Do antibacterial skin sutures reduce surgical site infections after elective open abdominal surgery? - Study protocol of a prospective, randomized controlled single center trial

Surgical site infections (SSI) are a risk inherent to surgical procedures and a frequent complication, notably after digestive surgery. SSI are associated with severe morbidity and mortality, especially in high-risk patient populations [1, 2]. According to Center for Disease Control (CDC) guidelines [1], SSI up to 30 days after surgery are included, or even a year later when a foreign material such as a prosthesis has been implanted. SSI can be classified as superficial if they involve the skin only or subcutaneous tissue at the site of the incision, deep when they affect more internal structures of the abdominal layer, and organ-spaced when they also involve the abdominal cavity and the space between the organs that were manipulated or opened during the surgical procedure [3, 4]. The cornerstones for reducing the risk of SSI include exquisite surgical technique, timely and appropriate antimicrobial prophylaxis [5], effective and persistent skin antisepsis, and identification of adjunctive strategies for reducing wound contamination [6] and promoting wound healing. SSI are primarily caused by Gram-positive organisms from the patient’s own flora on the skin, mucous membranes, or hollow viscera manipulated during surgical procedures [1].

Various bacteria may contaminate not only the tissue in a surgical wound but also the actual suture material. If the surgical suture is implicated as the cause of a wound infection, then an antibacterial coating should nearly eliminate the possibility of the suture material becoming a vector of infection. The use of antibacterial-coated medical devices has become widespread. Numerous biomedical devices, including urologic and central venous catheters and orthopedic, vascular, and cardiothoracic implants, are commercially available with antibacterial impregnation or surface coatings.

It has been reported that percutaneous sutures approximating skin edges were often colonized from the body surface into the wound track by strains of Staphylococcus epidermidis capable of producing an amorphous extracellular matrix (biofilm), protecting the microbial populations from host defense factors [7]. Triclosan as a broad spectrum antiseptic is known from in vitro and in vivo studies to reduce the adherence of selective clinical Gram-positive, Gram-negative, drug-resistant, and biofilm-forming strains to the surface of a widely used braided surgical suture (polyglactin 910). Triclosan-coated polyglactin 910 sutures exhibit an antibacterial activity sufficient to prevent in vivo bacterial colonization in a guinea pig model [8]. Further, it is documented to be safe and efficient [2] and did not adversely affect wound healing in patients undergoing general surgical procedures [9]. In view of the high frequency of SSI and its substantial impact on morbidity and mortality, the reduction of the SSI rate should be a major priority among all surgical disciplines.

Therefore, our objective is to determine whether subcuticular closure of an abdominal wound with triclosan-coated Monocryl plus® running skin sutures influences the rate of SSI at 30 days following elective abdominal surgery when compared to similar uncoated Monocryl® sutures. Secondary objectives are to determine whether the use of triclosan-coated sutures reduce the length of hospital stay, wound dehiscence, and mortality rate at 30 days and number of re-operations in the same 30-day period following surgery.

In line with in vitro results, we hypothesize that the use of antibacterial skin sutures (with triclosan-coated poliglecaprone 25) reduces the rate of SSI after open elective abdominal surgery. The postulated mechanism states a reduced colonization of poliglecaprone 25 sutures by several strains of bacteria when antibacterial-coated suture material is used.

The study protocol has been written in accordance with the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) checklist (Additional file 1).

This single-center prospective randomized controlled trial (RCT) is conducted at the Department of General-, Visceral- and Thoracic Surgery and the Department of Obstetrics and Gynecology at the AGAPLESION Diakonie Hospital Rotenburg (Wuemme) gGmbH, Germany. It is designed as a double-blind parallel-group superiority trial.

All patients planned for elective open general/colorectal or gynecological abdominal surgery will be consecutively informed about the study. Informed consent will be signed by each participating patient and a member of the study team at least 24 h before elective surgery. A flow diagram for this trial is shown in Fig. 1.

Baseline data such as gender, age, body mass index (BMI; calculated by Weight/Height²) will be collected from all included patients. Furthermore, factors that might influence the outcome of the surgery will be recorded. These factors include, but are not limited to, American Society of Anesthesiologists (ASA) classification, diabetes mellitus, antidiabetic medication, present immunosuppression, wound class according to CDC criteria (clean/clean-contaminated/contaminated/dirty), type of incision (transverse/longitudinal), operative time, amount of blood loss, length and orientation of incision.

Surgical site infections account for 14 to 16% of all nosocomial infections in hospitalized patients [1]. Furthermore, as much as 5% of all patients undergoing surgical procedures develop SSI with the burden of additional mortality and morbidity despite different prevention schemes [14‐16]. The first global guidelines for the prevention of surgical site infection were recently published by the WHO [17]. These guidelines address different measures to reduce SSI. The authors’ panel advocates the routine use of triclosan-coated sutures in surgical procedures independently of the type of surgery as a conditional recommendation, since there is a moderate quality of evidence in the analysed literature. The given recommendation is mainly based on the meta-analysis by Wu and colleagues [18]. It needs to be noted that the quality of the included RCTs was moderate or low and that some of the studies had an industrial sponsorship. Another weakness of this meta-analysis was the inclusion of different types of surgery (e.g., breast, vascular, orthopaedic, or colorectal surgery) which considerably differ in their SSI rates. Even emergency surgery was compared to elective surgery and open vs laparoscopic surgery, although one of the well documented benefits of laparoscopic surgery is the low rate of SSI [19] and an inverse relationship of SSI [20].

The meta-analysis by Henriksen [21] as well compared different types of surgery, such as elective open colorectal surgery, elective midline laparotomy, open appendectomy, and even laparotomies for fecal peritonitis. Edmiston et al. [22] and Chang et al. [23] pooled all available RCTs in their meta-analysis without stratifying the risk for wound class, type of operation, or organ/apparatus involved [11], as did Wu et al. [18] de Jonge et al. [24], Leaper et al. [25] as well as Hunger et al. [26].

Therefore, only patients undergoing open elective surgery were included in our trial. Most of the published RCTs and meta-analyses examined the effect on reduction of SSI of using antibacterial-coated suture material for fascial closure in abdominal surgery. Taking into account that the primary cause of SSI next to the bacterial flora of mucous membranes or hollow viscera is, in particular, the Gram-positive flora of the patient’s own skin [1], the focus of our research is on the choice of skin closure suture material to reduce SSI in abdominal surgery. Therefore, one of the potential strengths of our research is the use of antibacterial-coated suture material for the use of skin closure as triclosan is known to reduce the adherence of selective clinical Gram-positive, Gram-negative, drug-resistant, and biofilm-forming strains to the surface of the suture material. Moreover, triclosan is proven to be safe and does not affect wound healing [2].

To reduce postoperative SSI is undoubtedly of increasing interest as, apart from reduction of morbidity and mortality, hospitals are under pressure in terms of cost-effectiveness. SSI are further considered to reflect the quality of care in a hospital, as they are potentially preventable complications directly linked to surgery [10]. Therefore, it is of utmost interest to reduce postoperative SSI rates.