Diabetic Foot Infections Treatment & Management

Updated: Apr 05, 2017
  • Author: Michael Stuart Bronze, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Treatment

Approach Considerations

Cellulitis is the easiest diabetic foot infection to cure, because it does not pose the same circulatory limitations that the more serious infections do, making it easier for medications to reach the infection site. In contrast, chronic osteomyelitis, which is the most difficult diabetic foot infection to cure, requires surgical debridement before antibiotic therapy can be effective. The patient may participate in activities as tolerated. However, weight bearing may be contraindicated. Glycemic control must be achieved to favorably affect outcome; it is important for microbial eradication and tissue healing. 

Collaborative clinical practice guidelines for treating diabetic foot have been published by the Society for Vascular Surgery, the American Podiatric Medical Association, and the Society for Vascular Medicine. [10] Guideline developers highlighted the strong evidence for total contact casting in the treatment of plantar diabetic foot ulcers, which they indicated was not a new treatment, but one that is underutilized. Other important aspects in the guidelines are as follows:

  • Help identify high-risk patients
  • Periodic updates required based on the emergence of new evidence
  • Identification of, grading of, and protocols for various wound care treatments in diabetic foot
  • Implementation of guidelines into training programs

Go to Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Diabetic Foot; and Diabetic Ulcers to see more complete information on these topics.

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Offloading

A 9-member panel of podiatrists, surgeons, and other experts in diabetic foot care provided the following new guidelines based on the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system: [11, 12]

  • Vascular management, infection management and prevention, and pressure relief are essential to diabetic foot ulcer healing. Often denoted in the wound-care literature as VIP, this is the overall aggressive approach the panel deems necessary for foot ulcer healing.
  • Vascular assessment requires a combination of physical examination and laboratory tests. Blood pressure indices such as the ankle-brachial index have poor reliability in patients with diabetes, so they should not be used as the only assessment.
  • For infection diagnosis and treatment, the panel endorses the clinical practice guidelines of the Infectious Diseases Society of America.
  • Adequate offloading increases the likelihood of diabetic foot ulcer healing. Several studies suggest that offloading facilitates healing by reducing both pressure on the foot and strain rate.
  • For guidance on offloading the Charcot foot, the panel endorses the Charcot Foot in Diabetes Consensus Report. [13]
  • Total contact casting is the preferred method for offloading plantar diabetic foot ulcers because it has most consistently demonstrated the best healing outcomes and is a cost-effective treatment.
  • Advanced therapeutics are unlikely to succeed in improving wound-healing outcomes unless effective offloading is achieved.
  • Several studies support the use of advanced therapies, such as cellular or tissue-based wound-healing products, as adjunctive wound care treatments, but only if offloading is also achieved.
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Antimicrobial Therapy

Infections in patients with diabetes are difficult to treat because these patients have impaired microvascular circulation, which limits the access of phagocytic cells to the infected area and results in a poor concentration of antibiotics in the infected tissues. For this reason, cellulitis is the most easily treatable and reversible form of foot infections in patients with diabetes. Deep-skin and soft-tissue infections are also usually curable, but they can be life threatening and result in substantial long-term morbidity. [3, 4, 5, 6, 7]

For specific information concerning the evaluation and management of diabetic foot infections, including choices of antimicrobial agents, the reader is referred to authoritative guidelines published by the Infectious Diseases Society of America. [14]

If infection is suspected, the choice of antibiotics should be based on type/severity of the infection and the likelihood that resistant organisms are involved. Ideally, antibiotics should be chosen based on culture and sensitivity data, but these are not always available. Because data are limited, it is often difficult to compare treatment regimens for efficacy.

Patients with mild infections can be treated in outpatient settings with oral antibiotics that cover skin flora including streptococci and Staphylococcus aureus. Agents such as cephalexin, dicloxacillin, amoxicillin-clavulanate, or clindamycin are effective choices. If methicillin-resistant S aureus (MRSA) infection is suspected, then clindamycin, trimethoprim-sulfamethoxazole, minocycline, or linezolid may be used. If gram-negative aerobes and/or anaerobes are suspected, dual drug treatment with trimethoprim-sulfamethoxazole plus amoxicillin-clavulanate or clindamycin plus a fluoroquinolone such as levofloxacin or moxifloxacin may be used.

For moderate-to-severe infections, patients should be hospitalized for parenteral antibiotic therapy. Empiric choices should cover streptococci, MRSA, aerobic gram-negative bacilli, and anaerobes. MRSA is covered by vancomycin, linezolid, or daptomycin. Acceptable choices for gram-negative aerobic organisms and anaerobes include ampicillin-sulbactam, piperacillin-tazobactam, meropenem, or ertapenem. Alternatively, ceftriaxone, cefepime, levofloxacin, moxifloxacin, or aztreonam plus metronidazole would be sufficient to cover aerobic gram-negative and anaerobic organisms. Tigecycline has been studied, but published experience is limited.

Duration of therapy should be individualized. For those treated in outpatient settings with oral antibiotics, duration of treatment is usually 7-14 days. In those treated parenterally but without osteomyelitis, 2-4 weeks is sufficient.

In patients with diabetic foot osteomyelitis, a 6-week course of antibiotics may be sufficient even in the absence of surgery, according to a randomized prospective study of 40 French patients. Current guidelines recommend at least 3 months or more of antibiotic therapy when diabetic foot osteomyelitis is not treated surgically or when residual dead bone remains after surgery. In the study, however, remission occurred in 12 patients (60%) treated for 6 weeks and in 14 patients (70%) treated for 12 weeks (P = 0.50). [15, 16]

Antibiotics were administered orally for the entire treatment period or intravenously for 5 to 7 days and then orally. Remission was defined as complete and sustained healing of the wound, if present; absence of recurrent infection; and no need for surgical intervention by at least 1 year months after completion of antibiotic treatment. Antibiotic-related adverse events were observed in six (30%) of the patients in the 6-week-treatment group and 10 (50%) of the patients in the 12-week treatment group. [15, 16]

Duration of treatment may be shortened in those patients who undergo amputation as part of the treatment regimen. Consultation with an infectious diseases expert is recommended.

In terms of the infecting microorganisms and the likelihood of successful treatment with antimicrobial therapy, acute osteomyelitis in patients with diabetes is essentially the same as in those without diabetes.

As previously mentioned, in chronic osteomyelitis, a sequestrum and involucrum form; these represent islands of infected bone. Bone fragments that are isolated have no blood supply; systemic antibiotics do not penetrate these devascularized, infected bone fragments. Therefore, antibiotic therapy alone cannot cure patients with chronic osteomyelitis.

Adequate surgical debridement, in addition to antimicrobial therapy, is necessary to cure chronic osteomyelitis. Immobilization is important in acute or chronic osteomyelitis.

Dry gangrene is usually managed with expectant care, and gross infection is usually not present. Wet gangrene usually has an infectious component and requires surgical debridement and/or antimicrobial therapy to control the infection.

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Surgical Debridement

Surgical debridement in diabetic patients with chronic osteomyelitis is the most important therapeutic intervention, as this condition cannot be cured without it. This is because debridement removes the infected, bony fragments that antibiotics cannot reach so that affected areas can be treated with antimicrobial therapy; in some cases, amputation is required. Patients who have fetid foot require extensive surgical debridement and/or amputation. If amputation is performed, physical therapy and rehabilitation may be started on an inpatient basis and completed on an outpatient basis.

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Consultations

Appropriate consultation with a surgeon should be obtained for debridement and/or amputation in chronic osteomyelitis, as well as for debridement or decompression of compartment syndromes in patients with deep-skin and soft-tissue infections. In addition, a vascular surgical evaluation to bypass large-vessel occlusive disease should be considered in patients with diabetic foot infections and peripheral vascular disease. Note, however, that large-vessel bypass does not cure the microvascular component of diabetic foot infections.

An infectious disease specialist should be consulted in the treatment of all patients with diabetic foot infections to optimize the antimicrobial therapy.

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Long-Term Monitoring

Cellulitis

No further care is necessary.

Skin and soft-tissue infection

Additional debridement is generally indicated. The best care plan is aggressive therapy to avoid surgery beyond transmetatarsal amputation (ie, limit surgical extirpation to the forefoot).

Acute osteomyelitis

Monitor the patient's condition to ensure that the infection has resolved.

Chronic osteomyelitis

Ensure that debridement is complete and that no further remnants of infected bone remain.

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