Diabetic Foot

Infected neuropathic foot ulcer

Microbiology

• Mild (superficial, no bone or joint involvement): usually S. aureus or aerobic streptococci

• Limb or life-threatening deep, bone/joint involvement, systemic tox.. limb ischemia monomicrobial or polymicrobial with aerobes + anaerobes aerobes staphylococci, streptococci, enterococci. and GNR (including Pseudomonas)

anaerobes anaerobic streptococci. Bacteroides. Clostridium (rare)

Clinical manifestations

• Ulcer with surrounding erythema and warmth • purulent drainage

• Tenderness may be absent due to neuropathy

• * Crepitus (indicating gas and .. mixed infection w/ GNR & anaerobes or Qostridium)

• i Underlying osteomyelitis

• ♦ Systemic toxicity (fever, chills, leukocytosis, hyperglycemia) Diagnostic studies

• Superficial swabs from ulcers not helpful (only yield superficial colonizing organisms)

• Wound cx (eg. curettage at base of ulcer after debridement) has * Se

• Blood cx should be obtained in all Pts.® in 10-15%

• Osteomyelitis should always be ruled out (see below for specific imaging tests)

probing to bone (ability to reach bone via ulcer/tract) has high Sp but low Se bone bx most reliable

Treatment (ni}m 1994:331:854)

• Bedrest, elevation, non-weight-bearing status

• Antibiotics

Severity of infection

Empiric antibiotics

Mild

penkillinase-resistant PCN or 1st gen. ceph. (TMP-SMX if MRSA suspected)

Chronic non-limb/life-threatening

[FQ f clindamycin] or ampicillin-sulbactam or ticarcillin-clavulanate

Ufe-threatening

[Imipenem - vanco] or [vanco • aztreonam + metronidazole] or [ampicillin-sulbactam - AG]

• Surgery: early, aggressive, and repeated surgical debridement; revascularization or amputation may be necessary

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