Diabetic foot infections (DFI)

Duration: Depends on severity and presence/absence of osteomyelitis - see individual sections for further advice.

Moderate to severe diabetic foot infections are often polymicrobial, and if results of recent sampling after debridement are available, therapy should be based on culture results.

Sampling of diabetic foot ulcers must be undertaken after thorough cleaning of the ulcer surface. Tissue or bone samples are more likely to yield significant growth than swabs from the surface of the ulcer.

Uninfected (Grade 1)

No systemic or local symptoms or signs of infection

Infection criteria

At least two of these items are present:

• Local swelling or induration
• Erythema >0.5cm in any direction from the rim of the wound
• Local tenderness or pain
• Local increased warmth
• Purulent discharge
• And no other cause(s) of an inflammatory response of the skin (e.g. trauma, gout, acute Charcot neuro-osteoarthropathy, fracture, thrombosis or venous stasis)

Note: Infection refers to any part of the foot, not just of a wound or an ulcer. The presence of clinically significant foot ischemia can make both diagnosis and treatment of infection considerably more difficult.

Mild DFI (grade 2)

Infection with no systemic manifestations (see grade 3) involving:

• only the skin or subcutaneous tissue (not any deeper tissues), and
• any erythema present does not extend >2cm in any direction from the rim of the wound

Use the table below for the antimicrobial treatment overview of mild DFI (grade 2):

• FigureMild DFI (Grade 2) - Treatment Overview

Moderate DFI (grade 3) - outpatient treatment

Infection with no systemic manifestations, and involving:

• erythema extending ≥2cm in any direction from the rim of the wound and/or
• tissue deeper than skin and subcutaneous tissues (e.g. tendon, muscle, joint, bone)

Infection involving bone (osteomyelitis) - if osteomyelitis is demonstrated in the absence of ≥2 signs/symptoms of local or systemic inflammation, classify the foot as either grade 3(O) (if <2 SIRS criteria) or grade 4(O) if ≥2 SIRS criteria)

All moderate infection / osteomyelitis should be reviewed by the acute podiatry team to ensure ongoing review culture / sensitivity results, tolerability of therapy and bloods / ECG monitoring as required.

Use the table below for the antimicrobial treatment overview of moderate DFI (grade 3) - outpatient treatment:

• FigureModerate DFI (Grade 3) - Outpatient Treatment

Moderate - severe DFI (inpatient treatment)

Moderate DFI (Grade 3):

• erythema extending ≥2 cm in any direction from the rim of the wound , and/or
• tissue deeper than skin and subcutaneous tissues (e.g. tendon, muscle, joint, bone)

Infection involving bone (osteomyelitis) - if osteomyelitis is demonstrated in the absence of ≥2 signs/symptoms of local or systemic inflammation, classify the foot  as either grade 3(O) (if <2 SIRS criteria) or grade 4(O) if ≥2 SIRS criteria)

Severe DFI (Grade 4):

Any foot infection with associated systemic manifestations (of the systemic inflammatory response syndrome [SIRS]), as manifested by ≥2 of the following:

• Temperature >38°C or <36°C
• Heart rate >90 beats/minute
• Respiratory rate >20 breaths/minute or PaCO2 <4.3 kPa (32mmHg)
• White blood cell count >12,000/mm3, or <4,000/mm3, or >10% immature (band) forms

Use the table below for the antimicrobial treatment overview of moderate - severe DFI (inpatient treatment):

• FigureModerate - Severe DFI (Inpatient Treatment)