SILVER-BASED ANTIMICROBIAL DRESSING IN THE PREVENTION
OF SURGICAL SITE INFECTION – A PILOT STUDY
Jan Stryja MD1, Daniel Riha MD2, Jerzy Szkatula MD2
Vascular surgeon senior consultant: 1Salvatella LTD, Trinec, Czech Republic, 2Podlesi Hospital, Trinec, Czech Republic
Conflicts of interest: None. Company manufacturing the product tested in the study provided free samples of the dressing without any other influence on the clinical evaluation.
Surgical site infection (SSI) is a postoperative complication affecting many surgical patients worldwide. Up to 60% of SSIs have been estimated to be preventable and their risk can be minimised by applying best practice in the perioperative period. Excellent surgical technique, implementation of preoperative preventive precautions and proper wound management are considered to be a foundation of the undisturbed healing process and one of the ways to decrease the number of clinically manifesting SSIs.
The aim of our observational pilot study of a case-series is to describe SSI-related serviceability of novel silver-based dressing material [StopBac] appointed for acute wound management from a study of a group of 22 patients with the ongoing planned surgery.
The observational pilot study of a case-series has been designed as a descriptive clinical study for quality assurance purposes to evaluate the efficacy of a silver dressing [StopBac]. Inclusion criteria involved all male and female patients over 18 years old who were consecutively scheduled to undergo “clean” surgical procedures. We monitored the total number of dressing changes until the stitches removal and the incision has healed, the possible local and systemic clinical signs of infection, the current state of a wound and patient’s and surgeon’s satisfaction with the dressing.
We illustrate our good clinical experience with tested material by no observed superficial or deep surgical site infection at the studied group of patients during both the treatment period and the follow-up period (in total lasting 4 weeks). All incisions (100%, 22) have healed by primary intention with no complication of wound dehiscence. The dressing was well tolerated by the patients (71.4% rated as “excellent”, 23.8% rated as “very good”) and the HCP’s satisfaction rates were also positive (66.7% rated as “excellent”, 33.3% rated as “very good”).
The tested dressing has shown good clinical serviceability and was well tolerated by the patients. In high-risk patients and high-risk surgical procedures, we do not see any reason to decline usage of antimicrobial silver-based dressing in the perioperative management of surgical wounds. To obtain robust evidence for broad usage of antimicrobial dressing on non-complicated incisions it is necessary to design and carry out the new big randomised controlled trial.
Keywords: surgical site infection, antimicrobial dressing
Surgical site infection (SSI) is a postoperative complication affecting many surgical patients worldwide. It is the third most commonly reported health-associated infection (1) and results in significant patient postoperative morbidity, mortality and increase of additional health-care related costs. SSIs are defined (2) as infections occurring up to 30 days after surgery (or up to one year after surgery in patients receiving implants) and affecting either the skin incision or deep tissue at the operation site. The risk of SSI is influenced by a number of intrinsic and extrinsic factors, particularly the number of microorganisms present at or introduced into the incision during the surgical procedure.
The incidence of SSIs varies depending on multiple factors, including the type of operation, pre-existing patient’s health status and perioperative management. In 2017, Berríos-Torres et al. (8) have published, that almost 50% of SSIs become evident after discharge. It can be influenced by the effort to shorten patient’s stay (often seen in many hospitals), which leads to his/her early discharge and can make diagnosing and surveillance of SSIs more difficult. It is questionable, whether running health care systems across Europe are able to make appropriate conditions for good surveillance and smooth diagnosing of SSIs in outpatient setting.
Up to 60% of SSIs have been estimated to be preventable (3) and their risk can be minimised by applying best practice in the perioperative period. Preventive precautions of SSIs are focused, especially on the reduction of the risk factors present at the time of surgery to reduce or forestall contamination of the operating site. The rates of SSIs associated with surgery (4) on sterile sites are therefore very low (<2%), compared with the rates of SSIs associated with surgery on contaminated sites, which may be over 10%. The excellent surgical technique is considered to be a foundation of the undisturbed healing process (2) and one of the ways to decrease the number of clinically manifesting SSIs.
Current clinical recommendations for SSI prevention come out from already published guidelines: The World Health Organization (WHO) Global Guideline on the prevention of surgical site infection from 2018 (16), NICE Surgical Site Infection: Prevention and treatment guideline updated in 2017 (12), and Centers for Disease Control and Prevention (CDC) guidelines Guideline for the Prevention of Surgical Site Infection (8) published in 2017. They highlight following the specific recommendations for preoperative phase (staphylococcus aureus screening and decolonisation, smoking cessation, modification of long term existing medical conditions, thoughtful hair removal, patient showering and reasonable surgical antibiotic prophylaxis), intraoperative phase (preparation of surgical hand and skin at the surgical site, wearing of sterile gowns and sterile gloves, maintaining patient perioperative normothermia and optimal oxygenation, and covering surgical incisions with an appropriate interactive dressing) and postoperative phase (aseptic technique for changing or removing surgical wound dressings, administration of adequate nutritional interventions and securing proper wound care after discharge from hospital).
Antimicrobial dressings are definitely effective tool of infected wound local treatment. Although they are used in clinical practice very often, we have very few data and evidence for their universal usage in wound management, especially for prevention of wound infection (5). Silver dressings provide extensive coverage against bacteria, fungi and viruses, including nosocomial pathogens and methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), make it a valuable adjunct in the prevention and treatment of infection. In 2017, Tisosky et al. (6) has published a clinical trial showing that the use of a silver dressing significantly reduced the incidence of superficial and deep prosthetic joint infection following total joint replacement. A literature review (15) published in 2014 reported that silver-nylon dressings are associated with decreased SSI risk in small studies across several specialities, including colorectal surgery, neurosurgery, spinal surgery and some cardiac and orthopaedic procedures, although the authors recommend larger powered trials are required in these cohorts to determine the comparative effectiveness of silver-nylon dressing in the prevention of SSIs. The 2017 evidence update of the NICE guidelines (12) agrees that no particular dressing type emerges as the most effective in reducing the risk of SSI, although silver nylon dressings may be more effective than gauze.
Positive outcomes of clinical trials based on the influence of silver dressing on SSI incidence reduction provides some space for stating that antimicrobial dressings could decrease the negative impact of extrinsic SSI risk factors related to contamination of the body surface in the patient. But despite these conclusions, at this time the evidence confirming that antimicrobial dressings can reduce the risk of SSI is weak.
The aim of our observational pilot study of a case-series is to describe SSI-related serviceability of a novel silver-based dressing material [StopBac] appointed for acute wound management from a study of a group of 22 patients with ongoing planned surgery.
The observational pilot study of a case-series has been designed as a descriptive clinical study for quality assurance purposes to evaluate the efficacy of a silver dressing [StopBac]. The study was approved by the local ethic committee. The multicentric study was carried out in patients who visited surgical outpatient clinic Salvatella LTD, Trinec, Czech Republic, or surgical department of Hospital Podlesi, Trinec, Czech Republic, for planned surgery from September 2019 to November 2019. Salvatella LTD is an outpatient healthcare facility specialized in surgery, vascular surgery and complex treatment of non-healing wounds. It is located at North-Moravian region. Hospital Podlesi is a part of the Czech cardiovascular centre network. Its surgical department provides specialized care for patients with surgical and vascular disorders. The catchment area has more than 500 000 inhabitants.
Patients included in the sample were selected by random. Inclusion criteria involved all male and female patients over 18 years old who were consecutively scheduled to undergo “clean” surgical procedures in outpatient and inpatient settings at both mentioned health-care facilities and has signed informed consent to participate at the study. Patients were treated by three experienced surgeons in two institutions. Exclusion criteria included surgical procedures to treat infections, primarily infected wounds, known allergy to tested dressing and inability to follow the study protocol or recommendations specific to the primary diagnosis.
Patient characteristics were collected, including age at surgery, sex, smoking habits, body mass index, grave comorbidities and medication. All surgical incisions were treated by primary closure using skin sutures. The intervention consisted of the application of sterile tested dressing [StopBac] onto the sutured incision at the time of surgery, and reapplications of tested dressing during following dressing changes. The tested dressing was placed on the incision before the patient left the operation hall and removed according to the clinical needs of the wound (leakage, spontaneous dressing release, need to examine the wound by a surgeon). At the end of the treatment period, the stitches have been removed from the incision (upon the decision of attending surgeon) and the wound has been covered by the last sheet of dressing [StopBac]. Clinical data were collected and continuously recorded by attending surgeon in the clinical report. The same investigator observed the patient at the hospital (in case of inpatient intervention), at the outpatient clinic and during the follow-up period. We monitored the frequency and a total number of dressing changes until the stitches removal and the incision has healed, the possible local and systemic clinical signs of infection and current state of a wound.
The postoperative protocol was consistent among all surgeons and both institutions, compliant with an institutional standardized protocol for all patients. No patient received perioperative antibiotics. Study patients were followed prospectively to determine the onset of superficial or deep infection. The treatment period was terminated in two weeks after surgery by removal of the suture material and followed by the follow-up term lasting next 2 weeks. The final diagnosis for SSI was made by the attending surgeon and based on the criteria defined by WHO guidelines (11) for safe surgery and NICE Guidance (12) published in 2017 (the presence of clinical signs of infection: purulent drainage, wound pain or tenderness, localised swelling, redness, heat, cellulitis of soft tissue at the place of surgery or wound abscess) at the end of the follow-up period (i.e. 4 weeks after surgery). The dressing tolerance (assessed by the patient) and satisfaction with the local treatment and dressing has been evaluated by HCP or patients by labeling the corresponding answer from the offered options (see table 5) during the final clinical appointment at the end of the second week of the observation.
Tested dressing [StopBac] has been developed by a Czech technological company, Grade Medical in 2018. Production of the dressing uses patented nanotechnology called “sol-gel” working with a spray atomisation method. The inner surface of the dressing comprises of organic-anorganic hybrid oligomer with silver ions bound in a fluid containing silver nitrate (13), see figure 1 and figure 2.
In a moist environment, the silver ions are released from the dressing pad and interfere with present microorganisms. It provides an antibacterial barrier on the surface of a wound against external contamination. This is how the dressing could reduce the risk of wound infection. Two types of dressing [StopBac] were available (StopBac STERILE Standard and StopBac STERILE Aquastop) for dressing changes during the trial. The dressing is available for clinical usage in two forms – the first one with an adhesive border for low exuding acute wounds, the second one without border for non-healing infected wounds.
The study group consisted of 22 surgeries (postoperative wounds) performed on 22 patients from September 1, 2019, to November 30, 2019. One patient has been excluded from the observation due to not following the study protocol in the study period, so for final evaluation of the study, we have admitted 21 patients. For demographic details of the study group see table 1. All patients underwent surgical interventions coming under clean or clean-contaminated wounds (2) with generally low risk of surgical site infections. For detailed list of executed surgical interventions and the length of procedure see table 2.
We did not observe any superficial or deep surgical site infections at the studied group of patients during both the treatment period and the follow-up period (in total lasting 4 weeks). All incisions have healed by primary intention with no complication of wound dehiscence (see table 3).
The tested dressing had a similar total length of treatment for surgeries in both inpatient and outpatient setting (see table 4). In the case of inpatient treatment, patients were discharged from the hospital the second day (2.6 ± 0.8 day; median 2 days) after surgery. In both groups, stitches have been removed from the wound margins on the 10th day after wound closure (hospital surgeries 10.4 ± 1.8 days; median 10 days, outpatient surgeries 11.5 ± 2.6 days; median 10 days).
Tested dressing has been changed four times per treatment period (see table 4). In 81% (n=17) of wounds we didn’t notice any wound exudation and the surface remained dry. We observed two adverse events with no association to the tested dressing: one patient after varicose vein surgery suffered from embolization to the lung, complication has been resolved without any consequence. One patient after inguinal hernia laparoscopic repair noticed seroma formation in the inguinal canal.
Four patients (19%) noticed temporary itching under the adhesive border of the dressing with complete subsiding of this symptom after tested silver-based dressing treatment termination. Overall tolerance of the dressing evaluated by the patient was “excellent” in 74.1% and “very good” in 23.8% of cases, together with “excellent” patient’s satisfaction with the dressing (see table 3c). HCP-evaluated satisfaction with the dressing was rated “excellent” in 66.7% and “very good” in 33.3% of cases (see table 3c).
SSIs are unpleasant complications of the surgical procedures impairing the patient’s quality of life and causing dissatisfaction and frustration of the surgeons and other clinicians. They are connected with significant increase of patient morbidity, mortality and total treatment costs. SSIs increase the length of hospitalization and incur considerable extra health-care costs (7).
In common clinical practice, the preoperative elimination of all intrinsic and extrinsic risk factors of SSIs can be difficult. Regardless the health-care facilities have to follow many preventive procedure-dependent and patient-related precautions to forestall transmission of germs into the site of surgery at the perioperative period, surgical site infections remain a real threat. The efforts to prevent SSIs are based on early detection of high-risk patients, preoperative preparation of the patient, medical staff and equipment, gentle and tactful operative technique, and postoperative wound management. In early postoperative time dressing covering the incision act as a barrier with given absorptive capacity to manage wound exudation and secure steady healing-friendly environment.
As Woo published in 2012 (9), silver-based antimicrobial dressings can decrease the bacterial burden on the surface of chronic wound, protect wound surfaces from microbial invasion and effectively suppress bacterial proliferation; for acute wound setting the evidence remains questionable. Routine usage of antimicrobial dressings for postoperative management of surgical wounds can increase the treatment costs, can affect patient by possible local action of the antimicrobials and could have an impact on antimicrobial resistance of present germs. In 2019 Stanirowski et al. (14) published results of a randomised controlled trial recruited women (N=543) undergoing caesarean section with conclusion, that the use of bacterial-binding dressings following caesarean section has the potential to reduce the incidence of SSI and costs.
The positive impact on the reduction of surgical site infection incidence described also Tisosky at al. (6) in 2017. Their case-control study (N=834) discovered, that the use of a silver dressing significantly reduced the incidence of superficial and deep prosthetic joint infection following total joint replacement.
This pilot study describes our experience with a novel silver-based dressing material appointed for acute wound management. Regarding the theoretical assumptions, antimicrobial acting of dressing [StopBac] would be effective in decreasing the incidence of SSI also. Regarding the available ECDC data (10), in 2015 the SSIs incidence for colon surgery in the Czech Republic reached 8 cases per 100 operations. Data for other surgical procedures performed in the Czech Republic are not available right now. If we apply this data to our study group we would expect recognising 1.7 SSIs in total.
Comparing the Czech countrywide incidence and our study group incidence of SSIs, we can’t exclude the positive effect of tested antimicrobial dressing, but critical analysis of this finding and known limitations of this study (low number of participants, no control group and no randomisation, broader spectrum of surgical procedures, surgeries performed in outpatient and inpatient setting) leads us to say we are not able to prove direct effect of tested dressing on zero incidence of SSIs observed in our study group. Despite this, patients and HCP involved in this study expressed good subjective clinical experience based on evaluation of the dressing tolerance (“excellent”; range 1-5) and overall satisfaction with local treatment of wound and tested dressing (for patients and HCP: “excellent”; range 1-5). The number of adverse events with association to the tested dressing was low, in all cases influenced by adhesive border of the dressing (erythema, itching, burning).
IMPLICATIONS FOR CLINICAL PRACTICE
Tested sterile antimicrobial dressing [StopBac] can be used in clinical practice for covering surgical wounds. We have confirmed its safety and good tolerance by the patients in inpatient and outpatient settings.
There is a need for completing well-designed randomised prospective studies confirming the effect of different types of antimicrobial dressings on the reduction of SSI incidence on bigger populations of high-risk patients.
Regarding the aims of this study we can confirm good serviceability of tested dressing in both outpatient and inpatient setting. In high-risk patients and high-risk surgical procedures, we do not see any reason to decline usage of antimicrobial silver-based dressings in the perioperative management of surgical wounds. To obtain robust evidence for broad usage of tested antimicrobial dressing on non-complicated incisions it is necessary to design and carry out bigger randomised controlled trial.
- Suetens C, Latour K, Kärki T et al. Prevalence of healthcareassociated infections, estimated incidence and composite antimicrobial resistance index in acute care hospitals and long-term care facilities: results from two European point prevalence surveys, 2016 to 2017. Euro Surveill 2018; 23(46):1800516. https://doi. org/10.2807/1560-7917.ES.2018.23.46.1800516
- European Centre for Disease Prevention and Control. Surgical site infections. In: ECDC. Annual epidemiological report for 2016. Stockholm; 2018 ECDC
- Dumville JC, Gray TA, Walter CJ et al. Dressings for the prevention of surgical site infection. Cochrane Database Syst Rev 2014; (9):CD003091. https://doi.org/10.1002/14651858.CD003091.pub3
- Tisosky AJ, Iyoha-Bello O, Demosthenes N, Quimbayo G, Coreanu T, Abdeen A. Use of a Silver Nylon Dressing Following Total Hip and Knee Arthroplasty Decreases the Postoperative Infection Rate. J Am Acad Orthop Surg Glob Res Rev. 2017;1(7):e034. Published 2017 Oct 17. doi:10.5435/JAAOSGlobal-D-17-00034
- Jenks PJ, Laurent M, McQuarry S, Watkins R. Clinical and economic burden of surgical site infection (SSI) and predicted financial consequences of elimination of SSI from an English hospital. J Hosp Infect 2014; 86(1): 24–33. https://doi.org/10.1016/j.jhin.2013.09.012
Testování antibakteriálního krytí na hojení ran StopBac bylo publikováno
v prestižním lékařském periodiku EWMA Journal.
Editorial listopadového vydání je k nahlédnutí zde.
O AUTORECH STUDIE
MUDr. Jan Stryja z chirurgické, cévní a podiatrické ambulance Salvatella a kardiovaskulárního centra Nemocnice Podlesí a.s. v Třinci. MUDr. Jan Stryja se zaměřuje na cévní chirurgii a všeobecnou chirurgii, léčbu nehojících se ulcerací a komplikovaných chirurgických ran, podiatrii – léčba pacientů s diagnózou diabetická noha a také edukaci zdravotníků i laické veřejnosti v problematice léčby ran. MUDr. Jan Stryja je autorem více než 30 souhrnných a originálních prací, řady přednášek a workshopů na téma léčba nehojících se ran, trofických ulcerací a cévních onemocnění dolních končetin. Více informací naleznete na stránkách ambulance Salvatella (podiatrie).
MUDr. Daniel Říha působí jako lékař v Centru cévní a miniinvazivní chirurgie Nemocnice Podlesí v Třinci a také jako vedoucí lékař Orthopedia.
MUDr. Jerzy Szkatula je lékařem Neurologického oddělení Nemocnice Třinec.