What is the recommended treatment plan for a patient with Pseudomonas and Staphylococcus infections between their toes?

Treatment of Pseudomonas and Staphylococcus Infection Between the Toes

Start with piperacillin-tazobactam 3.375 grams IV every 6 hours for 7-10 days if this is a moderate-to-severe infection, or use oral ciprofloxacin 500-750 mg twice daily for 7-10 days if this is a mild infection with confirmed susceptibility. 1, 2, 3

Severity Assessment Determines Route and Agent

Mild infection (minimal cellulitis, no systemic signs):

• Use oral ciprofloxacin 500-750 mg twice daily, which covers both Pseudomonas and Staphylococcus 1, 3
• Alternative: oral levofloxacin 750 mg once daily 1
• Duration: 7-10 days for soft tissue infection 1

Moderate-to-severe infection (significant cellulitis, systemic symptoms, or failed oral therapy):

• Start IV piperacillin-tazobactam 3.375 grams every 6 hours 1, 2
• This provides coverage for MSSA, Pseudomonas, gram-negatives, and anaerobes 1, 2
• Switch to oral ciprofloxacin or levofloxacin once systemically well and showing improvement 4
• Duration: 10-14 days total for moderate-to-severe infections 1

MRSA Considerations

Check for MRSA risk factors before finalizing your regimen:

• Previous MRSA infection/colonization within past year 1
• Recent hospitalization or antibiotic use 1
• Local MRSA prevalence >50% 1

If MRSA risk is present, add or substitute:

• Vancomycin 15-20 mg/kg IV every 8-12 hours 1
• Alternative: linezolid 600 mg PO/IV twice daily 1
• Alternative: daptomycin 4-6 mg/kg IV once daily 1

For mild MRSA infections, oral options include trimethoprim-sulfamethoxazole or doxycycline 1

Pseudomonas-Specific Guidance

Pseudomonas is often a colonizer rather than true pathogen in diabetic foot infections, particularly in temperate climates where it accounts for <10% of true infections 1, 4. However, targeted therapy is appropriate when confirmed by culture and the patient has:

• Macerated ulcer or warm climate exposure 1
• Foot soaking history 1
• Failed prior non-pseudomonal therapy 1

Do not use aminoglycosides as monotherapy despite susceptibility results, as they have poor tissue penetration 4

Critical Adjunctive Measures

Beyond antibiotics, success requires:

• Aggressive surgical debridement of all infected and necrotic tissue 4
• Proper wound care with daily dressing changes 1
• Offloading pressure from affected area 1
• Correction of metabolic abnormalities (hyperglycemia) 4

Monitoring Response

• Inpatients: assess daily for improvement in erythema, warmth, drainage 4
• Outpatients: reassess every 2-5 days initially 4
• Stop antibiotics when infection signs resolve, not when wound fully heals 1, 4

Common Pitfalls to Avoid

• Do not treat uninfected wounds with antibiotics - colonization does not equal infection 1
• Do not empirically cover Pseudomonas without risk factors or confirmation 4, 5
• Do not continue antibiotics until complete wound healing - this promotes resistance 4
• Do not use fluoroquinolones if recent fluoroquinolone exposure - select alternative agent 1
• Do not forget surgical consultation for severe infections or lack of improvement 4