Protocol for the surveillance of surgical site infections and prevention indicators in European hospitals : Healthcare-Associated Infection surveillance Network (HAI-Net) surgical site infection (SSI) protocol, version 2.3.
Date: 2025-03-31
Institutions: European Centre for Disease Prevention and Control
Subjects: data collection, health care, health statistics, hospitalisation, medical data, medical error, medical report, public health, report, standard, surgery

STANDARDS AND PROTOCOLS

Protocol for the surveillance 
of surgical site infections 
and prevention indicators in 
European hospitals

Healthcare-Associated Infection surveillance Network 
(HAI-Net) surgical site infection (SSI) protocol, version 2.3

ECDC STANDARDS AND PROTOCOLS 

Protocol for the surveillance of surgical 
site infections and prevention indicators in 
European hospitals 

Healthcare-Associated Infection surveillance Network (HAI-Net) surgical 
site infection (SSI) protocol, version 2.3  

This report of the European Centre for Disease Prevention and Control (ECDC) was coordinated by Tommi Kärki.  

Contributing authors  

Tommi Kärki, Carl Suetens, Diamantis Plachouras.  

Acknowledgements  

ECDC would like to thank the HAI-Net SSI operational contact points and Member States experts for providing 
input during an online protocol meeting in February 2024 and reviewing the draft protocol in autumn 2024. 

Suggested citation: European Centre for Disease Prevention and Control. Protocol for the surveillance of surgical 
site infections and prevention indicators in European hospitals – HAI-Net SSI protocol, version 2.3. Stockholm: 
ECDC; 2025. 

Stockholm, March 2025 

ISBN: 978-92-9498-786-0 
doi: 10.2900/5093297 
Catalogue number: TQ-01-25-018-EN-N 

© European Centre for Disease Prevention and Control, 2025 

Reproduction is authorised, provided the source is acknowledged.

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HAI-Net surgical site infection protocol, version 2.3    

Contents 
Abbreviations ....................................................................................................................................................... 1 
1. From HAI-Net SSI 2.2 to 2.3: summary of major changes ................................................................................... 3 
2. Minimal datasets for the surveillance of surgical site infections ............................................................................ 4 
3. Definitions ....................................................................................................................................................... 5 
3.1 Case definitions of SSIs ....................................................................................................................... 5 
3.1.1 Superficial incisional ..................................................................................................................... 5 
3.1.2 Deep incisional ............................................................................................................................. 5 
3.1.3 Organ/space ................................................................................................................................ 5 
3.2 Other key definitions ........................................................................................................................... 6 
3.2.1 Basic SSI risk index ...................................................................................................................... 6 
3.2.2 Wound contamination class ........................................................................................................... 6 
3.2.3 The ASA physical status classification (ASA score) ........................................................................... 7 
3.2.4 Duration of operation ................................................................................................................... 7 
3.3 Structure and process indicators for SSI prevention ................................................................................ 7 
3.3.1 Hospital/Unit-level SPIs ................................................................................................................. 7 
3.3.2 SPIs aggregated by operation type ................................................................................................ 7 
4. Indicators to be produced at the European level on the occurrence and characteristics of surgical site infections .. 10 
4.1 Percentage of SSIs by category .......................................................................................................... 10 
4.2 Incidence density of in-hospital SSIs ................................................................................................... 10 
5. Data collection ............................................................................................................................................... 11 
5.1 Population under surveillance ............................................................................................................. 11 
5.2 Type of surgery under surveillance ..................................................................................................... 11 
5.3 Levels of data requirement ................................................................................................................. 11 
5.4 Hierarchy of datasets ......................................................................................................................... 11 
5.5 Technical variables ............................................................................................................................ 12 
6. Hospital/unit data (patient-, unit-based and minimal surveillance option) ........................................................... 13 
6.1 Hospital and unit characteristics – Form A1 ......................................................................................... 13 
6.2 Structure and process indicators – Form A2 ......................................................................................... 14 
6.3 Unit-based and minimal surveillance option denominator and SSI data – Form AL3 ................................. 15 
7. Patient/operation data (required in patient-based surveillance option) ............................................................... 17 
7.1 Patient-based surveillance option patient/operation data – Form A3....................................................... 17 
7.2 Unit-based surveillance option patient/operation data – Form AL4 ......................................................... 18 
8. Surgical site infection data and microorganism/resistance data (patient-/unit-based surveillance option) .............. 20 
8.1 SSI data – Form A3/AL4 .................................................................................................................... 20 
9. Confidentiality ................................................................................................................................................ 22 
9.1 Patient confidentiality ........................................................................................................................ 22 
9.2 Hospital and unit confidentiality .......................................................................................................... 22 
9.3 Publication policy .............................................................................................................................. 22 
References......................................................................................................................................................... 23 

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Abbreviations 
ASA 
CARD 
CABG 
CBGB 
CBGC 
CHOL 
COLO 
CSEC 
EC 
EU 
GP 
HAI 
HAI-Net 
HELICS 
HPRO 
IPC 
ICU 
IPSE 
KPRO 
LAM 
LOS 
NHSN 
PAP 
REC 
SPI 
SSI 
TESSy 

American Society of Anesthesiologists 
Cardiac surgery 
Coronary artery bypass grafting 
Coronary artery bypass grafting with both chest and donor site incisions 
Coronary artery bypass grafting with chest incision only 
Cholecystectomy 
Colon surgery 
Caesarean section 
European Commission 
European Union 
General practitioner 
Healthcare-associated infection 
Healthcare-Associated Infection surveillance Network 
Hospitals in Europe Link for Infection Control through Surveillance project 
Hip prosthesis 
Infection prevention and control 
Intensive care unit 
Improving Patient Safety in Europe project 
Knee prosthesis 
Laminectomy 
Length of stay 
The US National Healthcare Safety Network (formerly NNIS System) 
Perioperative antibiotic prophylaxis 
Rectum surgery 
Structure and process indicator 
Surgical site infection 
The European Surveillance System 

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HAI-Net surgical site infection protocol, version 2.3    

Introduction and objectives 

The European Council Recommendation of 9 June 2009 on patient safety, including the prevention and control of 
healthcare-associated infections (HAIs) (2009/C 151/01), recommends ‘performing the surveillance of the incidence of 
targeted infection types’, ‘using surveillance methods and indicators as recommended by ECDC and case definitions as 
agreed upon at Community level in accordance with the provisions of Decision No 2119/98/EC’ [1,2]. 

In 2000–2002, harmonised methods for the surveillance of two targeted infection types, surgical site infections (SSIs) 
and healthcare-associated infections in intensive care units (ICUs), were developed by the network HELICS (Hospitals 
in Europe Link for Infection Control through Surveillance), funded by the European Commission’s Directorate-General 
for Health and Consumers (DG SANCO), and progressively implemented in Member States by HELICS and later as part 
of the Improving Patient Safety in Europe (IPSE) project. In July 2008, the coordination of the European surveillance of 
healthcare-associated infections was transferred from the IPSE network to the European Centre for Disease Prevention 
and Control (ECDC) in accordance with ECDC’s mandate. ECDC continued HAI surveillance with protocols that were 
first updated during the annual meetings of the HAI surveillance network in 2009–2010, followed by network meetings 
in 2013, 2014 and 2016, with the last previous protocol update published in 2017 with version 2.2 of the protocol. 
Further possible changes to the protocol were discussed at an in-person meeting in 2018, as well as in online meetings 
in 2022 and 2024. 

SSIs remain an important target for the surveillance of HAIs and an official priority for surveillance in several European 
countries. SSIs are among the most common HAIs [3]. They are associated with longer postoperative hospital stay, 
additional surgical procedures or stay at intensive care unit, and higher mortality. All patients undergoing surgery are 
at risk for complications, including SSIs. 

The main objective of the European protocol for the surveillance of SSIs is to ensure standardisation of definitions, 
data collection and reporting procedures for hospitals participating in the national/regional surveillance of surgical site 
infections across Europe, in order to contribute to the EU surveillance of healthcare-associated infections and to 
improve the quality of care in a multicentre setting. 

The specific objectives of the surveillance activities are: 

At the level of the hospital: 
• 

To lower the incidence of SSIs by encouraging the owners of the problem (primarily the surgical staff) to: 
− 
− 
− 

comply with existing guidelines and ‘good surgical practice’; 
correct or improve specific practices; and 
develop, implement and evaluate new preventive practices through follow-up and inter-hospital comparisons 
of adjusted SSI rates and of compliance with key preventive measures. 

Participation in the European network will also produce gains at local level from international comparisons that 
may provide insights that would not be revealed by surveillance limited at the regional or national level. 

At the level of regional or national network coordination: 
• 
• 

To prevent SSIs through surveillance; 
To  provide  the  units  with  the  necessary  reference  data  to  make  comparisons  of  risk-adjusted  rates  between 
units/hospitals: 
− 
− 
− 
To  compare  and  follow-up  the  implementation  of  key  preventive  measures  of  SSIs  between  hospitals  and 
between EU/EEA countries. 

to follow-up epidemiological trends in time; 
to identify and follow-up risk factors of SSIs; and 
to improve the quality of data collection; 

At the European level: 
• 

To prevent SSIs through surveillance by providing European reference data for adjusted SSI rates and compliance 
with key preventive measures; 
To monitor the burden of SSIs in European hospitals, in terms of incidence and attributable mortality; 
To monitor and describe the epidemiology of SSIs in selected surgical procedures in European hospitals;  
To identify regions or countries at higher need of EU support with regard to surveillance and control of SSIs; 
To facilitate  the  communication  and  the  exchange  of  experience  between  national/regional  networks  for  the 
surveillance of SSIs; 
To stimulate the creation of national/regional coordination centres for the surveillance of SSIs where these 
centres/networks do not exist; 
To provide methodological and technical support to the national/regional coordination centres; 
To improve surveillance methodology, data validation and utilisation; 
To explore the correlation between structure and process indicators and the incidence of SSIs throughout 
Europe in order to generate hypotheses and new insights in healthcare-associated infection prevention and 
control. 

• 

• 

• 
• 
• 
• 

• 

• 
• 
• 

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1. From HAI-Net SSI 2.2 to 2.3: summary of 
major changes 

The first version of this document was produced in October 2003 as the protocol Surveillance of Surgical Site 
Infections (HELICS/IPSE protocol 9.1, 2004). Changes to the protocol were applied either based on agreements made 
during the annual meetings of the European network for the surveillance of healthcare-associated infections (HAI-Net) 
in 2009, 2010 and 2012, or because they were necessary for the integration of the HAI surveillance data into The 
European Surveillance System (TESSy) of ECDC. Further changes on the protocol were published in May 2017 in 
version 2.2, including the shortening of the follow-up period for deep and organ/space SSIs if an implant is in place, 
and including the structure and process indicators (SPIs) for SSI prevention. An in-person meeting in 2018 and online 
meetings in 2022 and 2024 included discussions about the SSI protocol, and the current update was drafted based on 
the input received in the latter two meetings. 

The main changes include: 

• 

• 

• 

• 

• 
• 

Including isolated microorganism as a sub-criterion for deep incisional SSI, similarly to the already included 
criterion for superficial and organ/space SSIs. 
ICD-10-PCS coding and mapping to high-level procedure types is now included in the relevant annex and 
published with the protocol update. The ICD-10-PCS mapping is based on the NHSN mapping published in 
2024, available at: https://www.cdc.gov/nhsn/opc/ssi/index.html 
A change for the protocol as well as a change in the EpiPulse Cases metadata definition in 2026 to allow high-level 
aggregated minimal surveillance option for the reporting of hospital/unit-specific SSIs with denominators, without 
inclusion of patient-based data. Minimal datasets for the different surveillance options are defined in Annex 3. 
The data collection option of ICD-9-CM or other coding for surgical procedures is removed from the unit-based 
(‘light’) surveillance to allow further simplification of the minimal unit-level metadata. 
Reporting adds emphasis on SSIs with microbiological findings (for the countries that report microorganism data). 
The percentile cut-off for the duration of operation, part of the NHSN risk index, is now calculated from the 
surveillance data instead of using pre-specified cut-offs. 

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HAI-Net surgical site infection protocol, version 2.3    

2. Minimal datasets for the surveillance of 
surgical site infections 

The SSI protocol contains a wide set of variables for manual SSI surveillance, which remains the gold standard in 
several EU/EEA countries as well as outside Europe. However, to encourage participation and accessibility of SSI 
surveillance from only partially compatible systems, this protocol specifies a minimal surveillance option that defines an 
explicit minimal dataset to aid data preparation from various systems with different data availability. The minimal 
dataset contains only the absolute minimum requirements for SSI surveillance participation for the generation of the 
key epidemiological indicators and is a simplified subset of the unit-based surveillance option. This minimal dataset will 
be introduced with the update of the HAI-SSI data collection from TESSy to EpiPulse Cases in 2026.This will include 
the updated metadata with rules on warnings and errors and the high-level aggregation minimal surveillance option. 

The majority of participating countries have been providing data on all the recommended variables allowing risk 
adjustment of SSI rates through the use of the basic NNIS (now NHSN, The US National Healthcare Safety Network) 
risk index for inter-hospital comparisons [3,4,5], but the new minimal surveillance option provides a less labour-
intensive solution, with no possibility for risk-adjusted comparisons. 

Case definitions and included patients are the same for all surveillance options, but while in the patient-based 
surveillance option risk factors are collected for each patient (with or without an SSI), in the unit-based surveillance 
option denominator data are aggregated at the hospital (or optionally surgical unit) level, and in the minimal 
surveillance option both the denominator and SSI numbers are aggregated by unit/hospital.  

Descriptions of the data items are provided in chapters 5–8. Minimal datasets are shown in Annex 3. As the 
minimal surveillance option is a subset of the unit-based option, no minimal dataset for the unit-based option is 
separately defined. 

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3. Definitions 

3.1 Case definitions of SSIs 
The same case definitions are used as in previous protocol versions, e.g. HELICS Surveillance of Surgical Site 
Infections – Version 9.1, September 2004 and HAISSI protocol – version 1.02 with the exception of the 90-day follow-
up period for deep or organ/space infections if implant is in place. 

3.1.1 Superficial incisional 

Infection occurs within 30 days after the operation and involves only skin and subcutaneous tissue of the incision and 
at least one of the following: 

• 
• 
• 

• 

purulent drainage with or without laboratory confirmation, from the superficial incision; 
organisms isolated from an aseptically obtained culture of fluid or tissue from the superficial incision; 
at least one of the following signs or symptoms of infection: pain or tenderness, localised swelling, redness, or 
heat and superficial incision is deliberately opened by surgeon, unless incision is culture-negative; 
diagnosis of superficial incisional SSI made by a surgeon or attending physician. 

3.1.2 Deep incisional 
Infection occurs within 30 days after the operation if no implant* is left in place or within 90 days if implant* is in place 
and the infection appears to be related to the operation and infection involves deep soft tissue (e.g. fascia, muscle) of 
the incision and at least one of the following: 

• 
• 
• 

• 

• 

purulent drainage from the deep incision but not from the organ/space component of the surgical site; 
organisms isolated from an aseptically obtained culture of fluid or tissue from the deep incision (e.g. fascia, muscle); 
a deep incision spontaneously dehisces or is deliberately opened by a surgeon when the patient has at least one of 
the following signs or symptoms: fever (> 38°C), localised pain or tenderness, unless incision is culture-negative; 
an abscess or other evidence of infection involving the deep incision is found on direct examination, during 
reoperation, or by histopathologic or radiologic examination; 
diagnosis of deep incisional SSI made by a surgeon or attending physician. 

* The US National Nosocomial Infection Surveillance definition: a nonhuman-derived implantable foreign body (e.g., prosthetic heart 
valve, nonhuman vascular graft, mechanical heart, or hip prosthesis) that is permanently placed in a patient during surgery [6]. 

3.1.3 Organ/space 
Infection occurs within 30 days after the operation if no implant* is left in place or within 90 days if implant* is in place 
and the infection appears to be related to the operation and infection involves any part of the anatomy (e.g. organs 
and spaces) other than the incision that was opened or manipulated during an operation and at least one of the 
following: 

• 
• 
• 

• 

purulent drainage from a drain that is placed through a stab wound into the organ/space; 
organisms isolated from an aseptically obtained culture of fluid or tissue in the organ/space; 
an abscess or other evidence of infection involving the organ/space that is found on direct examination, during 
reoperation, or by histopathologic or radiologic examination; 
diagnosis of organ/space SSI made by a surgeon or attending physician. 

* The US National Nosocomial Infection Surveillance definition: a nonhuman-derived implantable foreign body (e.g., prosthetic heart 
valve, nonhuman vascular graft, mechanical heart, or hip prosthesis) that is permanently placed in a patient during surgery [6]. 

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3.2 Other key definitions 

3.2.1 Basic SSI risk index 

The basic SSI risk index is the index used in the US National Healthcare Safety Network (NHSN) and assigns surgical 
patients into categories based on the presence of three major risk factors [4,5,6,7,8,9,10]: 

• 

• 
• 

operation lasting more than the duration cut point hours, where the duration cut point is the approximate 75th 
percentile of the duration of surgery in minutes for the operative procedure; 
contaminated (class 3) or dirty/infected (class 4) wound class; 
ASA classification of 3, 4, or 5. 

The patient’s SSI risk category is the number of these factors present at the time of the operation. 

Calculation of basic SSI risk index 

Calculation 

Score =0, if: 

Wound contamination class 

ASA classification 
Duration of operation 

T (see table in chapter 3.2.4) 
Basic SSI risk index = 

W1, W2 

A1, A2 
≤ T 

Sum of scores 

3.2.2 Wound contamination class 
Wound contamination class as described by Altemeier et al. [9]. 

Wound contamination classification 

Wound 

Description 

Score=1, if: 

W3, W4 

A3, A4, A5 
> T 

A clean wound is an uninfected operative wound in which no inflammation is encountered and the 
respiratory, alimentary, genital or uninfected urinary tracts are not entered. In addition, clean wounds are 
primarily closed and, if necessary, drained with closed drainage. Operative incisional wounds that follow 
non-penetrating trauma should be included in this category. 

Clean-contaminated wounds are operative wounds in which the respiratory, alimentary, genital or 
uninfected urinary tracts are entered under controlled condition and without unusual contamination. 
Specifically operations involving the biliary tract, appendix, vagina and oropharynx are included in this 
category provided no evidence of infection or major break in technique is encountered. 

Contaminated wounds include open, fresh, accidental wounds. In addition, operations with major 
breaks in sterile technique or gross spillage from the gastrointestinal tract, and incisions in which acute, 
nonpurulent inflammation is encountered are included in this category. 

Dirty or infected wounds include old traumatic wounds with retained devitalised tissue and those that 
involve existing clinical infection or perforated viscera. This definition suggests that the organisms causing 
postoperative infection were present in the operative field before the operation. 

W1 

W2 

W3 

W4 

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3.2.3 The ASA physical status classification (ASA score) 
Physical status classification developed by the American Society of Anesthesiologists (ASA) [10]. 

ASA physical status classification 

ASA score 
A1 
A2 

Definition 
A normal healthy patient 

A patient with mild systemic disease or 
condition 

A3 

A patient with severe systemic disease 

A4 

A5 

A patient with an incapacitating systemic 
disease that is a constant threat to life 

A Moribund patient who is not expected to 
survive without the operation 

Examples 

Healthy, non-smoking, no or minimal alcohol use 

Mild diseases or conditions only without substantive 
functional limitations. Examples include (but not limited 
to): current smoker, social alcohol drinker, pregnancy, 
obesity (30<body mass index<40), well-controlled 
diabetes mellitus or hypertension, mild lung disease 

Substantive functional limitations; 
One or more moderate to severe diseases. 
Examples include (but not limited to): poorly 
controlled diabetes mellitus or hypertension, chronic 
obstructive pulmonary disease, morbid obesity (body 
mass index ≥40), active hepatitis, alcohol dependence 
or abuse, implanted pacemaker, moderate reduction of 
ejection fraction, end stage renal disease undergoing 
regularly scheduled dialysis, premature infant 
postconceptional age < 60 weeks 

Examples include (but not limited to): ongoing cardiac 
ischemia or severe valve dysfunction, severe reduction 
of ejection fraction, sepsis, disseminated intravascular 
coagulation or end stage renal disease not undergoing 
regularly scheduled dialysis 

Examples include (but not limited to): ruptured 
abdominal/thoracic aneurysm, massive trauma, 
intracranial bleed with mass effect, ischaemic bowel in 
the face of significant cardiac pathology or multiple 
organ/system dysfunction 

3.2.4 Duration of operation 

The duration of operation is reported in minutes. The 75th percentile cut-off values for each selected NHSN procedure 
are dynamically calculated from the annual European surveillance data. In case of a reintervention within 72 hours 
after the primary procedure, the duration of the re-intervention needs to be added to the duration of the primary 
procedure. 

3.3 Structure and process indicators for SSI prevention 
Structure and process indicators (SPIs) of SSI prevention were selected based on the strength of available evidence 
and feasibility of their collection. Two of the SPIs are collected at the hospital/unit level. Other SPIs will be collected 
aggregated by operation type. 

The collection of the SPI data is recommended for a minimum of three months and/or for 30 surgical procedures of a 
certain type per surveillance year (for example selecting the first 30 surgical procedures of a certain type from the start 
of the surveillance period). These data should be collected for at least one of the selected surgical procedure type(s), 
as agreed at the national/regional surveillance network level.   

3.3.1 Hospital/unit-level SPIs 

Two SPIs are collected at the hospital-level: 

• 

• 

• 

Alcohol handrub (AHR) consumption during the previous year in surgical wards that participate to the SSI 
surveillance per 1 000 patients-days in surgical wards that participate to the SSI surveillance.  
NOTE: The AHR consumption and the patient-days should represent the same ward(s). Data are to be collected 
from the hospital pharmacy or ward records for the year prior to the surveillance year. 
Is there a system for root cause analysis/review of SSIs in place in the hospital, and if so, in which cases 
the root cause analysis/review is triggered? Root cause analysis/review is defined as the systematic analysis of 
all the factors which are predisposed to, or had the potential to prevent, an error; in this case SSI [11]. 

Both of these SPIs can be collected per each hospital or per unit/ward. 

3.3.2 SPIs aggregated by operation type 

Other structure and process indicators are collected only as aggregated by selected surgical procedure type(s). For 
each SPI, the number of all observations and the number of observations that are compliant with the SPI should be 
reported. In the case of observations where the information is not available, i.e. is non-measured or non-documented, 
the observations should be omitted for the SPI in question. 

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The selected SPIs can be categorised in three groups: 1) Perioperative antibiotic prophylaxis (PAP) indicators; 2) 
Preoperative skin preparation indicators; and 3) other SSI prevention indicators. 

3.3.2.1 Perioperative antibiotic prophylaxis 
Perioperative antibiotic prophylaxis (PAP) is defined as administration of systemic antibiotics before or during a surgical 
procedure [12]. It is not within scope of this protocol to assess which operations require PAP, nor the appropriateness 
of the administered PAP. In order to evaluate the compliance for the PAP indicators, auditing a selected number of 
surgical procedures in which PAP is indicated by the local protocol is recommended. In case of caesarean section, PAP 
means prophylaxis given after clamping of umbilical cord. Prophylaxis for premature rupture of membranes (PROM) is 
not considered as PAP. 

Two PAP indicators have been added to the SSI protocol: 

•  Administration of PAP within 60 minutes before incision (except when administering vancomycin and 

fluoroquinolones). 

•  Discontinuation of PAP within 24 hours after initiation of surgery. 

Both of these SPIs are based in the ECDC systematic review and evidence-based guidance on perioperative antibiotic 
prophylaxis [12]. Adhering to optimal timing for preoperative prophylaxis as well as avoiding the prolongation of 
prophylaxis are also strong recommendations in the WHO Global Guidelines for the Prevention of Surgical Site 
Infection supported by moderate quality of evidence [13]. They are also included in the WHO safe surgery checklist, 
and supported by the SHEA/IDSA practice recommendation for prevention of SSIs [14,15,16]. Data for both indicators 
should be collected from the review of the patient charts or checklists. 

For the first PAP indicator the compliance with the administration within 60 minutes before incision will be assessed for 
all surgical procedures where PAP was indicated (according to the local protocol) and administered:  

For the second PAP indicator the compliance with the discontinuation of PAP within 24 hours after initiation of surgery 
will be assessed for all surgical procedures where PAP was indicated (according to the local protocol) and 
administered: 

3.3.2.2 Preoperative skin preparation 
The following preoperative skin preparation indicators have been added to the protocol: 

•  No hair removal, or if hair removal was necessary, only clipping. 

•  Use of alcohol-based antiseptic solutions based on Chlorhexidine gluconate (CHG) for surgical 

site skin preparation in the operating room (OR) (if no patient contraindication exists). 

Moderate evidence is presented both in the WHO Global Guidelines for the Prevention of Surgical Site Infection and in 
the SHEA/IDSA practice recommendation for prevention of SSIs for no hair removal, with a strong recommendation in 
the WHO Guidelines [13,14,15]. Furthermore, moderate or moderate to low evidence is also backing the alcohol-based 
antiseptic solutions based on CHG preoperative skin antisepsis in the SHEA/IDSA practice recommendation as well as 
the WHO Guidelines [13, 14, 15]. The abovementioned indicator for alcohol-based skin antisepsis includes all alcohol-
based skin antisepsis solutions based on CHG used in the OR prior to the incision but does not include other skin 
antisepsis performed before the entry to the OR. Data for both SPIs should be collected by observation or from the 
review of the patient charts, not only if included in the local protocol or standard operating procedure. In case of hair 
removal, patient’s possible self-shaving performed at home is recommended to be recorded as a non-compliant 
observation. 

For the compliance with no hair removal (or if hair removal was necessary, only clipping) will be assessed for all 
surgeries in the selected operation type:  

For the compliance with the use of alcohol-based antiseptic solutions based on CHG for surgical skin preparation in the 
OR will be assessed for all surgeries where no contraindication:  

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3.3.2.3 Other prevention indicators 

The last group of SPIs that are collected aggregated per operation type include two indicators: 

• 

Ensuring the patient's normothermia in the perioperative period (within one hour of the end of operation) 
(36-38°C (rectal measurement) or 35,5-37,5 °C (non-rectal measurement)), if no contraindication. 
•  Using a protocol for intensive perioperative blood glucose control and blood glucose levels 

monitored for adult patients undergoing surgical procedures. 

Both the monitoring and ensuring patient’s normothermia and glucose monitoring and control in the perioperative 
period have been presented in the WHO Global Guidelines for the Prevention of Surgical Site Infection as well as in the 
SHEA/IDSA practice recommendation for prevention of SSIs. In the SHEA/IDSA practice recommendation high 
evidence was presented for maintaining normothermia during the perioperative period and for glucose control in 
cardiac surgery patients, and moderate evidence for glucose control in noncardiac surgery patients, whereas in the 
WHO Guidelines evidence for maintaining normothermia was deemed moderate and evidence for glucose control low 
[13,15,16]. The WHO Guidelines found smaller effect in studies concentrating on intraoperative intensive blood glucose 
control compared to those with intensive postoperative protocol, whilst for the normothermia the WHO Guidelines 
recommend the use of warming devices in the operating room and during the surgical procedure [13]. 

The SPI on the compliance with normothermia in the perioperative period should be collected as either direct 
observation or from the review of patient charts. The temperature should be measured in the recovery room within 
one hour after the end of the surgical procedure. Normothermia should NOT be assessed for surgical procedures 
where normothermia is contraindicated, as for example in the case of induced hypothermia for CABG. Normothermia is 
defined as the patient's temperature within one hour of the end of operation (36-38°C (rectal measurement) or 35,5-
37,5 °C (non-rectal measurement)), if no contraindication: 

The SPI on the use of protocols for intensive perioperative blood glucose control for adult patients undergoing surgical 
procedures refers to blood glucose control intra- and postoperatively (24 hours after initiation of surgical procedure). It 
should be collected from the review of the patient charts or checklists [15]. The SPI will focus on whether protocol for 
intensive perioperative blood glucose control is used and the blood glucose levels are monitored rather that the exact 
blood glucose levels, and will be assessed for all surgical procedures in the selected procedure type:  

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4. Indicators to be produced at the European 
level on the occurrence and characteristics of 
surgical site infections 

For each procedure under surveillance and for each level of the NHSN risk index, the EU database will produce the 
rates of SSIs (in total and for superficial, deep, organ-space, separately), as a percentage of the number of 
interventions and as an incidence density (number of SSI with onset before hospital discharge per 1 000 patient days 
in the hospital). 

4.1 Percentage of SSIs by category 
The first indicator (% SSIs) gives the most complete picture for a given operative procedure but is highly dependent 
on the intensity of post-discharge surveillance, which varies considerably between hospitals and between countries. 
The indicator may be presented separately for all SSIs and only for a subset of deep and organ/space SSIs, as well as 
separately for SSIs with microbiological findings (for the countries that report microorganism data).  

Percentage of SSIs  
= 
(by category) 

all first SSIs* in that category x 100  
all operations in that category 

* DateOfOnset-DateOfOperation ≤30 or ≤90 days if implant is in place (if calculating the date of operation as day 1: DateOfOnset-
DateOfOperation+1 ≤31 or ≤91) 

4.2 Incidence density of in-hospital SSIs 
The second indicator (number of in-hospital SSIs/1 000 patient-days in the hospital) only considers infections detected 
in the hospital and therefore it does not reflect the complete epidemiological picture, e.g. in procedures with short 
post-operative hospital stay. However, it is independent of post-discharge surveillance and corrects for differences in 
post-operative hospital stay. Therefore, this indicator may be more reliable for inter-hospital or inter-network 
comparisons. The indicator may be presented separately for all SSIs and only for a subset of deep and organ/space 
SSIs, as well as separately for SSIs with microbiological findings (for the countries that report microorganism data). 

Incidence density 

in-hospital SSIs   = 
(by category) 

 all in-hospital SSIs in that category x 1000 
 in-hospital postoperative patient days with known discharge date in that category   

* DateOfOnset-DateOfOperation ≤30 or ≤90 days if implant is in place (if calculating the date of operation as day 1: DateOfOnset-
DateOfOperation+1 ≤31 or ≤91) 

Step 1. Delete/exclude all operations (with or without SSI) where DateOfHospitalDischarge is unknown. 

Step 2. Calculate in-hospital postoperative patient days as sum of (DateOfHospitalDischarge-DateOfOperation+1).  

Step 3. Apply 30/90-day rule on (in-hospital) SSIs. 

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5. Data collection 

5.1 Population under surveillance 

All data from participating hospitals (or specific wards within a hospital) that perform procedures included in the 
European protocol are eligible for inclusion. A minimum period of three months or continuous collection of data on 
SSIs in the participating hospitals is recommended for all surveillance options. 

5.2 Type of surgery under surveillance 
To obtain sufficient numbers of records allowing statistically valid conclusions, the diversity of operations to be 
recorded is limited and focuses on relatively frequently registered procedures that are likely to be interpreted similarly 
in different settings. The code definitions and mappings for ICD-10-PCS are included in the annexes of this protocol, 
based on mappings from NHSN, available at: https://www.cdc.gov/nhsn/opc/ssi/index.html 

ICD-10-PCS coding is more detailed than the previously used ICD-9-CM coding and may be reported separately in the 
patient-based surveillance option, similarly as the previous ICD-9-CM or other internationally used surgical procedure 
coding. For the historic ICD-9-CM coding, please refer to the HAISSI protocol version 2.2 Annex 1, available at: 
https://www.ecdc.europa.eu/sites/default/files/documents/HAI-Net-SSI-protocol-v2.2.pdf 

Selected type of surgical procedures for surveillance with high-level description 

NHSN 

category 

COLO 

REC 

CHOL 

HPRO 

KPRO 

LAM 

CSEC 

CARD 

CABG 

CBGB 

CBGC 

High-level description 

Colon surgery 
Incision, resection or anastomosis of the large bowel; includes 
large-to-small and small-to-large bowel anastomosis 
Laparoscopic excision of large intestine 
Enterotomy 
Intestinal anastomosis 

Rectum surgery 

Cholecystectomy 

Removal of gallbladder, includes procedures performed using the laparascope 

Arthroplasty of hip 

Arthroplasty of knee 

Laminectomy 
Exploration or decompression of spinal cord through excision or 
incision into vertebral structures 

Caesarean section 

Cardiac surgery 

Coronary artery bypass, unspecified 

Coronary artery bypass grafting with both chest and donor site incisions 
Chest procedure to perform direct revascularisation of the heart; includes obtaining suitable vein 
from donor site for grafting 

Coronary artery bypass grafting with chest incision only 
Chest procedure to perform direct vascularisation of the heart using, for example, the internal 
mammary artery 

5.3 Levels of data requirement 
In 2026, ECDC plans a transition from TESSy to the EpiPulse Cases system, where the requirements of the variables 
will be updated. The specifications will be made available with the launch of EpiPulse Cases. 

5.4 Hierarchy of datasets 
The set of variables for HAI-Net SSI reporting consists of nine technical variables and a set of epidemiological 
variables. The dataset definition is expected to remain similar between TESSy and EpiPulse Cases, but the naming of 
the files/levels and some variables might change. Technical variables are only relevant for the surveillance network 
coordination. 

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HAI-Net SSI patient-based surveillance option (RecordType ‘HAISSI’) contains five datasets in four hierarchical levels: 

1. 

2. 

First level ‘HAISSI’ includes data referring to the hospital/unit that are repeated in all records reporting the 
operation data, infection data and microorganisms and resistance data.  
The level is required. 
Second level ‘HAISSI$IND’ includes variables about structure and process indicators for SSI prevention. The 
level is optional. 

2.       Second level ‘HAISSI$OP’ includes variables about patient, operation and risk factors.  

The level is required. 

3.       Third level ‘HAISSI$OP$INF’ includes variables about SSIs.  

The level is required. 

4.       Fourth level ‘HAISSI$OP$INF$RES’ includes variables about pathogens and their resistance.  

  The level is optional. 

HAI-Net SSI unit-based and minimal surveillance option data (RecordType ‘HAISSILIGHT’) contains three possible 
datasets in two to four hierarchical levels: 

1. 

First  level  ‘HAISSILIGHT’  includes  data  referring  to  the  hospital/unit  that  are  repeated  in  all  records 
reporting the operation data, infection data and microorganisms and resistance data.  
The level is required. 

2.       Second level ‘HAISSILIGHT$OPCAT’ includes variables about operations and number of SSIs.  

2. 

3. 

4. 

The level is required. 
Second  level  ‘HAISSILIGHT$IND’  includes  variables  about  structure  and  process  indicators  for  SSI 
prevention.  
The level is optional. 
Third level ‘HAISSILIGHT$OPCAT$INF’ includes variables about SSIs and operations.  
The level is optional. 
Fourth level ‘HAISSILIGHT$OPCAT$INF$RES’ includes variables about pathogens and their resistance.  
The level is optional. 

5.5 Technical variables 
Reporting country: ISO codes (International Organization for Standardization ISO 3166-1 -alpha-2-code elements): 
AT = Austria, BE = Belgium, BG = Bulgaria, CY = Cyprus, CZ = Czech Republic, DE = Germany, DK = Denmark, EE 
= Estonia, ES = Spain, FI = Finland, FR = France, GB = Great Britain, GR = Greece, HR = Croatia, HU = Hungary, 
IE = Ireland, IT = Italy, IS = Iceland, LI = Liechtenstein, LV = Latvia,  LT = Lithuania,  LU = Luxembourg, MT = 
Malta, NL = Netherlands, NO = Norway, PL = Poland, PT = Portugal, RO = Romania, SK = Slovakia, SI = Slovenia, 
SE = Sweden. 

Network id: Unique identifier for each network – Member State selected and generated. Code can be omitted, if the 
hospital identifiers are unique within the reporting country, but should be combined with HospitalId if same codes are 
used across different subnetworks that are reported through by single DataSource (e.g. data from five regional CCLIN 
networks reported as one database by France). 

Subject: HAISSI 

The rest of the technical variables are shown in the current TESSy metadata and are expected to remain similar in 
EpiPulse Cases. However, some variables will change name or be removed (e.g. RecordTypeVersion will not be used in 
EpiPulse Cases), and unknown (‘UNK’) or NA values will in general not be accepted. 

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6. Hospital/unit data (patient-, unit-based and 
minimal surveillance option) 

Hospital/unit data are the same for patient-/unit-based and minimal surveillance option and use the same form A1 to 
collect hospital/unit data. The first level (RecordType ‘HAISSI’ or ‘HAISSILIGHT’) is required. 

6.1 Hospital and unit characteristics – Form A1 
Hospital code (required): Unique identifier for each hospital – Member State selected and generated, should remain 
identical in different surveillance periods/years. Required. 

Hospital surveillance period start (required): The start date of the surveillance period or the surveillance year. 

Hospital Type: PRIM = Primary level, SEC = Secondary level, TERT = Tertiary level, SPEC = Specialized/Other 
Primary: 
• 
• 
• 

often referred to as ‘district hospital’ or ‘first-level referral’; 
often corresponds to a general hospital without teaching function; 
few  specialities  (mainly  internal  medicine,  obstetrics-gynaecology,  paediatrics,  general  surgery  or  only 
general practice); 
limited laboratory services are available for general, but not for specialised pathological analysis. 

• 

Secondary: 
• 
• 
• 

Tertiary: 
• 
• 
• 

• 

• 
• 
• 

often referred to as ‘provincial hospital’; 
often corresponds to general hospital with teaching function; 
highly differentiated hospital by function with five to 10 clinical specialities, such as haematology, oncology, 
nephrology, ICU; 
takes some referrals from other (primary) hospitals. 

often referred to as ‘central’, ‘regional’ or ‘tertiary-level’ hospital; 
often corresponds to University hospital; 
highly specialised staff and technical equipment (ICU, haematology, transplantation, cardio-thoracic surgery, 
neurosurgery); 
clinical services are highly differentiated by function; 
specialised imaging units; 
provides regional services and regularly takes referrals from other (primary and secondary) hospitals. 

Specialised hospital: 
• 
• 
• 

single clinical specialty, possibly with sub-specialties; 
highly specialised staff and technical equipment; 
e.g. paediatric hospital, infectious diseases hospital. 

Hospital size: Total number of beds in the hospital or rounded to the closest 100 beds. 

Hospital location: Region as NUTS-1 code where hospital is located. See: 
http://ec.europa.eu/eurostat/web/nuts/overview 

Method used for post-discharge surveillance: Method used for post-discharge surveillance of surgical site 
infections: 

READM = Detection at readmission (=passive post-discharge surveillance): patient is readmitted with SSI, 
often because of the SSI;  

REPSURG = Reporting on surgeon’s initiative: surgeon actively reports post-discharge infections detected at 
outpatient clinic or private clinic follow-up to the hospital surveillance staff, e.g. using standardised forms, 
web-based system, e-mail or telephone;  

REPGP = Reporting on GP’s initiative: general practitioner (GP) reports post-discharge infections detected at 
follow-up consultation to the hospital surveillance staff, e.g. using standardised forms, web-based system, e-
mail or telephone;  

REPPAT = Reporting on patient’s initiative: e.g. form send to hospital surveillance staff;  

ICSURG = Obtained by IC staff from surgeon: the hospital surveillance staff – usually infection control (IC) 
staff – obtains information from surgeon using telephone, additional questionnaire, visit to surgeon or patient 
chart review;  

ICGP = Obtained by IC staff from GP: hospital surveillance staff obtains information from general practitioner 
using telephone, additional questionnaire or visit; 

CPAT = Obtained by IC staff from patient: hospital surveillance staff obtains information from patient using 
telephone or additional questionnaire; 

NONE = No post-discharge surveillance done. 

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Alcohol handrub (AHR) consumption per year in surgical wards/units: AHR consumption per year in all 
surgical wards/units participating in SSI surveillance in the hospital. 

Patient-days per year in surgical wards/units: Patient-days per year in all surgical wards/units participating in 
SSI surveillance in the hospital. Note: should be the denominator data for the AHR consumption, thus from the same 
wards as the AHR consumption in litres. 

Do you have a system for root cause analysis/review in place: Does the hospital have a system for root cause 
analysis/review in place. Y = Yes; N = No. 

Root cause analysis specification: If there is a system for root cause analysis in place, specify in which cases. 

Unit ID: Unique identifier for each surgical unit – Member State selected and generated. 

6.2 Structure and process indicators – Form A2 
The second level (RecordType ‘HAISSI$IND’ and ‘HAISSILIGHT$IND’) includes variables about structure and process 
indicators for SSI prevention. The collection of structure and process indicator data is recommended, but the data level 
is optional for patient-/unit-based and minimal surveillance options. In case data for structure and process indicators 
are reported, several variables on the level are required. 

Operation code (required): NHSN code of the primary operative procedure under surveillance according to SSI 
surveillance protocol for which the structure and process indicator data is collected: CARD = cardiac surgery; CBGB = 
coronary artery bypass grafting with both chest and donor site incisions; CBGC = coronary artery bypass grafting with 
chest incision only; CABG = coronary artery bypass grafting, not specified; COLO = colon surgery; CHOL = 
cholecystectomy; CSEC = caesarean section; HPRO = hip prosthesis; KPRO = knee prosthesis; LAM = laminectomy; 
REC = rectum surgery. 

Indicator period start (required): Start date of the structure and process indicator data collection. 

Indicator period end: End date of the structure and process indicator data collection. 

Indicator code (required): Code of the structure and prevention indicator:  

ASTPAP60MIN = Administration of PAP within 60 minutes before incision (except when administering 
vancomycin and fluoroquinolones);  

ASTPAP24HRS = Discontinuation of PAP within 24 hours after initiation of surgery;  

NOHAIRREM = No hair removal, or if hair removal was necessary, only clipping;  

ALCSKINANT = Use of alcohol-based antiseptic solutions based on CHG for surgical site skin preparation in 
the OR;  

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NORMTHERM = Ensuring the patient's normothermia within one hour of the end of operation (36-38°C (rectal 
measurement) or 35,5-37,5 °C (non-rectal measurement));  

GLUCMONIT = Protocol for intensive perioperative blood glucose control used and blood glucose levels 
monitored.  

Number of observations (required): Number of observations for each indicator code. 

Number of compliant observations (required): Number of compliant observations for each indicator code. 

Comments: Comments on the SPI data. Free text. 

6.3 Unit-based and minimal surveillance option denominator 
and SSI data – Form AL3 
The second level in the unit-based and minimal surveillance options (RecordType ‘HAISSILIGHT$OPCAT’) includes 
denominator data and variables about each operation category. The level is required in the unit-based and minimal 
surveillance options. Since protocol version 2.3, it also includes variables for minimal surveillance option for SSIs. 

Operation code (required): NHSN (National Healthcare Safety Network) code of the primary operative procedure 
under surveillance according to SSI surveillance protocol for which the aggregated denominator data and SSI data are 
collected: CARD = cardiac surgery; CBGB = coronary artery bypass grafting with both chest and donor site incisions; 
CBGC = coronary artery bypass grafting with chest incision only; CABG = coronary artery bypass grafting, not 
specified;COLO = colon surgery; CHOL = cholecystectomy; CSEC = caesarean section; HPRO = hip prosthesis; KPRO 
= knee prosthesis; LAM = laminectomy; REC = rectum surgery 

Endoscopic procedure: Denominator data entry is for endoscopic/laparoscopic operations or open operations. 

Note that endoscopic/laparoscopic requires that the entire operation was performed using endoscopic/laparoscopic 

approach. 

Surveillance period started (required): Start date of the time period covered by this denominator entry.  

Surveillance period ended (required): End date of the time period covered by this denominator entry. 

Number of operations: Number of surgical procedures in the category of operations according to operation code, 
endoscopic/laparoscopic (if given) during the survey period. 

Number of operations with known discharge date: Number of surgical procedures in the category of operations 
with known discharge date according to operation code, endoscopic/laparoscopic (if given) during the survey period. 

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Number of postoperative patient days: Number of post-operation hospital patient days. Definition: the sum of 
patient days in the hospital following the operation (discharge date − operation date + 1) according to operation 
code, endoscopic/laparoscopic (if given) during the survey period. 

Number of superficial SSIs: Number of superficial surgical site infections in the category of operations according to 
operation code, endoscopic/laparoscopic (if given) during the survey period. 

Number of deep SSIs: Number of deep surgical site infections in the category of operations according to operation 
code, endoscopic/laparoscopic (if given) during the survey period. 

Number of organ/space SSIs: Number of organ/space surgical site infections in the category of operations 
according to operation code, endoscopic/laparoscopic (if given) during the survey period. 

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7. Patient/operation data (required in patient-
based surveillance option) 

7.1 Patient-based surveillance option patient/operation data – 
Form A3 
The second level of the patient-based surveillance option (RecordType ‘HAISSI$OP’) includes variables about patient, 
operation and risk factors and are collected for each patient/operation. The level is required in patient-based 
surveillance option. 

Patient/operation variables: 
Patient counter: Numeric code for each patient, unique within hospital. Anonymous code assigned by hospital to 
specify patient. 
Age:  Age of the patient at date of operation. 
Gender: The gender of the patient who undergoes the operation. F = Female; M=Male; OTH = Other. 
Date of hospital admission: Date patient was admitted to hospital in order to undergo the operation under 
surveillance. 
Date of hospital discharge: Date the patient was discharged from hospital where they underwent the operation 
under surveillance or date of in-hospital death or date of last follow-up in hospital if discharge date is unknown. This 
date is used to calculate the number of post-operative in-hospital patient days. 
Date of last follow-up post-discharge:  Date last information on the patient was obtained after discharge from 
hospital, for example from surgeon (out-patient department or private practice) or general practitioner. This date is 
used to calculate the total amount of follow-up days (in-hospital and post-discharge). (DateOfLastFollowup) 
Date of last follow-up in hospital: Date last information on the patient was obtained during the hospitalisation, for 
example from surgeon. Can be used when different from date of hospital discharge, e.g. if hospital stay is longer than 
30 days, or follow-up of surveillance was discontinued for other reasons while patient was still in hospital to calculate 
the total amount of follow-up days (in-hospital). 
Outcome from hospital: Patient status at the last reported hospital discharge or at end of follow-up in hospital. 
Operation ID (required): Unique identifier for each operation – Hospital selected and generated. 
Date of operation (required): Date operation under surveillance was carried out. 
Operation code (required): NHSN (National Healthcare Safety Network) code of the primary operative procedure 
under surveillance according to SSI surveillance protocol. 
ICD-10-PCS code: ICD-10-PCS code of the primary operative procedure under surveillance according to SSI 
surveillance protocol. See Annex 4. Recommended coding system. 
Other operation code: Other code of the primary operative procedure under surveillance according to 
SSI surveillance protocol, for example ICD-9-CM. Please also specify the other coding system in a separate field (see 
below). Alternative coding system may be used if ICD-10-PCS code cannot be reported. 
Name of the non ICD-10-PCS code: Name of the other code used for the primary operative procedure under 
surveillance: ICD-9-CM = International classification of diseases-9 coding, as in the previous protocol versions; ICD-10-
AM = International classification of diseases-10-AM; ICD-11 = International classification of diseases 11 (2022 
onwards); CCAM = Classification des Actes Médicaux; CVV = Classificatie van verrichtingen; GOA = Gebührenordnung 
für Ärzte; ICPM = International Classification of Procedures in Medicine; NCSP = Nomesco Classification of Surgical 
Procedures; NPS = Nomenclature des prestations de santé; OPS-301 = Operationen- und Prozedurenschlüssel; OPCS-
4 = OPCS Classification of Interventions and Procedures version 4. Alternative coding system may be used if ICD-10-
PCS code cannot be reported. 
Endoscopic procedure: Enter ‘Yes’ only if the entire operation was performed using an endoscopic/laparoscopic 
approach. 
Multiple operations: Enter ‘Yes’ if multiple procedures were performed through the same incision within the same 
session in the operating room. Duration of operation should be calculated for the combined duration of all procedures. 
If more than one NHSN operative procedure category was performed through the same incision, attribute the SSI to 
the procedure that is thought to be associated with the infection [17]. 
Implant in place: Enter ‘Yes’ if there is an implant in place. The follow-up period if an implant in place should be 
extended to 90 days after the operation for deep or organ/space infections. Implant is defined according to the US 
National Nosocomial Infection Surveillance definition: a nonhuman-derived implantable foreign body (e.g., prosthetic 
heart valve, nonhuman vascular graft, mechanical heart, or hip prosthesis) that is permanently placed in a patient 
during surgery [6]. 
Wound contamination class: The wound contamination class as described in the section 3.2.2: W1 = Clean; W2 = 
Clean-contaminated; W3 = Contaminated; W4 = Dirty or infected. 
Duration of operation: Duration of operation (in minutes) from skin incision to skin closure. In case of 
reintervention within 72 hours after the primary procedure, the duration of the reintervention needs to be added to 
the duration of the primary procedure. 
Urgent operation: Planning time of the operation. ‘Yes’ means urgent operation that was not planned at least 24 
hours in advance. ‘No’ means elective operation that was planned at least 24 hours in advance. 

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ASA classification: Physical status classification developed by the American Society of Anesthesiology. Status at the 
time of the operation: A1 = Normally healthy patient; A2 = Patient with mild systemic disease or condition; A3 = 
Patient with severe systemic disease that is not incapacitating; A4 = Patient with an incapacitating systemic disease 
that is a constant threat to life; A5 = Moribund patient who is not expected to survive for 24 hours with or without 
operation. 
Patient received surgical prophylaxis: Perioperative systemic administration of antimicrobial agent(s) at or within 
two hours prior to primary skin incision with the aim of preventing sepsis in the operative site. In case of caesarean 
section, after clamping of umbilical cord. 
Surgical site infection (required): Presence of a SSI for this operation. For CBGB, only chest wound infections are 
to be reported. 

7.2 Unit-based surveillance option patient/operation data – 
Form AL4 
The third level of the unit-based surveillance option (RecordType ‘HAISSILIGHT$OPCAT$INF’) includes variables about 
patients and operations that are only collected for patients and operations with a SSI. The level is not reported in the 
minimal surveillance option. 

Demographic/operation variables (unit-based reporting surveillance): 

Patient counter: Numeric code for each patient, unique within hospital. Anonymous code assigned by hospital to 
specify patient. 
Age:  Age of the patient at date of operation. 
Gender: The gender of the patient who undergoes the operation. F = Female; M=Male; OTH = Other. 
Date of hospital discharge: Date the patient was discharged from hospital where they underwent the operation 
under surveillance or date of in-hospital death or date of last follow-up in hospital if discharge date is unknown. This 
date is used to calculate the number of post-operative in-hospital patient days. 
Outcome from hospital: Patient status at the last reported hospital discharge or at end of follow-up in hospital. 
Operation ID (required): Unique identifier for each operation – Hospital selected and generated. 
Date of operation (required): Date of operation under surveillance. 
Operation code (required): NHSN (National Healthcare Safety Network) code of the primary operative procedure 
under surveillance according to SSI surveillance protocol. 
Endoscopic procedure: Enter ‘Yes’ only if the entire operation was performed using an endoscopic/laparoscopic 
approach. 
Implant in place: Enter ‘Yes’ if there is an implant in place. The follow-up period if an implant in place should be 
extended to 90 days after the operation for deep or organ/space infections. 

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8. Surgical site infection data and 
microorganism/resistance data (patient-/unit-
based surveillance option) 

8.1 SSI data – Form A3/AL4 
The SSI data (RecordTypes HAISSI$OP$INF and HAISSILIGHT$OPCAT$INF) collected are collected on the third level 
in both patient-/unit-based surveillance option. These data are collected for each infection episode, by type of 
infection. The level is required for patient-/unit-based surveillance option. 

Date of infection onset (required): Date when the first clinical evidence of SSI appeared or the date the specimen 
used to make or confirm the diagnosis was collected, whichever comes first. 
Type of infection (required): Type of infection (see section 3.1): S=Superficial incisional; D = Deep incisional; O 
= Organ/space.   
SSI diagnosis: SSI diagnosis in-hospital or post-discharge. 
SSI Post-discharge surveillance Method: Method used for post-discharge surveillance of SSIs (see also section 
6.1): READM = Detection at readmission; REPSURG = Reporting on surgeon’s initiative; REPGP = Reporting on GP’s 
initiative; REPPAT = Reporting on patient’s initiative; ICSURG = Obtained by IC staff from surgeon; ICGP = Obtained 
by IC staff from GP; ICPAT = Obtained by IC staff from patient. 

SSI outcome (relationship to HAI): the relationship of an SSI to the outcome in patients with an SSI can be 
assessed with either one of the following two scales [van der Kooi T et al. Eurosurveill 202, 26(23). 
https://doi.org/10.2807/1560-7917.ES.2021.26.23.2000052] 

1.  3-CAT: (three-category scale) 

Discharged alive: patient was discharged alive; OR patient was still in the hospital and alive at end of follow-up 
during this hospital stay.  
Death, HAI definitely contributed to death: use this category if a causal link between SSI and death can be 
demonstrated. 
Death, HAI possibly contributed to death: use this category if no causal link between SSI and this case’s death 
can be demonstrated, but it is still plausible that SSI was at least a contributory factor.   
Death, unrelated to HAI: use this category if the cause of death can be demonstrated not to be related to SSI. 
Death, relationship to HAI unknown: use this category if no evidence of contributory factors to the cause of death 
is available. 

2. WHOCAT: a scale based on the WHO death certification methodology: 

Discharged alive: patient was discharged alive; OR patient was still in the hospital and alive at the end of follow 
up during the hospital stay. 
Death, no contribution of HAI: HAI did not contribute to the death or the contribution was redundant, i.e. the 
patient would have died anyway; 
Death, HAI contributory cause: HAI was a contributory cause but not related to the disease or condition 
causing the death; 
Death, HAI part of the causal sequence: HAI was part of the causal sequence of events that led to death but 
not sufficient on its own; 
Death, HAI sole cause: HAI was the sole cause of death – no other disease or condition causing the death was 
present (sufficient condition). 
Death, relationship to HAI unknown or not verified: Contribution of HAI to dea th of the pa tient unknown or not 
verified  

• 

• 

• 

• 

• 

• 

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8.2 Microorganism and antimicrobial resistance data – Form A3/AL4 

The fourth level (RecordTypes ‘HAISSI$OP$INF$RES’ or ‘HAISSILIGHT$OPCAT$INF$RES’) includes variables 
about isolated microorganisms and antimicrobial resistance. The level is optional but recommended to 
identify SSIs with reported pathogen(s). 

Isolate result (required): Microorganism or reason why not available. See Annex 1. 
Antibiotic code: Antibiotic code tested for susceptibility. See Annex 3. 
SIR: Final interpretation result of all different susceptibility tests performed. See Annex 2. Report S (susceptible, 
standard dosing regimen), I (susceptible, increased exposure) or R (resistant) for the antimicrobial group (preferred) 
or for tested antimicrobials within the group. Reporting group susceptibility requires that at least one antimicrobial 
belonging to the group is tested. If several antibiotics within the group were tested (e.g. carbapenems (CAR)), report 
the least susceptible result for the group (e.g. meropenem R + imipenem I = CAR R). 
Pandrug-resistant (PDR): Microorganism is pandrug resistant. Not PDR = N (susceptible to at least one 
antimicrobial), possible PDR = P (I/R to all antimicrobials tested in hospital), confirmed PDR = C (I/R to all 
antimicrobials confirmed by reference laboratory) [18]. 

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9. Confidentiality 

9.1 Patient confidentiality 
It will not be possible to identify individual patients in the European database on SSI by coding patient information 
only at the hospital level or at the level of the official networks in the countries. However, for validation purposes, the 
hospitals should be able to trace back patients based on the anonymous unique operative procedure ID. 

9.2 Hospital and unit confidentiality 
Individual hospitals will not be identifiable in the European database on SSI by coding hospital information at the hospital 
level or at the level of the official networks in the countries. When presenting the results of the European SSI surveillance, 
it has to be secured that no individual hospital can be recognised. 

9.3 Publication policy 
Data will be published in ECDC’s Annual Epidemiological Reports and in disease-specific reports on HAI surveillance, in 
online reports and scientific publications. Data can only be published if the official surveillance networks in the countries 
give written consent for publication. If requested by a network, publications have to acknowledge the data source (i.e. 
the networks) and provide contact information. 

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References 

1. 

2. 

3. 

4. 
5. 

6. 

7.  

8.  

9.  

10.  

11.  

12.  

13.  

14.  

15.  

16.  

17.  

18.  

Council recommendation of 9 June 2009 on patient safety, including the prevention and control of healthcare-
associated infections (HAI) (2009/C 151/01). 
Decision No 2119/98/EC of the European Parliament and of the Council of 24 September 1998 setting up a 
network for the epidemiological surveillance and control of communicable diseases in the Community. Official 
Journal of the European Communities 1998:L268/1-6. Available at: http://eur-
lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31998D2119:EN:HTML 
European Centre for Disease Prevention and Control (ECDC). Point prevalence survey of healthcare-associated 
infections and antimicrobial use in European acute care hospitals 2011–2012. Stockholm: ECDC; 2013. 
Available at: https://www.ecdc.europa.eu/en/publications-data/point-prevalence-survey-healthcare-
associated-infections-and-antimicrobial-use-0  

NNIS Manual, May 1999. Surgical patient surveillance component: Part XI-3. 

Gaynes RP. Surgical Site Infections and the NNIS SSI Risk Index: room for improvement. Infect Control Hosp 
Epidemiol 2000;21(3):184-5. 

Mangram AJ, Horan TC, Pearson ML, Silver LC, Jarvis WR. Guideline for Prevention of Surgical Site Infection, 
1999. Am J Infect Control 1999;27:97-134. Available at: 
http://www.cdc.gov/ncidod/dhqp/pdf/guidelines/SSI.pdf 

National Nosocomial Infections Surveillance (NNIS) System Report, data summary from January 1992 through 
June 2004, issued October 2004. Available at: http://www.cdc.gov/ncidod/dhqp/pdf/nnis/2004NNISreport.pdf 

Culver DH, Horan TC, Gaynes RP, Martone WJ, Jarvis WR, Emori TG, et al. Surgical wound infection rates by 
wound class, operative procedure and patient risk index. Am J Med 1991;91(suppl 3B):152S-7S.  

Altemeier WA, Burke JF, Pruitt BA, Sandusky WR. Manual on control of infection in surgical patients (2nd ed.) 
Philadelphia, PA: JB Lippincott, 1984. 

American Society of Anesthesiologists. ASA physical status classification system. 2014. Available at: 
http://www.asahq.org/~/media/sites/asahq/files/public/resources/standards-guidelines/asa-physical-status-
classification-system.pdf 

World Health Organization (WHO). Patient safety workshop: learning from error. Geneva: WHO; 2010. 
Available at: http://apps.who.int/iris/bitstream/10665/44267/1/9789241599023_eng.pdf 

European Centre for Disease Prevention and Control (ECDC). Systematic review and evidence-based guidance 
on perioperative antibiotic prophylaxis. Stockholm: ECDC; 2013. Available at: 
https://www.ecdc.europa.eu/sites/default/files/media/en/publications/Publications/Perioperative%20antibiotic
%20prophylaxis%20-%20June%202013.pdf  

World Health Organization (WHO). Global guidelines for the prevention of surgical site infection. Geneva: 
WHO; 2016. Available at: http://www.who.int/gpsc/ssi-prevention-guidelines/en/ 

World Health Organization (WHO). Implementation manual. Surgical safety checklist. Geneva: WHO; 2008.  
Available at: http://www.who.int/patientsafety/safesurgery/ss_checklist/en/ 

Yokoe DS, Anderson DJ, Berenholtz SM, Calfee DP, Dubberke ER, Ellingson KD, et al. A compendium of 
strategies to prevent healthcare-associated infections in acute care hospitals: 2014 updates. Infect Control 
Hosp Epidemiol 2014;35(8):967-77. 

Anderson DJ, Podgorny K, Berríos-Torres SI, Bratzler DW, Dellinger EP, Greene L, et al. Strategies to prevent 
surgical site infections in acute care hospitals: 2014 update. Infect Control Hosp Epidemiol 2014;35(Suppl 
2):S66-88. 

Centers for Disease Control and Prevention (CDC). Surgical Site Infection (SSI) Event. 2017. Available at: 
https://www.cdc.gov/nhsn/pdfs/pscmanual/9pscssicurrent.pdf 

Magiorakos AP, Srinivasan A, Carey RB, Carmeli Y, Falagas ME, Giske CG, et al. Multidrug-resistant, 
extensively drug-resistant and pandrug-resistant bacteria: an international expert proposal for interim 
standard definitions for acquired resistance. Clin Microbiol Infect 2012;18(3):268-81. Available at: 
http://www.sciencedirect.com/science/article/pii/S1198743X14616323  

23 

 
 
 
ECDC STANDARDS AND PROTOCOLS 

HAI-Net surgical site infection protocol, version 2.3    

Annex 1. Microorganisms code list 

The code list is adapted from the original WHOCARE coding system. The current list is a selection of 
microorganisms based on their frequency of occurrence in healthcare-associated infections in different EU networks 
and infection types and/or on their public health importance. The minimal list represents the minimal level of detail 
that should be provided by every network. 

Microorganism selection and minimal list 

Gram-positive cocci 

Gram-negative cocci 

Gram-positive bacilli 

Enterobacterales 

24 

Microorganism 
Staphylococcus aureus 
Staphylococcus epidermidis 
Staphylococcus haemolyticus 

Coag-neg. staphylococci, not specified 
Other coagulase-negative staphylococci (CNS) 
Staphylococcus sp., not specified 
Streptococcus pneumoniae 
Streptococcus agalactiae (B) 
Streptococcus pyogenes (A) 
Other haemol. Streptococcae (C, G) 
Streptococcus sp., other 
Streptococcus sp., not specified 
Enterococcus faecalis 
Enterococcus faecium 
Enterococcus sp., other 
Enterococcus sp., not specified 
Gram-positive cocci, not specified 
Other Gram-positive cocci 
Moraxella catharralis 
Moraxella sp., other 
Moraxella sp., not specified 
Neisseria meningitidis 
Neisseria sp., other 
Neisseria sp., not specified 
Gram-negative cocci, not specified 
Other Gram-negative cocci 
Corynebacterium sp. 
Bacillus sp. 
Lactobacillus sp. 
Listeria monocytogenes 
Gram-positive bacilli, not specified 
Other Gram-positive bacilli 
Citrobacter freundii 
Citrobacter koseri (e.g. diversus) 
Citrobacter sp., other 
Citrobacter sp., not specified 
Enterobacter cloacae 

Enterobacter aerogenes – renamed to Klebsiella 
aerogenes* 
Enterobacter agglomerans 
Enterobacter sakazakii 
Enterobacter gergoviae 
Enterobacter sp., other 
Enterobacter sp., not specified 

Code 
STAAUR 
STAEPI 
STAHAE 

STACNS 
STAOTH 
STANSP 
STRPNE 
STRAGA 
STRPYO 
STRHCG 
STROTH 
STRNSP 
ENCFAE 
ENCFAI 
ENCOTH 
ENCNSP 
GPCNSP 
GPCOTH 
MORCAT 
MOROTH 
MORNSP 
NEIMEN 
NEIOTH 
NEINSP 
GNCNSP 
GNCOTH 
CORSPP 
BACSPP 
LACSPP 
LISMON 
GPBNSP 
GPBOTH 
CITFRE 
CITDIV 
CITOTH 
CITNSP 
ENBCLO 

ENBAER 
ENBAGG 
ENBSAK 
ENBGER 
ENBOTH 
ENBNSP 

Minimal list 
STAAUR 

STACNS 

GPCTOT 

STRSPP 

ENCSPP 

GPCTOT 

GNCTOT 

GPBTOT 

CITSPP 

ENBSPP 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Microorganism 
Escherichia coli 
Klebsiella aerogenes 

Klebsiella pneumoniae 

Klebsiella oxytoca 
Klebsiella sp., other 
Klebsiella sp., not specified 
Proteus mirabilis 

Proteus vulgaris 
Proteus sp., other 
Proteus sp., not specified 
Serratia marcescens 

Serratia liquefaciens 
Serratia sp., other 
Serratia sp., not specified 
Hafnia sp. 

Code 
ESCCOL 
KLEAER 

KLEPNE 

KLEOXY 
KLEOTH 
KLENSP 
PRTMIR 

PRTVUL 
PRTOTH 
PRTNSP 
SERMAR 

SERLIQ 
SEROTH 
SERNSP 
HAFSPP 

Minimal list 
ESCCOL 

KLESPP 

PRTSPP 

SERSPP 

ETBTOT 

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Microorganism 

Code 

Minimal list 

Gram-negative bacilli, 
Enterobacteriaceae 
(continued) 

Gram-negative bacilli, 
other 

Anaerobes 

Other bacteria 

26 

Morganella sp. 
Providencia sp. 
Salmonella Enteritidis 
Salmonella Typhi or Paratyphi 
Salmonella Typhimurium 
Salmonella sp., not specified 
Salmonella sp., other 
Shigella sp. 
Yersinia sp. 
Other enterobacterales 
Enterobacterales, not specified 
Acinetobacter baumannii 
Acinetobacter calcoaceticus 
Acinetobacter haemolyticus 
Acinetobacter lwoffii 
Acinetobacter sp., other 
Acinetobacter sp., not specified 
Pseudomonas aeruginosa 
Stenotrophomonas maltophilia 
Burkholderia cepacia 
Pseudomonadaceae family, other 
Pseudomonadaceae family, not specified 
Haemophilus influenzae 
Haemophilus parainfluenzae 
Haemophilus sp., other 
Haemophilus sp., not specified 
Legionella sp. 
Achromobacter sp. 
Aeromonas sp. 
Agrobacterium sp. 
Alcaligenes sp. 
Campylobacter sp. 
Flavobacterium sp. 
Gardnerella sp. 
Helicobacter pylori 
Pasteurella sp. 
Gram-neg bacilli, not specified 
Other Gram-neg bacilli, non enterobacterales 
Bacteroides fragilis 
Bacteroides other 
Clostridioides difficile 
Clostridioides other 
Propionibacterium sp. 
Prevotella sp. 
Anaerobes, not specified 
Other anaerobes 
Mycobacterium, atypical 
Mycobacterium tuberculosis complex 
Chlamydia sp. 
Mycoplasma sp. 
Actinomyces sp. 

MOGSPP 
PRVSPP 
SALENT 
SALTYP 
SALTYM 
SALNSP 
SALOTH 
SHISPP 
YERSPP 
ETBOTH 
ETBNSP 
ACIBAU 
ACICAL 
ACIHAE 
ACILWO 
ACIOTH 
ACINSP 
PSEAER 
STEMAL 
BURCEP 
PSEOTH 
PSENSP 
HAEINF 
HAEPAI 
HAEOTH 
HAENSP 
LEGSPP 
ACHSPP 
AEMSPP 
AGRSPP 
ALCSPP 
CAMSPP 
FLASPP 
GARSPP 
HELPYL 
PASSPP 
GNBNSP 
GNBOTH 
BATFRA 
BATOTH 
CLODIF 
CLOOTH 
PROSPP 
PRESPP 
ANANSP 
ANAOTH 
MYCATY 
MYCTUB 
CHLSPP 
MYPSPP 
ACTSPP 

ACISPP 

PSEAER 
STEMAL 

PSETOT 

HAESPP 

LEGSPP 

GNBTOT 

BATSPP 

ANATOT 

BCTTOT 

 
 
 
 
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Fungi 

Nocardia sp. 
Other bacteria 

Other bacteria, not specified 
Candida albicans 

Candida auris 
Candida glabrata 
Candida krusei 
Candida tropicalis 
Candida parapsilosis 
Candida sp., other 
Candida sp., not specified 
Aspergillus fumigatus 
Aspergillus niger 
Aspergillus sp., other 
Aspergillus sp., not specified 
Other yeasts 
Fungi other 
Filaments other 

NOCSPP 
BCTOTH 

BCTNSP 
CANALB 

CANAUR 
CANGLA 
CANKRU 
CANTRO 
CANPAR 
CANOTH 
CANNSP 
ASPFUM 
ASPNIG 
ASPOTH 
ASPNSP 
YEAOTH 
FUNOTH 
FILOTH 

CANSPP 

ASPSPP 

PARTOT 

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Viruses 

Microorganism 
Other parasites 
Adenovirus 
Cytomegalovirus (CMV) 
Enterovirus (polio, coxsackie, echo) 
Hepatitis A virus 
Hepatitis B virus 
Hepatitis C virus 
Herpes simplex virus 
Human immunodeficiency virus (HIV) 
Influenza A virus 
Influenza B virus 
Influenza C virus 
Norovirus 
Parainfluenzavirus 
Respiratory syncytial virus (RSV) 
Rhinovirus 
Rotavirus 
SARS virus 

SARS-CoV-2 
Varicella-zoster virus 
Virus, not specified 
Other virus 

Microorganism not identified or not found 
Examination not done 
Sterile examination 
Result not (yet) available or missing 

Code 
PAROTH 
VIRADV 
VIRCMV 
VIRENT 
VIRHAV 
VIRHBV 
VIRHCV 
VIRHSV 
VIRHIV 
VIRINA 
VIRINB 
VIRINC 
VIRNOR 
VIRPIV 
VIRRSV 
VIRRHI 
VIRROT 
VIRSAR 

VIRCOV 
VIRVZV 
VIRNSP 
VIROTH 
_NONID 
_NOEXA 
_STERI 
_NA 

Minimal list 

VIRTOT 

_NONID 
_NOEXA 
_STERI 
_NA 

_NONID: evidence exists that a microbiological examination has been done, but the microorganism cannot be correctly classified 
or the result of the examination cannot be found; _NOEXA: no diagnostic sample taken, no microbiological examination done; 
_STERI: a microbiological examination has been done, but the result was negative (e.g. negative culture), _NA Result not (yet) 
available or missing. *Klebsiella aerogenes: both KLEAER and the old code ENBAER (Enterobacter aerogenes) are accepted. 

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Annex 2. Antimicrobial resistance (AMR) 
markers and codes 

Recommended method to collect AMR markers:  

For each AMR marker, indicate whether the microorganism was S (susceptible, standard dosing regimen), I 
(susceptible, increased exposure) or R (resistant), for the following antimicrobials: 

Staphylococcus aureus:  

• 

• 

Meticillin-resistant S. aureus (MRSA): Susceptibility to oxacillin (OXA) or other marker of MRSA such as 
cefoxitin (FOX), cloxacillin (CLO), dicloxacillin (DIC), flucloxacillin (FLC), meticillin (MET)  

Vancomycin-intermediate or vancomycin-resistant S. aureus (VISA, VRSA): Susceptibility to glycopeptides 
(GLY): vancomycin (VAN) or teicoplanin (TEC) 

Enterococcus spp.: 

• 

Vancomycin-resistant Enterococcus spp. (VRE): Susceptibility to glycopeptides (GLY): vancomycin (VAN) or 
teicoplanin (TEC) 

Enterobacteriaceae (Escherichia coli, Klebsiella spp., Enterobacter spp., Proteus spp., Citrobacter spp., Serratia 

spp., Morganella spp.) 

• 

• 

Susceptibility to third-generation cephalosporins (C3G): cefotaxime (CTX), ceftriaxone (CRO), ceftazidime 
(CAZ) 

Susceptibility to carbapenems (CAR): imipenem (IPM), meropenem (MEM), doripenem (DOR) 

Pseudomonas aeruginosa: 

• 

Susceptibility to carbapenems (CAR): imipenem (IPM), meropenem (MEM), doripenem (DOR) 

Acinetobacter spp.: 

• 

Susceptibility to carbapenems (CAR): imipenem (IPM), meropenem (MEM), doripenem (DOR) 

 
 
 
 
 
 
 
 
 
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Annex 3. Minimal dataset description 

Unit-based ‘light’ surveillance 

Patient-based ‘standard’ surveillance 

Form 

•  Hospital data for each hospital 

•  Hospital data for each hospital 

•  Form A1  

o  HospitalId 
o  DateUsedForStatistics (year) 
o 

TESSy/EpiPulse Cases technical variables  

o  HospitalId 
o  DateUsedForStatistics (year) 
o 

TESSy/EpiPulse Cases technical variables 

•  Aggregated denominator and numerator 

N/A 

•  Form AL3 

PeriodStart and PeriodEnd 

data for each hospital 
o 
o  OPCode 
o 
o 
o 
o 
o 
o 

NumOperations 
NumPostOpDays 
NumSuperficialSSI 
NumDeepSSI 
NumOrganSpaceSSI 
NumUnknownSSI 

•  Form A3 

•  Patient/operation-based data 

o  DateOfOperation 
o  DateOfHospitalDischarge 
o  OPCode 
o  OperationId 

•  Surgical site infection data 

o  DateOfOnset 
o 
SSIType 

n
o
i
t
a
m
r
o
f
n

i

d
e
t
c
e
l
l

o
C

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Annex 4. ICD-10-PCS code lists for surgical 
procedures 

See the MS Excel tables, based on the National Healthcare Safety Network (NHSN) ICD-10 Operative Procedure 
Code Mappings, updated in 2024, available on the protocol download site. 

 
 
 
 
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