Diabetic foot

Diabetic foot is characterized by non-healing ulcers to the feet. Usually, pathogenesis involves peripheral neuropathy related ulcers surrounded by necrotic tissue that become colonized and/or infected with multiple bacteria. Low-pathogenic colonists of the skin like coagulase-negative staphylococci and Corynebacterium spp may become pathogenic. And gram-negative bacteria like Pseudomonas aeruginosa and members of the Enterobacteriaciae may become part of the colonizing flora. PEDIS score classifies 4 grades of severity:

1. Wound lacking purulence or any manifestation of inflammation
2. Prescence of ≥ 2 manifestations of inflammation but any cellulitis or erythema extends ≤ 2 cm around the ulcer and the inflammation is superficial and there are no complications or systemic symptoms. Manifestations of inflammation:
   • purulence or erythema
   • pain
   • tenderness
   • warmth
   • induration
3. Infection as above but with ≥ 1 of the following charactgeristics:
   • cellulitis extending ≥ 2 cm from the ulcer
   • lymphangitic streaking
   • spread of infection beneath the superficial fascia
   • deep tissue abscess
   • gangrene
   • involvement of muscle, tendon, joint or bones
4. Infection in a patient with systemic toxicity or metabolic instability (fever, chills, tachypnea, hypotension, confusion, vomiting, leukocytosis, acidosis, severe hypoglycemia, azotemia)

 Culture from the ulcer is unnecessary for uninfected diabetic feet (PEDIS 1) and mildly severe infected foot that are antibiotic naive (PEDIS 2). Culture may be performed for routine monitoring and inventarisation of the wound. For severe infection, culture of the wound is advised to direct therapy and blood cultures are advised for systemically ill patients. Wound must be cleaned before swabbing for cultures. 

Therapy

IDSA sugeested empirical regimens for diabetic foot infection:

• dicloxacillin
• clindamycin
• cephalexin
• trimethoprim-sulfamethoxazole
• amoxicillin-clavulanate
• levfloxacin
• cefoxitin
• ceftriaxone
• ampicillin-sulbactam
• linezolid (with or without aztreonam)
• daptomycin (with or without aztreonam)
• ertapenem
• cefuroxime (with or without metronidazole)
• ticarcilline-clavulanate
• pipercillin-tazobactam
• levofloxacin or ciprofloxacin with clindamycin
• imipenem-cilastatin

Adapted from IDSA-endorsed guidelines published here.

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4. Skin – localized lesion
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