A 58-year-old man with type 2 diabetes mellitus (HbA1c 9.2%) undergoes elective open cholecystectomy for symptomatic cholelithiasis. On postoperative day 5, the wound shows erythema, induration, and purulent drainage. Culture grows Staphylococcus aureus. The patient is afebrile with stable vitals. What is the most appropriate immediate next step in management?

Explanation

## Postoperative Wound Infection Management **Key Point:** Purulent drainage with positive culture on postoperative day 5 indicates established surgical site infection (SSI) requiring source control — debridement is the cornerstone of management, not antibiotics alone. ### Clinical Context - Patient has risk factors: diabetes (impaired neutrophil function and angiogenesis), hyperglycemia (HbA1c 9.2%), and open surgical approach - Purulent drainage + erythema + induration = clinical signs of infection - Positive culture (S. aureus) confirms bacterial etiology - Afebrile status does NOT exclude need for intervention; local infection can be contained without systemic toxicity ### Why Debridement Is Mandatory 1. **Source control principle:** Infected/devitalized tissue must be removed to allow healing 2. **Biofilm prevention:** S. aureus readily forms biofilm on necrotic tissue; antibiotics alone cannot penetrate 3. **Timing:** Day 5 is optimal window — infection is localized, not yet systemic 4. **Tissue sampling:** Intraoperative culture and sensitivity guide definitive antibiotic therapy **High-Yield:** In the **proliferative phase** of wound healing (days 3–21), infection disrupts collagen deposition and angiogenesis. Removing the source is essential before antibiotics can work. **Clinical Pearl:** Diabetes impairs the inflammatory phase (days 0–5) — neutrophil recruitment and bacterial clearance are delayed. This patient's S. aureus infection at day 5 is a classic diabetic complication; aggressive source control prevents progression to necrotizing fasciitis. ### Management Algorithm ```mermaid flowchart TD A[Postoperative wound infection + purulent drainage]:::outcome --> B{Systemic toxicity?}:::decision B -->|Yes, fever/shock| C[Urgent debridement + broad-spectrum IV antibiotics]:::urgent B -->|No, afebrile/stable| D[Wound exploration under anesthesia]:::action D --> E[Debride necrotic/infected tissue]:::action E --> F[Send tissue culture + sensitivity]:::action F --> G[Start targeted antibiotics based on culture]:::action G --> H[Daily dressing changes, assess healing]:::action H --> I[Repeat debridement if needed]:::decision I -->|Infection resolved| J[Wound closure/skin graft]:::outcome I -->|Ongoing infection| K[Further debridement]:::urgent ``` **Mnemonic: SOURCE CONTROL** — **S**urgical removal of infected tissue, **O**pen drainage, **U**nderstanding biofilm, **R**emove devitalized tissue, **C**ulture for guidance, **E**arly intervention [cite:Sabiston 21e Ch 6]