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Diabetic Foot Infection Adapted from Diabetes Care. 2013;36(9):2862-71. and Clin Infect Dis. 2012;54(12):e132-73.

• Diabetic foot infection (DFI) is diagnosed clinically by the presence of at least two signs or symptoms of inflammation:

• Local swelling or induration
• Erythema
• Local tenderness or pain
• Local warmth
• Purulent discharge (thick, opaque to white or sanguineous secretion)

• DFI is classified based on its severity according to the Infectious Diseases Society of America (IDSA) guideline or the PEDIS grade developed by International Working Group on the Diabetic Foot (IWGDF).

Clinical Manifestation PEDIS Grade IDSA Severity No symptoms or signs of infection 1 Uninfected Local infection involving only the skin and the subcutaneous tissue without involvement of deeper tissues and without signs of SIRS If erythema, must be >0.5 cm to ≤2 cm around the ulcer. Exclude other causes of an inflammatory response of the skin (eg, trauma, gout, acute Charcot neuro-osteoarthropathy, fracture, thrombosis, venous stasis). 2 Mild Local infection with erythema >2 cm or involving structures deeper than skin and subcutaneous tissues (eg, abscess, osteomyelitis, septic arthritis, fasciitis) without signs of SIRS 3 Moderate Local infection with the signs of SIRS, as manifested by ≥2 of the following: Temperature >38 °C or <36 °C Heart rate >90 beats/min Respiratory rate >20 breaths/min or PaCO2 <32 mm Hg White blood cell count >12,000 or <4,000 cells/μL or ≥10% immature (band) forms 4 Severe

• Hospitalization is appropriate for the following conditions:

• Severe (grade 4) infections
• Moderate (grade 3) infections with complicating features

• Severe peripheral arterial disease or limb ischemia
• Lack of home support

• Patients unable to comply with the required outpatient treatment regimen for psychological or social reasons
• Patients not responding to outpatient treatment

• Infected wounds should be cultured by obtaining tissue samples during any surgical procedure or by tissue biopsy or wound base curettage. Bone cultures are optimal for detecting the pathogen in osteomyelitis, but blood cultures are only necessary for those with a severe (grade 4) infection.

• Conditions to request consultation from specialists:

• Urgent surgical intervention should be sought for DFIs accompanied by gas in the deeper tissues, an abscess, or necrotizing fasciitis, and less urgent surgery for DFIs with substantial nonviable tissue or extensive bone or joint involvement.
• Consult a vascular surgeon to consider revascularization if ischemia complicates a DFI.
• Infectious diseases specialists should be consulted when cultures yield multiple or antibiotic-resistant organisms, the patient has substantial renal impairment, or the infection does not respond to appropriate medical or surgical therapy in a timely manner.

• No adjunctive therapy has been proven to improve resolution of infection, but for selected diabetic foot wounds that are slow to heal, clinicians might consider using bioengineered skin equivalents, growth factors, granulocyte colony-stimulating factors, hyperbaric oxygen therapy, or negative pressure wound therapy.

Special Considerations for Diabetic Foot Osteomyelitis

• When a radical resection leaves no remaining infected tissue, a short duration (2–5 days) of antibiotic therapy should be given. When there is persistent infected or necrotic bone, prolonged (≥4 weeks) antibiotic treatment is required.

• Adjunctive treatments for DFO such as hyperbaric oxygen therapy, growth factors (including granulocyte colony-stimulating factor), maggots (larvae), or topical negative pressure therapy (eg, vacuum-assisted closure) are not supported by the current IDSA guideline.

Antibiotic Therapy

• Clinically uninfected wounds should not be treated with antibiotic therapy. For all infected wounds, antibiotic therapy combined with appropriate wound care is recommended.

• Selection of empiric antimicrobial regimen and the route of administration should be based on the severity of DFI and the likely etiologic agents.

• Mild (grade 2) to moderate (grade 3) DFI without recent antibiotic treatment:

• Highly bioavailable oral antibiotics against aerobic gram-positive cocci may be sufficient.
• Topical therapy may be considered in selected mild superficial infections.

• Severe (grade 4) DFI:

• Parenteral, broad-spectrum antibiotics are recommended while culture results and susceptibility data are pending.
• Switch to oral agents when the patient is systemically well and culture results are available.

• Methicillin-resistant Staphylococcus auerus (MRSA) coverage should be considered in the following conditions:

• Prior history of MRSA infection
• High local prevalence of MRSA colonization or infection
• Clinically severe diabetic foot infection

• Anti-pseudomonal agent is usually unnecessary except for patients with risk factors:

• High local prevalence of Pseudomonas aeruginosa infection
• Frequent exposure of the foot to water
• Warm climate

• Duration of antibiotic therapy:

• Therapy should be continued until resolution of infection but not through complete healing of the wound.
• Antibiotic is usually given 1–2 weeks for mild infections and 2–3 weeks for moderate to severe infections.

• A broad-spectrum antibiotic regimen is recommended for severe infections, covering staphylococci, streptococci and commonly reported gram-negative pathogens.

• Initial therapy must usually be parenteral and empiric, based on the likeliest pathogens and their probable antibiotic susceptibility patterns.

• Where the likelihood is more than minimal of infection with methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, extended-spectrum beta-lactamase–producing gram-negatives, or obligately anaerobic bacteria, antibiotics effective against these organisms should be considered.

• No one agent or regimen has shown superiority in treating DFIs.

▸ Click on the following categories to expand treatment regimens.

Mild     High suspicion of MRSA   ▸  Low suspicion of MRSA     Moderate   ▸  High suspicion of MRSA   ▸  Low suspicion of MRSA   ▸  High suspicion of P. aureuginosa     Severe   ▸  Broad-spectrum regimen

High suspicion of MRSA ▸ Doxycycline OR ▸ TMP/SMZ Low suspicion of MRSA Preferred Regimen ▸ Dicloxacillin OR ▸ Cephalexine OR ▸ Amoxicillin-clavulanic acid OR ▸ Clindamycin High suspicion of MRSA Preferred Regimen High suspicion of MRSA ▸ Linezolid OR ▸ Daptomycin OR ▸ Vancomycin Low suspicion of MRSA Preferred Regimen ▸ Levofloxacin' OR ▸ Moxifloxacin OR ▸ cefoxitin OR ▸ Ceftriaxone OR ▸ Tigecylin OR ▸ Imipenem-cilastatin High suspicion of P. aureuginosa Preferred Regimen ▸ Piperacilin-tazobactam 'Broad-spectrum regimen Preferred Regimen ▸ Vancomycin PLUS ▸ Ceftazidime OR ▸ Cefepime OR ▸ Piperacillin-Tazobactam OR ▸ Aztreonam OR ▸ [[