Surgical Site Infections

SSI: Definition & Classification - Defining the Enemy

• Definition: Post-op infection at/near incision. Within 30 days (90 if implant). Involves skin, subcutaneous, deep tissues (fascia/muscle), or organ/space.
• CDC Types:
  • Superficial Incisional:
    • Skin, subcutaneous. Within 30 days.
    • Criteria: Pus; +ve culture; inflammation signs (pain, swelling, redness, heat); surgeon Dx.
  • Deep Incisional:
    • Fascia, muscle. Within 30 days (90 if implant).
    • Criteria: Deep pus; dehiscence/opened + fever/pain; abscess.
  • Organ/Space:
    • Manipulated organ/space. Within 30 days (90 if implant).
    • Criteria: Drain pus; +ve culture from site; abscess.

⭐ S. aureus is the most common SSI pathogen.

SSI: Pathogens & Risks - Rogues' Gallery

Common Culprits:

• Staphylococcus aureus: #1 offender (skin, nares). Includes MRSA.

  ⭐ Staphylococcus aureus is the most common pathogen causing SSIs, responsible for up to 30% of cases.

• Coagulase-Negative Staphylococci (CoNS): Prosthetics, devices.
• Enterococcus spp.: Gut, GU procedures.
• Gram-Negative Rods:
  • E. coli: Colorectal, appendicitis.
  • Pseudomonas aeruginosa: Burns, ICU, prolonged stay.
• Anaerobes (Bacteroides fragilis): Bowel, OB-GYN surgery.

Key Risk Factors:

• Patient-Related:
  • Diabetes (glucose >200 mg/dL)
  • Obesity (BMI >30)
  • Smoking
  • S. aureus nasal carriage
  • Immunocompromise
• Procedure-Related:
  • Wound class (Contaminated/Dirty > Clean)
  • Prolonged duration
  • Emergency surgery
  • Implants
  • Inadequate antibiotic prophylaxis

SSI: Prevention Strategies - Fortress Protocol

• Pre-operative Shield:
  • Patient optimization: Glycemic control (BG < 200 mg/dL), smoking cessation (4 wks prior), nutrition.
  • Decolonization: Nasal mupirocin (S. aureus carriers); CHG showers.
  • Hair removal: Clippers (not razors), immediately pre-surgery.
  • Antimicrobial Prophylaxis (AMP):
    • Administer: Within 60 min pre-incision (Vanco/FQ: 120 min).
    • Choice: Guideline-directed.
    • Duration: Discontinue within 24 hrs post-op.
• Intra-operative Barrier:
  • Asepsis: Strict hand hygiene; CHG-alcohol skin prep.
  • OR environment: Positive pressure ventilation, ↓OR traffic, sterile instruments.
  • Physiological stability: Normothermia (>36°C), Oxygenation (FiO2 80%), glycemic control.
  • Surgical technique: Gentle handling, hemostasis, obliterate dead space.
• Post-operative Vigilance:
  • Wound care: Sterile dressing 24-48 hrs; aseptic dressing changes.
  • Glucose control: Maintain normoglycemia.
  • Surveillance: Monitor SSI signs; team feedback.

⭐ Most SSIs (≈80%) are caused by the patient's endogenous flora; pre-operative skin decolonization & preparation are key.

SSI: Diagnosis & Management - Battle Plan

Diagnosis:

• Clinical: Pus, erythema, pain, warmth, dehiscence at incision. Fever >38°C, ↑WBC count.
• Timing: Typically within 30 days post-op (or up to 1 year if implant in situ).
• Labs: Wound culture (aspirate/biopsy preferred over swab). Blood cultures if systemic signs present.
• Imaging: Ultrasound (USG) or CT for deep/organ-space SSI detection.

Management Strategy:

• Source Control FIRST:
  • Open incision, drain, debride non-viable tissue. Infected implant may need removal.
• Antimicrobials:
  • Empiric: Broad-spectrum (e.g., Vancomycin + Pip-Tazo) covering common pathogens.
  • Definitive: Culture-guided. Duration varies by SSI severity.
• Supportive Care: Wound dressings (NPWT), nutrition.

⭐ Staphylococcus aureus is the most common pathogen causing SSIs. Consider MRSA coverage empirically in high-risk settings.

High‑Yield Points - ⚡ Biggest Takeaways

• SSIs are the most common nosocomial infection in surgical patients.
• Staphylococcus aureus is the most frequent pathogen responsible for SSIs.
• Classified into Superficial incisional, Deep incisional, and Organ/space infections.
• Key risk factors include patient comorbidities (e.g., diabetes, obesity) and procedural aspects (e.g., prolonged surgery, wound contamination class).
• Preoperative antibiotic prophylaxis, typically with Cefazolin, administered within 1 hour before incision is crucial.
• Proper aseptic techniques during surgery and postoperative wound care are vital for prevention.
• Wound classification (Clean, Clean-contaminated, Contaminated, Dirty) directly correlates with SSI risk.