What is the best treatment for a post-surgical infection with mild pus in an adult patient after excision of a chronic cyst in the sideburn region?

Treatment of Post-Surgical Infection After Chronic Cyst Excision

Open the wound immediately and drain any purulent material; antibiotics are only needed if systemic signs of infection are present (fever, tachycardia, hypotension, altered mental status) or if erythema extends more than 5 cm from the incision. 1

Immediate Wound Management

The primary treatment is surgical, not medical. The wound must be opened promptly to allow drainage of the purulent material. 1

• Remove sutures at the site of infection to allow adequate drainage 1
• Irrigate the wound thoroughly with sterile saline 1
• Pack the wound loosely with gauze if there is a significant cavity 1
• Do not reclose the wound—allow it to heal by secondary intention 1

When to Add Antibiotics

Antibiotics are NOT routinely needed for superficial surgical site infections after adequate drainage. 1, 2 The infected cyst has been removed, eliminating the source of infection. 2

Indications for Antibiotic Therapy

Add antibiotics ONLY if any of the following are present:

• Systemic signs: Fever (≥38°C), tachycardia, hypotension, oliguria, or altered mental status 1
• Extensive cellulitis: Erythema and induration extending >5 cm from the wound edge 1
• Immunocompromised status: Diabetes, chemotherapy, high-dose steroids, or transplant recipient 1
• Deep tissue involvement: Concern for fascial involvement or deep space infection 1

Antibiotic Selection (If Indicated)

For the sideburn region (clean surgical site), the expected pathogen is Staphylococcus aureus from skin flora. 1

First-line oral options:

• Cephalexin 500 mg every 6 hours 2, 3
• Dicloxacillin 500 mg four times daily 2

If MRSA suspected or penicillin allergy:

• Clindamycin 300-450 mg three times daily 2

Duration: 5-7 days if antibiotics are used 2

Critical Pitfall to Avoid

The most common error is reflexively prescribing antibiotics after drainage when they are not indicated. 4, 5, 2 The WHO and CDC explicitly state there is no evidence supporting postoperative antibiotics after successful surgical drainage of superficial infections without systemic signs. 4, 5, 2

• Antibiotics do not improve healing of adequately drained superficial wound infections 1, 2
• Unnecessary antibiotics increase antimicrobial resistance, Clostridioides difficile infection risk, and adverse drug reactions 5
• The presence of mild pus alone is NOT an indication for antibiotics—drainage is the definitive treatment 1, 6

Postoperative Wound Care

Proper wound care is more important than antibiotics for preventing complications. 2

• Warm soaks 3-4 times daily to promote drainage 6
• Daily dressing changes with saline irrigation 1, 2
• Remove packing within 24-48 hours and reassess 1
• Monitor for signs of worsening infection: Increasing erythema, fever, or systemic symptoms 1, 2
• Follow-up in 48-72 hours to ensure adequate drainage and wound healing 2

Special Consideration: Suture-Related Infection

If infection persists despite adequate drainage, consider suture-associated biofilm infection. 7 Retained suture material can harbor polymicrobial biofilms that perpetuate chronic infection. 7

• Remove ALL suture material from the infected area 7
• Debride any necrotic or infected tissue 1
• Culture the wound if infection persists after drainage 1

Algorithm Summary

1. Open wound and drain pus (always required) 1
2. Assess for systemic signs (fever, tachycardia, hypotension, altered mental status) 1
3. Measure erythema (>5 cm from incision edge?) 1
4. If NO systemic signs and erythema <5 cm: Drainage alone, no antibiotics 1, 2
5. If systemic signs OR erythema >5 cm: Add cephalexin 500 mg every 6 hours for 5-7 days 2, 3
6. Daily wound care with warm soaks and dressing changes 6
7. Follow-up in 48-72 hours 2