International
Glossary

Surgical Site Infection

Surgical site infections (SSI) are a problem for all surgical specialities and rank among the most common nosocomial infections in several countries, for example Germany*. To ensure consistent diagnosis of the different surgical site infections, e.g. for surveillance, the CDC case definitions are used**:

A1 Superficial incisional SSI

The infection at the incision area occurs within 30 days (90 days, respectively) after the operative procedure and involves only skin or subcutaneous tissue. In addition, the infection must meet one of the following criteria:

  1. Purulent discharge from the superficial incision.

  2. Microorganisms isolated (culture or non-culture based method) from an aseptically obtained culture of fluid or tissue from the superficial incision or subcutaneous tissue.

  3. One of the following signs of infection: pain or tenderness, localized swelling, redness, or heat,

    and

    the superficial incision is deliberately opened by the surgeon (this criterion does not apply when the microbiological culture from the superficial incision tested negative).

  4. Diagnosis by the attending physician.

A2 Deep incisional SSI

The infection occurs within 30 days (90 days, respectively) after the operative procedure and appears to be related to the operative procedure and involves fascia and muscle tissue. In addition, the infection must meet one of the following criteria:

  1. Purulent discharge from the deep incision but not from the organ or cavity (these infections belong to category A3).

  2. All of the following 3 criteria apply

    - The patient exhibits at least one of the following symptoms: fever (>38 °C), localized pain or tenderness.

    - The deep incision spontaneously dehisces or is deliberately opened by a surgeon.

    - Microorganisms isolated (culture or non-culture based method) from aseptically obtained material for purposes of clinical diagnosis or treatment, or no microbiological testing was performed. (This criterion does not apply when the microbiological culture from the deep incision tested negative).

  3. An abscess or other evidence of infection involving the deep layers is found on direct examination, during reoperation, or by histopathologic or radiologic examination.

  4. Diagnosis by the attending physician.

A3 Organ and cavity SSI

  1. The infection occurs within 30 days (90 days respectively) after the operative procedure and appears to be related to the operative procedure and involves parts of the body that are opened or manipulated during the operative procedure. In addition, the infection must meet one of the following criteria: Purulent discharge from a drain that is placed into the organ or cavity.

  2. Microorganisms isolated (culture or non-culture based method) from an aseptically obtained culture of fluid (and wound swab respectively), or tissue from the organ or cavity.

  3. An abscess or other evidence of infection involving the organ or cavity is found on direct examination, during reoperation, or by histopathologic or radiologic examination.

  4. Diagnosis by the attending physician.

There are a number of preventive measures that have been proven by evidence:

Recommendations of the WHO:

Recommendations of the Robert Koch-Institute:

* Behnke et al. Prävalenz von nosokomialen Infektionen und Antibiotika-Anwendung in deutschen Krankenhäusern.
Deutsches Ärzteblatt 2017, 114(50): 851-857

**Nationales Referenzzentrum für Surveillance von nosokomialen Infektionen, Robert Koch-Institut. Definitionen nosokomialer
Infektionen für die Surveillance im Krankenhaus-Infektions- Surveillance-System (KISS-Definitionen), Berlin 2017

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