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diabetic foot infection

Classification: - mild infections - do not extend deeper than skin & subcutaneous tissue - may be associated with purulence, warmth, tenderness, edema - erythema extends < 2 cm beyond ulcer - moderate infection - erythema extends > 2 cm beyond ulcer - infection extends deeper than skin & subcutaneous tissue - severe infection - associated with systemic signs of infection - hypotension, confusion, metabolic acidosis, acute kidney injury, severe hyperglycemia [1] Diagnostic criteria: - pus, purulent drainage, foul odor or >= 2 signs of inflammation Laboratory: - deep tisue culture (curettage or tissue biopsy) prior to antibiotic therapy - bone culture if bone biopsy Special laboratory: - assess for arterial insufficiency using ankle-brachial index [1] - positive probe to bone test suggests osteomyelitis - bone biopsy if suspected osteomyelitis Radiology: - foot X-ray (all patients)* - ultrasound if abscess - MRI if osteomyelitis suspected (but not confirmed on X-ray or probe to bone test)# * if sepsis, empiric antibiotics prior to foot X-ray [6] * imaging modalities Modality sensitivity specificity plain radiography 0.54 0.68 leukocyte scan 0.74 0.68 3-phase bone scan 0.81 0.28 MRI 0.90 0.79 Management: - wound care (see diabetic foot ulcer) - assess need for surgical debridement, revascularization, amputation - glycemic control - off-loading of biomechanical stress - antibiotic therapy: - diabetic foot infections diagnosed clinically (see Diagnostic criteria:) - avoid antibiotics in the absence of signs or symptoms of infection [5] - empiric antibiotics should cover gram positive bacteria including S aureus - empiric coverage should include Pseudomonas for Asians & North Africans [5] - mild non-purulent infections (see classification) - oral cephalexin, dicloxacillin, amoxicillin clavulanate or clindamycin - mild purulent infection - oral doxycycline or trimethoprim-sulfamethoxazole with a beta-lactam - moderate infections (see classification) - outpatient treatment for MRSA only if risk factors (see MRSA) - amoxicillin clavulanate + ciprofloxaxin for 14 days if no risk factors for MRSA provides dual coverage for Pseudomonas aeruginosa - severe infections - IV beta piperacillin tazobactam, carbapenem or metronidazole + fluroquinolone or 3rd generation cephalosporin + vancomycin, daptomycin or linezolid (MRSA) [1] - vancomycin, cefepime & metronidazole for sepsis [6] - antibiotic duration for skin & soft tissue infection - 1-2 weeks, up to 4 weeks may be necessary if improvement is slow [5] - diabetic foot osteomyelitis - therapy guided by results of bone culture from bone biopsy - adjunctive rifampin associated with improved amputation-free survival [2] - 6 weeks of antibiotics for osteomyelitis without amputation [5] - 3 weeks after amputation with positive bone margins [5] - 3 weeks of antibiotics may be non-inferior to 6 weeks [3] - G-CSF, topical antiseptics, silver, honey, bacteriophages, topical antibiotics, & hyperbaric oxygen not recommended [5] Notes: - also see diabetic foot ulcer

Related

diabetic foot diabetic foot ulcer; diabetic foot lesion; diabetic lower extremity lesion

General

foot infection

References

  1. Medical Knowledge Self Assessment Program (MKSAP) 18, 19. American College of Physicians, Philadelphia 2018, 2021. - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  2. Wilson BM, Bessesen MT, Doros G et al. Adjunctive rifampin therapy for diabetic foot osteomyelitis in the Veterans Health Administration. JAMA Netw Open 2019 Nov 1; 2:e1916003. PMID: 31755948 https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2755865
  3. Gariani K et al. Three versus six weeks of antibiotic therapy for diabetic foot osteomyelitis: A prospective, randomized, non-inferiority pilot trial. Clin Infect Dis 2020 Nov 26; PMID: 33242083 https://academic.oup.com/cid/advance-article-abstract/doi/10.1093/cid/ciaa1758/6006875
  4. Lipsky BA, Senneville E, Abbas ZG et al Guidelines on the diagnosis and treatment of foot infection in persons with diabetes (IWGDF 2019 update). Diabetes Metab Res Rev. 2020 Mar;36 Suppl 1:e3280. PMID: 32176444
  5. Senneville E, Albalawi Z, van Asten SA et al. IWGDF/IDSA guidelines on the diagnosis and treatment of diabetes-related foot infections (IWGDF/IDSA 2023). Clin Infect Dis 2023 Oct 2; [e-pub] PMID: 37779323 Review https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciad527/7287196
  6. NEJM Knowledge+
  7. Dinh MT, Abad CL, Safdar N. Diagnostic accuracy of the physical examination and imaging tests for osteomyelitis underlying diabetic foot ulcers: meta-analysis. Clin Infect Dis. 2008 Aug 15;47(4):519-27. doi: 10.1086/590011. PMID: 18611152 PMCID: PMC7450707 Free PMC article.