What is the treatment for a polymicrobial skin infection with Pseudomonas, beta-lactamase positive Prevotella disiens, and Group C Streptococcus?

Treatment Explanation for Polymicrobial Skin Infection

Your Infection and Why It Requires This Specific Treatment

You have a complex skin infection caused by three different bacteria working together: Pseudomonas (a water-loving bacteria), Prevotella disiens (an anaerobic bacteria that doesn't need oxygen), and Group C Streptococcus (a common skin bacteria). This combination requires attacking all three organisms simultaneously with different antibiotics that work together 1.

Your Antibiotic Regimen Explained

Ciprofloxacin 750mg by mouth twice daily for 10 days

• This targets the Pseudomonas and Group C Streptococcus 1
• Ciprofloxacin is specifically recommended by the Infectious Diseases Society of America for polymicrobial infections when combined with metronidazole 1
• The 750mg twice-daily dose provides excellent activity against Pseudomonas aeruginosa, which is notoriously difficult to treat 1, 2
• Critical: Take this on an empty stomach (1 hour before or 2 hours after meals) and avoid dairy products, antacids, or supplements containing calcium, magnesium, iron, or zinc within 6 hours of each dose, as these dramatically reduce absorption 1

Metronidazole 500mg by mouth three times daily for 10 days

• This specifically kills the Prevotella disiens (the anaerobic bacteria) 1
• Metronidazole has the greatest spectrum against anaerobic bacteria like Prevotella species 1
• The combination of ciprofloxacin plus metronidazole is the standard guideline-recommended regimen for mixed aerobic-anaerobic skin infections 1
• Warning: Absolutely no alcohol consumption during treatment and for 72 hours after finishing metronidazole, as this causes severe nausea, vomiting, and potentially dangerous reactions 1

Your Wound Care Regimen Explained

4% Chlorhexidine Soaks (7.5ml in 600ml water, twice daily for 15 days)

• This provides topical antiseptic action to reduce bacterial load on the skin surface and prevent reinfection 1
• Soak the affected area for 10-15 minutes twice daily
• The chlorhexidine concentration you're using is appropriate for skin antisepsis without causing excessive irritation 1
• Continue this for 15 days (5 days longer than antibiotics) to ensure complete surface decontamination 1

Drying Between Toes Thoroughly and Using Lamb's Wool

• Moisture between toes creates the perfect environment for bacterial growth, especially Pseudomonas which thrives in moist environments 1
• After each soak and after bathing, dry meticulously between each toe using a clean towel or hairdryer on cool setting
• Lamb's wool separates the toes to prevent moisture accumulation and skin-to-skin contact that promotes bacterial growth 1
• Replace the lamb's wool daily with fresh material 1

Why This Specific Combination Matters

The Infectious Diseases Society of America guidelines specifically recommend fluoroquinolone (ciprofloxacin) plus metronidazole for polymicrobial skin infections involving both aerobic and anaerobic bacteria 1. Your infection requires this dual approach because:

• Ciprofloxacin alone misses anaerobes like Prevotella 1
• Metronidazole alone has no activity against aerobes like Pseudomonas and Streptococcus 1
• Using both together provides complete coverage of all three organisms causing your infection 1

Critical Instructions for Success

Complete the Full Course

• Take all antibiotics for the full 10 days even if you feel better after 3-4 days 1
• Stopping early allows resistant bacteria to survive and causes relapse 1
• The infection may appear improved within 48-72 hours, but bacteria remain deep in tissues 1

Warning Signs Requiring Immediate Medical Attention

Seek emergency care immediately if you develop any of these 1:

• Fever over 101°F (38.3°C) or worsening fever after initial improvement
• Rapidly spreading redness beyond the marked borders
• Severe pain that seems out of proportion to the appearance
• Skin turning dark purple, black, or developing blisters
• Numbness or tingling in the affected area
• Confusion, dizziness, or feeling extremely ill
• These could indicate necrotizing fasciitis (flesh-eating infection) requiring emergency surgery 1, 3

Common Side Effects to Expect

Ciprofloxacin 1, 4, 5:

• Nausea (occurs in about 5-10% of patients)
• Mild diarrhea
• Headache
• Stop immediately and call your doctor if you develop tendon pain, especially in ankles or shoulders

Metronidazole 1:

• Metallic taste in mouth (very common, harmless)
• Nausea
• Dark urine (harmless, expected)

Why 10 Days for Antibiotics but 15 Days for Soaks?

The antibiotics kill active bacteria systemically, but surface colonization persists longer 1. The extra 5 days of chlorhexidine soaks after antibiotics finish ensures complete surface decontamination and prevents immediate reinfection from residual surface bacteria 1.

Follow-Up Expectations

• You should see improvement in pain, redness, and swelling within 48-72 hours 1
• If no improvement by day 3-4 of antibiotics, contact your doctor immediately 1
• Complete resolution typically takes 7-14 days after finishing antibiotics 1
• Schedule follow-up 2-3 days after completing all treatment to ensure complete resolution 1