Surgical Site Infections

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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. Surgical Site Infection Layers Diagram

S. aureus is the most common SSI pathogen.

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.

Common SSI Pathogens: Gram-positive & Anaerobic

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

Surgical Site Infection Prevention Bundle

  • 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.

Practice Questions: Surgical Site Infections

Test your understanding with these related questions

In a surgical post-op ward, a patient developed wound infection. Subsequently 3 other patients developed similar infections in the ward. What is the most effective way of preventing the spread of infection?

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Flashcards: Surgical Site Infections

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_____ is a gram negative coccobacillus, obligate aerobe that causes resistant hospital-acquired infections.

TAP TO REVEAL ANSWER

_____ is a gram negative coccobacillus, obligate aerobe that causes resistant hospital-acquired infections.

Acinetobacter baumannii

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