Diabetic Foot Infection
PATHOGENS
- Most diabetic foot infections (DFIs) are polymicrobial; however, if the patient hasn’t recently received abx therapy, it is often monomicrobial due to staphylococcal or streptococcal infection.
- Frequent pathogens: based on deep wound or bone cultures. Pathogens recovered from superficial swabs should be viewed with suspicion.
- Initially, wounds usually have Gram-positive flora from the skin; as it becomes more chronic, it tilts toward Gram negatives. Following broad-spectrum abx, flora may evolve to MRSA, VRE and more resistant Gram negatives.
- Aerobic Gram positive:
- Staphylococcus aureus
- Among the most commonly isolated pathogens in N. America and European series.
- Streptococcal spp.
- Especially GAS, GBS, group C or G streptococci
- Enterococcus spp.
- Coagulase-negative staphylococci are usually contaminants obtained from superficial swabs but should be considered genuine if obtained from deep tissue or bone.
- Staphylococcus aureus
- Aerobic Gram negatives
- Enterobacteriaceae
- Pseudomonas aeruginosa (although frequently a commensal when found, studies using abx without antipseudomonal activity often yield similar results, e.g., ertapenem v. piperacillin/tazobactam[19])
- Anaerobes, facultative anaerobes: usually when ulcers are deep, chronic and/or necrotic tissue is present.
- Superficial, early infections (cellulitis, cellulitis involving blisters and shallow ulcers) are typically caused by S. aureus or beta-hemolytic streptococci.
- Infections of ulcers that are chronic or previously treated with antibiotics may be caused by aerobic Gram-negative bacilli, S. aureus or Streptococci.
- Deep soft tissue infections, osteomyelitis, and gangrene are more often polymicrobial, including aerobic Gram-negative bacilli and anaerobes (anaerobic streptococci, Bacteroides fragilis group, Clostridium species), but Staphylococcus aureus is also common as a single pathogen.
- Multi-drug resistant Gram-negative organisms described in DFI, especially ESBL, but most resistant organisms w/ reports from India and warmer climates.
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Last updated: March 10, 2024
Citation
Auwaerter, Paul. "Diabetic Foot Infection." Johns Hopkins ABX Guide, The Johns Hopkins University, 2024. Pediatrics Central, peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540161/all/Diabetic_Foot_Infection.
Auwaerter P. Diabetic Foot Infection. Johns Hopkins ABX Guide. The Johns Hopkins University; 2024. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540161/all/Diabetic_Foot_Infection. Accessed December 12, 2024.
Auwaerter, P. (2024). Diabetic Foot Infection. In Johns Hopkins ABX Guide. The Johns Hopkins University. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540161/all/Diabetic_Foot_Infection
Auwaerter P. Diabetic Foot Infection [Internet]. In: Johns Hopkins ABX Guide. The Johns Hopkins University; 2024. [cited 2024 December 12]. Available from: https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540161/all/Diabetic_Foot_Infection.
* Article titles in AMA citation format should be in sentence-case
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