Surgical Site Infections

Surgical Site Infections - Defining the Enemy

• SSI: Infection at/near surgical incision. Occurs within 30 days post-op, or 90 days if implant present.
• CDC Classification (based on site):
  • Superficial Incisional: Involves skin & subcutaneous tissue of the incision.
  • Deep Incisional: Involves deep soft tissues (fascia, muscle layers) of the incision.
  • Organ/Space: Involves any organ or space (other than incision) opened or manipulated during surgery.

⭐ SSIs are the most common healthcare-associated infection (HAI) in surgical patients, affecting up to 5% of procedures.

Surgical Site Infections - Bugs & Breaches

• Key Pathogens (Bugs):
  • Staphylococcus aureus (MSSA/MRSA): Most common.
  • Gram-negatives: E. coli, Pseudomonas aeruginosa, Klebsiella spp.
  • Anaerobes: Bacteroides fragilis (esp. gut/pelvic surgery).
• Contributing Factors (Breaches):
  • Patient Factors: Diabetes, obesity, smoking, malnutrition, immunosuppression.
  • Procedural Factors:
    • Surgery duration >2 hrs.
    • Wound class (Dirty > Contaminated > Clean-Contaminated > Clean).
    • Surgical technique (hematoma, dead space).
    • Inadequate skin prep/antibiotic prophylaxis.
    • 📌 Shaving (use clippers just before surgery).

⭐ Most SSIs are caused by the patient's endogenous flora (skin, mucous membranes, or hollow viscera).

Surgical Site Infections - Dodging Infection Darts

• Risk Factors:
  • Patient: Diabetes (HbA1c > 7%), smoking, obesity (BMI > 30), malnutrition (Albumin < 3 g/dL), immunosuppression, MRSA carriage.
  • Procedure: ↑Duration, emergency, implants, wound class (Dirty > Contaminated > Clean-contam. > Clean), poor technique.
• Prevention Pillars:
  • Pre-op:
    • Optimize: Glucose (<200mg/dL), nutrition, smoking cessation (4-6 wks).
    • Skin: CHG shower, clip hair (no shaving).
    • Prophylactic Antibiotics (AMP):
      • IV within 60 min pre-incision (Vanco/FQ: 120 min).
      • Correct drug. Re-dose if surgery >2 half-lives or blood loss >1500mL.
  • Intra-op:
    • Strict asepsis, normothermia, supplemental O2.
    • Gentle tissue handling, minimize dead space.
  • Post-op:
    • Sterile dressing 24-48h. Glucose control.
    • Stop AMP within 24h (Cardiac: 48h).

⭐ Prophylactic antibiotics: Administer within 60 minutes before incision (Vancomycin/Fluoroquinolones: 120 minutes). Discontinue within 24 hours post-op.

Surgical Site Infections - Spot, Diagnose, Defeat

• Spotting SSI:
  • Local: Pain, erythema, warmth, swelling, purulent discharge.
  • Systemic: Fever >38°C, tachycardia, ↑WBC.
  • Timing: Superficial (first 30 days), Deep/Organ-space (up to 1 year if implant).
• Diagnosis:
  • Clinical: Local signs (pus, dehiscence) & systemic signs.
  • Culture: Wound aspirate/biopsy for C&S (before Abx).
  • Imaging: USG/CT for deep/organ-space collections.
  • Labs: ↑WBC, ↑CRP; blood cultures if sepsis suspected.
• Defeating SSI (Management): 📌 4 D's: Drainage, Debridement, Dressings, Drugs (Antibiotics).
  • Open & drain collections. Debride necrotic tissue.
  • Antibiotics: Empiric: cover S. aureus (Cloxacillin/Cephalosporin); add Gram-neg/anaerobic for severe/deep. Then C&S guided.
  • Consider Negative Pressure Wound Therapy (NPWT).

⭐ Staphylococcus aureus is the most common pathogen in SSIs.

High‑Yield Points - ⚡ Biggest Takeaways

• Staphylococcus aureus is the most common pathogen causing SSIs.
• SSIs are classified by depth: Superficial incisional, Deep incisional, Organ/Space.
• Give prophylactic antibiotics (e.g., Cefazolin) within 1 hour before incision.
• Key risk factors: diabetes, obesity, smoking, malnutrition, immunosuppression, prolonged surgery.
• Prevention: aseptic technique, clipping hair (not shaving), normothermia, glycemic control.
• Diagnosis is primarily clinical; wound culture guides antibiotics for established infection.