Nationales Referenzzentrum
für Surveillance
von nosokomialen Infektionen


Module Summary

Module: OP-KISS

Surveillance goal: Infection surveillance

Surveillance principle: Patient/ward based

Patient group: Inpatients undergoing certain surgical procedures


OP-KISS consists of surgical site infection surveillance following very frequent or specifically relevant indicator operative procedures. Participating centers select indicator operative procedures for surveillance in their ward. Patients are kept under surveillance for up to 30 days post-procedure (or up to 1 year if implants are involved). Surveillance ends with discharge or renewed surgery. Postoperative lower respiratory tract infections may also be recorded. In this case, all patients undergoing an indicator operative procedure are kept under surveillance for lower respiratory tract infections as well as surgical site infections.

OP-KISS component (surgical site infection surveillance)

Surgical site infections (SSI) are the third most common kind of nosocomial infection and are a problem for all surgical specialties. SSI often have serious consequences for affected patients and for the entire unit and have always especially been taken into account by doctors and patients.

In order to make comparisons possible between different clinics, infection rates for different kinds of operation have to be analysed separately. For this reason, KISS concentrates on a series of indicator operative procedures which are especially common or in which SSI are particularly relevant (see INDICATOR-OP). Participating units select one or more types of indicator operative procedure from a catalogue, which includes over 25 kinds of operation from almost all surgical specialities. Indicative operation groups are defined by their OPS codes or to some degree by their ICD-10-GM codes. In order to determine the number of SSI, every patient who underwent a selected indicative operation is tracked post-op at least until his or her hospital discharge. Consistent diagnosis can be achieved with the use of CDC criteria for SSI. These infections are sorted into superficial, deep and organ/space infections. The SSI rate per type of procedure can be calculated from the number of SSI that occurred following all indicative operations of that group.

Risks are stratified in order to compensate for differences in patient population between clinics and in order to determine the individual risk of a patient based on certain known risk factors. To this end, the internationally used NNIS score is applied, which considers operation duration, the patient’s ASA score and the degree of wound contamination. Operations are divided into risk categories according to the number of risk variables present.

Separate wound infection rates are calculated for laparoscopic and open invasive procedures for certain kinds of operations (appendectomy, colon surgery, and cholecystectomy, for example). In order to simplify data interpretation, the NRZ calculates a standardised SSI ratio for each type of operation. This ratio reflects the relation the number of observed SSI to the expected number of SSI according to the patient risk spectrum. Appropriate data for each indicative operation have to be documented for the calculation of wound infection rates and for classification into risk categories.

The NRZ provides KISS participants with an electronic system for documenting surveillance data. Hospitals interested in participating in OP-KISS first have to complete a course in surveillance methods and diagnosis. An appropriate course will use examples to train diagnostic skills, among other methods. Interested parties can find the next dates for introductory courses on our homepage under “Events.” 


Brümmer S, Brandt C, Sohr D, Gastmeier P.
Does stratifying surgical site infection rates by the National Nosocomial Infection Surveillance risk index influence the rank order of the hospitals in a surveillance system?
J Hosp Infect 2008; 69 (): 295-300.

Brümmer S, Sohr D, Rüden H, Gastmeier P.
Wundinfektionen nach laparoskopischen Operationen; Ergebnisse des Krankenhaus-Infektions-Surveillance-Systems.
Der Chirurg 2007; 78: 910-14.

Mannien J, van den Hof S, Brandt C, Behnke M, Wille J, Gastmeier P. Comparison of National surgical site infection surveillance data between The Netherlands and Germany: PREZIES versus KISS.
J Hosp Infect, 66: 2007; 224-231.

Bärwolff S, Sohr D, Geffers C, Brandt C, Vonberg R, Halle H, Rüden H, Gastmeier P.
Reduction of surgical site infections after caesarean delivery using surveillance.
J Hosp Infect 2006; 64: 156-61.

Brandt C, Sohr D, Behnke M, Daschner F, Rüden H, Gastmeier P.
Reduction of surgical site infection rates associated with active surveillance.
Infect Control Hosp Epidemiol 2006; 27: 1287-90.

Gastmeier P, Brandt C, Sohr D, Rüden H.
Postoperative Wundinfektionen: Der Chirurg als Täter oder Opfer.
Der Chirurg 2006; 77: 506-11.