What is the best treatment for a patient with a 1-week history of an infected wound on the right knee, presenting with an abrasion filled with pus, surrounding erythema, and hyperpyrexia (fever)?

Treatment of Infected Knee Wound with Systemic Signs

This patient requires immediate incision and drainage of the purulent wound, empiric systemic antibiotics covering Staphylococcus aureus and Streptococcus species, and urgent assessment for deeper infection or necrotizing fasciitis given the high fever and week-long duration.

Immediate Management Priorities

Assess for Life-Threatening Infection

• Examine for signs of necrotizing fasciitis: crepitus, extensive necrosis, bullae, pain out of proportion to findings, or rapid progression 1
• Check for systemic inflammatory response beyond fever: hypotension, tachycardia >110 bpm, altered mental status 1
• If any concerning features present, obtain urgent surgical consultation for potential operative debridement 1

Wound Management

• Incision and drainage is the primary and most critical intervention for this purulent wound 1
• Evacuate all purulent material and continue dressing changes until healing by secondary intention 1
• Obtain wound cultures from deep tissue or purulent material before starting antibiotics 1
• Perform Gram stain to guide initial therapy 1

Antibiotic Therapy

Indication for Systemic Antibiotics

This patient clearly requires antibiotics given:

• Temperature >38.5°C (patient has 39.5°C) 1
• Surrounding erythema extending beyond wound margins 1
• One-week duration suggesting established infection 1

Empiric Antibiotic Selection

• Start with coverage for aerobic gram-positive cocci (S. aureus and Streptococcus species), as these are the most common pathogens in non-surgical clean wounds 1
• Consider local MRSA prevalence when selecting agent 1

Appropriate empiric options include:

• Anti-staphylococcal penicillin (e.g., flucloxacillin, nafcillin) if MRSA unlikely 1
• First-generation cephalosporin (e.g., cephalexin) 1
• Vancomycin or linezolid if MRSA suspected or high local prevalence 1

Route and Duration

• Parenteral therapy initially given high fever and systemic signs 1
• Transition to oral highly bioavailable antibiotics once clinically improving 1
• Duration: 2-4 weeks for moderate-to-severe soft tissue infections with systemic signs 1
• Continue antibiotics until infection resolves (not necessarily until wound heals) 1

Critical Pitfalls to Avoid

Do Not Rely on Antibiotics Alone

• Antibiotics without drainage is inadequate treatment for purulent infections 1
• Studies show no benefit from antibiotics alone when drainage is needed 1

Recognize When Broader Coverage Needed

• If patient fails to improve within 24-48 hours, consider:
  • Polymicrobial infection requiring broader spectrum coverage 1
  • Deeper infection requiring surgical exploration 1
  • Resistant organisms 1

Monitor for Progression

• Daily reassessment is essential to ensure treatment effectiveness 1
• Worsening erythema, persistent fever, or increasing pain despite treatment mandates surgical consultation 1

Adjunctive Measures

• Elevate the affected limb to reduce edema 2
• Consider venous thromboembolism prophylaxis if patient requires hospitalization 2
• Ensure tetanus prophylaxis is current
• Address any underlying risk factors (diabetes, immunosuppression, vascular disease) 1