Preventing surgical site infections: an update

Asurgical site infection (SSI) is determined as an infection that occurs within 30 days of surgery if no implant is left in place, or within a year if an implant is in place and the infection appears to be related to the operation. 

There are many factors contributing to the development of SSIs. These can be divided into pre- peri- and postoperative factors that are patient-related (for example, age, obesity, diabetes), procedure-related (for example, prolonged surgical duration, preoperative hair removal) and/or structure-related (for example, laminar airflow, surveillance). 

This article provides an overview of the latest insights into preventive measures to help reduce SSIs to a minimum. 

In addition to increased morbidity and mortality, SSI affects the duration of hospital admission, and consequently the health care costs. On average 5% of all patients who undergo surgery develop SSIs, which are associated with an extra seven days as an inpatient and an increased postoperative mortality. Wound infection rates after abdominal surgery in recent studies range from 9.4% (laparoscopic) to 15.7 % (open).(1-3) 

In general, cases with SSIs contribute to a threefold increase of health care costs, compared with cases without SSI. According to a recent review, additional costs of SSIs vary between $3.859 and $40.559 per patient, deeper infections typically accounting for the majority of costs.(4)

The Guideline for Prevention of Surgical Site Infection, issued in 1999 by the Centers for Disease Control and Prevention (CDC), was used widely in the United States and many European countries, but was not updated despite new findings and insights emerging. The latest US guideline is the SHEA/IDSA practice recommendation: Strategies to Prevent Surgical Site Infections in Acute Care Hospitals.(5) 

Risk-assessment and prediction 

Patients who are colonised with Staphylococcus aureus (S. aureus) are at increased risk for healthcare-associated infections with this organism. Preoperative screening and decolonisation of nasal carriers can reduce S. aureus-induced surgical site infections, most impressively in patients undergoing cardiothoracic procedures.(6,7) 

In general, patient characteristics can be divided into factors that can or cannot be influenced by the patients themselves. Factors such as a body mass index of more than 30, nicotine use, nutritional state and infection at remote site can be influenced, whereas age, underlying disease, malignancy, wound classification and the need to implant prosthetic material cannot. 

Outcome of SSIs in the elderly is significantly poorer than in younger patients. Age obviously cannot be changed, but other risk factors that are common in elderly patients can be changed. Nutritional state and glucose control should be adapted to reduce the chance to develop SSI.

To support the improvement of medical care in the US the ‘5 million lives campaign’ was initiated in 2006(8) and included prevention measures for SSI. The improvement ‘bundle’ contained selection, timing and duration of antimicrobial prophylaxis, glucose control in cardiac surgery, hair removal technique and the use of basic preventive strategies as describes in the CDC guidelines, for example showering with antiseptic soap. 

The guidelines from the National Institute for Health and Clinical Excellence (NICE) advise antibiotic prophylaxis before implant surgery, clean-contaminated surgery and contaminated surgery.(9) The goal of antibiotic prophylaxis is to administer the right antibiotics, at the right time with the right dose, to achieve optimal tissue concentration at the time of incision. In general, administration is recommended within the hour before incision. More accurately, most antibiotics should be administered 30–59min before the incision to achieve good tissue concentrations.(10)  

The CDC guidelines recommend avoiding hair removal at operative sites. An exception can be made for hair around the incision site that interferes with the operation. In this case the use of clippers is superior to razors because of the potential risk of nicks to the skin, which could be a point of entry for microorganisms.(5) 

Surgical skin disinfection is an essential part of SSI prevention. Presently, NICE is still recommending povidone-iodine or chlorhexidine as the most suitable antiseptics, with no differentiation between aqueous or alcohol-based solutions. Darouiche and colleagues were the first to demonstrate superiority of chlorhexidine in alcohol over povidine–iodine in water in reducing the infection rate in superficial and deep incision sites.(11,12) Future studies should compare chlorhexidine–alcohol versus povidone–iodine–alcohol and the optimal concentration of chlorhexidine and the possible effect of an ‘applicator’ needs to be established. 

Staff behaviour 

A clean operating environment should produce minimum SSIs. Maintaining the highest standards of cleanliness can be accomplished by limiting traffic flow and movements of surgical staff in and out of the operating room(9) as well as by thorough cleaning of the operating rooms. Furthermore, healthcare workers should comply with basic infection control measures, such as wearing masks, caps and scrubs. 

While scalpels are still used routinely for skin incisions, the use of diathermy is gaining greater acceptance. The advantages of diathermy over scalpels are increased haemostasis and reduction of operation time; the disadvantage might be an increase in tissue trauma.(3) In general, the way of making an incision does not appear to influence wound healing. Few studies have been published, showing no significant effect on SSIs between the incision techniques mentioned.(13–16)

Successful use of an adhesive (antimicrobial) incision drape to prevent SSIs depends on the composition of the drape, preparation of the skin, technique of application and adhesion to wound edges. Contamination of the wound with skin organisms seems to be reduced when the application is correct.(2) Further studies are required to set a recommendation for reducing SSIs concerning wound incision and skin sealant methods. 

Hypothermia can delay wound healing and predispose to wound infections. In patients undergoing colorectal resection surgery, maintaining normothermia (temperature higher than 36.0°C) perioperatively is likely to decrease the incidence of infectious complications and to shorten duration of hospital stay.(17,18) A randomised clinical trial by Melling and colleagues showed that warming patients before clean surgery helps prevent SSIs.(19)

A simple and effective guideline can prevent perioperative hypothermia because there are several methods of warming available for use before and during the operation.(20) 

Ventilation systems for operation rooms are not only a subject of debate but also have major consequences for hospital finances. Whereas some guidelines (for example, the Dutch)(21) see laminar airflow (LAF) plenum as a prerequisite for implant surgery especially, the HICPAC guideline for environmental infection control (2003)(22) offers no specific recommendation with regard to the operation room ventilation. Several studies show no benefit of operation room ventilation with LAF. A study comparing vertical LAF with turbulent ventilation with HEPA air showed no difference, or even a greater risk for severe SSIs following hip prosthesis surgery.(23) A follow-up study by the same group evaluated the impact of the plenum size of the LAF system. Again, no differences were observed, thereby corroborating their earlier results.(24)

Suture material 

Differences in suture materials can influence the incidence of SSIs. In vitro studies of bacterial adherence to surgical sutures were carried out by Edmiston et al in 2006.(25) There was a reduced bacterial adherence to triclosan-coated sutures, which was associated with decreased microbial viability, compared with non-coated sutures.(25) In 2010 a prospective randomised, double-blind, multicentre study compared SSI rates in patients sutured with triclosan-coated versus non-coated sutures in a variety of surgical procedures. The incidence of SSIs was significantly lower in the study group compared with the control group.(26) An in vitro study by Masini et al comparing different, non-antimicrobial suture materials concluded that monofilament sutures should be used for closure of wounds that are contaminated or at risk for contamination.(27) 

Intraoperative drains are required to facilitate the outflow of pus, blood and other fluids, because accumulation can lead to an increase in postoperative infections; however, a drain is a potential route for bacterial contamination. Drains should only be used when absolutely necessary and should be removed as early as possible.(3)

Wound care 

Wound care after surgery can influence development of SSIs. If a wound is contaminated a postoperative infection is more likely to occur. Protection of a primary closed incision with a sterile dressing for 24–48 hours after surgery is recommended. Careful hand hygiene should be observed (disinfection) and patients and their families should be educated regarding proper incision care and the symptoms of SSIs.(5) 

Elevated blood glucose levels are linked with the body’s resistance to infections. A randomised trial in patients undergoing cardiac surgery demonstrated an increased incidence of death and stroke when intensive insulin therapy was used perioperatively, compared with conventional treatment.(28) It is still unclear whether the effect is a result of a certain level of blood glucose or owing to a more constant level of blood glucose.(9) 

Several studies, particularly in cardiac surgery, suggest that SSIs can be reduced during the immediate postoperative period by blood glucose control, although the mechanism by which this occurs is not clear. The current recommendation of the IDSA guidelines is a postoperative blood glucose level of less than 200 mg/dl.(5) 

Surveillance 

SSI surveillance with appropriate feedback to healthcare workers is an important component of strategies to reduce the risk of SSIs; however, the results are not immediate. The effect due to surveillance and feedback is not immediate. For hospitals participating in the Dutch surveillance system, a significant reduction of SSIs was only achieved after the first three years.(29) 

Surveillance of SSIs should be performed for high-risk, high-volume surgical procedures. These should be targeted on the basis of a risk assessment of patient populations, operative procedures performed and available data on SSIs. Data need to be identified, collected, stored and analysed for the surveillance program. It is also important to provide ongoing feedback on SSI surveillance, and process measures to surgical and perioperative personnel. This information should be given confidentially, routinely and to individual surgeons, the surgical division and/or department chiefs. Finally, to increase the efficiency and the sensitivity of surveillance, an automated data-collection system should be implemented.(5) 

According to surveillance results, education is important and can lead to conformity of healthcare workers, which, in turn, can lead to increased compliance and reduction of SSIs. 

SSIs will never be prevented completely, and control and reduction of SSIs will remain a topic of much interest. A multifactoral approach is required, and regular updating of evidence-based guidelines and a system of continuous surveillance of SSIs are crucial. Keeping healthcare workers up to date on worldwide ideas and visions will aid infection control procedures and prevention of SSIs.

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