Surgical Site Infection Prevention (Perioperative)
Comprehensive overview of the topic.
Exam Warning
SSI prevention is a high-yield exam topic. Examiners expect knowledge of evidence-based bundles, Australian antibiotic guidelines (TG), timing of prophylaxis, skin preparation agents, and specific considerations for implant surgery. Know the differences between clean, clean-contaminated, and contaminated wounds and their prophylaxis requirements.
SSI Definitions
Definitions and Classification
CDC Classification System
Surgical site infections (SSIs) are classified based on depth and timing:
Superficial Incisional SSI:
- Occurs within 30 days of surgery
- Involves only skin and subcutaneous tissue
- Must have at least one of: purulent drainage, organisms from culture, signs of infection (pain, swelling, redness, heat)
- Deliberately opened by surgeon (unless culture negative)
Deep Incisional SSI:
- Occurs within 30 days (no implant) or 90 days (implant present)
- Involves deep soft tissues (fascia, muscle)
- Purulent drainage from deep space or dehiscence
- Abscess or evidence of infection on imaging or re-exploration
- Most concerning in orthopaedics due to implant involvement
Organ/Space SSI:
- Involves anatomic structures opened or manipulated during surgery
- Examples: septic arthritis, osteomyelitis, epidural abscess
- Specific to orthopaedics: prosthetic joint infection, spinal implant infection
- Highest morbidity and often requires implant removal
The classification is critical for surveillance, benchmarking, and quality improvement initiatives. Deep and organ/space SSIs have significantly higher morbidity and costs.
Epidemiology and Risk Factors
Patient-specific factors significantly influence SSI risk:
Non-Modifiable Factors:
- Age (greater than 65 years increases risk 1.5-2x)
- Male sex (slightly higher risk)
- Genetic factors (immune function variants)
- Obesity (BMI greater than 30, risk increases 2-3x per 5-unit increase)
Modifiable Factors:
- Diabetes mellitus (poor control most significant - HbA1c greater than 8%)
- Smoking (relative risk 1.5-3x, impairs wound healing)
- Malnutrition (albumin less than 35 g/L, pre-albumin less than 18 mg/dL)
- Immunosuppression (steroids, chemotherapy, biologics)
- Anemia (hemoglobin less than 110 g/L)
- Remote infection sites (UTI, skin infection, dental abscess)
Optimization Opportunities:
- Smoking cessation (minimum 4 weeks pre-operatively, ideally 8 weeks)
- Glycemic control (HbA1c less than 7%, perioperative glucose less than 10 mmol/L)
- Nutritional supplementation (protein, vitamins)
- Treatment of remote infections
- Weight loss for elective procedures (if time permits)
- Medication adjustment (hold immunosuppressants when safe)
The most impactful modifiable factor is glycemic control in diabetics. Every 1% increase in HbA1c above 7% increases SSI risk by approximately 20%.
At a Glance
Surgical site infection (SSI) prevention requires a multimodal bundle approach targeting pre-operative, intra-operative, and post-operative phases. Key interventions include antibiotic prophylaxis timing (within 60 minutes of incision), chlorhexidine-alcohol skin preparation, MRSA screening and decolonization for high-risk procedures, and maintaining normothermia and euglycaemia (glucose under 10 mmol/L). Major modifiable risk factors include diabetes (HbA1c over 8%), smoking (minimum 4 weeks cessation), obesity, and prolonged operative duration. SSIs are classified by depth (superficial, deep, organ/space) with extended 90-day surveillance for implant surgery, where deep and organ/space infections may necessitate implant removal.
Pre-operative Prevention Strategies
Screening and Decolonization
MRSA Screening and Decolonization
MRSA colonization increases SSI risk 2-9 fold in carriers. Screening and decolonization protocols are evidence-based interventions:
Screening Protocol:
- Universal screening for high-risk procedures (arthroplasty, spinal instrumentation)
- Nasal swab PCR testing (rapid resu
Key Mnemonics
DIABETIC SMOKERMajor SSI Risk Factors
Memory Hook:Think of the stereotypical high-risk patient - a diabetic smoker needing surgery
60-30-2-4 RuleAntibiotic Prophylaxis Timing
Memory Hook:Remember the critical time intervals for prophylaxis dosing
WOUND WATCHSSI Warning Signs for Patients
Memory Hook:Tell patients to WATCH their WOUND for these warning signs
lts, 24 hours)
- Additional sites for high-risk patients (throat, perineum, wounds)
- Timing: Minimum 1 week before surgery (allows time for decolonization)
Decolonization Regimen (if positive):
- Mupirocin 2% nasal ointment (both nares, twice daily, 5 days)
- Chlorhexidine 4% body wash (daily, 5 days)
- Clean environment (wash bedding, clothing during treatment)
- Re-swab after completion (confirm clearance)
Australian Context: Not universally funded but increasingly adopted for high-risk arthroplasty patients. Cost-effectiveness demonstrated when SSI rates exceed 1%. Some states have mandatory screening programs.
Alternative Regimens:
- Povidone-iodine nasal antiseptic (alternative to mupirocin)
- Chlorhexidine-alcohol body wipes (inpatient convenience)
- Extended courses for recurrent colonization (10 days)
Evidence supports this intervention particularly for MRSA carriers undergoing implant surgery, where it reduces SSI rates by 40-60%.
Medical Optimization
Hyperglycemia is one of the most important modifiable risk factors:
Pre-operative Assessment:
- HbA1c measurement (target less than 7% for elective surgery)
- Consider delaying surgery if HbA1c greater than 8% (non-urgent cases)
- Diabetic medication review and optimization
- Endocrinology consultation for poorly controlled diabetes
Perioperative Management:
- Target blood glucose 6-10 mmol/L perioperatively
- More frequent monitoring in diabetics (every 2-4 hours)
- Insulin infusion protocols for major surgery
- Avoid hypoglycemia (less than 4 mmol/L increases complications)
Evidence Base:
- Each 1 mmol/L increase in perioperative glucose above 6.1 mmol/L increases SSI risk 20%
- Tight glycemic control (less than 8 mmol/L) reduces deep SSI by 50%
- Benefits seen in diabetic and non-diabetic patients
Australian Protocol (eTG):
- Continue long-acting insulin (reduce by 20-25%)
- Hold short-acting insulin on day of surgery
- Use variable-rate insulin infusion for prolonged fasting
- Resume normal regimen when eating and drinking
- Monitor and adjust based on frequent glucose checks
Post-operative:
- Continue glucose monitoring (minimum 48 hours for major surgery)
- Target less than 10 mmol/L in recovery period
- Liaison with diabetes team for adjustment
- Patient education on infection signs and glucose correlation
Glycemic control is perhaps the single most modifiable risk factor with the strongest evidence base across all surgical specialties.
Do not delay urgent or emergency surgery for medical optimization. The benefits of delaying surgery must outweigh the risks of the underlying condition progressing. For trauma and acute infections, proceed with surgery and optimize concurrently.
Antibiotic Prophylaxis - Pre-operative Timing
Timing Principles
Appropriate timing of antibiotic prophylaxis is critical for efficacy:
Optimal Timing:
- 30-60 minutes before skin incision (60 minutes for vancomycin due to slow infusion)
- Ensures therapeutic tissue levels at time of bacterial inoculation
- Too early: Antibiotic levels decline before wound closure
- Too late: Bacteria already established in wound
Australian Guidelines (eTG):
- Single dose 30-60 minutes pre-incision for most procedures
- Cefazolin 2g IV (3g if weight greater than 120 kg) standard for clean orthopaedic
- Flucloxacillin 2g IV alternative (narrower spectrum, less resistance pressure)
- Vancomycin 15-20 mg/kg IV (over 60-90 min) if MRSA risk or beta-lactam allergy
- Plus gentamicin 4-6 mg/kg IV for contaminated wounds
Re-dosing Requirements:
- Cefazolin: Every 2-4 hours if surgery exceeds one half-life (2 hours)
- Vancomycin: No re-dosing needed for most cases (long half-life 6-8 hours)
- Gentamicin: Usually single dose sufficient
- After tourniquet release (give dose before inflation, re-dose if multiple tourniquet applications)
Special Circumstances:
- Tourniquet surgery: Administer before tourniquet inflation (ensure wound bed levels)
- Massive transfusion: Re-dose after significant blood loss (greater than 1500 mL)
- Long procedures: Re-dose at 2x half-life intervals
- Revision surgery: Broader spectrum may be indicated (case-dependent)
Documentation:
- Checklist verification (WHO surgical safety checklist)
- Time of administration recorded
- Re-dosing documented in anesthetic record
- Antibiotic type and dose confirmed
The 30-60 minute window is critical. Studies show SSI rates increase 2-fold if antibiotics given after incision or greater than 2 hours before incision.
Intra-operative Prevention Strategies
Skin Preparation
Choice of skin preparation significantly impacts SSI risk:
Chlorhexidine-Alcohol (Preferred):
- 2% chlorhexidine gluconate in 70% isopropyl alcohol
- Most effective agent (superior to povidone-iodine in meta-analyses)
- Immediate action plus residual effect (6+ hours)
- Broad spectrum (Gram positive, Gram negative, fungi)
- Reduces SSI by 40% compared to povidone-iodine
- Allow 3 minutes drying time (essential for efficacy and fire prevention)
Povidone-Iodine:
- 10% povidone-iodine solution or 0.7% iodine with alcohol
- Slower onset (2 minutes to maximal effect)
- Shorter residual activity (1-2 hours)
- Broad spectrum including spores
- Use if chlorhexidine contraindicated (allergy, mucous membranes, neuraxial)
- Less effective in reducing SSI
Application Technique:
- Clean to dirty direction (centrifugal from incision site)
- Adequate time for antiseptic action (2-3 minutes)
- Complete drying before draping (fire risk with alcohol-based if wet)
- No wiping after application (removes residual antiseptic)
- Avoid pooling in skin folds or under patient (chemical burns, fire hazard)
Special Sites:
- Face/neck: Avoid chlorhexidine near eyes and ears (ototoxicity, eye damage)
- Neuraxial procedures: Povidone-iodine only (chlorhexidine neurotoxicity risk)
- Mucous membranes: Povidone-iodine (chlorhexidine causes irritation)
Australian Recommendations: Chlorhexidine-alcohol is first-line for skin preparation in orthopaedic surgery per NSQHS infection prevention standards. Stock multiple agents for contraindications.
Operating Room Environment
Ventilation and Laminar Flow
Operating room air quality directly impacts SSI risk in implant surgery:
Standard Operating Room Ventilation:
- Minimum 15 air changes per hour (Australian Standard AS 1668)
- Positive pressure relative to corridors
- HEPA filtration (high-efficiency particulate air)
- Filtered, temperature-controlled air supply
- Appropriate humidity (30-60%)
Laminar Flow Systems:
- Ultra-clean air (less than 10 colony-forming units per cubic meter)
- Unidirectional airflow over surgical field
- 300-400 air changes per hour in laminar zone
- Reduces airborne bacteria by 90-99% vs conventional
- Recommended for arthroplasty and spinal instrumentation
Evidence for Laminar Flow:
- Controversial - some studies show SSI reduction, others no benefit
- Benefit most clear in total joint arthroplasty (older studies)
- May be overcome by modern prophylaxis bundles
- Swedish data suggests benefit (mandatory for arthroplasty)
- UK data mixed (SPARE trial showed no benefit with modern prophylaxis)
Operating Room Discipline:
- Minimize traffic (each person increases bacterial counts)
- Keep doors closed (maintains pressure gradient and air flow)
- Limit personnel (only essential staff in room)
- Restrict entry/exit during critical periods
- No talking directly over open wounds (droplet spread)
Australian Context: Laminar flow not mandated but common in dedicated arthroplasty theaters. AS/NZS 1668 and AS/NZS ISO 14644 set ventilation standards. Increasing use in public and private joint replacement centers.
The debate continues, but consensus supports laminar flow for high-risk implant surgery (arthroplasty, spinal instrumentation) as part of comprehensive infection prevention despite mixed evidence.
Sterile Technique and Draping
Proper hand antisepsis is fundamental to sterile technique:
Alcohol-Based Surgical Rub (Preferred):
- 60-80% alcohol with emollients and antiseptic (chlorhexidine or povidone-iodine)
- 2-3 mL applied to dry hands and forearms
- Rub until completely dry (2-3 minutes)
- No water required
- Superior antisepsis compared to traditional scrub
- Faster and less skin irritation
- Recommended by WHO and CDC
Traditional Surgical Scrub:
- Chlorhexidine 4% or povidone-iodine 7.5% scrub solution
- 2-6 minute scrub (first case of day vs subsequent)
- Systematic hand and forearm washing
- Nail cleaning (first case only, avoid damaging nail beds)
- Rinse hands higher than elbows (water flows distally)
- Dry with sterile towel (hands first, then forearms)
Common Errors:
- Inadequate duration (rushing)
- Missing anatomical areas (nail beds, interdigital spaces)
- Contaminating scrubbed hands (touching faucet, splash contamination)
- Insufficient drying before gowning
Gloving:
- Double gloving recommended for implant surgery (reduces perforation exposure)
- Closed gloving technique (for first pair)
- Change outer gloves if contaminated or hourly (perforation risk)
- Indicator systems can detect perforations
- Consider orthopedic gloves (thicker, more puncture-resistant)
Australian Standards: AS 4815-2001 defines requirements for surgical hand preparation. Most hospitals have transitioned to alcohol-based rubs as primary method with scrub solution as backup.
Exam Pearl
The "sterile cockpit" concept borrowed from aviation safety means during critical phases of surgery (implant insertion, bone grafting, wound closure), all non-essential activity ceases - no phone calls, no teaching conversations, no equipment handoffs. This reduces distractions and contamination risk.
Wound Management Techniques
Wound Closure Overview
Wound Closure Principles
Goals of Closure:
- Eliminate dead space
- Approximate tissue layers precisely
- Minimise tension on wound edges
- Protect from bacterial contamination
Layered Closure:
- Deep fascia: Absorbable braided suture (Vicryl, PDS)
- Subcutaneous: Eliminate dead space, reduce tension
- Skin: Subcuticular preferred (lowest SSI risk)
Closure Methods
| Method | Advantages | SSI Considerations |
|---|---|---|
| Subcuticular | No suture tracts, cosmesis | Lowest SSI risk |
| Staples | Fast, cost-effective | Higher SSI than subcuticular |
| Interrupted nylon | Strong, adjustable tension | Suture tract risk |
Wound Healing Phases
Phases of Wound Healing
Haemostasis (Immediate):
- Platelet aggregation and clot formation
- Vasoconstriction followed by vasodilation
- Growth factor release
Inflammation (Days 1-4):
- Neutrophil and macrophage infiltration
- Debris removal and bacterial killing
- Critical phase - avoid disruption
Proliferation (Days 4-21):
- Fibroblast migration and collagen synthesis
- Angiogenesis and granulation tissue
- Epithelialisation begins (48-72 hours)
Remodelling (Weeks to Months):
- Collagen reorganisation and strengthening
- Maximum strength at 6-12 weeks (80% of normal)
- Scar maturation continues for 1-2 years
SSI Risk by Phase
| Phase | Duration | SSI Relevance |
|---|---|---|
| Haemostasis | Minutes to hours | Hematoma increases SSI 3x |
| Inflammation | Days 1-4 | Immune response critical |
| Proliferation | Days 4-21 | Keep wound protected |
| Remodelling | Weeks-months | Late infection still possible |
Wound Classification
Surgical Wound Classification
Class I - Clean:
- Elective, non-traumatic, no GI/GU/respiratory entry
- SSI rate: 1-3%
- Examples: THA, TKA, spinal fusion
Class II - Clean-Contaminated:
- Controlled entry to GI/GU/respiratory tract
- SSI rate: 5-10%
- Examples: Spine with intradural pathology
Class III - Contaminated:
- Open traumatic wounds (less than 4 hours)
- Major break in sterile technique
- SSI rate: 10-15%
- Examples: Open fracture Grade 1-2
Class IV - Dirty/Infected:
- Established infection, devitalized tissue
- SSI rate: 15-40%
- Examples: Open fracture Grade 3, debridement for osteomyelitis
Wound Classification Summary
| Class | Definition | SSI Rate |
|---|---|---|
| I - Clean | Elective, closed, no entry | 1-3% |
| II - Clean-Contaminated | Controlled entry | 5-10% |
| III - Contaminated | Open trauma, technique break | 10-15% |
| IV - Dirty | Established infection | 15-40% |
SSI Clinical Assessment
Recognising SSI
Signs of Superficial SSI:
- Erythema (greater than 1 cm from wound edge)
- Warmth and tenderness
- Purulent discharge
- Wound dehiscence
Signs of Deep SSI:
- All superficial signs plus systemic features
- Fever (greater than 38°C)
- Pain disproportionate to expected
- Elevated inflammatory markers (CRP, ESR)
Signs of Organ/Space SSI:
- Joint effusion (prosthetic joint infection)
- Neurological deficit (spinal epidural abscess)
- Sinus tract formation
- Loosening on imaging
SSI Assessment Criteria
| Feature | Superficial | Deep | Organ/Space |
|---|---|---|---|
| Location | Skin/subcutaneous | Fascia/muscle | Joint/bone |
| Fever | Usually absent | Often present | Usually present |
| Markers | Normal/mild rise | Elevated CRP | High CRP/ESR |
| Imaging | Not required | May help | Essential |
SSI Investigations
Diagnostic Workup
Blood Tests:
- FBC (leucocytosis, left shift)
- CRP (elevated, useful for monitoring)
- ESR (elevated in chronic infection)
- Blood cultures (if systemic signs)
Wound Assessment:
- Superficial swab (limited value, often colonisation)
- Deep tissue culture (gold standard)
- Aspirate of fluid collection
- Intraoperative samples (5+ specimens for PJI)
Imaging:
- X-ray (implant loosening, gas, bony changes)
- Ultrasound (fluid collections, guide aspiration)
- MRI (soft tissue involvement, epidural abscess)
- CT (detailed bony assessment, abscess localisation)
Investigation Utility
| Test | Best For | Limitations |
|---|---|---|
| CRP | Early detection, monitoring | Non-specific |
| Deep culture | Organism identification | False negatives if on antibiotics |
| MRI | Soft tissue/epidural abscess | Metal artefact, cost |
| Joint aspirate | PJI diagnosis | Requires lab processing |
SSI Management Principles
Treatment Approach
Superficial SSI:
- Open wound if purulent
- Local wound care
- Oral antibiotics if cellulitis
- Usually resolves with conservative measures
Deep SSI (Without Implant):
- Surgical debridement
- IV antibiotics initially
- Step-down to oral when improving
- Duration 2-4 weeks
Deep SSI (With Implant - Early):
- DAIR protocol if less than 4 weeks post-op
- Debridement, antibiotics, implant retention
- Exchange modular components
- Long-term suppressive antibiotics may be needed
SSI Treatment Summary
| Type | Primary Treatment | Antibiotic Duration |
|---|---|---|
| Superficial | Open/drain, local care | 5-7 days if needed |
| Deep (no implant) | Debridement, IV antibiotics | 2-4 weeks |
| Deep (with implant) | DAIR or revision | 6 weeks to lifelong |
Surgical Technique Considerations
Meticulous surgical technique is fundamental to SSI prevention:
Tissue Handling:
- Minimize trauma (gentle retraction, appropriate instruments)
- Preserve blood supply (avoid excessive periosteal stripping)
- Protect soft tissues (no crush injuries from clamps)
- Limit electrocautery use (devitalizes tissue)
- Irrigate regularly (remove debris and bacteria)
Hemostasis:
- Achieve meticulous hemostasis before closure
- Hematoma increases SSI risk 3-fold
- Use appropriate techniques (cautery, topical agents, tourniquet timing)
- Consider tranexamic acid (reduces bleeding and transfusion)
- Post-operative drains if dead space significant (controversial)
Dead Space Management:
- Eliminate dead space where possible (layered closure)
- Tack soft tissues to bone (prevent fluid accumulation)
- Drains for large potential spaces (controversial, may increase infection)
- If using drains, closed suction preferred
- Remove drains early (24-48 hours to minimize infection risk)
Irrigation:
- Copious irrigation before closure (3-9 liters for arthroplasty)
- Normal saline is standard (equal to antibiotic or antiseptic irrigation)
- Pulse lavage may increase soft tissue damage (low pressure preferred)
- Final irrigation after implant insertion and before closure
- Remove all irrigation fluid before closure
Closure:
- Layered closure (reduces dead space)
- Absorbable sutures for deep layers
- Skin closure: Subcuticular preferred (removes SSI risk from superficial sutures/staples)
- Alternatively, staples or sutures (remove at 10-14 days)
- Adhesive strips or glue for skin edge approximation
- Waterproof dressing (prevents bacterial ingress for 48-72 hours)
These technical factors are surgeon-controlled and represent major opportunities to reduce SSI risk through excellence in operative technique.
Wound drains are controversial for SSI prevention. While they remove potential fluid collections, they provide a portal for bacterial entry. If used, employ closed suction drains, use strict aseptic technique for management, and remove within 24-48 hours. Never use drains in clean cases without significant dead space.
Post-operative Prevention Strategies
Wound Care
Appropriate wound dressing is the first line of defense post-operatively:
Initial Dressing:
- Sterile, absorbent, occlusive dressing
- Applied in OR before drapes removed
- Waterproof outer layer (prevents contamination)
- Secure but not constrictive (avoid tourniquet effect)
- Leave intact for minimum 48-72 hours (epithelialization period)
Dressing Changes:
- Minimize dressing changes (each change is contamination risk)
- Change only if soiled, saturated, or non-adherent
- Strict aseptic technique for changes (clean gloves, antiseptic)
- Document appearance at each change (drainage, erythema, edema)
- Educate patient on signs of infection
Negative Pressure Wound Therapy (NPWT):
- Increasingly used for high-risk wounds
- Maintains clean, moist environment
- Reduces edema and promotes healing
- May reduce SSI in high-risk patients (obesity, diabetes, revision)
- Evidence strongest in trauma and high BMI
- Typically 5-7 days duration for prophylactic use
- Cost consideration (expensive vs standard dressing)
Showering:
- Avoid getting wound wet for 48-72 hours (epithelialization period)
- After epithelialization, brief showering allowed (no soaking)
- Pat dry immediately after shower
- No swimming or bathing until wound fully healed (minimum 2-3 weeks)
- Waterproof dressings allow showering from day 1 (some protocols)
Signs Requiring Dressing Change:
- Visible saturation or strike-through
- Odor
- Patient reports wetness or loosening
- Visible soiling (blood, drainage)
- Non-adherent or falling off
The goal is to maintain a clean, protected environment during the critical wound healing period while minimizing unnecessary wound exposure.
Post-operative Glucose Control
Continued Glycemic Management
Post-operative hyperglycemia increases SSI risk even in non-diabetics:
Target Glucose Levels:
- All patients: Less than 10 mmol/L for first 48 hours
- Diabetic patients: 6-10 mmol/L optimal (avoid hypoglycemia)
- Avoid hypoglycemia (less than 4 mmol/L increases complications)
Monitoring:
- Point-of-care glucose testing (fingerstick)
- Minimum every 6 hours for first 24-48 hours (major surgery)
- More frequent if diabetic or insulin infusion (every 2-4 hours)
- Continue until eating normally and glucose stable
Management:
- Sliding scale insulin (reactive approach, less ideal)
- Variable-rate insulin infusion (proactive, better control for major surgery)
- Resume home medications when tolerating oral intake
- Endocrinology consultation for difficult-to-control cases
Non-Diabetic Hyperglycemia:
- Stress response to surgery (cortisol, catecholamines)
- More common in major surgery, long cases, significant trauma
- Treat even in non-diabetics if glucose greater than 10 mmol/L
- Usually resolves as stress response diminishes (48-72 hours)
Evidence: Post-operative hyperglycemia (greater than 10 mmol/L) doubles SSI risk. Each 1 mmol/L increase above 6 mmol/L increases risk 10-20%. Benefits of control seen in diabetic and non-diabetic patients.
Australian Protocol: Many hospitals have post-operative glucose monitoring protocols for major orthopaedic surgery, regardless of diabetic status. Standardized insulin protocols improve consistency and safety.
Post-operative glucose control is an often-overlooked aspect of SSI prevention but has strong evidence and is easily modifiable with proper protocols.
Patient Education and Monitoring
Empowering Patients in SSI Prevention
Patient engagement is crucial for early detection and prevention of SSI:
Pre-operative Education:
- Infection signs and symptoms (redness, swelling, warmth, drainage, fever, pain)
- Wound care instructions (keep clean and dry, dressing changes)
- When to contact surgeon (clear criteria)
- Importance of adherence to restrictions (wound protection, activity)
- Role of patient in prevention (hygiene, medication compliance)
Discharge Instructions:
- Written information in plain language
- Visual aids (pictures of normal vs infected wounds)
- 24-hour contact number for concerns
- Follow-up appointment schedule
- Red flags requiring immediate attention
Monitoring Schedule:
- First post-operative visit: 10-14 days (wound check, suture removal)
- Second visit: 6 weeks (clinical and radiographic assessment)
- Additional visits as indicated by symptoms or risk factors
- Patient-initiated contact for concerns (low threshold to call)
Red Flags for Patients:
- Increasing pain after initial improvement
- Fever (greater than 38°C)
- Increasing redness or swelling around wound
- Purulent drainage or foul odor
- Wound dehiscence or separation
- Systemic symptoms (chills, malaise, confusion in elderly)
Barriers to Compliance:
- Health literacy (education level, language)
- Cognitive impairment (elderly, dementia)
- Social support (lives alone, limited assistance)
- Access to healthcare (remote location, transport)
Strategies to Overcome Barriers:
- Interpreter services for non-English speakers
- Family member involvement in education
- Community nursing support for wound care
- Telehealth follow-up for remote patients
- Simplified written materials with pictures
Australian context: Many patients discharged within 1-3 days for arthroplasty (enhanced recovery protocols). This makes patient education and self-monitoring critical as most SSI present after discharge.
Special Considerations
Implant Surgery
Joint arthroplasty requires enhanced SSI prevention due to catastrophic consequences of prosthetic joint infection:
Pre-operative Optimization:
- MRSA screening and decolonization (universal for arthroplasty)
- Dental clearance (treat active dental infections minimum 2 weeks before)
- Skin optimization (no active dermatitis, psoriasis, infections)
- Medical optimization (strict glycemic control, smoking cessation, weight optimization)
- Nutritional assessment (albumin greater than 35 g/L)
- Remote infection clearance (UTI, respiratory, skin infections)
Intra-operative Measures:
- Laminar flow operating rooms (when available)
- Body exhaust suits (controversial, some data supports)
- Double gloving with indicator systems
- Antibiotic-loaded cement (reduces early PJI in cemented arthroplasty)
- Minimize OR traffic (strict discipline)
- Dilute betadine lavage before closure (some surgeons use, evidence mixed)
- Extended antibiotic prophylaxis (controversial, single dose usually sufficient)
Post-operative Protocols:
- Strict wound monitoring (early PJI detection)
- Glucose control (target less than 10 mmol/L for 48 hours)
- Antibiotic prophylaxis for procedures (dental, urological, GI) - controversial timing
- Patient education on late PJI risk (years after surgery)
Evidence for Antibiotic Cement:
- Reduces early PJI by 30-50% in cemented arthroplasty
- Most benefit in high-risk patients (revision, immunosuppression, diabetes)
- Gentamicin most common (broad spectrum, heat stable)
- Concerns about resistance (use prophylactic doses, not therapeutic)
Australian Guidelines: Most Australian arthroplasty surgeons use antibiotic cement for cemented primary TKA. Less consensus for THA (more frequently uncemented). Standard practice for revision arthroplasty.
Antibiotic Stewardship
Balancing Prevention and Resistance
Appropriate antibiotic use prevents SSI while minimizing resistance development:
Principles of Stewardship:
- Use narrowest spectrum effective antibiotic
- Single dose for clean surgery (additional doses rarely beneficial)
- No routine post-operative antibiotics (prophylaxis only)
- Stop prophylaxis by 24 hours post-operatively (most cases)
- Document clear indication for extended courses
When to Extend Prophylaxis:
- Controversial and generally not recommended
- Possible exceptions: Retained hematoma, prolonged drains (debatable)
- Discuss with infectious disease if considering extension
- Not indicated for fear/anxiety about infection
Avoiding Overuse:
- Treating colonization (positive cultures without infection symptoms)
- Empiric treatment without infection (abnormal labs, low-grade fever)
- Extended durations without clear endpoint
- Broad spectrum without culture guidance
Australian Guidelines (eTG):
- Single dose cefazolin for clean orthopaedic surgery
- Discontinue within 24 hours post-operatively
- No routine prophylaxis after prosthetic joint for dental procedures (controversial, patient-specific decisions)
- Antibiotic choice guided by local resistance patterns
Resistance Concerns:
- MRSA rates increasing with overuse of vancomycin
- Extended-spectrum beta-lactamase (ESBL) organisms
- Multi-drug resistant Gram negatives
- Clostridium difficile from broad-spectrum use
Monitoring:
- Hospital antibiograms (resistance patterns)
- SSI rates (stratified by antibiotic choice)
- C. difficile infection rates (marker of antibiotic overuse)
- Surgeon-specific data (feedback for improvement)
Stewardship requires institutional commitment with pharmacy, infectious disease, and surgical collaboration. Education about resistance is key to changing prescribing culture.
Extended antibiotic prophylaxis (greater than 24 hours post-operatively) for routine clean orthopaedic surgery has no evidence of benefit and contributes to antibiotic resistance. Do not continue antibiotics simply because drains remain in place or out of anxiety about infection. Treat infections, do not prevent them with prolonged antibiotics.
Comprehensive SSI Prevention Bundles
Evidence-Based Bundles
Bundled Interventions
SSI prevention bundles combine multiple evidence-based interventions for synergistic effect:
Core Bundle Elements:
- Appropriate antibiotic selection and timing (60 minutes pre-incision)
- Glucose control (less than 10 mmol/L perioperatively)
- Normothermia (greater than 36°C intraoperatively)
- Chlorhexidine-alcohol skin preparation
- Appropriate hair removal (clippers, not razors)
- Sterile technique and OR discipline
Enhanced Bundle (Implant Surgery): 7. MRSA screening and decolonization 8. Pre-operative chlorhexidine bathing 9. Laminar flow operating rooms 10. Antibiotic-loaded cement (cemented arthroplasty) 11. Intrawound vancomycin (spinal instrumentation) 12. Negative pressure wound therapy (high-risk wounds)
Implementation:
- Checklist-driven (WHO surgical safety checklist + institution-specific)
- Team education and buy-in (surgeons, anesthesia, nursing)
- Audit and feedback (compliance rates, SSI outcomes)
- Continuous quality improvement (PDSA cycles)
- Multidisciplinary ownership (not just surgical)
Evidence: Bundle approaches reduce SSI by 40-60% compared to individual interventions. Compliance with all elements is key - partial compliance provides partial benefit. Checklist use improves compliance dramatically.
Australian Example: Many hospitals have adopted arthroplasty SSI prevention bundles based on international guidelines (AAOS, NICE, CDC). State-based quality improvement initiatives track compliance and outcomes.
Barriers to Implementation:
- Complexity (multiple elements to coordinate)
- Cost (some interventions expensive - NPWT, laminar flow)
- Cultural resistance (changing established practices)
- Time pressure (pre-operative preparation time)
- Lack of ownership (who is responsible for bundle compliance)
Success requires institutional commitment, leadership support, dedicated resources, and sustained effort. Bundles are most effective when integrated into routine workflow rather than additional tasks.
SSI Prevention Bundle Components by Evidence Level
| intervention | evidenceLevel | ssirReduction | implementation | cost |
|---|---|---|---|---|
| Antibiotic prophylaxis (appropriate timing) | Level 1 (RCT, meta-analysis) | 50-70% | Standard, checklist verification | Low ($5-20 per case) |
| Chlorhexidine-alcohol skin prep | Level 1 (RCT, meta-analysis) | 40-50% | Standard, product availability | Low ($10-30 per case) |
| Glucose control (perioperative) | Level 2 (cohort studies) | 30-50% | Protocol-driven, monitor compliance | Low ($20-50 per case) |
| Hair clipping (not shaving) | Level 1 (meta-analysis) | 50% vs razors | Education, equipment availability | Very low ($2-5 per case) |
| MRSA decolonization (if positive) | Level 1 (RCT, meta-analysis) | 40-60% in carriers | Screening program, patient compliance | Moderate ($50-100 per case screened) |
| Normothermia maintenance | Level 1 (RCT) | 30-40% | Warming devices, protocol | Moderate ($30-100 per case) |
| Laminar flow OR (arthroplasty) | Level 2-3 (observational, mixed results) | 20-50% (variable data) | Infrastructure, capital expense | Very high (millions for installation) |
| Intrawound vancomycin (spine) | Level 2 (meta-analysis observational) | 50-70% | Surgeon adoption, formulary | Low ($10-30 per case) |
| Negative pressure wound therapy | Level 2 (RCT in subgroups) | 30-50% in high-risk | Product availability, training | High ($200-500 per case) |
| Antibiotic-loaded cement (TKA) | Level 1 (RCT, meta-analysis) | 30-50% | Standard in many centers | Moderate ($100-300 per case) |
Complications of SSI
SSI Consequences
Patient Impact:
- Extended hospital stay (7-14 additional days)
- Multiple surgeries (debridement, revision)
- Prolonged antibiotic therapy (weeks to months)
- Functional impairment and disability
- Psychological distress
Implant-Related Complications:
- Prosthetic joint infection (most devastating)
- Implant loosening and failure
- Chronic osteomyelitis
- Need for revision or removal
- Limb salvage procedures or amputation
SSI Impact
| Complication | Frequency | Consequence |
|---|---|---|
| Extended stay | 90% of SSIs | 2-3x hospital costs |
| Reoperation | 50-80% of deep SSI | Additional morbidity |
| Implant failure | 30-50% of PJI | Major revision surgery |
| Mortality | 2-3x increase | Sepsis, complications |
Postoperative Care Summary
Post-Op SSI Prevention Protocol
First 48-72 Hours:
- Keep surgical dressing intact
- Monitor glucose (target less than 10 mmol/L)
- Maintain normothermia
- Early mobilisation when appropriate
- Pain control (avoid immunosuppressive doses of NSAIDs)
Discharge Planning:
- Wound care education
- Red flag symptoms to report
- Follow-up appointments scheduled
- Contact numbers for concerns
Follow-up Schedule:
- 10-14 days: Wound check, suture removal
- 6 weeks: Clinical and radiographic assessment
- Extended surveillance for implant surgery (90 days)
Post-Op Care Priorities
| Timeframe | Priority | Action |
|---|---|---|
| 0-48 hours | Dressing intact | No unnecessary wound exposure |
| 48-72 hours | Glucose control | Monitor and treat hyperglycaemia |
| Discharge | Education | Teach red flags and wound care |
| 2 weeks | Wound healing | Remove sutures/staples, assess healing |
Prevention Outcomes
Impact of Prevention Bundles
SSI Rate Reductions:
- Comprehensive bundles reduce SSI by 40-60%
- Antibiotic timing alone reduces SSI 50-70%
- MRSA decolonisation reduces SSI 40-60% in carriers
- Chlorhexidine prep reduces SSI 40% vs povidone-iodine
Quality Indicators:
- SSI rates are key surgical quality metrics
- Public reporting in many jurisdictions
- Pay-for-performance incentives
- Hospital accreditation requirements
Bundle Outcomes
| Intervention | SSI Reduction | Evidence Level |
|---|---|---|
| Full bundle compliance | 40-60% | Level 2 (multiple studies) |
| Antibiotic timing | 50-70% | Level 1 (RCT) |
| MRSA decolonisation | 40-60% | Level 1 (meta-analysis) |
| Chlorhexidine-alcohol | 40% | Level 1 (Cochrane) |
Evidence Base Summary
Key Evidence Sources
Level 1 Evidence:
- Antibiotic prophylaxis timing (multiple RCTs)
- Chlorhexidine-alcohol vs povidone-iodine (Cochrane)
- MRSA decolonisation (meta-analysis)
- Hair clipping vs shaving (meta-analysis)
- Normothermia maintenance (RCT)
Level 2 Evidence:
- Bundle approach effectiveness
- Glucose control targets
- Intrawound vancomycin (spine)
- Antibiotic-loaded cement (arthroplasty)
Key Studies
| Study | Finding | Impact |
|---|---|---|
| Classen (1992) | Antibiotic timing critical | 30-60 min window standard |
| Dumville (2015) | ChlorPrep superior | Chlorhexidine-alcohol first line |
| Schweizer (2013) | MRSA decolonisation works | 58% SSI reduction |
| Chiang (2014) | Intrawound vancomycin | 66% reduction in spine SSI |
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Pre-operative SSI Risk Assessment and Optimization
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Intra-operative SSI Prevention - Implant Surgery
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MCQ Practice Points
Exam Pearl
Q: What is the optimal timing for prophylactic antibiotic administration in orthopaedic surgery?
A: Antibiotics should be administered within 60 minutes before incision (ideally 30-60 minutes). For vancomycin or fluoroquinolones, start infusion 60-120 minutes before incision due to longer infusion times. Goals: achieve adequate tissue levels at time of incision. Redosing required if surgery exceeds 1-2 half-lives of antibiotic (e.g., cefazolin every 3-4 hours) or blood loss exceeds 1500mL. Discontinue within 24 hours postoperatively - extended prophylaxis does not reduce SSI and increases resistance/C. difficile risk.
Exam Pearl
Q: What is the recommended antibiotic prophylaxis for patients with penicillin allergy undergoing arthroplasty?
A: Depends on allergy severity: Mild penicillin allergy (rash only, no anaphylaxis): Cefazolin is safe (cross-reactivity less than 1% with 1st-generation cephalosporins). Severe/anaphylactic allergy: Vancomycin 15mg/kg (covers gram-positives including MRSA) plus or minus gentamicin or aztreonam (for gram-negative coverage). Alternative: Clindamycin 600-900mg. Note: Vancomycin alone does not cover gram-negatives. In MRSA-colonized patients, add vancomycin to cefazolin regardless of allergy status.
Exam Pearl
Q: What patient factors increase risk of surgical site infection in orthopaedic surgery?
A: Modifiable factors: Diabetes (HbA1c greater than 7.5%, glucose greater than 200mg/dL perioperatively), smoking (cease 4 weeks preoperatively), obesity (BMI greater than 40), malnutrition (albumin less than 3.5g/dL, TLC less than 1500), S. aureus nasal colonization (treat with mupirocin). Non-modifiable: Advanced age, immunosuppression, ASA score greater than 2, previous surgery at same site. Preoperative optimization: Glucose control, smoking cessation, nutritional supplementation, MRSA decolonization (chlorhexidine washes, nasal mupirocin).
Exam Pearl
Q: What is the role of chlorhexidine skin preparation in preventing surgical site infection?
A: Chlorhexidine-alcohol is superior to povidone-iodine for SSI prevention (NEJM POISE study - 40% reduction in superficial SSIs). Key points: Alcohol component provides rapid kill; chlorhexidine has residual activity. Allow to dry completely (2-3 minutes) before draping - reduces fire risk and optimizes antisepsis. Contraindicated: Near eyes, ears, mucous membranes. Preoperative chlorhexidine bathing (night before and morning of surgery) reduces skin bacterial colonization. Combine with nasal decolonization for MRSA carriers.
Exam Pearl
Q: What intraoperative measures reduce surgical site infection risk?
A: Antibiotic cement in arthroplasty (particularly revision surgery, high-risk patients). Laminar airflow theatres - controversial, may not reduce SSI vs conventional flow. Body exhaust suits - reduce bacterial shedding from surgical team. Minimize traffic in operating theatre. Maintain normothermia (hypothermia impairs neutrophil function). Glycemic control (glucose less than 180-200mg/dL). Wound irrigation with saline; antiseptic irrigation (dilute povidone-iodine, chlorhexidine) - evidence mixed. Double gloving and glove changes every 2 hours or after contamination.
Australian Context
Australian Guidelines and Resources
eTG Antibiotic Guidelines:
- Cefazolin 2g IV first-line for clean orthopaedic
- Flucloxacillin 2g IV alternative (narrower spectrum)
- Vancomycin for MRSA or beta-lactam allergy
- Single dose standard (no extended prophylaxis)
NSQHS Standards:
- Standard 3: Preventing and Controlling Infections
- SSI surveillance requirements
- Antimicrobial stewardship programs
- Hand hygiene compliance monitoring
Registry Data:
- AOANJRR tracks PJI rates for arthroplasty
- Surgeon and institution-specific reporting
- Benchmarking against national averages
- Quality improvement initiatives
Australian Resources
| Resource | Application | Access |
|---|---|---|
| eTG | Antibiotic selection | Subscription required |
| NSQHS Standards | Hospital accreditation | Free online |
| AOANJRR | Arthroplasty outcomes | Annual reports free |
| ACSQHC | Safety and quality | Free resources |
SSI Prevention Exam Essentials
High-Yield Exam Summary
Pre-operative Optimization
- •Glycemic control: HbA1c less than 7% for elective surgery, perioperative glucose less than 10 mmol/L
- •MRSA screening and decolonization: Mupirocin 2% nasal + chlorhexidine 4% wash x 5 days
- •Smoking cessation: Minimum 4 weeks (ideally 8 weeks) for meaningful SSI reduction
- •Nutritional assessment: Albumin greater than 35 g/L, supplement if deficient (7-14 days)
- •Chlorhexidine bathing: Night before and morning of surgery reduces bacterial load 90%
Antibiotic Prophylaxis
- •Timing: 30-60 minutes before incision (60 min for vancomycin)
- •Cefazolin 2g IV (3g if weight greater than 120 kg) - standard for clean orthopaedic
- •Vancomycin 15-20 mg/kg IV if MRSA or beta-lactam allergy (over 60-90 min)
- •Re-dosing: Every 2-4 hours for cefazolin if prolonged case (after 2 half-lives)
- •Duration: Single dose (no benefit beyond 24 hours post-op for clean surgery)
Skin Preparation
- •Chlorhexidine-alcohol 2%/70% preferred (40% SSI reduction vs povidone-iodine)
- •Application: Centrifugal from incision, 3-minute drying time essential
- •Hair removal: Clipping only if necessary (never shaving - increases SSI 2-3x)
- •Timing: Clip immediately before surgery (not night before)
- •Avoid: Chlorhexidine near eyes, ears (ototoxicity) and neuraxial procedures (neurotoxicity)
Intra-operative Measures
- •OR environment: Laminar flow for arthroplasty, minimize traffic, closed doors
- •Normothermia: Maintain greater than 36°C (forced air warming, warm IV fluids)
- •Sterile technique: Proper hand prep (alcohol rub or scrub), sterile draping
- •Surgical technique: Minimize tissue trauma, meticulous hemostasis, eliminate dead space
- •Irrigation: Copious normal saline (3-9 L for arthroplasty), final irrigation before closure
Post-operative Care
- •Dressing: Occlusive, waterproof, leave intact 48-72 hours (epithelialization period)
- •Glucose control: Continue monitoring, target less than 10 mmol/L for 48 hours
- •Drains: Early removal 24-48 hours if used (controversial - many avoid for routine cases)
- •Patient education: WOUND WATCH signs (warmth, oozing, uncontrolled pain, new fever, dehiscence)
- •Monitoring: First visit 10-14 days, low threshold for patient-initiated contact if concerns
Implant Surgery Specifics
- •Arthroplasty: MRSA screening, laminar flow, antibiotic cement (reduces PJI 30-50%)
- •Spine instrumentation: Intrawound vancomycin powder 1-2g (reduces SSI 50-70%)
- •Trauma/open fractures: Early antibiotics (within 1 hour), cefazolin + gentamicin for Grade 2-3
- •Negative pressure wound therapy: High-risk wounds (obesity, revision, trauma, long fusions)
- •Enhanced surveillance: 90 days for implant surgery vs 30 days for non-implant
Risk Factors (High-Yield)
- •Patient: Diabetes (especially HbA1c greater than 8%), obesity (BMI greater than 30), smoking, malnutrition, immunosuppression
- •Surgical: Duration (each hour increases risk 1.5x), implants, revision surgery, contaminated wounds
- •Modifiable: Glucose, smoking (4-8 weeks cessation), nutrition, MRSA, remote infections
- •Non-modifiable: Age (greater than 65), male sex, genetics, emergency surgery
Australian Context
- •eTG guidelines: Cefazolin first-line for clean orthopaedic, single dose, stop by 24 hours
- •NSQHS Standards: Infection prevention and control requirements, SSI surveillance
- •PBS: Subsidized antibiotics, nutritional supplements for specific indications
- •AOANJRR: Registry tracks PJI rates for arthroplasty, surgeon and institution-specific data
- •MRSA screening: Not universally funded, increasing adoption for high-risk arthroplasty
Summary
Surgical site infection prevention in orthopaedic surgery requires a comprehensive, evidence-based approach spanning the entire perioperative period. Success depends on implementing multiple interventions in a bundled fashion, as no single measure is sufficient.
Pre-operatively, focus on modifiable risk factors: glycemic control (HbA1c less than 7%, perioperative glucose less than 10 mmol/L), smoking cessation (minimum 4 weeks), nutritional optimization, MRSA screening and decolonization, and pre-operative chlorhexidine bathing. These interventions can reduce SSI risk by 40-70% in high-risk patients.
Intra-operatively, meticulous attention to antibiotic timing (30-60 minutes before incision), skin preparation (chlorhexidine-alcohol preferred), appropriate hair removal (clipping not shaving), maintenance of normothermia, operating room discipline, and surgical technique are critical. Each element has Level 1 evidence supporting efficacy.
Post-operatively, appropriate wound care, continued glucose monitoring, early drain removal if used, and comprehensive patient education ensure continued infection prevention and early detection if infection occurs.
Special considerations for implant surgery include enhanced protocols such as laminar flow operating rooms, antibiotic-loaded cement for cemented arthroplasty, and intrawound vancomycin for spinal instrumentation. Open fractures require early antibiotics (within 1 hour), timely debridement, and appropriate soft tissue management.
For exam preparation, focus on evidence levels for interventions, Australian guidelines (eTG), timing of antibiotic prophylaxis, skin preparation agents, and comprehensive bundle approaches. Understanding both the evidence and practical implementation demonstrates clinical competence and commitment to patient safety.