Surgical Site Infection

Surgical site infection is infection involving the operative incision, deeper soft tissues or operated organ space.

Clinically divide it into:

• Superficial incisional infection involving skin and subcutaneous tissue
• Deep incisional infection involving fascia or muscle
• Organ space infection involving the operated cavity or organ

Management becomes progressively more source control dependent as infection extends deeper.

Superficial infection causes wound pain, erythema, warmth, swelling or purulent drainage.

Deep infection may produce increasing wound pain, induration, wound breakdown or deep purulent discharge.

Organ space infection may present predominantly with fever, tachycardia, ileus, abdominal pain or sepsis with little external wound abnormality.

Rapid progression, disproportionate pain, bullae, crepitus, skin necrosis or systemic toxicity should trigger immediate evaluation for necrotising infection.

Superficial incisional infection is usually diagnosed clinically.

CT with IV contrast: use for suspected deep incisional or organ space infection; identify deep collection or source requiring drainage.

Obtain wound cultures from purulent material when antimicrobial therapy is required or infection is severe, recurrent or healthcare associated.

The primary treatment of a superficial purulent surgical site infection is opening the incision and draining infected material. Antibiotics alone do not adequately treat a closed infected wound.

Remove sufficient sutures or staples to allow complete drainage. Debride devitalised tissue.

Systemic antibiotics are not required for every small superficial wound infection after effective drainage if there is minimal surrounding cellulitis and no systemic response. IDSA supports antibiotics when there is significant systemic response or extensive surrounding inflammation.

For cellulitic infection after a clean operation where methicillin susceptible staphylococci and streptococci are likely:

Cefazolin 2 g IV every 8 hours in a hospitalised adult with normal renal function.

Where MRSA risk is substantial, use vancomycin with dosing guided by weight, renal function and AUC monitoring. For serious MRSA infection, the target vancomycin AUC is 400 to 600 mg hour/L.

Following gastrointestinal or perineal surgery, antimicrobial therapy must also cover enteric Gram negative organisms and anaerobes. A reasonable severe regimen is:

Piperacillin tazobactam 4.5 g IV every 8 hours by extended infusion.

Deep fascial infection requires operative assessment because fascial necrosis or dehiscence may coexist.

Organ space infection requires drainage or other definitive source control. Once adequate intra abdominal source control is achieved, prolonged antibiotics are usually unnecessary and therapy should generally be limited to 4 days.