streptococcus species, as well as some gram-negative and anaerobic bacteria 1.

Key Considerations

• The choice of antibiotic should be based on the severity of the infection, the likely causative pathogens, and their antibiotic susceptibilities 1.
• A course of antibiotic therapy of 1–2 weeks is usually adequate for most soft tissue diabetic foot infections (DFIs) 1.
• For patients with penicillin allergies, alternatives include clindamycin (300-450 mg four times daily) or trimethoprim-sulfamethoxazole (1-2 double-strength tablets twice daily) plus metronidazole (500 mg three times daily) to ensure anaerobic coverage.
• Moderate to severe infections, deep infections, or those with signs of systemic illness may require intravenous antibiotics or hospitalization.

Adjunctive Measures

• Regular wound care, offloading pressure from the affected area, and tight glucose control are essential adjunctive measures.
• Patients should seek immediate medical attention if the infection worsens, spreads, or if they develop fever, increasing pain, or drainage from the wound, as diabetic foot infections can progress rapidly and potentially lead to serious complications including osteomyelitis or need for amputation.

Evidence Summary

The Infectious Diseases Society of America (IDSA) and the International Working Group on the Diabetic Foot (IWGDF) provide guidelines for the diagnosis and treatment of diabetic foot infections, emphasizing the importance of selecting antibiotic regimens based on the severity of the infection and the likely causative pathogens 1. The guidelines also stress the need for adjunctive measures such as wound care and glucose control to optimize outcomes.

From the FDA Drug Label

Clindamycin is indicated in the treatment of serious infections caused by susceptible anaerobic bacteria. Clindamycin is also indicated in the treatment of serious infections due to susceptible strains of streptococci, pneumococci, and staphylocci... Serious skin and soft tissue infections. The best oral antibiotic for cellulitis on a diabetic foot is clindamycin (PO), as it is indicated for the treatment of serious skin and soft tissue infections, including those caused by streptococci and staphylococci, which are common pathogens in diabetic foot infections 2.

• Key points:
  • Clindamycin is effective against a range of bacteria that can cause skin and soft tissue infections.
  • It should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria.
  • Bacteriologic studies should be performed to determine the causative organisms and their susceptibility to clindamycin.

From the Research

Oral Antibiotics for Cellulitis on Diabetic Foot

• The choice of oral antibiotic for cellulitis on a diabetic foot depends on several factors, including the severity of the infection, the presence of aerobic Gram-positive cocci, and the risk of methicillin-resistant Staphylococcus aureus (MRSA) 3.
• For mild or moderate infections, oral therapy is adequate, while severe infections require parenteral therapy 3.
• Amoxicillin-clavulanate is a commonly used oral antibiotic for diabetic foot infections, including those caused by aerobic Gram-positive and Gram-negative bacteria, as well as anaerobes 4, 5, 6.
• The use of antibiotics should be guided by clinical clues, such as the presence of cellulitis, abscess, or osteomyelitis, and should be targeted at the most likely pathogens 3, 7.
• It is essential to note that antibiotics are not effective in healing wounds, but rather in treating infection, and their use should be judicious to avoid promoting antibiotic resistance 7.

Specific Oral Antibiotics

• Amoxicillin-clavulanate has been shown to be effective in treating diabetic foot infections, including those caused by Staphylococcus aureus and other aerobic Gram-positive and Gram-negative bacteria 4, 5, 6.
• Ciprofloxacin has also been used in combination with amoxicillin-clavulanate to treat diabetic foot infections, including those caused by Raoultella ornithinolytica 5.
• The choice of oral antibiotic should be based on the severity of the infection, the presence of underlying conditions, and the susceptibility of the causative pathogens 3, 7.

Treatment Duration and Dosage

• The duration of treatment with oral antibiotics for diabetic foot infections can vary, but typically ranges from 7 to 14 days 5.
• The dosage of oral antibiotics should be individualized based on the patient's renal function, the severity of the infection, and the susceptibility of the causative pathogens 6.
• Optimization of amoxicillin-clavulanate therapy based on pharmacokinetic/pharmacodynamic parameters can enhance the antimicrobial effect and improve treatment outcomes 6.