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:
- Old age
- Malnutrition
- Obesity
- Corticosteroid use
- Diabetes mellitus
- Smoking
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.