IDSA Issues Diabetic Foot Infection Management Guidelines

Laurie Barclay, MD

May 23, 2012

May 23, 2012 — Correct multidisciplinary treatment of common diabetic foot infections can reduce amputations, according to guidelines for diagnosis and treatment issued by the Infectious Diseases Society of America (IDSA). The new recommendations, which are a revision and update of IDSA's 2004 diabetic foot infections guidelines, were published online May 22 and in the June 15 print issue of Clinical Infectious Diseases.

"Lower extremity amputation takes a terrible toll on the diabetic patient," lead author and review panel chair Benjamin A. Lipsky, MD, professor of medicine at the University of Washington and VA Puget Sound, Seattle, said in a news release. "People who have had a foot amputated often can no longer walk, their occupational and social opportunities shrink, and they often become depressed and are at significant risk for a second amputation. Clearly, preventing amputations is vital, and in most cases, possible."

The vasculopathy and neuropathy often associated with diabetes result in impaired circulation and sensation in the feet, which in turn may lead to improper care of an unnoticed blister or cut. Nearly one quarter of persons with diabetes will have a foot ulcer at some point during their lifetime. The most prevalent cause of lower extremity amputations is infected foot wounds in people with diabetes.

Without prompt and aggressive treatment, infected diabetic foot wounds result in necrosis of soft tissue and bone, which must be surgically removed. Extensive infections may require amputation of the toe, foot, or even part of the lower limb. Persons with diabetes account for more than three quarters of all nontraumatic amputations, and a foot ulcer is the inciting cause in 85% of these surgeries.

After foot amputation, 5-year survival is only 50%. However, proper care of diabetic foot infections can prevent about half of lower extremity amputations unrelated to trauma. The new guidelines stress the importance of a multidisciplinary team, including infectious diseases specialists, podiatrists, surgeons, and orthopedists, in providing optimal care for this widespread problem.

Specific Recommendations

The new guidelines include extensive, evidence-based answers to 10 common questions a healthcare provider is most likely to need to address when treating a patient with diabetes who has a foot wound.

Highlights of specific recommendations in the guidelines include the following:

  • A foot wound is likely to be infected if there is inflammation or purulence and/or if 2 or more of the following signs are present: redness, warmth, tenderness, pain, or swelling.

  • About half of ulcers are not infected, and these should not be treated with antibiotics.

  • Rapid, appropriate treatment of infected foot wounds is mandatory.

  • All persons with infected ulcers should receive appropriate antibiotic therapy.

  • Persons with a severe infection (accompanied by systemic signs or metabolic disturbances) should be immediately hospitalized.

  • Workup of an infected foot ulcer should include imaging of the foot to identify or rule out osteomyelitis and wound culture to identify the responsible pathogen(s) and to determine antibiotic sensitivity.

  • Although plain radiography may suffice, magnetic resonance imaging is far more sensitive and specific to diagnose osteomyelitis. This diagnosis should be confirmed by bone culture and histology.

  • Most diabetic foot infections are polymicrobial, with the most common pathogens being aerobic Gram-positive cocci (GPC), particularly staphylococci. Aerobic Gram-negative bacilli are often copathogens in chronic infections or in those arising after antibiotic treatment. Obligate anaerobes may be copathogens in ischemic or necrotic ulcers.

  • In addition to antibiotics, treatment of infected foot wounds should include surgical debridement of dead tissue, proper wound dressing, removing pressure on the wound, and improving circulation to the infected area.

  • A postdebridement specimen should be sent for aerobic and anaerobic culture.

  • Ischemia in the foot may require revascularization surgery.

  • Errors in management may include initial treatment limited to antibiotics, use of an inappropriate antibiotic, failure to provide proper wound care and surgical interventions, and failure to treat peripheral arterial disease or other underlying conditions.

  • In many acutely infected patients, empiric antibiotic therapy can narrowly target GPC. Patients at risk for infection with antibiotic-resistant organisms and those with chronic, previously treated, or severe infections usually need broader spectrum regimens.

  • The multidisciplinary team caring for patients with diabetic foot infections should include infectious diseases specialists, podiatrists, surgeons and orthopedists. Telemedicine may be useful in rural areas to increase availability of consultation with appropriate experts.

  • Patients require regular follow-up after treatment of a diabetic foot wound.

  • Clinicians and healthcare organizations should attempt to monitor and improve their procedures and outcomes in caring for diabetic foot infections.

  • These recommendations are not intended to replace clinical judgment, but to support individualized decision-making targeting each patient's circumstances.

"There is quite a bit of over-prescribing or inappropriate prescribing of antibiotics for diabetic foot wounds, which doesn't help the patient and can lead to antibiotic resistance," said coauthor Warren S. Joseph, DPM, consultant for lower extremity infectious diseases at Roxborough Memorial Hospital, Philadelphia, Pennsylvania, in the news release. "The guidelines note that when antibiotics are necessary they should be discontinued when the infection is gone, even if the wound hasn't completely healed."

The guidelines discuss a detailed approach to help determine whether a wound is likely to be infected or not. The panel recommends using a validated classification system such as those developed by the International Working Group on the Diabetic Foot or by IDSA to classify infections and help define the mix of types and severity of their cases and their outcomes. Beyond the classic signs of inflammation and purulent secretions, the panel offers the following clues that suggest possible infection: nonpurulent secretions, friable or discolored granulation tissue, undermining of wound edges, and foul odor. Those with a positive probe-to-bone test, an ulceration that has been there for more than 30 days, a history of recurrent foot ulcers, a traumatic foot wound, peripheral vascular disease in the affected limb, previous lower extremity amputation, loss of sensation, renal insufficiency, and/or history of walking barefoot are at increased risk for diabetic foot infection.

IDSA provided support for these guidelines. Some of the guidelines authors report various financial relationships with Merck, Pfizer, Wyeth-Ayerst, Cubist, Smith-Nephew, Innocoll, Oculus, TaiGen, Schering Plough, the International Working Group on the 8 Diabetic Foot, sanofi aventis, Ortho McNeil, Orthopedic Implants for Deputy Orthopedics, and/or Small Bone Innovation.

Clin Infect Dis. 2012;54:1679-1684. Full text

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