3IMPORTANT ISSUES IN THE APPROACH TO SURGICAL SITE INFECTION PREVENTION

Background

SSIs are potential complications associated with any type of surgical procedure. Although SSIs are among the most preventable HAIs (1, 2), they still represent a significant burden in terms of patient morbidity and mortality and additional costs to health systems and service payers worldwide (3–11). SSI is both the most frequently studied and the leading HAI reported hospital-wide in LMICs (3, 4). For these reasons, the prevention of SSI has received considerable attention from surgeons and infection control professionals, health care authorities, the media and the public. In particular, there is a perception among the public that SSIs may reflect a poor quality of care (12). The aim of this review is to provide an update of the global data on SSI with a special focus on LMICs, notably to assess infection rates, associated risk factors and the economic burden.

Summary of the available evidence

1. Burden of SSI

a. Evidence from high-income countries

i. USA

In 2010, an estimated 16 million surgical procedures were performed in acute care hospitals in the USA (13). In a recent report on the rates of national and state HAIs based on data from 2014, 3654 hospitals reported 20 916 SSI among 2 417 933 surgical procedures performed in that year (5).

Of note, between 2008 and 2014 there was an overall 17% decrease in SSI in the 10 main surgical procedures. As an example, there was a decrease of 17% in abdominal hysterectomy and 2% in colon surgery (5).

By contrast, a multi-state HAI prevalence survey conducted in 2011 estimated that there were 157 000 SSIs related to any inpatient surgery and SSI was ranked as the second most frequently reported HAI between 2006 and 2008 (14). Another study reported data from the National Healthcare Safety Network (NHSN) between 2006 and 2008 that included 16 147 SSIs following 849 659 surgical procedures across all groups, representing an overall SSI rate of 1.9% (15).

AMR patterns of HAI in the USA have been described (16) and compared to a previous report (17). Among the 1029 facilities that reported one or more SSI, Staphylococcus aureus was the most commonly reported pathogen overall (30.4%), followed by coagulase-negative staphylococci (11.7%), Escherichia coli (9.4%) and Enterococcus faecalis (5.9%). Table 3.1.1 summarizes the distribution of the top seven reported pathogens (16).

Table 3.1.1

Distribution and percentage of pathogenic isolates associated with SSI and resistant to selected antimicrobial agents, NHSN, 2009–2010.

To investigate the costs of SSI, a study used the 2005 hospital stay data from the US Nationwide Inpatient Sample, which represents 1054 hospitals from 37 states. Extra hospital stay attributable to SSI was 9.7 days with increased costs of US$ 20 842 per admission. From a national perspective, SSI cases were associated with 406 730 extra hospital days and hospital costs exceeding US$ 900 million. An additional 91 613 readmissions for the treatment of SSI accounted for a further 521 933 days of care at a cost of nearly US$ 700 million (18).

Applying two different consumer price index adjustments to account for the rate of inflation in hospital resource prices, the Centers for Disease Control and Prevention estimated that the aggregate attributable patient hospital costs for SSI infection ranged between US$ 1087 and US$ 29 443 per infection (adjusted for the 2007 US$ level). Using the consumer price index for urban consumers and inpatient hospital services, SSI is considered as the HAI with the largest range of annual costs (US$ 3.2–8.6 billion and US$ 3.5–10 billion, respectively) (19).

ii. European countries

The European point prevalence survey of HAIs and antimicrobial use conducted in 2011–2012 showed that SSIs are the second most frequent HAI in hospitals (20). A recent report from the ECDC on SSI surveillance of SSI provided data for 2010 and 2011 (6) from 20 networks in 15 European Union countries and one European Economic Area country using a standardized protocol (21). Hip prosthesis was the most frequently reported surgical procedure and represented 33% of all operations. The cumulative incidence of patients with SSI was the highest in colon surgery with 9.5% (episodes per 100 operations), followed by 3.5% for coronary artery bypass graft, 2.9% for caesarean section, 1.4% for cholecystectomy, 1.0% for hip prosthesis, 0.8% for laminectomy and 0.75% for knee prosthesis (6). The results showed also decreasing trends in SSI incidence in several types of procedure (caesarean section, hip prosthesis and laminectomy) (Figure 3.1.1), thus suggesting that prevention efforts, including surveillance, were successful in participating hospitals (6, 22).

Figure 3.1.1

Cumulative incidence for SSI by year and type of procedure: European Union/European Economic Area countries, 2008–2011. Data source: ECDC, HAI-Net SSI patient-based data 2008–2011 (http://ecdc.europa.eu/en/activities/surveillance/Pages/data-access.aspx#sthash.hHYRJ9ok.dpuf, (more...)

A study published in 2004 reviewed data from 84 studies and estimated the economic costs of SSIs in Europe to range between € 1.47–19.1 billion. It predicted also that the average patient stay would increase by approximately 6.5 days and cost 3 times as much to treat an infected patient. The analysis suggested that the SSI-attributable economic burden at that time was likely to be underestimated (10).

In France, it was estimated that 3% of surgical procedures resulted in infection for a total annual cost of nearly € 58 million. Moreover, patients who experienced SSI had a significantly increased mortality risk (from 4- to 15-fold) and a 3-fold increased length of hospital stay (23).

The prevalence of SSI in Switzerland was reported to be 5.4% in a study conducted in 50 acute care hospitals participating in the Swiss Nosocomial Infection Prevalence surveillance programme (24). Another study described a 13-year multicentre SSI surveillance scheme performed from 1998 to 2010. Reported SSI rates were: 18.2% after 7411 colectomies; 6.4% after 6383 appendicectomies; 2.3% after 7411 cholecystectomies; 1.7% after 9933 herniorrhaphies; 1.6% after 6341 hip arthroplasties; and 1.3% after 3667 knee arthroplasties (25).

In Italy, the SSI rate reported by the “Sistema Nazionale di Sorveglianza delle Infezioni del Sito Chirurgico” (national SSI surveillance system) from 355 Italian surgical wards between 2009 and 2011 was 2.6% episodes per 100 procedures (1628 cases/60 460 procedures); 60% of SSIs were diagnosed through 30-day post-discharge surveillance. SSI rates were higher in colon (9.0%) and rectal surgery (7.0%), laparotomy (3.1%) and appendectomy (2.1%) (26).

In England, the most recent summary of data collected by National Health Service hospitals reported cumulative SSI rates from January 2008 to March 2013. The highest rate was reported among large bowel surgery (8.3%; 95% CI: 7.9–8.7 per 1000 inpatient days), followed by small bowel surgery (4.9%; 95% CI: 4.3–5.7), bile duct, liver and pancreatic surgery (4.9%; 95% CI: 4.1–5.9) and cholecystectomy (4.6%; 95% CI: 3.1–6.6). The lowest rate was reported for knee prosthesis (0.4%; 95% CI: 0.3–0.4) (8).

Data collected from April 2010 to March 2012 estimated that the median additional length of stay attributable to SSI was 10 days (7–13 days), with a total of 4694 bed-days lost over the 2-year period (27).

iii. Australia

A study evaluated the time trends in SSI rates and pathogens in 81 Australian health care facilities participating in the Victorian Healthcare Associated Infection Surveillance System. A total of 183 625 procedures were monitored and 5123 SSIs were reported. S. aureus was the most frequently identified pathogen, and a statistically significant increase in infections due to ceftriaxone-resistant E. coli was observed (relative risk: 1.37; 95% CI: 1.10–1.70) (9).

iv. Japan

Data from the Japan nosocomial infection surveillance system showed that 470 hospitals voluntarily participated in SSI surveillance in 2013 (28, 29). A retrospective study evaluated also the influence of SSI on the postoperative duration of hospitalization and costs between 2006 and 2008 after abdominal or cardiac surgery. Overall, the mean postoperative hospitalization was 20.7 days longer and the mean health care expenditure was US$ 8791 higher in SSI patients. SSI in abdominal surgery extended the average hospitalization by 17.6 days and increased the average health care expenditure by US$ 6624. Among cardiac surgical patients, SSI extended the postoperative hospitalization by an average of 48.9 days and increased health care expenditure by an average of US$ 28 534 (30). A recent study assessed SSI rates and risk factors after colorectal surgery using the Japan nosocomial infection surveillance system national database. The cumulative incidence of SSI for colon and rectal surgery was 15.0% (6691/44 751 procedures) and 17.8% (3230/18 187 procedures), respectively (31).

v. Republic of Korea

A prospective multicentre surveillance study published in 2000 concluded that SSI constituted 17.2% of all HAIs reported from 15 acute care hospitals (32, 33). The 2009 national SSI surveillance system report described the incidence and risk factors for SSI in 7 types of procedures. The SSI rate per 100 operations was 3.68% (22/1169) after craniotomies, 5.96% (14/235) for ventricular shunt operations, 4.25% (75/1763) for gastric operations, 3.37% (22/653) for colon surgery, 5.83% (27/463) for rectal surgery, 1.93% (23/1190) for hip joint replacement and 2.63% (30/1139) for knee joint replacement (34).

A web-based surveillance of SSIs was performed between 2010 and 2011 to determine the incidence of SSIs after 15 surgical procedures in 43 hospitals. The overall SSI rate represented 2.10% of the total of 18 644 operations and differed after various types of surgery (35). In addition, a systematic review of the literature published between 1995 and 2010 on the epidemiological and economic burden of SSI in the Republic of Korea reported an overall incidence of SSI ranging from 2.0% to 9.7% (36). SSIs were associated with increased hospitalization costs and each episode of SSI was estimated to cost around an additional 2 000 000 Korean Republic won (approximately US$ 1730). Postoperative stays for patients with SSIs were 5 to 20 days longer (36).

In a recent study conducted between 2008 and 2012, the SSI rate following gastrectomy was 3.12% (522/16 918), 2.05% (157/7656) for total hip arthroplasty and 1.90% (152/7648) for total knee arthroplasty. There was a significant trend of decreased crude SSI rates over 5 years (37).

vi. Gulf Council Countries

We were not able to retrieve published national data on SSI rates from any of the Gulf Council Countries (Bahrain, Kingdom of Saudi Arabia, Kuwait, Oman, Qatar and the United Arab Emirates). However, in Saudi Arabia, a 5-year analysis of SSI in orthopaedic surgery in one hospital estimated a rate of 2.55% (38). Another study from the King Abdulaziz Medical City (Saudi Arabia) compared SSI rates for herniorraphy and cholecystectomy in 2007 to 1999–2000. In 2007, SSI rates per 100 operations in 2007 were 0.88% for herniorrhaphy and 0.48% for cholecystectomy, while in 2007, rates were reduced by 80% for herniorrhaphy (P=0.049) and 74% for cholecystectomy (P=0.270) (39).

vii. Singapore

In a systematic literature review (2000 to 2012) (40) of the burden of HAI in South-East Asia, the pooled incidence of SSI was 7.8% (95% CI: 6.3–9.3). A study conducted between January and March 2008 in a tertiary care hospital in Singapore reported an SSI incidence of 8.3% for general, neurologic and orthopaedic surgical procedures (41).

viii. Uruguay

The national incidence data on SSI for 2012–2013 reported that the incidence rate for appendectomy was 3.2%, 2.5% for cardiac surgery, 6.2% for cholecystectomy and 15.4% for colon surgery (42).

ix. Chile

The 2013 national report on HAI surveillance showed a SSI rate of 3.09% for coronary bypass surgery and 1.89% for hip joint replacement. Infection rates in cholecystectomy performed via laparotomy were 4.12% (95% CI: 2.8–6.11) times higher than laparoscopic cholecystectomy (P<0.0001) (43).

b. WHO systematic reviews on SSI in LMICs

The WHO report on the global burden of endemic HAI provided SSI data from LMICs. The pooled SSI incidence was 11.8 per 100 surgical patients undergoing surgical procedures (95% CI: 8.6–16.0) and 5.6 per 100 surgical procedures (95% CI: 2.9–10.5). SSI was the most frequent HAI reported hospital-wide in LMICs and the level of risk was significantly higher than in developed countries (3, 4).

Recently, WHO conducted an update of the systematic literature review of from 1995 to 2015 with a special focus on SSI in LMICs (WHO unpublished data). A total of 231 articles in English, French, German, Spanish and Portuguese were included. The pooled SSI rate was 11.2 per 100 surgical patients (95% CI: 9.7–12.8) for incidence/prospective studies. There was no statistical difference in SSI rates when stratified by study quality, patient age groups, geographic regions, country income, SSI definition criteria, type of setting or year of publication. However, there were statistical differences between studies according to the type of surgical population procedures (P=0.0001) and the number of patients per study (P=0.0004).

In incidence studies, the SSI rate was higher for procedures in oncology (17.2%; 95% CI: 15.4–19.1), orthopaedic (15.1%; 95% CI: 10.2–20.6), general surgery (14.1%; 95% CI: 11.6–16.8) and paediatric surgery (12.7%; 95% CI: 6.7–20.3). The SSI rate expressed as the number of SSI infections per 100 surgical operations was reported in 57 (24.7%) studies. The pooled SSI rate using this measure was 6.1% (95% CI: 5.0–7.2) for incidence/prospective studies (Figure 3.1.2).

Table 3.1.2

Summary of SSI rates in different countries.

Some studies (44–50) investigated SSI rates after caesarean section surgery and showed a substantial variability in the definition of SSI and in reported rates. High rates of SSI following caesarean section were reported in several LMICs: 16.2% in a study from Nigeria (44), 19% from Kenya (45), 10.9% from Tanzania (46) and 9.7% by Viet Nam (47). In 2 studies from Brazil, one reported a rate of 9.6% (48) and the other a higher rate of 23.5% (49). In comparison, a much lower average SSI rate of 2.9% is reported in Europe (6, 21).

Conclusions

Despite robust data on the burden of SSI in some countries or regions, accurate estimates of the global burden in terms of SSI rates and the economic aspects still remain a goal for the future. As an example, SSI and overall HAI data are not yet included in the list of diseases for which the global burden is regularly estimated by WHO or other international organizations gathering data on global health. Although SSI rates vary between countries and geographical regions, they represent an important problem, with a significantly higher burden in developing countries. If SSI rates are to serve as a quality indicator and comparison benchmark for health care facilities, countries and the public, they must be determined in a reliable way that produces robust infection rates to ensure valid comparisons. There is a global need to address changes to SSI definitions, strengthen and validate SSI data quality, and to conduct robust SSI economic and burden studies.

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Definitions of surveillance and SSI

Surveillance is defined as “the ongoing, systematic collection, analysis, interpretation and evaluation of health data closely integrated with the timely dissemination of these data to those who need it” (3).

There are many definitions of SSI and a systematic review identified as many as 41 different definitions. However, only five were described as being standardized definitions created by multidisciplinary groups (Table 3.2.1) (4). More than one third of included studies used the US CDC definitions (either 1988 or 1992). While the authors of this review suggest that a single definition allows longitudinal analysis and benchmarking, they conclude by stating that “there is no single, objective gold standard test for surgical wound infection” (4). In addition, many countries use the HAI SSI protocol developed by the ECDC (http://ecdc.europa.eu/en/healthtopics/Healthcare-associated_infections/surgical-site-infections/Pages/SSI.aspx, accessed 20 May 2016).

Table 3.2.1

Definitions of SSI.

Aims of surveillance

The primary aim of surveillance is the collection of data on SSI rates in order to obtain a measure of the magnitude of the problem. These data must then be analysed to identify and investigate trends, including a careful interpretation of results. Finally, surveillance data should guide the identification of improvement actions and evaluate the effectiveness of these interventions. In this context, the feedback of SSI rates to relevant stakeholders is important.

Should surveillance be conducted?

The positive impact of HAI surveillance was first described in the landmark study on the efficacy of a nosocomial infection control programme conducted in the USA in the 1970s. In this trial, it was shown that an IPC programme with both surveillance and control components could lower SSI rates significantly (5). Importantly, surveillance of SSI is part of the WHO safe surgery guidelines (6). Many countries have introduced mandatory surveillance of HAI, including SSI, such as the UK and certain states in the USA, whereas other countries have voluntary-based surveillance, such as France, Germany and Switzerland. However, there are considerable differences related to the types of surveillance, as well as in the length and type of surveillance (7, 8). Increasingly, national networks and “networks of networks” are being created, such as the CDC NHSN, the ECDC HAI Surveillance Network (HAI-Net) and the International Nosocomial Infection Control Consortium.

By using standardized definitions of HAI and specifically SSI, these networks allow inter-hospital comparisons and benchmarking. An essential component of these surveillance networks is feedback to individual hospitals, as discussed below.

It has been postulated that a “surveillance effect” might occur, similar to the Hawthorne effect in clinical trials, that is, the simple fact of being conscious that one is being observed may independently lead to improved practices or improved adherence to guidelines (9).

Another way in which a successful surveillance programme may decrease SSI rates is that the feedback given to the institution may prompt investigation of why its rates are higher than the benchmark. Certain process indicators (if not already collected) may then identify the reason for “underperformance” and prompt local initiatives to improve performance on these indicators. There is conflicting evidence that conducting surveillance as part of a network has a positive impact on SSI rates (Table 3.2.2). Some studies report a successful reduction of SSI rates after participation in a surveillance network (10–12), while others report no effect (13). However, there is an important methodological issue that could “dilute” the reduction in the time trend of SSI rates, which is the fact of adding smaller hospitals in a network without taking into account their year of participation in the network. This obstacle was overcome in an analysis of German data where hospitals were stratified by year of participation (9) and in an analysis of Dutch (14) and Swiss (13) data where SSI rates were stratified by surveillance time to operation in consecutive one-year periods using the first year of surveillance as a reference. The Dutch and German studies reported decreasing time trends of SSI rates after surveillance, whereas the Swiss study did not.

Table 3.2.2

Temporal trends of SSI rates after surveillance in selected networks.

Conversely, as shown in clinical trials, intensive surveillance may lead to the detection of higher SSI rates than under standard surveillance conditions. As an example, in a recent clinical trial comparing skin antiseptic agents for caesarean section, the SSI rate was 4.0% in one arm and 7.3% in the other (15). These rates seem higher than the most recently available data from the ECDC, which show an SSI rate of 2.9% (inter-country range: 0.4%–6.8%) (16).

Establishing a surveillance system

According to the US Association for Professionals in Infection Control and Epidemiology (20), there is “no single or “right” method of surveillance design or implementation” (21). However, the following minimal requirements for ensuring quality of surveillance have been identified by the Association (21).

• A written plan that states goals, objects and elements of surveillance process
• Constant rigour of intensity of surveillance
• Consistent elements of surveillance (for example, definitions, calculation methods)
• Adequate human resources (professionals trained in epidemiology)
• Informatic services, computer support
• Evaluation methods.

For a surveillance programme to be successful, there should be a method of data validation to ensure that data are accurate and reliable (22), particularly for benchmarking purposes, as discussed further (23).

Methods for conducting surveillance

In the field of SSI, most surveillance systems target colorectal surgery and total hip and knee arthroplasty. The most common outcome indicator is the cumulative SSI incidence (or SSI rate). Detecting SSI using prevalence methods is less reliable given the high proportion of SSIs that manifest after discharge.

For any given period, denominator data represent the total number of procedures within each category. The number of patients can be used also as the denominator, but it is less precise because more than one infection can occur in the same patient. Numerator data will be the number of SSIs in that same period. Demographic data (age, sex, timing and choice of antimicrobial prophylaxis, American Society of Anesthesiologists score, duration of the operation and wound contamination class) are recorded for all patients, including the site of infection and type of SSI (superficial, deep, organ/space) for those with SSI. Linkage with microbiological data may also be useful.

The gold standard is prospective direct surveillance, although it is time- and labour-intensive and costly (24). The CDC recommendations describe indirect methods of surveillance (sensitivity of 84–89%; specificity 99.8%) as a combination of:

1. Review of microbiology reports and patient medical records.
2. Surgeon and/or patient surveys.
3. Screening for readmission and/or return to the OR.
4. Other information, such as coded diagnoses, coded procedures, operative reports or antimicrobials ordered. (24)

The importance of post-discharge surveillance

It is estimated that a significant proportion of SSIs are detected following patient discharge. This proportion varies across settings and according to different definitions, but it has been estimated to be between 13% to 71% (25). The fact that hospital length of stay has been steadily decreasing over the past decades has probably contributed to shifting the burden from inpatient to outpatient infections. Moreover, implant-associated infections may not become apparent until one year after the procedure. For this reason, many surveillance networks recommend the practice of post-discharge surveillance. There is no known gold standard procedure for post-discharge surveillance and a systematic review identified only 7 reports of studies comparing different surveillance methods (26). Due to variations in data collection and classification, as well as missing information regarding diagnostic criteria, no synthesis of post-discharge surveillance data was possible. The authors concluded that more research is required regarding the measurement of SSI after hospital discharge.

There has been recent controversy regarding the CDC decision to shorten post-discharge surveillance to 90 days instead of one year after certain procedures (27). This change was aimed at simplifying post-discharge surveillance and reducing delayed feedback, but it has not been universally adopted as yet (28). A report compared historical prospective SSI surveillance data from a USA network to the retrospective application of the new CDC definitions (29). The authors found that 9.6% of SSIs detected by the former definition went undetected with the new definitions; 28.8% of these undetected SSIs concerned hip and knee prostheses. The proportion of missed SSIs varied by procedure, but they were high for hip (8.8%) and knee prostheses (25.1%). Another report from the Dutch SSI surveillance network analysed the influence of the duration and method of post-discharge surveillance on SSI rates in selected procedures (30). The proportion of missed SSIs was variable, but they were 6% and 14% for hip and knee prostheses, respectively. More importantly, the study showed that the new CDC method of performing post-discharge surveillance was associated with a higher risk of not detecting a SSI when compared with the former method.

How to report surveillance data

Although most surveillance systems report SSI rates, there has been debate in the literature regarding the best choice of outcome indicator. Some authors argue that the incidence density of in-hospital SSI is a more suitable choice of outcome indicator by taking into account different lengths of hospital stay and different post-discharge surveillance methods (31). This indicator requires recording the date of patient discharge.

In order to adjust for variations in case-mix, it is recommended to present risk-adjusted SSI rates in addition to crude rates (32). The most commonly used method of risk adjustment is the NNIS risk index whose aim is to predict the occurrence of an SSI in a given patient (33). This risk index has been updated and includes procedure-specific factors that improve its predictive power, but it is not widely used (28, 34). Of note, collecting data for the NNIS risk index may be difficult in settings with limited resources where very limited information is reported in patient records. As an example, in a recent systematic review conducted by WHO, only 14 of 231 SSI surveillance studies from developing countries reported using the NNIS risk index (WHO unpublished data).

Some surveillance systems report standardized infection ratios, which is the ratio between the observed and the expected infection rates (35, 36). A ratio higher than 1.0 indicates that more SSIs occurred than were expected, whereas a ratio lower than 1.0 indicates the opposite (36). The simplest manner to calculate the expected number of SSIs is by multiplying the number of operations in each procedure category by the SSI rate and dividing by 100. This accounts for the case-mix and is therefore a risk-adjusted summary measure (36).

Other surveillance systems (UK, Switzerland) use a funnel plot to improve the precision of the estimates of SSI rates, which are dependent on the number of operations performed. SSI rates are plotted against the number of procedures for each hospital and 95% CIs are drawn. In this manner, outliers (hospitals with unusually high rates) can be easily identified (37).

Difficulties associated with surveillance

Active surveillance is a resource- and time-consuming activity. Constraints can be both in financial terms and/or in the availability of trained and dedicated staff. Surveillance data need validation and interpretation by supervising IPC professionals and/or epidemiologists. A major and very common constraint to HAI surveillance in developing countries is the lack of reliable microbiology support. However, this may have a less significant impact on SSI surveillance as a clinical diagnosis can often be made without microbiological confirmation. Thus, the correct collection of clinical data (preferably electronically) is essential for a successful surveillance system. Another difficulty in low-income countries is the high loss of patient follow-up for post-discharge surveillance due to long distances between surgical care services and the patient’s place of residence and/or the patient’s financial constraints. Based on some interesting publications (38), WHO has developed an adapted approach to SSI post-discharge surveillance by issuing pre-discharge instructions to the patient to allow him/her to recognize signs of infection and maintain follow-up through telephone calls. Finally, in the absence of effective infection control programmes and societies (local and national), it is difficult to introduce a sustainable surveillance system.

Use of surveillance for benchmarking

The use of HAI surveillance data, including SSIs, has been advocated for benchmarking purposes (23). Benchmarking can be used for several purposes, including for the publication of “league tables” as in the UK and USA (39). In addition, it is also used in the USA as the basis for modifying hospital payments to facilities paid by Medicare (24). There are advantages and disadvantages of benchmarking as there are important pitfalls that should be actively avoided. There is a possibility that surveillance systems with more intensive and sensitive surveillance methods that result in higher SSI rates may be unfairly penalised.

Even in the presence of uniform standardized definitions, several studies have shown that inter-rater agreement for SSI is rather low (40–42). One study evaluated inter-rater agreement by submitting 12 case-vignettes of suspected SSI to IPC physicians and surgeons from 10 European countries (41). It was found that there was poor agreement regarding SSI diagnosis and the type of SSI, with variations between and within countries. An analysis of data submitted from 11 countries to the ECDC HELICS (Hospitals in Europe for Infection Control through Surveillance) network showed that there was a substantial variation not only in terms of case-mix (as measured by the NNIS risk index score), but also in the reporting of SSI (highly variable inter-country proportions of superficial SSI ranging from 20–80%) and the length and intensity of postoperative follow-up (31).

An audit of SSI surveillance methods in England showed that differences in data collection methods and data quality were associated with large differences in SSI rates (43). What is striking is that even in the presence of mandatory surveillance with a clearly defined national protocol, a substantial proportion of responders (15%) used alternative definitions (43).

Conclusions

Ideally, surveillance of SSI should be an integral part of IPC programmes of health care organizations and priorities for public health agencies worldwide. However, caution must be exerted when interpreting SSI data, especially when making comparisons, due to a possible heterogeneity of definitions used, surveillance methods, risk stratification and reporting.

Further studies are needed to determine the most sensitive methods of diagnosing SSI, both for in-patients and as part of PDS, and the most efficient methods of collecting data. It is of the utmost importance to develop and test reliable adapted definitions and surveillance methods for settings with limited resources. The role of automated computerized algorithms needs to be also further evaluated. Similarly, the role of SSI surveillance data for benchmarking purposes needs to be clarified, especially when public reporting is involved.

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3.3.1. Environment

For many years, environmental contamination was considered to be less important than many other factors in contributing to HAI. However, recent evidence shows that a contaminated health care environment plays a significant role in the transmission of microorganisms (1,2). It is essential that the operating room (OR) is thoroughly cleaned on a daily basis. Proper mechanical ventilation is also necessary to prevent surgical wound contamination from unfiltered air drawn into the OR and to dilute and remove microorganisms shed in skin scales (3). Specific guidance on the most appropriate ventilation systems in the OR and an evidence-based recommendation on laminar flow are included in chapter 4.23 of these guidelines.

Environmental cleaning and waste management in the OR

Cleaning consists of the removal of dust, soil and contaminants on environmental surfaces and ensures a hygienic and healthy environment both for patients and staff. The environment should be thoroughly cleaned and general principles of good practice should be taken into consideration (Box 3.3.1). Cleaning requirements for various surfaces are detailed in Table 3.3.1.

Box 3.3.1

General principles for environmental cleaning.

Table 3.3.1

Cleaning requirements for various surface types in ORs.

At the beginning of each day, all flat surfaces should be wiped with a clean, lint-free moist cloth to remove dust and lint. Between cases, hand-touch surfaces (Figure 3.3.1) and surfaces that may have come in contact with patients’ blood or body fluids, should be wiped clean first by using a detergent solution and then disinfected according to hospital policy and allowed to dry.

Figure 3.3.1

Example of cleaning frequencies in preoperative and postoperative care areas. Reproduced with permission from reference .

All spills must be carefully cleaned up and the surface cleaned and disinfected according to hospital policy. Domestic heavy duty gloves should be always worn to undertake this task. Use a single-use plastic apron if contamination of the body is likely. Use of a gown and mask is not necessary. If there is a risk of spills with chemicals, the use of a face shield or goggles should be considered, depending on the type of chemical products used for disinfection. All waste from the OR should be collected and removed in closed leak-proof containers; soiled linen should be placed in plastic bags for collection. All reusable medical devices should be sent for reprocessing to the sterile services department or the decontamination unit. The operating table should be cleaned and wiped with a detergent solution, including the mattress and the surface. All surfaces that have come in contact with a patient or a patient’s body fluids must be cleaned and disinfected using an appropriate disinfectant solution according to local protocols.

At the end of every day, it is necessary to perform a total cleaning procedure. All areas of the surgical suite, scrub sinks, scrub or utility areas, hallways and equipment should be thoroughly cleaned, regardless of whether they were used or not during the last 24 hours. Soiled linen should be removed in closed leak-proof containers. All contaminated waste containers should be removed and replaced with clean containers. Sharps’ containers should be closed and removed when they are three quarters full. All surfaces should be cleaned from top to bottom using a detergent, followed by a disinfectant if necessary, and then allowed to dry. To reduce the microbial contamination of environmental surfaces, such as walls, ceilings and floors, they should be thoroughly cleaned from top to bottom with a detergent and allowed to dry. The routine use of a disinfectant or fumigation of the OR is not necessary even after contaminated surgery.

3.3.2. Decontamination of medical devices and surgical instruments

Decontamination is a complex and highly specialized subject. This section provides a brief summary on the decontamination and reprocessing of reusable medical devices and patient care equipment.

In countries with established programmes, decontamination is a speciality in its own right and is an independent, quality-assured and accountable service delivered to health care institutions. The entire process of decontamination is highly regulated and governed by clearly defined guidelines and standards, which are established at both national and international (International Organization for Standardization) levels. This ensures validation of the processes and patient safety (7–10).

In LMICs, decontamination science is in its infancy and few structured decontamination programmes exist, as was evident during the recent Ebola outbreak. In these countries, where the lack of sterile instruments and/or the availability of a properly designed OR and sterile services department have a considerable impact, SSI can be described as surgery-associated infection (11,12). In response to this need, the WHO/Pan American Health Organization (PAHO) have produced a decontamination and reprocessing manual for health care facilities (13) to support and guide operational activities to improve standards of care.

In the USA, the term decontamination does not include cleaning and refers to all reprocessing following on thereafter. In the UK and Europe, decontamination relates to the entire process, including cleaning, and this term is used in this chapter (see Table 3.3.2).

Table 3.3.2

Glossary of terms.

Essentials of decontamination

All medical devices that are reprocessed, such as surgical instruments, must undergo rigorous cleaning prior to decontamination and sterilization procedures. Soaking contaminated medical devices prior to cleaning in disinfectants of any kind is not sufficient or recommended (14). Regardless of the type of operative procedure, the decontamination steps in reprocessing surgical instruments and other medical devices are the same. The life cycle of decontamination illustrates (Figure 3.3.2) the salient features of decontamination, with each step being as important as the next.

Figure 3.3.2

The cycle of decontamination of a reusable surgical instrument. Reproduced with permission from reference .

Risk assessment of contaminated instruments

The risk of transferring microorganisms from instruments and equipment is dependent on the following factors:

• the presence of microorganisms, their number, and their virulence;
• the type of procedure that is going to be performed (invasive or non-invasive);
• the body site where the instrument or equipment will be used.

Risk assessment for the reprocessing of medical devices was best described by Spaulding (15) and has since been modified. After thorough cleaning, the decision to disinfect or sterilize is based on whether the device is stable to heat or not. In addition, the body site where the instrument or equipment will be used/have contact with will determine whether cleaning or high level disinfection or sterilization is required. According to the Spaulding classification, medical devices are categorized as critical, semi-critical or non-critical according to the degree of risk of infection transmission (Table 3.3.3).

Table 3.3.3

Spaulding classification of equipment decontamination (15).

Decontamination facility

The work space

All reprocessing of medical devices must take place in the sterile services department, which should be a separate demarcated department or in a designated decontamination area. Many countries have centralized decontamination areas (central sterile services department) and provide services to the OR, wards and clinical areas. Centralized decontamination processes make the decontamination process cheaper, increase the process safety and enhance its quality. A structured transportation system for clean and used equipment must also be in place. Of note, when the decontamination area space is very limited (usually just one room) and reprocessing is expected to take place in the smallest and least appropriate space with old equipment and overcrowded surfaces, the risk of contamination of clean trays is highly likely. Decontamination of medical devices in clinical areas is not recommended.

Standard operating procedures for decontamination and sterilization

All decontamination units must have written policies and procedures for each stage of the decontamination process and should include:

• formal staff qualification, education/training and competency assessment;
• cleaning;
• high-level disinfection (all processes available);
• preparation and packaging of medical devices;
• sterilizer operating procedures;
• monitoring and documenting of chemical or cycle parameters;
• workplace health and safety protocols specific to the chemical sterilant;
• handling, storage and disposal of the sterilant according to the manufacturer’s instructions for use and local regulations;
• use of physical, chemical and/or biological indicators;
• quality systems;
• validation of cleaning, disinfection and sterilization.

Provisions for hand hygiene and personal protective equipment

Equipped hand hygiene stations should be available at the entrance and exit of the sterile services department or decontamination areas. Appropriate personal protective equipment must be provided at each entry point into the sterile services department or decontamination area. Personal protective equipment is designed to be disposable, but it is reused in some low-resource settings. This is acceptable provided that the personal protective equipment, for example, an apron, is cleaned by wiping with a damp cloth and allowed to dry. The apron should then be wiped with 70% alcohol and allowed to dry. A discard bucket for used personal protective equipment must be provided at the exit point, preferably near the wash hand basin.

The workflow

There should be clearly demarcated areas during the reprocessing of medical devices, such as the dirty area where the items are received and cleaned, the inspection-assembly-packaging and the sterilization or high-level disinfection areas, and finally those dedicated to the storage of sterile packs and their transportation. It is recommended that these areas be physically demarcated to avoid cross-contamination from dirty to clean. When this is not possible because of lack of space, obstacles should be placed in order to only permit a unidirectional movement of staff and equipment from dirty to clean without any possibility of overlap.

Transportation of used medical devices

Once devices have been used in the clinical area such as the OR, they should be prepared for transportation to the sterile services department by counting and collecting the devices, rinsing them under cold running water, allowing excess water to drain away, and placing them in a closed container or tray, which will keep them moist until they are removed. These trays (and the accompanying checklist) should be transported in a robust trolley, preferably with closed sides, to the decontamination area. Soaking of medical devices in disinfectant prior to cleaning or during transportation is not recommended as there is a danger of spilling contaminated fluids (13) (Box 3.3.2). Used devices should be received, checked and sorted for cleaning in the “dirty” area. Cleaning is normally done either manually or by automated methods.

Box 3.3.2

Recommendations related to the soaking of instruments in disinfectant prior to cleaning.

Manual cleaning

Cleaning by hand will require well-trained operators to wear appropriate personal protective equipment (waterproof aprons, domestic heavy duty gloves, face cover to protect mucous membranes and head cover [optional]), dilute the detergent accurately according to the manufacturer’s guidelines, open up all the hinges on the devices and clean these by holding the item below the surface of the water (water temperature no more than 50°C) while using a soft nylon brush to remove debris. Visual inspection of the hinges, teeth and serrated edges should be carried out to ensure cleanliness. There is no controlled validation of manual cleaning apart from protein detection, which is expensive. Water or air pressure guns are used to blow through and clear lumen devices.

Automated cleaning

Reprocessing medical devices through a washer disinfector is safer and usually more efficient. Devices are cleaned using water jets, then washed with detergent and warm water, followed by a thermal disinfection cycle (some machines have a drying cycle). The load is substantial, although some washer disinfectors are capable of reprocessing up to 60 trays per hour. Most importantly, each cycle is validated with physical and biological parameters (13).

Inspection, assembly and packaging

Using a magnifying glass and good lighting, clean devices are carefully checked to confirm cleanliness and being fit for purpose and then reassembled. If the medical device is found not to be clean, it is returned for re-cleaning; damaged devices are replaced and the completed tray is wrapped ready for sterilization. Packaging is usually done by double wrapping for surgical trays or sterilization pouches for single items. Packaging material should be robust, permeable to steam, but maintain a fluid barrier, and should protect the sterility of the package prior to use.

Decontamination of endoscopes

An increasing number of diagnostic and therapeutic procedures are now being carried out using rigid or flexible endoscopes (16). Effective decontamination will protect the patient from infection, ensure the quality of diagnostic procedures and samples and prolong the life of the equipment (17) (Table 3.3.4). The source of infection may be due to:

Table 3.3.4

Types of endoscopic procedures.

• the previous patient or inadequate decontamination of the endoscope before reuse;
• endogenous skin, bowel or mucosal flora;
• contaminated lubricants, dyes, irrigation fluid or rinse water;
• inadequate decontamination of the reprocessing equipment.

Staff should be aware of the complexities of the endoscopes they are processing to ensure that the construction of the endoscope is fully understood. Failures in decontamination, particularly for flexible endoscopes, have been reported due to failure to access all channels of the endoscope. Irrespective of the method of disinfection or sterilization, cleaning is an essential stage in the decontamination procedure and the manufacturers’ instructions should be followed at all times. An endorsement of compatibility of the endoscope with the decontamination process is essential.

Rigid endoscopes are relatively easy to clean, disinfect and sterilize as they do not have the sophistication of functionality, construction and channel configuration and compatibility issues that exist with flexible endoscopes. Where possible, all reprocessing of autoclavable endoscopes and their accessories should take place in a sterile services department or dedicated decontamination unit as the process controls and validation are already in place. It should never take place in the clinical area (17).

Flexible endoscopes are heat-sensitive and require chemical disinfection (or low temperature disinfection) (18). Decontamination of flexible endoscopes should take place in a dedicated well-ventilated room (up to 12 air changes per hour) away from the procedure room. There should be adequate ventilation to remove potentially harmful disinfectant vapour. The room should be equipped with a sink with sufficient capacity to accommodate the largest endoscopes and a dedicated wash hand basin equipped with soap and disposable paper towels.

There should be a workflow direction within the room from dirty to clean to avoid the possibility of recontamination of decontaminated endoscopes from those just used on a patient. Systems should be in place to indicate which endoscopes are ready for patient use and recorded either manually or by an automated endoscope reprocessor. Modern units will have a 2-room system with pass-through washer disinfectors to separate the clean and dirty areas. Storage of endoscopes should be organized to avoid any recontamination of processed endoscopes. There should be sufficient storage for the consumables used during the decontamination procedure, for example, personal protective equipment, chemicals, cleaning brushes and sufficient capacity for waste disposal.