In the UK, surgical site infections (SSIs) are among the most serious and costly hospital infections.1 Infected patients are twice as likely to die following surgery,2 stay at least twice as long in hospital3 and cost almost three times more to treat than uninfected patients.4 More than 460,000 surgical procedures are estimated to result in wound infection, each year,5 with MRSA (Methicillin-resistant Staphylococcus aureus) accounting for a particularly high proportion. SSIs can occur when microorganisms naturally found on the skin of a patient enter the body when the skin’s protective barrier is compromised during the surgical procedure. There are many guidelines that suggest critical steps healthcare facilities can take to reduce the risk of surgical site infection, yet despite these recommendations SSIs continue to represent a significant and costly problem for the healthcare system. Since the publication of the NICE guidelines on prevention and treatment of surgical site infection, in October 2008, new data has also come to the fore which suggests that best practice needs to be reviewed.
Skin preparation – new evidence
Specifically, experts are calling for a reevaluation of the way patients are prepped for surgery, following the results of a trial comparing the efficacy of skin antiseptics in reducing the risk of SSIs. A prospective, randomised, multicentre clinical trial, conducted by Rabih Darouiche MD and colleagues, demonstrated that the use of 2% chlorhexidine gluconate and 70% isopropyl alcohol pre-operative skin preparation (ChloraPrep) reduced total surgical site infections (SSIs) by 41%, compared to use of povidone-iodine solution – the most commonly used pre-operative skin preparation.6 “In 2002, the US Centres for Disease Control and Prevention (CDC) issued recommendations indicating that 2% chlorhexidine gluconate and 70% isopropyl alcohol should be used instead of povidone-iodine preparations, or alcohol alone, to cleanse the skin at the site of insertion of vascular catheters. Although the recommendations became the standard of care in catheter insertion, the CDC did not issue these recommendations for skin preparation prior to surgery,” Rabih Darouiche explained. “Due to a lack of guidance on skin antiseptics in the US, three-quarters of the 30 million surgeries performed each year continued to use povidone-iodine,” he continued. “We wanted to establish whether 2% chlorhexidine gluconate and 70% isopropyl alcohol would be superior in preventing SSIs in line with the recommendations for catheter care, therefore.” Rabih Darouiche explained that there has been considerable interest in this issue. It is estimated that between 300,000 to 500,000 cases of SSI occur each year in the US alone. Although SSI is one of the most common infections and one of the most serious, optimal prevention has not yet been achieved. “Non-antimicrobial interventions (such as maintaining normothermia and ensuring adequate oxygenation), as well as antimicrobial interventions (such as antibiotic prophylaxis and the use of antimicrobial sealant), were some of the examples of approaches that collectively helped to reduce the rate of infection,” he commented. “However, in our view, this was not enough. We wanted to identify a preventative solution that was not only effective and safe, but also practical. Studies on the use of mupirocin have been well designed and produced promising results. However, testing for nasal carriage of Staphylococcus aureus and administering a course of mupirocin pre-operatively, involves a greater level of complexity, time and expertise, compared to skin preparation. The latter can be performed in a single application without advanced technical skills and, unlike molecular-based testing, everyone can use this approach.” Rabih Darouiche and his colleagues started work on the design of the study in 2002, which covered six centres and included 849 patients in the analysis. Patients in the two groups were similar with respect to multiple factors, including demographics, medical conditions, individual risk for infection, and both the length and type of surgery. The results of the study were finally published earlier this year in the New England Medical Journal.6 The researchers reported that the overall rate of surgical-site infection was significantly lower in the chlorhexidinealcohol group than in the povidone-iodine group (9.5% vs 16.1%; P=0.004; relative risk, 0.59; 95% confidence interval, 0.41 to 0.85).6 Chlorhexidine-alcohol was significantly more protective than povidone-iodine against both superficial incisional infections (4.2% vs 8.6%, P=0.008) and deep incisional infections (1% vs 3%, P=0.05) but not against organ-space infections (4.4% vs 4.5%).6 Rabih Darouiche pointed out that only 17 patients needed to receive the 2% chlorhexidine gluconate and 70% isopropyl alcohol skin antisepsis, instead of povidone-iodine, in order to prevent one case of surgical site infection. To put this into perspective, between 33 and 100 patients have to receive the chlorhexidine-based skin preparation, instead of povidone-iodine, to prevent one case of catheter-related bloodstream infection. The potential impact on patient outcomes is even greater therefore. According to the supplier of ChloraPrep, CareFusion, one of the key advantages of 2% chlorhexidine gluconate and 70% isopropyl alcohol is that it keeps fighting bacterial growth for at least 48 hours after application. Povidone-iodine, on the other hand, is neutralised by blood and other organic matter, reducing its effectiveness to two hours. This residual effect allows for added protection for patients against infections after surgery and not just during the procedure. “Our research has been received with considerable enthusiasm in the US and there are a number of organisations focusing on the quality of healthcare that have already made plans to include the approach as a new standard of care,” revealed Rabih Darouiche. “This includes not just regulatory agencies, but also professional and clinical associations.” He hopes that the UK and other nations will now embrace the evidence with the same enthusiasm: “If a UK study had resulted in such clear and powerful conclusions, we would have a responsibility in the US to learn from this and apply the recommendations. The UK now has this opportunity. Moreover, there is now enough evidence to mandate the use of this approach for pre-op preparation in my view.” Commenting on the study findings, Professor David Leaper, emeritus professor, University of Newcastle upon Tyne, and visiting professor of surgery at the wound healing research unit, Cardiff University, said: “In the UK, SSI represents approximately 20% of healthcareassociated infections (HCAIs) and one in twenty people having surgery develop an SSI. It is a largely preventable complication of surgery and is the subject of many ‘care bundles’ including the Safe Surgery Saves Lives campaign endorsed by the World Health Organisation. “Skin preparation prior to surgery has received scant attention for several decades. This new piece of research6 has shown convincingly that ChloraPrep can significantly reduce SSIs after cleancontaminated surgery and is clearly superior to widely accepted and ritualistic skin preparation using povidone-iodine. There is an added reduction in both postoperative morbidity and mortality related to SSI and significant potential to reduce a major financial burden to the NHS.”
Optimum wound care
SSI prevention was also high on the agenda at the recent Tissue Viability Society annual conference. Experts gathered to discuss the practical implications of the NICE surgical site infection guidelines and the role that wound care has in preventing SSIs. Fiona Downie, nurse consultant, tissue viability, Papworth Hospital NHS Foundation Trust, commented that the NICE document gives “good commonsense recommendations” and is “an excellent start towards reducing SSIs”. However, she added that simply having the guidelines “on the shelf” is not enough – how they are implemented is crucial. Furthermore, she pointed out that guidelines need to be “live” documents and regularly reviewed; there are gaps in the evidence that need to be addressed; while surveillance for SSIs is currently inadequate. “The principle recommendations within the NICE guidelines have been known for many years – including skin prep, pre-op clipping, bathing, aseptic technique, as well as the need for clean hands in theatre, but there are areas where we need much more evidence – particularly in wound care,” she commented. She raised a number of questions that remain unanswered, at present, including: What do we want from a post-op dressing? What does “an appropriate interactive dressing” (as referred to in the NICE guidelines) actually mean to most clinicians and how long should it stay in place? “NICE has looked at the evidence relating to this but current studies are not sufficiently robust to show convincing differences between different dressing types,” Fiona Downie continued. She pointed out that professionals involved with wound care need to address the following issues:
• What do we actually want from ‘the ideal post-op dressing’ and does it exist?
• Is there a need for comparative dressing studies?
• Do vapour permeable barrier dressings help prevent infection?
• Should antimicrobial dressings be used to dress post-operative wounds? Moreover, what is the risk (if any) of antibacterial resistance?
A robust study with a clear outcome of SSI prevention is required, she asserted, adding that healthcare professionals need to be “singing from the same hymn sheet” with regards to surveillance and wound care strategies. In particular, clinicians are not adhering to the same definitions for identifying SSIs – there are a number of categorical frameworks in use, including those outlined by the HPA and CDC, which means there is a lack of consistency in detection and classification. She called for a single, international definition for SSI classification to enable accurate comparisons to be made. Clarification of the NICE guidelines is also required in the way dressings are categorised as “passive”, “interactive” and “active”, as these mean different things to different people. “This is not common language in wound healing circles. We need a consensus on how dressings are classified, as well as evidence to support a consensus on what these dressings do, how and when they should be used, and how long they should stay in place,” she commented. She asked the audience to raise their hands to indicate how long dressings are kept in place post-operatively, at their organisations – illustrating the fact that there was considerable variation between Trusts. The length of time ranged from two days to four, and in some cases even longer. She asked delegates to consider “what was the rationale behind the length of wear time?” and “what was the evidence to support this practice?” She explained that at her own Trust they discovered there may be practical reasons for leaving the dressing on longer than the existing policy of two days, as some patients were found to be contaminating their wounds when eating, after the dressing was removed. NICE identified two studies that looked at the length of wear time and its influence on infection (Heal 2006, Chrintz et al 1989). Unfortunately, there was no conclusive evidence and she pointed out that, once again, studies have not been adequately powered in this area. Other areas that require further study, in her view, include wound cleansing, the use of antimicrobials, secondary intention healing, and best practice for debridement. She questioned whether sterile water is necessary for wound cleansing, pointing out that patients are sent for baths and showers, which use tap water. There also needs to be more data on antimicrobials – which ones are optimal and when are they appropriate? In addition, when should topical negative pressure be used as opposed to a standard dressing? When should hydrocolloids, hydrogels or sharp debridement be used? “The evidence is not currently available to answer these questions. In addition, are the NICE guidelines enough?” she commented. “Do staff know these basic principles and do they practice them? Staff need to be familiar the guidelines and be aware of any changes. Moreover, we need to consider how new evidence is incorporated into the guidelines and applied in practice. “The document needs to be live – the results of the study on chlorhexidine vs iodine-povidone,6 for example, were published after the NICE guidelines were released. Therefore, the recommendation to use either forms of skin antisepsis needs to be reviewed in light of new data.” Fiona Downie added that there needs to be local guidelines for different specialties – wound care for orthopaedic patients may require a different approach to cardiac surgery, for example. In addition, there needs to be a local, multi-disciplinary group in each Trust to scrutinise pre-, intra-, and post-operative care. At present, surveillance of SSIs is often carried out by infection control teams and not tissue viability nurses, however. “If the tissue viability team are not involved in this process, we need to know whether or not those conducting surveillance have had the necessary training to correctly identify an infected wound. Over the years, literature has highlighted the fact that many healthcare professionals are poor at identifying infection. Deep organ space infections are easy to identify, but superficial infections are more difficult to categorise,” Fiona Downie pointed out. She added that surveillance is particularly problematic with shorter post-operative hospital stays – although questionnaires can be used after discharge, this relies on the patient’s ability to assess infection. “The HPA publishes figures for SSIs, but are these just snapshots?” she continued. “Surveillance and audit will help Trusts to ensure the guidelines are doing what they are supposed to,” she continued. “Interestingly, when thorough surveillance has been undertaken for clinical outcome studies, the rates of SSIs have been found to be much higher than expected. We need to consider whether surveillance of SSIs should be mandatory for all specialties and it should be continuous.”
• The Tissue Viability Society conference and exhibition took place in Telford and was organised by Healthcare Events.
References
1 NICE 2008, Prevention and Treatment of Surgical Site Infection, October 2008. 2 Kirkland K.B. et al. The impact of surgical site infections in the 1990s: attributable mortality, excess length of hospitalisation and extra costs. Infection Control and Hospital Epidemiology, 1999;20:725-730. 3 Coello R., Charlett A., Wilson J., Ward V., Pearson A., Boriello P. Adverse impact of surgical site infections in English hospitals J. Hosp. Infect 2005; 60: 93-103. 4 Public Health Laboratory Service. Socio-economic Burden of Hospital Acquired Infection. 1999. 5 Based on 9.27 m surgical procedures in 2008 (www.hesonline.nhs.uk) and an infection rate of 5% (NICE 2008, Prevention and Treatment of Surgical Site Infection, October 2008). 6 Darouiche R.O. et al. N Engl J Med 2010;362: 18-2.