PAP Basics - Germ Warfare Intro
- Definition: Perioperative Antibiotic Prophylaxis (PAP): Antibiotics given immediately before, during, or after surgery.
- Primary Goal: Prevent Surgical Site Infections (SSIs); not for treating active infections.
- Mechanism: Ensure bactericidal antibiotic levels in tissues by incision time.
- Critical Timing:
- Standard agents: Within 60 min pre-incision.
- Vancomycin/Fluoroquinolones: Within 120 min pre-incision.
- Duration: Typically single dose; may extend up to 24 hrs post-operatively.
- Selection: Guided by procedure-specific pathogens & patient allergy profile.
⭐ PAP aims to reduce microbial burden at the surgical site, enabling host defenses to prevent SSI.
Wound Classification - Infection Risk Radar
| Wound Class | Description | Infection Risk | PAP Indication |
|---|---|---|---|
| Clean | Non-traumatic, no inflammation; aseptic technique maintained. Respiratory, GI, GU tracts not entered. | 1-2% | Usually not needed; consider for high-risk cases. |
| Clean-Contaminated | GI/GU/respiratory tract entered under controlled conditions; no unusual contamination. Minor technique break. | 5-15% | Indicated. |
| Contaminated | Open, fresh, accidental wounds; major break in technique; gross spillage from GI tract; acute non-purulent inflammation. | 15-30% | Indicated. |
| Dirty/Infected | Old traumatic wounds, devitalized tissue; existing clinical infection (e.g., pus); perforated viscera. | >30% | Indicated (therapeutic, not just prophylactic). |
Antibiotic Selection - Bug-Drug Matchmaking
| Procedure Category | Common Pathogens | Preferred Prophylaxis | Alternatives (Allergy/MRSA) |
|---|---|---|---|
| Clean Procedures (Cardiac, Ortho, Neuro, Vascular) | S. aureus, CoNS  | Cefazolin 2g IV (3g if >120kg) | Vancomycin 15mg/kg IV or Clindamycin 600-900mg IV |
| Clean-Contaminated | |||
| - GI (Upper, Biliary) | Skin flora, GNRs, Enterococci | Cefazolin 2g IV | Clinda + (Gent or FQ) |
| - Colorectal / Appendectomy | GNRs, Anaerobes   | Cefoxitin 2g IV / Cefotetan 2g IV OR Ertapenem 1g IV OR Amp/Sulbactam 3g IV | Metro + (CTX or FQ or Gent) |
| - Hysterectomy (Vag/Abd) | Skin, Vaginal, Enteric flora | Cefazolin 2g IV | Clinda + (Gent or FQ) |
| - GU (entering tract) | Enteric GNRs | Ciprofloxacin 400mg IV / TMP-SMX | Gentamicin |
Administration & Special Populations - Clock & Complications
- Administration Timing & Redosing (The Clock):
- Infuse antibiotics:
- Most: within 60 minutes before incision.
- Vancomycin, Fluoroquinolones: within 120 minutes (longer infusion).
- Intraoperative Redosing:
- Procedure >2 drug half-lives (e.g., Cefazolin q4h).
- Major blood loss (>1500 mL or >20 mL/kg).
- Infuse antibiotics:
- Duration of Prophylaxis:
- Typically single dose.
- ⭐ > Discontinue within 24 hours post-surgery, even with indwelling drains.
- Cardiothoracic surgery: may extend up to 48 hours.
- Adjustments for Special Populations:
- Obesity (BMI >30): ↑ dose (e.g., Cefazolin 2g for >80kg; 3g for >120kg).
- Renal Impairment (CrCl <50mL/min): Adjust dose/interval for Cefazolin, Vancomycin.
- Known MRSA Colonization/High Risk: Add Vancomycin to standard regimen.
- Managing Beta-Lactam Allergies:
- Potential Complications:
- Allergic reactions (mild rash to anaphylaxis).
- Antibiotic-associated diarrhea, Clostridioides difficile infection.
- Emergence of antimicrobial resistance.
- Surgical Site Infection (SSI) despite prophylaxis.
High‑Yield Points - ⚡ Biggest Takeaways
- Timing is crucial: administer within 60 minutes prior to incision (120 minutes for vancomycin/fluoroquinolones).
- Cefazolin is the most common prophylactic antibiotic for clean/clean-contaminated surgeries.
- For beta-lactam allergy or MRSA risk, use vancomycin or clindamycin.
- A single dose is generally sufficient; re-dose for surgeries >2 drug half-lives or major blood loss.
- Post-operative antibiotics are not routinely indicated for prophylaxis.
- Dirty/infected wounds require therapeutic antibiotics, not just prophylaxis_._
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