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SOURCE

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Source: Fish DN. Skin and soft-tissue infections. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 10th ed. New York, NY: McGraw-Hill; 2017. http://accesspharmacy.mhmedical.com/content.aspx?bookid=1861&sectionid=146071658. Accessed March 7, 2017.

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DEFINITION

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  • Foot infections in patients with diabetes.

  • Three types:

    • Deep abscesses.

    • Cellulitis of the dorsum.

    • Mal perforans ulcers.

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ETIOLOGY

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  • Begins with local bacterial invasion and is polymicrobic (average of 2.3–5.8 isolates per culture).

    • Most common pathogens: Staphylococci (especially Staphylococcus aureus) and streptococci.

    • Gram-negative bacilli and anaerobes occur in 50% of cases.

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PATHOPHYSIOLOGY

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  • Key factors in development of diabetic foot problems (may occur in isolation or together):

    • Neuropathy.

    • Angiopathy and ischemia.

    • Immunologic defects that impair wound healing.

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EPIDEMIOLOGY

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  • One of the most common diabetes complications caused by bacterial infection, responsible for up to 20% of all hospitalizations of diabetics.

  • Diabetic lower-extremity amputations account for approximately 70% of all nontraumatic amputations in the United States.

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PREVENTION AND SCREENING

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  • Optimize blood glucose control.

  • Encourage daily patient self-examination of feet.

  • Examine feet at every physician visit.

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RISK FACTORS

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  • Uncontrolled blood glucose.

  • Peripheral neuropathy.

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CLINICAL PRESENTATION

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  • Infections often more extensive than they initially appear.

  • Clinical signs of infection may not be present secondary to angiopathy and neuropathy.

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SIGNS AND SYMPTOMS

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  • Swelling or erythema in foot (patient unaware of pain due to peripheral neuropathy)

  • Warmth.

  • Presence of pus.

  • Draining sinuses.

  • Pain.

  • Tenderness.

  • Temperature: normal or mildly elevated.

  • Lesions vary in size when present.

  • Four-smelling odor suggests anaerobic organisms.

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DIAGNOSIS

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MEANS OF CONFIRMATION AND DIAGNOSIS
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  • Culture results.

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LABORATORY TESTS
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  • Culture and sensitivities.

    • Obtain specimen from deep culture, preferably expressed pus from wound base.

    • Culture for aerobic and anaerobic organisms.

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IMAGING
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  • Assess for osteomyelitis via radiograph, bone scan, or both, as appropriate.

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DIAGNOSTIC PROCEDURES
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  • Surgical debridement to obtain samples for culture and sensitivities.

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DIFFERENTIAL DIAGNOSIS
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DESIRED OUTCOMES

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  • Successfully treat infected wounds by using effective nondrug and antibiotic therapy.

  • Prevent additional infectious complications.

  • Preserve as much normal limb function as possible.

  • Prevent infectious complications.

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TREATMENT: GENERAL APPROACH

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  • Most infections successfully treated on outpatient basis with wound care and antibiotics.

  • Maximize glycemic control to ensure optimal wound healing.

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TREATMENT: NONPHARMACOLOGIC THERAPY

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  • Thoroughly debride necrotic tissue, with wound drainage and amputation as required.

  • Wounds must be kept clean and dressings changed 2–3 times ...

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