In this retrospective analysis, we found that the risk of SSI after gastrointestinal cancer surgery was significantly lower when OLG was used for preoperative skin preparation than when was used. The incisional SSI rate were 2.7% in OLG group and 10.3% in the control group. This result could directly imply the efficacy of olanexidine for surgical skin antisepsis in gastrointestinal surgery.
SSI can occur as a complication after surgery for gastrointestinal cancer and causes pain and psychological stress in patients, prolongs hospital stays and increases healthcare costs [15]. A high infection rate of 11.3–15.5 % has been reported after gastrectomy or colorectal surgery [1]. Several initiatives are aimed at reducing the risk of SSIs [2–4]. Many perioperative measures to reduce SSI have been reported, including enhanced nutritional support, perioperative oxygenation, different surgical techniques, wound dressing and the use of an antimicrobial agent [13].
The skin is a major source of pathogens that cause SSIs. Therefore, preoperative skin antisepsis may reduce the risk of SSI [5]. Antiseptics prevent infection by decreasing the number of microorganisms and thereby reduce the transmission of pathogens [10]. Currently, PVP-I, CHG and other alcohol-based preparations are widely used to disinfect surgical sites. The CDC guidelines recommend that skin preparation should be performed with an alcohol-containing agent only if there are no contraindications to its use, and other guidelines do not favor one antiseptic agent over another for skin preparation [16]. PVP-I and CHG both have broad-spectrum antibacterial effectiveness. However, PVP-I may not function well in the presence of organic materials, such as blood or pus, which can rapidly neutralize its bactericidal activity [10]. CHG also does not have sufficient activity to eradicate some pathogens, such as MRSA and VRE[11]. Furthermore, alcohol-based products are highly flammable and can burn the skin if not allowed sufficient time to dry [17–19]. Therefore, it is necessary to identify more effective antiseptics for surgical site preparation.
OLG, a novel biguanide antiseptic agent, has been commercially available since 2015 in Japan for use as a skin disinfectant for surgical sites [12]. It disrupts membrane integrity by binding to the cell membrane, resulting in irreversible leakage of intracellular components, which is the mechanism underlying its bactericidal and fungicidal activities [13]. OLG exerts strong and fast-acting bactericidal activity against a wide range of bacteria [10]. OLG might have higher bactericidal activity against MRSA and VRE both in vitro and in vivo animal models than those of CHG and PVP-I [13]. However, few clinical investigations have explored the use of OLG as a preoperative disinfectant in digestive surgery.
While Asukai et al performed a retrospective study in the field of orthopedics, but found no significant difference between OLG and PVP-I [14]. On the other hand, Obara et performed a randomized study in clean contaminated gastrointestinal and hepatobiliary pancreatic surgery, found significant difference between OLG and PVP-I, which were nearly equivalent to our study [20]. Almost all clean surgeries performed in the orthopedic department were included in this study, and the rate of SSI was low; therefore, it was difficult to identify a difference. However, the risk of SSI is higher in gastrointestinal surgery than in orthopedic surgery, and it is therefore possible to identify a significant difference in this group. Thus, the use of OLG may be more effective in surgery with a high risk of SSI.
Many factors affect SSI and have been previously reported in digestive surgery. Known risk factors for SSI include ASA stage, operation time, diabetes, BMI, and intraoperative blood transfusion. Laparoscopic surgery is considered to reduce SSI. Other reports include age, sex, use of prophylactic antibiotics, ostomy, preoperative use of nonabsorbable oral antibiotics, smoking ,type of skin closure, and total nutrition [21–29]. However, few common risk factors were identified in our surveillance data. This finding suggests that the risk factors for SSI may vary in accordance with the changing conditions experienced during surgery. The widespread use of laparoscopic surgery is a condition that changed markedly during the study period. While laparoscopic surgery is minimally invasive and usually performed with less blood loss than is observed during open surgery, its operation time is longer. The advantageous features of laparoscopic surgery may contribute to a decreased risk of SSI, as suggested in a previous study [30]. In our study, although the difference was not significant between laparoscopic surgery and open surgery in the rate of SSI, that might be due to the very low number of laparoscopic surgery in the control group. Since patients who underwent laparoscopic surgery were mainly included in the OLG group, it is possible that the rate of SSI was significantly lower in the OLG group, and this effect was therefore further examined for each approach in a subgroup analysis. The results showed that there was no significant difference, but the rate of SSI was lower in the OLG group than control group in both the open and laparoscopic surgery. Therefore, OLG may reduce SSI regardless of the selected approach (open or laparoscopic).
On the other hand, there was no significant difference between the OLG group and the control group for both gastric cancer and colorectal cancer. But in the colorectal cancer cases in which the rate of SSI was high, while the rate of SSI was originally low in the gastric cancer, the rate of SSI considerably lowed in the OLG group. This result also shows that the use of OLG may be more effective in surgery with a high risk of SSI.
Our study has several limitations. First, this was a single-center retrospective study in which the number of cases with SSI was small. It would have been useful to compare data within the same operative method, if possible, but this study was performed using the described methods for primary gastric or colorectal cancer since the case number is small in this middle sized general hospital in Japan. The content was nearly uniform since the operative procedure and perioperative management used during surgery and the preoperative and postoperative periods were always performed by the same individuals(three surgeons). However, because the groups were divided into two groups according to the disinfection method used during the study period, the ration of cases performed using laparoscopy increased over time, and a bias existed in the surgical approach between the two groups. Second, the skin of the surgical field was generally disinfected by dipping a sterilized coating material, such as a cotton ball, in sterilized disinfectant and then applying the dipped material to the skin using sterile forceps. PVP-I disinfection was performed using this method. OLG disinfection was instead performed using an applicator in which the disinfectant and the coating material were aseptically integrated. The use of an applicator reduces the burden of medical workers during disinfection procedures, and it may also reduce the risk of bacterial contamination and contribute to the reduction of SSI because it is sterilized and packaged. For a precise comparison of the efficacy of the disinfectant itself, it may be necessary to perform disinfection using a similar approach in both groups. Finally, several evidence-based guidelines for the prevention of SSIs were updated during the study period; these included recommended antisepsis for preoperative surgical skin preparation according to the World Health Organization (WHO) and CDC and included chlorhexidine-alcohol-based (CHG-AL) agents but not aqueous PVP-I[15, 31]. Furthermore, one trial in which CHG-AL was demonstrated to be superior to PVP-I for pre-operative topical antisepsis in clean-contaminated surgery was followed by a meta-analysis and systematic review that confirmed this result[8, 32, 33]. Therefore, further studies aimed at comparing OLG with an alcohol-based agent such as CHG-AL, are needed to verify the effectiveness of OLG.
In conclusion, in this retrospective study, we demonstrate that OLG is more effective than PVP-I for preventing SSIs during gastrointestinal cancer surgery. Particularly, the use of OLG may also be more effective in surgeries with a high risk of SSI as colorectal cancer. This result indicates that OLG may be useful in reduction SSI in patients undergoing gastrointestinal surgery.