Clinical meaning
Surgical site infections (SSIs) are infections occurring within 30 days of surgery (or 90 days for implant procedures) at the incision or in deep tissues manipulated during the operation. SSIs are classified as superficial incisional (skin and subcutaneous tissue), deep incisional (deep soft tissue, fascia, muscle), or organ/space (any body area opened during surgery other than the incision). Surgical wound classification guides infection risk: Class I (clean) has <2% infection risk, Class II (clean-contaminated) 3-11%, Class III (contaminated) 13-17%, and Class IV (dirty-infected) >27%. The Surgical Care Improvement Project (SCIP) established evidence-based measures including prophylactic antibiotic timing (within 60 minutes of incision), appropriate hair removal (clipping not shaving), glucose control in cardiac surgery, and normothermia maintenance. Biofilm formation on implanted materials creates antibiotic-resistant bacterial communities.
Exam relevance
Risk factors: - Diabetes mellitus with poor glycemic control (glucose >200 mg/dL perioperatively) - Obesity with increased subcutaneous tissue and poor wound perfusion - Smoking impairing microvascular perfusion and oxygen delivery to wound - Prolonged surgical duration exceeding expected time for procedure - Emergency surgery with contaminated or dirty wound classification