Wound dressings from a hygienic point of view using the example of sorbion sachet S.

Nosocomial infections present a growing challenge in wound care, especially in light of the rising distribution of multiresistant bacterial strains. Because wounds are an ideal breeding ground for pathogens, special care must be taken in choosing the right dressing. Following the traditional preventive approach, exposure of the nursing staff as well as the wounds to pathogens should be reduced. Dressings allowing a reduced frequency of dressing changes may help accomplish this. During dressing changes the dressing should allow for safe handling with a low risk of contamination. To protect the patient, the dressing should minimise exposure to pathogens during wear time as well as promote healing even if the dressing remains on the wound for a longer period of time. The dressing sorbion sachet S is used as an example to examine possible strategies.

Introduction

In the course of medical history, hygiene has contributed greatly to patient well-being. However, new challenges have arisen, especially in the prevention of health care-associated infections (HAIs). Since about 1965 the number of nosocomial infections from pathogens such as Staphylococcus aureus has been increasing, with gram-negative strains appearing around 1980 and resistant Enterococci appearing at the beginning of the 90s [1]. Due to the growing spread of methicillin resistant Staphylococcus aureus (MRSA), gram-negative bacteria with extended spectrum betalactamase (ESBL), vancomycin-resistant Enterococcus (VRE) and other multiresistant pathogens, the issue of HAIs is attracting publicity outside the confines of medical literature. This awareness is further increased by a rise in community-acquired infections outside of hospitals, which have been significantly increasing in parallel with HAIs since the end of the 1980s.

Although the numbers in the literature are varying, we can assume an incidence of nosocomially acquired infections of 4–10%, the majority in intensive care unit (ICU) patients. On average, one in every 6 patients in the ICU and one in 30 patients on the general ward acquire a nosocomial infection. Besides increasing the length of stay in the hospital by 4 to 30 days, especially in patients with a serious primary disease and multiple comorbidities, mortality is dramatically higher. In addition to the medical and social problems these infections pose for those affected, they are also a considerable burden on the social welfare system. The German health insurance DAK calculated the total costs in Germany for MRSA infections alone at 610,483,565 € in 2006/2007 [2]. Costs for aftercare and other economic costs must be added to this. A major study conducted in the USA shows the importance of hygiene in dealing with this issue: hospitals that implemented effective hygiene measures were able to lower the rate of infection by 27–35%, whereas it rose by 9–26% in a control group over the same observation period [3]. The same study deemed up to 32% of the infections as avoidable.

The wound as a portal for pathogens

HAI pathogens normally need an entry portal to cause infection. Accordingly, a large percentage of infections can be traced back to post-ventilation pneumonia or catheter-induced blood vessel and urinary tract infections. Nonetheless, wounds are also a major source of infection; post-operative wound infections alone make up 15–20% of nosocomial infections [4].

Wounds are an ideal reservoir for pathogens or facultative pathogens [5]. This is due in part because the natural skin barrier has been broken, but also because the wound climate is ideal for the reproduction of microorganisms (temperature, possible impaired circulation in the wound area, patient’s nutritional status, lowered immune defences) [6], [7].

Against this background, it is not surprising that persistent, chronic wounds are usually colonised with microbes. The same is true for traumatic wounds, especially bite wounds. A wound that is colonised with microorganisms without having a pathological relevance is called “colonised”. This does not necessarily interfere with the wound healing process. A variety of factors, either endogenous in nature or caused by exogenous factors such as a new pathogenic colonisation, can alter the pathogen population, with one or more microorganisms dominating. The resulting condition is known as “critically colonised”. Without intervention, a critical colonisation can initially cause a florid local infection, and in the worst case, a systemic infection [4]. The reasons for the transition from one degree of colonisation to the next are complex, multifactored and currently not fully understood.

Because every wound is considered being at least colonised, this pathogen reservoir deserves special attention. So from the standpoint of traditional hygiene, the standard prophylactic tools should be employed to wound care. Two approaches contribute to reducing exposure – hygiene of the nursing staff and protecting the wound from critical colonisation and infection. An important link between the two approaches is the wound dressing. With respect to hygiene, the following discussion deals with the necessary properties of a wound dressing, using the dressing sorbion sachet S as an example.

Requirements of a modern wound dressing

The best prevention is avoiding exposure. This applies to the nursing staff, whose tasks and close contact with the patient increase the risk of spreading wound pathogens. Standardised work methods and employee training are critical in avoiding this spreading. In addition, efforts should be taken to minimise exposure in terms of duration and intensity. In the simplest of cases, it means reducing the frequency of dressing changes, which can also be seen as economically beneficial. Modern wound dressings should therefore allow for a reduction in the frequency of dressing changes.

At first this sounds easy enough to achieve, but it requires an extremely high performance profile of the dressings if the longer wear time is not to negatively affect the patient. The dressing should be able to create and maintain a wound climate that promotes healing over the entire wear time. One product up to the task is the dressing sorbion sachet S (sorbion Aktiengesellschaft, Ostbevern, Germany). The product’s Hydration Response® Technology, a combination of physically modified cellulose fibres and gelling agents, absorbs and retains large quantities of wound exudate and corrosive agents damaging to the wound. The close interaction of the two components and their various mechanisms of action promote an optimal wound climate longer than many other products [8].

Once the frequency of dressing changes is lowered to the therapeutically reasonable minimum, the next goal is to reduce (unavoidable) contact between the nursing staff and the wound flora while the dressing is being changed. This can be achieved through antiseptic dressings, yet their use should be limited to the special indication of critically colonised or infected wounds. The dressing sorbion sachet S is designed to affect the wound flora in a different manner. The Hydration Response® Technology used in this product binds the absorbed fluid in its interior, along with the pathogens. In vitro experiments demonstrated that the surface of the dressing showed a considerably lower level of pathogens than other dressings after only a short time of absorbing highly infectious test fluids (Figure 1 (Fig. 1)). The pathogens were trapped in the interior of the product and were contained, even under pressure that occurs during dressing changes [9]. This is not necessarily the case in dressings based on PUR foam.

Figure 1

Qualitative demonstration of an in vitro experiment on absorbing pathogens. sorbion sachet S and another absorbent dressing were exposed to a solution containing 104 CFU/ml Staphylococcus aureus subsp. aureus Rosenbach, Gentamicin- and Methicillin-resistant, (ATCC 33592, [13]) and then pressed with a gloved hand. Immediately thereafter an impression of the glove was taken on an agar plate and incubated for 48 hours at 37°C [9].

To promote wound healing – leading to wound closure and thus best prevention of infection – an “ideally moist” wound environment should be created and maintained [10]. This requires balancing excess exudate and negative consequences such as wound edge maceration and increased risk of infection from soaked dressings, with the amount of moisture physiologically required to transport relevant growth factors, nutrients, etc. on the other side. The Hydration Response® Technology of the sorbion sachet S absorbs excess fluid – and with it the pathogens, as indicated by the in vitro data – and binds it in its interior. Its positive effect on the pathogen population in the wound is documented in statements from patients, who often report that odour, especially of chronic wounds, abates when products with Hydration Response® Technology are used.

The sorbion sachet S is able to loosen wound slough and bind it to its surface at the same time, in effect debriding the wound every time the dressing is changed. Even though the direct relationship between wound slough and biofilms is a matter of scientific debate, it does appear probable that slough plays a role in the generation of biofilms [11]. From a hygiene standpoint, soft debridement could represent a special form of prophylaxis.

Conclusion

It has been shown that in hospitals a reduction in the incidence of nosocomial infections can cover the additional expenses incurred by implementing hygiene measures [12]. A good choice of dressings can contribute to this. From a hygiene standpoint, a modern wound dressing should lower the exposure of nursing staff and the wound by reducing the number of dressing changes. In order to do so, the dressing, like the sorbion sachet S with its Hydration Response® Technology, must be able to maintain the moist wound climate required for healing even during an extended period of wear. The absorption and retention of pathogens combined with a low bacterial burden on the surface reduces the exposure of nursing staff during dressing changes as well as exposure of the wound between changes. It may therefore also be possible, in a way that conserves the tissue, to shift the pathogen spectrum to the positive, as expressed in patient reports of odour abatement in chronic wounds. Other properties such as the soft debridement effected by the sorbion sachet S may also contribute to this.

Competing interests

Dr. Alexander Maassen, is a paid employee of sorbion Aktiengesellschaft, Ostbevern, Germany. The article was not sponsored by the company.