Should I start antibiotics for a foul-smelling skin infection with brown drainage?

Management of Skin Infection with Foul Odor and Brown Drainage

For a skin infection presenting with foul odor and brown drainage, antibiotics should be started if there are signs of significant cellulitis, systemic symptoms, or if the patient is immunocompromised. 1

Assessment of Infection Severity

• Evaluate the extent of infection - look for erythema, induration, warmth, and pain extending beyond the immediate area of drainage 1
• Check for systemic signs of infection - fever >38.5°C, pulse >100 beats/minute, or white blood cell count >12,000 cells/μL 1
• Assess for signs of deeper tissue involvement using a sterile probe to determine depth and extent of the wound 1
• Evaluate for foul odor and brown drainage, which may indicate anaerobic involvement or complex polymicrobial infection 1

Treatment Algorithm

For Simple Superficial Abscesses:

• Incision and drainage is the primary treatment 1
• Antibiotics are not needed if:
  • Erythema/induration is limited to the defined area of the abscess (<5 cm)
  • No systemic signs of infection are present
  • Patient is immunocompetent 1

Antibiotics ARE Indicated If:

• Significant surrounding cellulitis extends beyond the abscess margins (>5 cm) 1
• Systemic signs of infection are present (fever >38.5°C, tachycardia >100 beats/min) 1
• Patient is immunocompromised 1
• Source control is incomplete (cannot fully drain the abscess) 1
• Foul odor with brown drainage suggests anaerobic involvement or complex infection 1

Antibiotic Selection

• For suspected complex infection with foul odor and brown drainage:

  • Empiric broad-spectrum antibiotic therapy with coverage of Gram-positive, Gram-negative, and anaerobic bacteria is recommended 1
  • Consider amoxicillin-clavulanate as first-line therapy for moderate infections 2
  • For more severe infections, parenteral therapy may be necessary (e.g., piperacillin-tazobactam, or a carbapenem) 1

• If MRSA is suspected:

  • Add coverage with vancomycin, linezolid, or daptomycin 1
  • For community-acquired MRSA with less severe presentation, consider clindamycin, trimethoprim-sulfamethoxazole, or linezolid 1, 3

Special Considerations

• Obtain cultures before starting antibiotics when possible to guide definitive therapy 1
• Tissue samples provide more accurate results than superficial swabs 1
• Foul odor with brown drainage often indicates anaerobic involvement, which requires appropriate antibiotic coverage 1
• In diabetic patients or those with peripheral vascular disease, more aggressive treatment may be needed due to impaired wound healing 1

Common Pitfalls to Avoid

• Failing to adequately drain an abscess - surgical drainage is the primary treatment 1
• Starting antibiotics for simple abscesses that only need drainage 1
• Not considering anaerobic coverage when foul odor is present 1
• Delaying treatment in patients with systemic signs of infection 1
• Using fluoroquinolones alone for suspected MRSA infections (inadequate coverage) 1

The presence of foul odor with brown drainage strongly suggests a complex infection that likely involves anaerobes, which typically requires both adequate drainage and appropriate antibiotic therapy 1.