surgical site infection

Introduction

Occurs within 30 days of surgical procedure.

Involves surgical field.

Etiology

• risk factors
  • history of skin infection
  • tobaccoism (smoking)
  • older age
  • immunosuppression*
  • duration of preoperative hospitalization
  • malnutrition, recent weight losss
  • cancer
  • shaving of hair
  • hypoxia
  • hypothermia
  • hyperglycemia
  • postoperative blood transfusion
  • Staphylococcus aureus carrier
  • inadequate surgical scrub, poor surgical technique
  • inappropriate use of antimicrobial prophylaxis
    • self-reported penicillin allergy associated with increased risk for surgical site infection
  • risk factors for MRSA
    • impaired functional status is a strong independent predictor
    • more severe wound
    • obesity
    • diabetes, postoperative hyperglycemia
    • pre-existing indwelling urinary catheter
    • longer duration of surgery
• organisms
  • Staphylococcus aureus is the most common pathogen
  • erysipelas caused by group A streptococci (case of venous procedure)
    • sharply demarcated erythema of the skin
  • Mycobacterium abscessus > Mycobacterium chelonae, Mycobacterium fortuitum

* intraoperative dexamethasone (used to prevent postoperative nausea/vomiting) does not predispose to surgical-site infections

Epidemiology

• overall incidence 1.2%
• risk maximum at 65 years of age, less in younger & older patients

Clinical manifestations

• most begin within 30 days of surgery or within 90 days after implant
• may be subtle
  • minimal clear drainage for 3 days after surgery not uncommon
  • erythema & pain at the incision site may not completely resolve in 3 days
  • if erythema & pain increase or new incisional drainage at surgical site post-op is noted, concern for a developing infection is warranted

Laboratory

• culture of wound drainage material, purulent fluid or infected deep tissue

* superficial wound swab cultures are likely to represent skin or wound colonization

Radiology

• CT if deep incisional infection or abscess suspected
• findings in patients with implants or prosthesis, generally non specific

Management

• treatment of deep incisional surgical site infections
  • surgical debridement with removal of necrotic tissue
  • abscess drainage
  • specific antimicrobial therapy
    • penicillin-based antibiotic for erysipelas
      • sharply demarcated raised superficial erythema (salmon red) of the skin
    • clarithromycin, amikacin, & moxifloxacin for Mycobacterium infection
  • otherwise, antimicrobial therapy not necessary with limited localized involvement & no systemic signs or symptoms
• prevention:
  • patients should shower or bath before surgery
  • surgical site should not be shaved
  • use triclosan-coated sutures for all surgery
  • antimicrobial prophylaxis 30-60 minutes before surgical incision
    • vancomycin or fluoroquinolone may be administered 10-120 minutes before surgical incision
    • maintain therapeutic levels throughout the procedure
  • stop prophylactic antibiotics when the procedure ends
    • postoperative antibiotic prophylaxis is associated with risks for acute kidney injury & C difficile colitis, without preventing surgical-site infections
  • avoid perioperative shaving of hair
  • use chlorhexidine-based skin preparation
    • use alcohol-based antiseptic [NEJM knowledge+ no reference]
  • administration of supplemental oxygen is controversial
  • glycemic control
    • postoperative glycemic control (< 180 mg/dL)
    • intensive perioperative glycemic control
    • apparently not routine [NEJM knowledge+ no reference]
  • tobacco cessation 30 days prior to surgery
  • bundle to screen for Staphylococcus aureus, decolonize carriers, & target antibiotic prophylaxis reduces surgical site infections by ~40%
    • nasal samples for Staphylococcus carrier state
      • nasal swab screening for S. aureus ~2 weeks before surgery
    • Staphylococcus carriers receive intranasal mupirocin & are bathed with chlorhexidine gluconate for up to 5 days before surgery
    • MRSA carriers receive vancomycin plus cefazolin or cefuroxime for perioperative prophylaxis
    • MSSA carriers & noncarriers receive cefazolin or cefuroxime
  • negative-pressure wound therapy may diminish risk of surgical site infection with primarily closed wounds with poor tissue perfusion due to surrounding soft tissue or skin damage

More general terms

• wound infection
• postoperative complication