Key Insights On Managing Infected Diabetic Ulcers

Author(s): 
Clinical Editor: Lawrence Karlock, DPM

Assessing and treating infected diabetic foot wounds can be challenging. Providing timely treatment is essential given the potential complications of diabetic foot infections but the rise in antibiotic resistance is a key issue to consider. With this in mind, our expert panelists discuss a variety of issues, ranging from empiric antibiotic selection and MRSA infected wounds to their approach in diagnosing osteomyelitis.

Q: What empiric antibiotics do you utilize for the infected neuropathic diabetic foot ulcer?
A:
Systemic antibiotics are unnecessary unless there is evidence of osteomyelitis or active cellulitis, explains Anthony F. Cutrona, MD. All of the panelists agree that whenever possible, the antibiotic regimen should be tailored to the results of deep tissue cultures. However, as Leon Brill, DPM, points out, there are times when you need to start empiric therapy as soon as possible. He also cautions that cultures are unreliable when patients have already been on a prolonged course of multiple antibiotics.

When it comes to empiric antibiotics, Dr. Brill says he always tries to provide coverage for Staph and Strep, preferring to use ampicillin/sulbactam for hospital patients and amoxicillin/clavulanate for outpatients. For skin and soft tissue infection, Dr. Cutrona utilizes oral empiric antibiotics such as doxycycline, trimethoprimsulfa, clindamycin, quinolones, metronidazole and linezolid. While all of these antibiotics have “excellent bioavailability,” Dr. Cutrona says one should weigh the cost issue. He notes that while doxycycline and metronidazole may be as cheap as 20 cents a tablet, a tablet of linezolid is $100.
When providing empiric treatment for patients who are not allergic to penicillin, Lawrence G. Karlock, DPM, says he opts for amoxicillin/clavulanate 875 mg bid or cefdinir 300 mg bid. For those who are allergic to penicillin, Dr. Karlock will usually combine an empiric combination of levaquin 750 mg qd with clindamycin 300 mg qid. When treating penicillin-allergic patients, Dr. Brill uses clindamycin empirically. He notes he may also add levofloxacin to extend the spectrum for both in-patients and outpatients.
Deeper infectious processes require intravenous antibiotics, according to Dr. Cutrona. When it comes to empiric IV antibiotics, Dr. Cutrona says combining beta-lactams (piperacillin-tazobactam, the fourth generation cephalosporin carbopenem) with clindamycin is “very effective.” He points out that clindamycin is synergistic with beta-lactam in Strep infections. If one is concerned about methicillin-resistant Staph aureus (MRSA), Dr. Cutrona says vancomycin can be an additive.

Q: What factors influence your decision to treat these patients on an outpatient basis versus admission to the hospital?
A:
Dr. Cutrona says one should evaluate the patient’s vitals. If the patient has hypotension, fever or exhibits lethargy or confusion, Dr. Cutrona says any of these signs would be a “basis for admission with or without significant local problems.” Dr. Brill concurs, noting that he admits patients who display constitutional symptoms of fever or malaise.
However, Dr. Karlock points out that a large percentage of diabetic patients with foot threatening infections do not necessarily develop these constitutional symptoms and may not necessarily show a left shift or a leukocytosis. Given this, Dr. Karlock says “We do not always base our decision to hospitalize these patients on this criteria.”
When determining the severity of the infection, Dr. Brill notes that he does not rely heavily on white blood cell counts or temperature because “these may remain low even in the face of sepsis due to the immunocompromised nature of the patient.”

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