What is the preferred antibiotic (ABx) regimen for a stoma site infection with green drainage?

Stoma Site Infection with Green Drainage: Antibiotic Selection

For a stoma site infection with green drainage (suggesting Pseudomonas aeruginosa), use piperacillin-tazobactam 3.375-4.5g IV every 6-8 hours, or alternatively ceftazidime 2g IV every 8 hours or cefepime 2g IV every 8-12 hours, combined with metronidazole 500mg every 8 hours if there is concern for anaerobic involvement from intestinal flora. 1

Clinical Context and Pathogen Considerations

Green drainage is highly characteristic of Pseudomonas aeruginosa infection, which requires specific anti-pseudomonal coverage that standard surgical site infection regimens may not provide. 1

Site-Specific Antibiotic Selection

The anatomic location of the stoma determines the appropriate empiric coverage:

For intestinal or genitourinary tract stomas (ileostomy, colostomy, urostomy):

• Single-agent regimens with anti-pseudomonal activity:

  • Piperacillin-tazobactam 3.375g every 6h or 4.5g every 8h IV 1
  • Imipenem-cilastatin 500mg every 6h or 1g every 8h IV 1
  • Meropenem 1g every 8h IV 1
  • Ertapenem 1g every 24h IV (note: lacks anti-pseudomonal activity) 1

• Combination regimens for confirmed/suspected Pseudomonas:

  • Ceftazidime 2g every 8h IV + metronidazole 500mg every 8h IV 1
  • Cefepime 2g every 8-12h IV + metronidazole 500mg every 8h IV 1
  • Ciprofloxacin 400mg IV every 12h + metronidazole 500mg every 8h IV 1
  • Levofloxacin 750mg IV every 24h + metronidazole 500mg every 8h IV 1

For stomas near the axilla or perineum:

• The same anti-pseudomonal coverage applies, but ensure anaerobic coverage with metronidazole or a β-lactam/β-lactamase inhibitor combination 1

Important Clinical Caveats

Culture and Susceptibility Testing

• Always obtain cultures from the stoma site drainage before initiating antibiotics, as this is a surgical site infection requiring pathogen-directed therapy 1
• Adjust antibiotics based on culture results and local resistance patterns, particularly for fluoroquinolone resistance in E. coli (increasingly common) 1

MRSA Considerations

If there is purulent drainage with systemic signs or the patient has healthcare-associated risk factors, add vancomycin 15mg/kg IV every 8-12h for empiric MRSA coverage until cultures return 1

Fluoroquinolone Limitations

While ciprofloxacin and levofloxacin have anti-pseudomonal activity, local E. coli resistance patterns should be reviewed before using fluoroquinolones as first-line agents, as resistance rates now exceed 20% in many communities 1

Source Control Requirements

• Surgical evaluation is mandatory - antibiotics alone are insufficient without adequate drainage and debridement 1
• Remove sutures if present and ensure adequate drainage of the infected stoma site 1
• Consider imaging (CT or ultrasound) if there is concern for deeper infection or abscess formation 1

Duration and Monitoring

• Continue antibiotics until clinical signs of infection resolve (typically 5-7 days for uncomplicated surgical site infections) 1
• Transition to oral therapy is appropriate once the patient is afebrile, tolerating oral intake, and showing clinical improvement 1
• Oral step-down options include ciprofloxacin 750mg PO every 12h plus metronidazole 500mg PO every 8h (if susceptible) 1

Red Flags Requiring Escalation

• Persistent fever or leukocytosis beyond 48-72 hours of appropriate therapy suggests inadequate source control or resistant organisms 1
• Necrotizing infection signs (severe pain, crepitus, systemic toxicity) require immediate surgical consultation and broader coverage including vancomycin or linezolid plus a carbapenem 1