Postoperative wound infection

Infection of postoperative wound, also called a surgical site infection, is one of the most common complications of postoperative wounds. They account for high morbidity and mortality. The majority of cases occur due to endogenous bacterial flora which is present on the mucous membranes or skin.

By definition, postoperative wounds must be infected within 30 days post-surgery. However, most cases occur after 3 – 7 days.

Etiology

The most common offending bacteria are staphylococcus aureus, coagulase-negative staphylococci, enterococci, and E. coli.

There are both patient-related risk factors and procedure-related risk factors for postoperative wound infection.

Patient-related risk factors:

Procedure-related risk factors:

Formation of haematoma at the site of the wound
Leaving drains in the wound
Leaving dead space in the wound
Long and difficult surgery
Poor preparation of surgical site

Clinical features

A postoperative wound infection will have clinical features similar to other infected wounds:

Erythema
Localised pain
Unexplained fever
Purulent discharge from the wound
Wound dehiscence
Delayed wound healing

Diagnosis and evaluation

The diagnosis is made based on clinical evaluation of the wound, including presence of the clinical features. A microbiological sample from the wound should be taken to isolate the microbe. If it’s suspected that the infection is deep, imaging with ultrasound or CT/MRI may be useful.

Treatment

All postoperative wounds are treated with wound exploration (opening) and serial (repeated) debridement and dressing changes. These wounds are often left to heal by secondary intention rather than primary closure. Moist dressing facilitate healing. Antibiotics are necessary only if the wound is deep or if the infection is systemic.

Negative pressure wound therapy, also called vacuum-assisted closure, refers to the use of a device which applies subatmospheric pressure to the wound surface. This facilitates wound healing and may be used.

Prevention

Proper operative risk stratification, preoperative skin preparation, maintenance of operating theatre sterility, and the use of prophylactic antibiotics, are the most important measures to prevent postoperative wound infection. The type of prophylactic antibiotic depends on the type of surgery. For most surgeries the choice is usually cefazolin.