Table 2.

Diabetic foot infections: pathogens and suggested empiric antimicrobial therapy (but consult local guidelines)

SeverityaUsual pathogensTreatment
No known drug allergyPenicillin allergy (non-severe eg rash)Penicillin allergy (severe eg anaphylaxis)
Uninfected
Mild (usually treated with oral agents)Meticillin-sensitive Staphylococcus aureus (MSSA); Streptococcus sppFlucloxacillin or co-amoxiclavDoxycycline, clindamycin or trimethoprim/sulfamethoxazole
Meticillin-resistant S aureus (MRSA)A glycopeptideA glycopeptide
Moderate (may be treated with oral or initial parenteral agents)MSSA; Streptococcus spp; Enterobacteriaceae; anaerobesCo-amoxiclav3rd generation cephalosporin eg ceftriaxone plus metronidazoleClindamycin and ciprofloxacin
Risk of Pseudomonas aeruginosaAnti-pseudomonal beta-lactam eg piperacillin- tazobactam or ceftazidime plus metronidazoleAnti-pseudomonal beta-lactam eg ceftazidime plus metronidazole
MRSAIf high risk of MRSA, add a glycopeptide
Severe (usually treated with parenteral agents)MRSA; Enterobacteriacae; Pseudomonas; anaerobesAntipseudomonal beta-lactam eg ceftazidime and metronidazole If high risk of MRSA, add a glycopeptideClindamycin and ciprofloxacin
  • aSeverity based on the Infectious Diseases Society of America severity score16 as follows:

  • Uninfected: No symptoms or signs of infection present (symptoms/signs defined as at least two of local swelling or induration, erythema, local tenderness or pain, local warmth, purulent discharge)

  • Mild: Local infection involving only the skin and subcutaneous tissue. If erythema, must be >0.5–≤2 cm around the ulcer. Exclude other causes of inflammatory response of the skin

  • Moderate: Local infection (as above) with erythema >2 cm, or involving structures deeper than skin and subcutaneous tissue, and no systemic inflammatory response signs

  • Severe: Local infection with signs of systemic inflammatory response with two or more of temperature >38°C or <36°C, heart rate >90 beats/min, respiratory rate >20 breaths/min or PaCO2 <32 mmHg, white blood cell count >12,000 or <4000 cells/μL or ≥10% immature (band) forms