What is the antibiotic of choice for cellulitis with a diabetic foot ulcer?

From the Guidelines

For cellulitis with diabetic foot ulcer, empiric antibiotic therapy should include coverage for both gram-positive and gram-negative organisms, including MRSA, with a recommended regimen of amoxicillin-clavulanate 875/125 mg orally twice daily plus trimethoprim-sulfamethoxazole (TMP-SMX) DS 1-2 tablets twice daily for mild to moderate infections, as suggested by the most recent guidelines 1.

Key Considerations

• The choice of antibiotic regimen should be based on the likely or proven causative pathogen(s) and their antibiotic susceptibilities, the clinical severity of the infection, evidence of efficacy for DFI, and costs 1.
• For more severe infections requiring hospitalization, consider intravenous therapy with piperacillin-tazobactam 4.5g every 6-8 hours or ertapenem 1g daily, plus vancomycin dosed by weight (15-20 mg/kg every 12 hours) 1.
• Treatment duration typically ranges from 7-14 days depending on clinical response, with longer courses sometimes needed for deeper infections 1.
• Antibiotic selection should be adjusted based on culture results when available, and proper wound care is essential, including debridement of necrotic tissue, offloading pressure from the ulcer, and optimizing glycemic control 1.

Additional Recommendations

• Regular wound assessment and consideration of osteomyelitis (which would require longer treatment) are important, and infectious disease consultation is recommended for severe or complicated infections, especially those with osteomyelitis or in patients with multiple antibiotic allergies 1.
• The goal is to avoid the presence of colonisers in the sample, thereby limiting the risk of unjustifiably prescribing broad-spectrum antibiotic agents, and clinicians should consider consulting infectious diseases/microbiology expert about antibiotic therapy for difficult cases 1.

From the FDA Drug Label

1. 3 Skin and Skin Structure Infections Piperacillin and Tazobactam for Injection is indicated in adults for the treatment of uncomplicated and complicated skin and skin structure infections, including cellulitis, cutaneous abscesses and ischemic/diabetic foot infections caused by beta-lactamase producing isolates of Staphylococcus aureus.

Piperacillin-tazobactam is an appropriate antibiotic choice for the treatment of cellulitis with diabetic foot ulcer in adults, as it is indicated for the treatment of complicated skin and skin structure infections, including ischemic/diabetic foot infections caused by beta-lactamase producing isolates of Staphylococcus aureus 2.

From the Research

Antibiotic Choice for Cellulitis with Diabetic Foot Ulcer

• The choice of antibiotic for the treatment of cellulitis with diabetic foot ulcer is crucial for effective management of the infection.
• According to a study published in 2005 3, piperacillin/tazobactam and ampicillin/sulbactam are both effective in treating moderate to severe diabetic foot infections, with clinical efficacy rates of 81% and 83.1%, respectively.
• Another study from 1998 4 found that piperacillin/tazobactam may be useful as monotherapy in diabetic foot infection, with 22 out of 23 patients showing improvement or clinical cure.

Comparison of Antibiotic Regimens

• A prospective, randomized clinical trial published in 2010 5 compared the efficacy and safety of piperacillin/tazobactam and imipenem/cilastatin for severe diabetic foot infections, and found that piperacillin/tazobactam produced a better clinical response rate, although the results did not reach statistical significance.
• A review of randomized controlled trials published in 2017 6 concluded that piperacillin/tazobactam is the drug of choice for the treatment of complicated skin and soft tissue infections, including diabetic foot ulcers, due to its broad antibiotic spectrum and clinical efficacy.

Considerations for Antibiotic Selection

• The selection of antibiotic should be based on the severity of the infection, the presence of osteomyelitis, and the susceptibility of the causative organisms to the antibiotic.
• According to the study published in 2005 3, piperacillin/tazobactam has the advantage of covering Pseudomonas aeruginosa, a common gram-negative pathogen in diabetic foot infections.
• The study published in 2017 6 recommends de-escalating antibiotic therapy as soon as the causative organisms are identified and their drug-sensitivity results are available, to minimize the risk of resistant bacteria.