Diabetic foot infection

Background

• 1st key factor is to assess extent & depth of ulcer (usu more extensive than they appear). Ulcer depth is imp predictor of healing rate, OM & risk of amputation.
• Failure of ulcer to heal by 50% or more after 1 month of Rx is a strong predictor that the ulcer is unlikely to heal after 3 mos.
• 75% of pts hv polymicrobial inf, usu 70% are g+. Severe limb/life threatening inf are more likely to involve g- aerobic & anaerobic bacteria w/ g+. MRSA is incr in freq.
• 50% or more of pts w/ SEVERE diabetic foot inf have no s/s of systemic tox (ie fever, tachy, incr wbc or Lt shift)

HPI

• Ask about recent trauma
• Duration of current lesions
• Associated systemic symptoms
• Prior treatments

Physical Exam

• Determine ulcer location, dimensions, depth, and appearance
• Note hair and nail growth, determine vascular status (palpate DP, PT, and popliteal pulse)
• Probe ulceration note involvement of bone, joint, tendon, or sinus tract formation
• DM foot ulcer infection presumed if:
  • 2 or more of following: erythema, warmth, tenderness, or swelling
  • OR if pus coming from ulcer site or nearby sinus tract
• Reminder:
  • DM ulcers usually occur at areas of increased pressure (sole of foot) or friction
  • Venous ulcers usually present above malleoli with irregular borders
  • Arterial ulcers usually found on the toes or shins, with pale, "punched-out" borders (typically painful)

Diagnosis

1. Gently probe wound w/ sterile probe, if probe hits bone, chance of osteo is 90% higher.
3. Inf of the wound is demonstrated by presence of purulent dc or 2 or more signs of inflammation (ttp, warmth, induration or erythema) around the ulcer.
4. Inf is severe if any of the following: abnl vs, rim of erythema around the ulcer is 2 cm or more in diameter, lymphangitic streaking or signs of fasciitis (such as crepitice or bullae), or if probe reaches bone/tendon/joint
5. ESR >40 incr chance of OM 12 fold, an ESR >70 makes dx nearly certain.
6. Charcot foot can look similar, but foot ulcer is usu absent, erythema & edema partially resolve w/ elevation of goot for 10 min.
7. Nd ABI if any of following: absence of DP & PT, claudication sx, isch foot pain.
8. Nd vascular surgeon if ABI <.4 (severe obst). .4-.69= mod obst, .7-.9 =mild obst, .9-1.3 =nl, >1.3 = med art ca (can see falsely high/nl ABI d/t medial calcification of the arteries).
9. Wound NOT likely to be infected if no systemic sx, no dc & no more than 1 s/s of local inflammation

Treatment

1. Abx for mild= keflex or augmentin or diclox or clinda. Abx for severe= unasyn or clinda & quinolone or clinda & ceftaz, add vanco if life threat.
2. Focusing Rx on g+ aerobes w/ oral abx (1-2 wk) appears effective for most mild inf. Must eliminate pressure on wound until healed, nd to elminate or decr periph edema. Dress wound w/ warm/moist env after debridement, absorbant drsng if exudate present.
3. Recurrence of amp is 50-70% over 3-5 yrs. Overall, 50-80% will heal w/in 6 mos w/ optimal care.
4. Goal for best reults is A1c level <7%, BP <130/80, no Etoh or smoking & LDL <100.

Source

7/2/09 PANI