What is the best antibiotic therapy for a 66-year-old female with type 2 diabetes, peripheral neuropathy, and a foot ulcer presenting with induration, purulent (Parlin) drainage, erythema, and no visible bone?

From the Guidelines

For a 66-year-old female with type 2 diabetes, peripheral neuropathy, and a foot ulcer showing signs of infection, the recommended antibiotic therapy would be a broad-spectrum regimen targeting both gram-positive and gram-negative organisms, with amoxicillin-clavulanate 875/125 mg orally twice daily for 7-14 days being a suitable initial empiric treatment. This recommendation is based on the guidelines provided by the Infectious Diseases Society of America and the International Working Group on the Diabetic Foot, which emphasize the importance of selecting an empiric antibiotic regimen based on the severity of the infection and the likely etiologic agent(s) 1.

The patient's infection appears to be a moderate diabetic foot infection, requiring oral antibiotics that cover Staphylococcus aureus, streptococci, and anaerobes commonly found in these infections. The treatment duration should be reassessed based on clinical response, with most uncomplicated infections responding within 7-10 days, as suggested by the guidelines 1.

In addition to antibiotics, proper wound care including debridement of necrotic tissue, offloading pressure from the wound, and regular dressing changes are essential components of treatment. Blood glucose control should also be optimized during treatment to promote healing. If the infection worsens or doesn't improve within 48-72 hours, the patient should be reevaluated for possible osteomyelitis or need for intravenous antibiotics.

Key considerations in selecting an antibiotic regimen include:

• The severity of the infection
• The likely etiologic agent(s)
• The patient's previous antibiotic use and potential allergies
• The local prevalence of antibiotic-resistant strains, such as MRSA
• The need for coverage against gram-negative organisms, such as Pseudomonas aeruginosa, in certain cases.

It is also important to note that the treatment should be based on the results of an appropriately obtained culture and sensitivity testing of a wound specimen, as well as the patient's clinical response to the empiric regimen 1.

Overall, the goal of treatment is to effectively manage the infection, promote wound healing, and prevent complications, while also considering the patient's quality of life and minimizing the risk of antibiotic resistance.

From the FDA Drug Label

Adults with cSSSI Adult patients with clinically documented complicated skin and skin structure infections (cSSSI) ... were enrolled in two randomized, multinational, multicenter, investigator-blinded trials comparing daptomycin for injection (4 mg/kg IV q24h) with either vancomycin (1 g IV q12h) or an anti-staphylococcal semi-synthetic penicillin

Table 15: Investigator’s Primary Diagnosis in the cSSSI Trials in Adult Patients (Population: ITT)

Primary Diagnosis Adult Patients (Daptomycin for Injection/ Comparator* )

Ulcer Infection 71 (27%) / 75 (28%) 53 (20%) / 68 (23%) 124 (23%) / 143 (26%)

The best antibiotic therapy for a 66-year-old female with type 2 diabetes, peripheral neuropathy, and a foot ulcer presenting with induration, purulent drainage, erythema, and no visible bone is daptomycin for injection (4 mg/kg IV q24h) or vancomycin (1 g IV q12h) or an anti-staphylococcal semi-synthetic penicillin.

• Key considerations:
  • The patient has a foot ulcer, which is a type of complicated skin and skin structure infection (cSSSI).
  • The patient's condition is similar to those in the clinical trials, which compared daptomycin with vancomycin or an anti-staphylococcal semi-synthetic penicillin.
  • The clinical success rates in the trials were similar between daptomycin and the comparators. 2

From the Research

Antibiotic Therapy for Diabetic Foot Ulcers

The best antibiotic therapy for a 66-year-old female with type 2 diabetes, peripheral neuropathy, and a foot ulcer presenting with induration, purulent (Parlin) drainage, erythema, and no visible bone is a complex decision that requires careful consideration of several factors.

• The patient's infection is likely to be polymicrobial, containing both aerobic gram-positive cocci and gram-negative rods, as well as anaerobes 3.
• Initial antibiotic selection is usually empiric, with modifications based on culture results and clinical response 3.
• Therapy should be active against staphylococci and streptococci, with broader-spectrum agents indicated if polymicrobial infection is likely 3.
• The duration of therapy ranges from a week (for mild soft tissue infections) to over 6 weeks (for osteomyelitis) 3.

Considerations for Antibiotic Selection

• The most commonly isolated pathogens in diabetic foot infections are Staphylococcus aureus and Streptococcus agalactiae, although polymicrobial infections are common 4.
• Antibiotic therapy should cover commonly isolated organisms and reflect local resistance patterns, patient preference, and the severity of the foot infection 4.
• Mild and some moderate infections may be treated with oral antibiotics, while severe infections require intravenous antibiotics 4.
• The use of broad-spectrum antibiotics, such as piperacillin-tazobactam, may be effective against gram-negative bacteria, including Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa 5.

Treatment Approach

• Early diagnosis, use of broad-spectrum antibiotics, and aggressive debridement, when needed, is advocated to prevent foot amputation 6.
• Patients with diabetes who have clean ulcers associated with peripheral vascular disease and positive ulcer swabs should be considered for early antibiotic treatment 7.
• The treatment approach should be individualized based on the patient's specific needs and circumstances, taking into account factors such as the severity of the infection, the presence of comorbidities, and the patient's overall health status 3, 6, 4, 7, 5.