Postoperative Wound Infections

Excerpt

Surgical site infections represent the primary source of nosocomial infections in surgical patients. Before the advent of the germ theory of infection and the recognition of the preventive efficacy of antisepsis, the incidence of postoperative surgical infections was alarmingly high, often resulting in limb amputation or mortality. However, the adoption of antiseptic techniques significantly ameliorated patient outcomes.

Surgical site infections contribute significantly to postoperative morbidity and mortality rates, with current data revealing that they are responsible for over 2 million nosocomial infections in the United States. The Centers for Disease Control and Prevention (CDC) classify surgical site infections into categories such as superficial, deep incisional, or organ/space infections. Any surgical wounds declared infected or opened by the surgeon are designated as surgical site infections. These infections must occur within 30 days following surgery or within 1 year after implantation to meet the classification criteria. For surgical site infection categories, please refer to the January 2023 CDC-National Healthcare Safety Network (NHSN) Patient Safety Component Manual for a more detailed description and information.

Superficial Incisional Infections

These surgical site infections exclusively affect the skin and subcutaneous tissues, constituting over 50% of all surgical site infections. Diagnosis of a superficial incisional infection necessitates meeting one of the following criteria:

1. Presence of purulent discharge from the surgical site.

2. Identification of an organism from the surgical site.

3. Clinical diagnosis of a surgical site infection by the surgeon.

4. Deliberate opening of the wound by the surgeon, accompanied by at least one associated infectious symptom, such as swelling, erythema, or localized pain or warmth.

Deep Incisional Infections

These infections involve soft tissues deep into the subcutaneous tissue, including muscles and fascial planes. This diagnosis requires 1 of the following criteria:

1. Presence of purulent discharge from the surgical site.

2. Wound dehiscence.

3. Deliberate re-opening of a deep incision by the surgeon due to suspicion of infection or wound spontaneously dehisces, and a positive wound culture and at least one infectious symptom is present (eg, fever, localized pain, or tenderness)

4. Evidence of abscess formation or infection involving deep tissues, as observed on a computed tomography (CT) scan.

Organ/Space Infections

These infections may involve any organ or anatomical space beyond the incision site but deeper than the fascial or muscle layers, including implant-related infections. Diagnosis requires meeting one of the following criteria:

1. Presence of purulent discharge from a drain placed in the organ, space, or cavity.

2. Identification of an isolated organism from the involved organ, cavity, or related abscess.

3. Evidence of abscess formation or infection involving the organ, cavity, or anatomical space, as observed on a CT scan.

4. Notably, a wound is not considered infected if only a stitch abscess, localized cellulitis, or an infected superficial stab puncture is present.

Most surgical site wound infections originate from endogenous flora typically found on mucous membranes, skin, or hollow viscera. Generally, when the concentration of microbiological flora exceeds 10,000 microorganisms per gram of tissue, the risk of wound infection escalates.