A 58-year-old man undergoes elective open cholecystectomy for symptomatic cholelithiasis. Regarding the classification and risk stratification of surgical site infections in this patient, all of the following are true EXCEPT:

Explanation

## SSI Classification and Risk Stratification ### Why Option 3 is Incorrect **Key Point:** Extended prophylactic antibiotic coverage for 48 hours postoperatively is NOT indicated for elevated NNIS risk. Prophylactic antibiotics should be discontinued within 24 hours of surgery (48 hours for cardiac surgery). **High-Yield:** The NNIS risk index identifies patients at higher risk, but the response is NOT prolonged antibiotic prophylaxis — instead, it should trigger: - Enhanced intraoperative measures (strict asepsis, adequate tissue perfusion, normothermia) - Careful operative technique - Appropriate redosing during prolonged procedures - Standard postoperative wound care **Warning:** Prolonging prophylactic antibiotics beyond 24 hours does NOT reduce SSI rates and instead: - Increases antibiotic resistance - Increases cost - Increases adverse drug events - Promotes Clostridioides difficile infection ### Correct Statements Explained | Statement | Details | Evidence | |-----------|---------|----------| | **Wound Classification** | Cholecystectomy = clean-contaminated (CDC Class II) because the biliary tract is entered | [cite:CDC Surgical Site Infection Guidelines] | | **NNIS Risk Index** | Combines ASA score (≥3 = 1 point), wound class (clean-contaminated or contaminated = 1 point), operative time >75th percentile = 1 point; ranges 0–3 | [cite:Harrison 21e Ch 119] | | **SSI Rates by Class** | Class I: 1–3%; Class II: 3–7%; Class III: 5–15%; Class IV: >15% | [cite:Robbins 10e Ch 8] | ### CDC Wound Classification ```mermaid graph TD A[Surgical Wound]:::outcome --> B{Contamination Level?}:::decision B -->|Clean: no entry to GI/biliary/GU/respiratory| C[Class I: 1-3% SSI]:::outcome B -->|Clean-contaminated: controlled entry to GI/biliary/GU/respiratory| D[Class II: 3-7% SSI]:::outcome B -->|Contaminated: major break in sterile technique or gross spillage| E[Class III: 5-15% SSI]:::outcome B -->|Dirty: preoperative perforation or sepsis| F[Class IV: >15% SSI]:::urgent ``` **Clinical Pearl:** NNIS risk stratification guides perioperative optimization, NOT antibiotic duration. Prophylaxis timing and redosing are driven by drug half-life and operative duration, not risk category.