Novel antiseptic compound OPB-2045G shows potent bactericidal activity against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus both in vitro and in vivo: a pilot study in animals

Randomized controlled trial of olanexidine gluconate and povidone iodine for surgical site infection after gastrointestinal surgery

Aim

Antiseptics used at surgical sites are vital to preventing surgical site infections (SSI). In this study, a comparative investigation of the novel antiseptics olanexidine gluconate (OG) and povidone-iodine (PI) was conducted to determine whether OG is more effective than PI against SSI after gastrointestinal surgery.

Methods

This prospective, randomized, single-blind, interventional, single-center study was conducted between August 2018 and February 2021. Patients scheduled for large-scale gastrointestinal surgeries were randomized into two groups and administered OG (OG group) or PI (PI group) as preoperative antiseptics. The primary endpoint was the SSI occurrence rate within 30 days after surgery.

Results

In total, 525 patients were enrolled in this study, of whom 256 and 254 were in the OG and PI groups, respectively. The total SSI occurrence rate in the OG group (10.8%; n = 26) and the PI group (13.0%; n = 33) was not significantly different (p = 0.335). The occurrence rate of superficial incisional SSI and organ/space SSI did not significantly differ between the groups; however, that of deep incisional SSI showed a significant difference, with 0.4% (n = 1) in the OG group and 4.3% (n = 11) in the PI group (p = 0.003).

Conclusion

OG, as a preoperative skin antiseptic, did not reduce the occurrence rate of total SSI. However, deep incisional SSI may be reduced using OG.

Evaluation of Antifungal Metabolites Produced by Lactic Acid Bacteria

This study aimed to select and characterize lactic acid bacteria (LAB) with potential antifungal activities against the filamentous fungi Alternaria alternata ATCC MYA-4642, Aspergillus flavus KACC 45470, Aspergillus niger KACC 42589, Cladosporium sphaerospermum ATCC MYA-4645, Penicillium chrysogenum ATCC MYA-4644, and Penicillium expansum KACC 40815. Initial screening of the antifungal activity has identified six LAB strains belonging to the genera Enterococcus and Leuconostoc, selected by their antagonistic activities against at least three of the filamentous fungi in the test panel. Preliminary prediction of bioactive compounds was carried out to narrow down the possible identity of the antagonistic metabolites produced by the studied LAB. Furthermore, metabolic profiles were assessed and used as a basis for the identification of key metabolites based on VIP scores and PCA plot scores. Key metabolites were identified to be β-phenyllactic acid, ⍺-hydroxyisobutyric acid, 1,3-butanediol, phenethylamine, and benzoic acid. Individual assessment of each metabolic compound against the test panel showed specificity inhibitory patterns; yet, combinations between them only showed additive, but not synergetic effects. The pH neutralization significantly reduced the antifungal activity of the cell-free supernatant (CFS), but no bioactive compounds were found to be stable in high temperatures and pressure. This study will be beneficial as an additional building block on the existing knowledge and future antifungal application of LAB produced metabolites. Furthermore, this study also provides a new bio-preservative perspective on unexplored antifungal metabolites produced by LAB as biocontrol agents.

Comparison of olanexidine versus povidone-iodine as a preoperative antiseptic for reducing surgical site infection in both scheduled and emergency gastrointestinal surgeries: A single-center randomized clinical trial

Aim

Surgical site infection (SSI) is one of the most common postoperative complications in gastrointestinal surgery. To clarify the superiority of 1.5% olanexidine, we conducted a randomized prospective clinical trial that enrolled patients undergoing gastrointestinal surgery with operative wound classes II-IV.

Methods

To evaluate the efficacy of 1.5% olanexidine in preventing SSIs relative to 10% povidone-iodine, we enrolled 298 patients in each group. The primary outcome was a 30-day SSI, and the secondary outcomes were incidences of superficial and deep incisional SSI and organ/space SSI. In addition, subgroup analyses were performed.

Results

The primary outcome of the overall 30-day SSI occurred in 38 cases (12.8%) in the 1.5% olanexidine group and in 53 cases (18.0%) in the 10% povidone-iodine group (adjusted risk ratio: 0.716, 95% confidence interval: 0.495-1.057, p = 0.083). Organ/space SSI occurred in 18 cases (6.1%) in the 1.5% olanexidine group and in 31 cases (10.5%) in the 10% povidone-iodine group, with a significant difference (adjusted risk ratio: 0.587, 95% confidence interval: 0.336-0.992, p = 0.049). Subgroup analyses revealed that SSI incidences were comparable in scheduled surgery (relative risk: 0.809, 95% confidence interval: 0.522-1.254) and operative wound class II (relative risk: 0.756, 95% confidence interval: 0.494-1.449) in 1.5% olanexidine group.

Conclusion

Our study revealed that 1.5% olanexidine reduced the 30-day overall SSI; however, the result was not significant. Organ/space SSI significantly decreased in the 1.5% olanexidine group. Our results indicate that 1.5% olanexidine has the potential to prevent SSI on behalf of povidone-iodine.

Effect of aqueous olanexidine versus alcohol-based chlorhexidine for surgical skin antisepsis on incidence of surgical site infections in gastrointestinal surgery: multicentre randomised controlled clinical trial (OEDO trial) protocol

INTRODUCTION

Surgical site infections (SSIs) are among the most common nosocomial infections in surgery patients. Two types of preparations, povidone-iodine and chlorhexidine-alcohol, are commonly used in preoperative antiseptic procedures worldwide. However, there are inconsistencies among international guideline recommendations concerning skin antiseptics. This trial aimed to evaluate the superiority of olanexidine, which reduced SSI rates more than povidone-iodine in our previous randomised trial, over chlorhexidine-alcohol in clean-contaminated surgery.

METHODS AND ANALYSIS

This multicentre randomised controlled clinical trial will compare two antiseptics (1.5% olanexidine and 1.0% chlorhexidine-alcohol) to prevent SSI in clean-contaminated gastrointestinal surgeries with surgical wounds. On providing consent, patients aged <18 years will be included. The primary outcome will be the postoperative 30-day overall SSI rate, while the secondary outcomes will be the postoperative 30-day superficial incisional SSI rate, deep incisional SSI rate, organ/space SSI rate, positive bacterial wound culture rate, cultured bacterial strains, rates of intervention-related toxicity and allergic events (eg, erythema, pruritus, dermatitis and other symptoms of allergy around the region disinfected by the antiseptic during surgery), rate of reoperations due to SSI, medical economic effect indicators (based on health insurance claims) and hospital duration. The Mantel-Haenszel method will be used to estimate the adjusted risk ratio and its 95% CI for the primary analysis, which will compare the treatment effects.

ETHICS AND DISSEMINATION

The protocol was approved by the Institutional Review Board of Keio University School of Medicine and subsequently by the board of each participating site. Participant recruitment began in January 2023. The final results will be published in medical journals after international peer review.

TRIAL REGISTRATION NUMBER

UMIN000049712.

Disinfection efficacy and mechanism of olanexidine gluconate against norovirus

BACKGROUND

The purpose of this study was to evaluate the virucidal activity of a new olanexidine-containing formulation for hand hygiene (olanexidine gluconate hand rub; OLG-HR) against non-enveloped viruses and to understand its mechanism of action.

METHODS

The virucidal activities of OLG-HR against two strains of caliciviruses and three adenovirus serotypes were evaluated through suspension tests. Also, virus-like particles were used to predict the effect of olanexidine gluconate on virus particle structure.

RESULTS

The results of suspension tests under conditions with and without interfering substances (1.5% BSA) indicated that OLG-HR had a broad-spectrum effect against non-enveloped viruses, and the virucidal effect was unaffected by organic contaminants. Furthermore, olanexidine inhibited the binding ability of virus-like particles to the binding receptor of human norovirus and increased the aggregation of virus-like particles in a dose-dependent manner. Transmission electron microscopy showed that the morphology of the virus-like particles was affected by exposure to olanexidine, indicating that the protein-denaturing effect of olanexidine gluconate caused the loss of receptor-binding capability of the viral capsid protein.

CONCLUSIONS

This study suggests that olanexidine gluconate is a potential biological and environmental disinfectant against norovirus and adenovirus.

Clinical study of a new skin antiseptic olanexidine gluconate in gastrointestinal cancer surgery

Background

Surgical site infection (SSI) is a common complication of gastrointestinal surgery. Olanexidine gluconate (OLG) is a novel skin antiseptic that is effective against a wide range of bacteria. The purpose of this study was to evaluate the bactericidal efficacy of OLG in gastrointestinal cancer surgery.

Methods

This retrospective study included a total of 281 patients who underwent gastrointestinal cancer surgery (stomach or colon). The patients were divided into two groups: 223 patients were treated with OLG (OLG group), and 58 patients were treated with povidone-iodine (PVP-I) (control group). The efficacy and safety outcomes were measured as the rate of SSI within 30 days after surgery. In addition, we conducted subgroup analyses according to the surgical approach (open or laparoscopic) or primary lesion (stomach or colon).

Results

There was a significant difference in the rate of SSI between the control group and OLG group (10.3% vs. 2.7%; p = 0.02). There was a significant difference in the SSI rate in terms of superficial infection (8.6% vs. 2.2%; p = 0.0345) but not in deep infection (1.7% vs. 0.5%; p = 0.371). There was no significant difference between the control group and OLG group in the overall rate of adverse skin reactions (5.2% vs. 1.8%; p = 0.157).

Conclusion

This retrospective study demonstrates that OLG is more effective than PVP-I in preventing SSI during gastrointestinal cancer surgery.

Antiviral Activity of Olanexidine-Containing Hand Rub against Human Noroviruses

Human norovirus (HuNoV) is the leading cause of epidemic and sporadic acute gastroenteritis worldwide. HuNoV transmission occurs predominantly by direct person-to-person contact, and its health burden is associated with poor hand hygiene and a lack of effective antiseptics and disinfectants. Specific therapies and methods to prevent and control HuNoV spread previously were difficult to evaluate because of the lack of a cell culture system to propagate infectious virus. This barrier has been overcome with the successful cultivation of HuNoV in nontransformed human intestinal enteroids (HIEs). Here, we report using the HIE cultivation system to evaluate the virucidal efficacy of an olanexidine gluconate-based hand rub (OLG-HR) and 70% ethanol (EtOH_70%) against HuNoVs. OLG-HR exhibited fast-acting virucidal activity against a spectrum of HuNoVs including GII.4 Sydney[P31], GII.4 Den Haag[P4], GII.4 New Orleans[P4], GII.3[P21], GII.17[P13], and GI.1[P1] strains. Exposure of HuNoV to OLG-HR for 30 to 60 s resulted in complete loss of the ability of virus to bind to the cells and reduced in vitro binding to glycans in porcine gastric mucin. By contrast, the virucidal efficiency of EtOH_70% on virus infectivity was strain specific. Dynamic light scattering (DLS) and electron microscopy of virus-like particles (VLPs) show that OLG-HR treatment causes partial disassembly and possibly conformational changes in VP1, interfering with histo-blood group antigen (HBGA) binding and infectivity, whereas EtOH_70% treatment causes particle disassembly and clumping of the disassembled products, leading to loss of infectivity while retaining HBGA binding. The highly effective inactivation of HuNoV infectivity by OLG-HR suggests that this compound could reduce HuNoV transmission.

Propensity-matched analysis of the efficacy of olanexidine gluconate versus chlorhexidine-alcohol as an antiseptic agent in thoracic esophagectomy

Background

In the present matched-cohort study, we investigated the efficacy of olanexidine gluconate in comparison with chlorhexidine-alcohol as an antiseptic agent in thoracic esophagectomy.

Methods

A total of 372 patients with esophageal cancer who were scheduled to undergo thoracic esophagectomy between 2016 and 2018 were assigned to one of two groups based on the preoperative antiseptic agent used in thoracic esophagectomy. We investigated the incidence of surgical site infectious complications in the propensity-matched cohort.

Results

Based on the propensity score, 116 patients prepared with 1.5% olanexidine gluconate and 114 patients prepared with 1.0% chlorhexidine-alcohol as surgical skin antisepsis were selected. No significant intergroup differences were observed with respect to incisional surgical site infection (0.8% in the olanexidine group versus 0.8% in the chlorhexidine group) and deep fascial/organ space surgical site infection (1.7%/10.3% in the olanexidine group versus 3.5%/15.7% in the chlorhexidine group, p = 0.39/p = 0.03). Notably, the respective incidences of surgical site infection except anastomotic leakage were 1.7% and 7.0% in the olanexidine and chlorhexidine groups (p = 0.04).

Conclusions

Olanexidine gluconate was well tolerated and significantly reduced incidence of surgical site infection except anastomotic leakage in comparison with chlorhexidine-alcohol as an antiseptic agent in thoracic esophagectomy with three-field lymph node dissection.

Clinical application of skin antisepsis using aqueous olanexidine: a scoping review

Surgical site infections (SSIs) and catheter‐related bloodstream infections (CRBSIs) caused by bacteria from surfaces poorly disinfected with chlorhexidine gluconate (CHG) and povidone‐iodine (PVP‐I) are increasing. Olanexidine gluconate (OLG) was developed in 2015 in Japan to prevent SSI and CRBSI caused by bacteria resistant to CHG and PVP‐I. This scoping review aimed to identify the knowledge gap between what is known and what is not known about the disinfection efficacy of OLG. We searched MEDLINE through PubMed, the Cochrane Central Register of Controlled Trials, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), the International Clinical Trials Registry Platform search database, ClinicalTrials.gov, and the Web‐based database of Japanese medical articles for works published to July 18, 2021. Manual reference searches were also carried out. A total of 131 studies were screened. Forty‐seven studies were included in this review and classified into two major categories: studies on pharmacological effects and spectrum (n = 29) and studies on clinical and adverse effects (n = 18). Olanexidine gluconate showed bactericidal activity against methicillin‐resistant Staphylococcus aureus and vancomycin‐resistant enterococci, in addition to common Gram‐positive and Gram‐negative bacteria. In clinical settings, although there is limited evidence on SSI prevention, 1.5% OLG might be more effective than 10% PVP‐I and 1% CHG in preventing SSI. However, the clinical usefulness of OLG is unclear due to the limited number of clinical studies. Also, clinical research is limited to studies targeting SSI prevention, and there are no clinical studies on CRBSI. Further clinical studies are needed on SSI and CRBSI prevention.

Pharmaceutical properties of a tinted formulation of a biguanide antiseptic agent, olanexidine gluconate

Olanexidine gluconate-containing preoperative antiseptic (OLG-C) is colorless, which makes it difficult to determine its area of application. To overcome this drawback, we realized a stable orange-tinted antiseptic (OLG-T) by adding new additives to OLG-C and investigated its pharmaceutical properties compared with OLG-C and povidone iodine (PVP-I). We evaluated the influence of the additives on the antimicrobial activity and adhesiveness of medical adhesives to OLG-T-applied skin by in vitro time-kill/ex vivo micropig skin assays and a peel test using excised micropig skin, respectively. In the in vitro time-kill assay, the bactericidal/fungicidal activity of OLG-T and OLG-C were equivalent. In the ex vivo micropig skin assay, their fast-acting and persistent bactericidal activities against vancomycin-resistant Enterococcus faecalis were higher than that of PVP-I. In the peel test, the adhesion force of the incise drape and the amount of stripped corneocytes on the peeled drape were comparable between OLG-T- and OLG-C-applied skin, but both were less than those of PVP-I-applied skin. The drapes for OLG-T- and OLG-C-applied skin had moderate adhesion force, and the drape-related injuries were expected to be weak. These results suggest that OLG-T performs no worse than OLG-C in terms of its antimicrobial activity and medical adhesive compatibility. Therefore, we expect OLG-T to lead to more convenient preoperative skin preparation and further contribute to lowering SSI rates.

Examination of the efficacy of olanexidine gluconate for surgical site infections in colorectal cancer elective surgery

INTRODUCTION

The preoperative skin antiseptic, olanexidine gluconate (OLG), which has been available in Japan since 2015, is also known to be effective against methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and Pseudomonas aeruginosa. This study attempted to clarify OLG efficacy against surgical site infections and antiseptic-related adverse events as compared to conventionally used povidone iodine (PVP-I).

METHODS

Propensity score matching was performed on 307 patients who underwent surgery for colorectal tumors at our hospital. All 116 cases (58 PVP-I cases, 58 OLG cases) who were diagnosed with colorectal cancer were included. We examined surgical site infection rate after disinfection using PVP-I and OLG, length of hospitalization stay (days) after surgery, adverse events associated with antiseptics, and additional medical costs associated with adverse events caused by antiseptics.

RESULTS

The surgical site infection rate was 8.6% in both the PVP-I and OLG groups, with no significant difference observed. The number of postoperative hospitalization days in the PVP-I group was 12.9 (±6.9) days and 16.4 (±14.6) days in the OLG group, which exhibited no significant difference (p = 0.10). Although no complications due to antiseptics were observed in the PVP-I group, skin-related side effects were observed in 8 patients (13.8%) in the OLG group. The median additional medical cost was 730 [120-1823] yen.

CONCLUSIONS

OLG was as effective as the conventional PVP-I for surgical site infections during colorectal cancer elective surgery. However, significantly higher skin disorders occurred in OLG, thereby making it necessary to evaluate antiseptic use in conjunction with patient burden.

Dialdehyde Nanocrystalline Cellulose as Antibiotic Substitutes against Multidrug-Resistant Bacteria

Antibiotic abuse resulted in the emergence of multidrug-resistant Gram-positive pathogens, which pose a severe threat to public health. It is urgent to develop antibiotic substitutes to kill multidrug-resistant Gram-positive pathogens effectively. Herein, the antibacterial dialdehyde nanocrystalline cellulose (DNC) was prepared and characterized. The antibacterial activity and biosafety of DNC were studied. With the increasing content of aldehyde groups, DNC exhibited high antibacterial activity against Gram-positive pathogens in vitro. DNC3 significantly reduced the amounts of methicillin-resistant Staphylococcus aureus (MRSA) on the skin of infected mice models, which showed low cytotoxicity, excellent skin compatibility, and no acute oral toxicity. DNC exhibited potentials as antibiotic substitutes to fight against multidrug-resistant bacteria, such as ingredients in salves to treat skin infection and other on-skin applications.

Cardiovascular Catheterization Using a New Antiseptic Agent Olanexidine Gluconate

Olanexidine gluconate 1.5% (Olanedine^®) is a colorless and transparent antiseptic agent introduced in 2015. In this study, we examined its usefulness and safety for cardiovascular catheterization and compared them to 10% povidone-iodine (PI). The study included 1,001 and 1,000 consecutively enrolled patients using Olanedine^® and PI, respectively [649 (PI, 687) males; mean age: 72.1 ± 9.6 (70.9 ± 9.6) years] who underwent cardiovascular catheterization [diagnostic cardiac catheterization: 624 (509) cases, percutaneous coronary intervention: 288 (390) cases, and endovascular treatment: 89 (101) cases]. Clinically, there were no significant differences in the backgrounds between the two groups. The amount of Olanedine^® used per case was approximately 20 mL. Blood tests were performed before and after catheterization. The presence or absence of discoloration on clothes containing cotton by Olanedine^® was also examined. One mild rash that disappeared within one day occurred in each of the two groups. Some blood tests before and after cardiac catheterization indicated significant differences, but they did not seem to be clinically relevant. The use of Olanedine^® in hemodialysis patients (117 cases) was uneventful. Its use in 37 patients with contraindications for ethanol disinfection was also uneventful. Although PI is extremely difficult to remove from white coats containing cotton, Olanedine^® did not cause any discoloration on clothes. This is the first report of cardiovascular catheterization using Olanedine^®. The efficacy and safety of Olanedine^® and PI seem to be equivalent. Olanedine^® could be a new useful option as a disinfectant of cardiovascular catheterization.

Characterization of Partially Purified Bacteriocins Produced by Enterococcus faecium Strains Isolated from Soybean Paste Active Against Listeria spp. and Vancomycin-Resistant Enterococci

Three out of one hundred eighty putative LAB isolates from Korean traditional fermented soybean paste were identified to be unique and bacteriocinogenic strains. Based on phenotypic and 16S rRNA sequencing analysis, selected strains were identified as Enterococcus faecium ST651ea, E. faecium ST7119ea and E. faecium ST7319ea. The bacteriocinogenic properties of the studied strains were evaluated against Listeria monocytogenes ATCC15313, Listeria innocua ATCC33090 and vancomycin-resistant E. faecium VRE19 of clinical origin. The strains E. faecium ST651ea, ST7119ea and ST7319ea expressed bacteriocins with an activity of 12,800 AU/mL, 25,600 AU/mL and 25,600 AU/mL, respectively, recorded against L. monocytogenes ATCC15131. According to the PCR-based screening of bacteriocin-related genes, which was further confirmed through amplicon sequencing, showed that strain E. faecium ST651ea carries entB and entP genes, whereas both E. faecium ST7119ea and ST7319ea strains harbor entA and entB genes. The molecular size of expressed bacteriocins was estimated by tricine-SDS-PAGE showing an approximative protein size of 4.5 kDa. The assessment of the spectrum of activity of bacteriocins ST651ea, ST7119ea and ST7319ea showed strong activity against most of clinical VRE isolates, majority of other Enterococcus spp. and Listeria spp. Bacteriocins ST651ea, ST7119ea and ST7319ea were partially purified by combination of 60% ammonium sulfate precipitation and hydrophobic chromatography on the SepPakC₁₈ column. Challenge test with semi-purified (60% 2-propanol fraction) bacteriocins resulted in a significant reduction of viable cells for all test organisms. Thus, indicating that all the bacteriocins evaluated can be used as potential biocontrol in food and feed industries as well as an alternative treatment for VRE-related infections in both veterinary and clinical settings.

Disinfection with single or double usage of new antiseptic olanexidine gluconate in general surgery: a randomized study

PURPOSE

Olanexidine gluconate is a newly developed solution for skin disinfection that was recently approved in Japan. We aimed to compare single and double application of the solution in preventing surgical site infection (SSI) in patients undergoing general surgery.

METHODS

This randomized study was conducted at the Tottori University Hospital. Patients scheduled to undergo gastrointestinal or hernia surgery were randomly assigned to one of two groups using either one or two Olanedine applicators for skin disinfection. The primary endpoint was the difference in SSI incidence between the two groups. The secondary endpoint was all adverse events related to olanexidine gluconate.

RESULTS

A total of 393 patients qualified for the study protocol: 193 received a single application, and 200 received a double application of Olanedine. SSI occurred in 10 patients (2.5%) overall; nine were superficial incisional SSIs, and one patient had a deep incisional SSI. Of the 10 patients who developed SSI, six (3.1%) were in the group receiving a single application, and four (2.0%) were in the group receiving a double application; there was no statistically significant difference between the two groups (P = 0.537). Allergic reactions or skin disorders related to olanexidine gluconate were not observed.

CONCLUSION

There was no difference in the SSI incidence between the use of one or two Olanedine applicators for skin preparation in elective general surgery. Therefore, a single application of Olanedine is sufficient and is recommended for general surgery as a standard disinfection precaution.

TRIAL REGISTRATION NUMBER

UMIN000027319; 5/12/2017.

Aqueous olanexidine versus aqueous povidone-iodine for surgical skin antisepsis on the incidence of surgical site infections after clean-contaminated surgery: a multicentre, prospective, blinded-endpoint, randomised controlled trial

BACKGROUND

Surgical site infection (SSI) is the most common problem after surgery. Although several guidelines have indicated the efficacy of antiseptics, such as chlorhexidine-alcohol and povidone-iodine, in reducing SSI rate, the optimal recommendation is still not established. Olanexidine might have higher bactericidal activity than other antiseptic agents. However, no randomised study has evaluated the efficacy and safety of olanexidine over conventional antiseptics. We compared the effect of aqueous olanexidine and aqueous povidone-iodine on the incidence of SSI following clean-contaminated surgery.

METHODS

This was a multicentre, prospective, randomised, blinded-endpoint superiority trial for surgical skin antisepsis in clean-contaminated gastrointestinal and hepatobiliary pancreatic surgeries in four Japanese hospitals. Patients aged 20 years or older who underwent elective clean-contaminated wound surgery were randomly assigned in a 1:1 replacement ratio using a computer-generated block randomisation. Patients were randomly assigned to surgical skin antisepsis with an aqueous formulation of 1·5% olanexidine or surgical skin antisepsis with an aqueous formulation of 10% povidone-iodine before surgery. We used olanexidine in a ready-to-use applicator, and povidone-iodine was administered by a brush or by compression using pliers. Both antiseptics were applied from the papilla with a cranial limit and to the upper thigh with a caudal limit. The antiseptics were allowed to dry for 3 min, and then surgery started. Participants, some investigators, and data analysts were masked to treatment allocation. Participant enrolment was done by non-masked investigators. The primary outcome was 30-day SSI assessed in the intention-to-treat population. The surgical wound site of each participant was observed daily. After discharge, participants underwent at least one outpatient visit within 30 days after surgery. This trial is registered with University hospital Medical Information Network, 000031560.

FINDINGS

Between June 10, 2018, and April 18, 2019, 883 patients were assessed for eligibility. 587 patients were eligible and 294 received olanexidine and 293 received aqueous povidone-iodine before surgery. 30-day SSI occurred in 19 (7%) patients in the olanexidine group and 39 patients (13%) patients in the povidone-iodine group (adjusted risk difference -0·069; 90% CI -0·109 to -0·029; adjusted risk ratio [RR] 0·48, 90% CI 0·30 to 0·74; p=0·002). Five patients (2%) in the olanexidine group and five (2%) in the povidone-iodine group developed adverse skin reactions (adjusted RR 0·99, 95% CI 0·29 to 3·40; p=1·00).

INTERPRETATION

Olanexidine significantly reduced the occurrence of overall SSI and superficial incisional SSI compared with aqueous povidone-iodine in clean-contaminated surgery. Our results indicate that olanexidine might have a role to prevent SSI in patients who undergo clean-contaminated surgeries.

FUNDING

Keio University and Ohyama Health Foundation.

Virucidal Efficacy of Olanexidine Gluconate as a Hand Antiseptic Against Human Norovirus

Human noroviruses are the major cause of non-bacterial acute gastroenteritis worldwide. Since no therapeutic agent has been proven to prevent human norovirus infection yet, preventive healthcare interventions to block the infection routes play an important role in infection control. One of the possible infection routes of human noroviruses are through contaminated hands, but no hand antiseptics have been proven effective. Olanexidine gluconate is a new biguanide compound that has already been approved for sale as an antiseptic for the surgical field in Japan. A new hand antiseptic was developed using olanexidine gluconate in this study, and its virucidal efficacy against human noroviruses was evaluated using modified RT-qPCR that can account for genome derived from intact viruses using RNase A and photo-reactive intercalators. We tested the virucidal efficacy of five materials; two olanexidine gluconate antiseptics (hand rub formulation and surgical field formulation), two kinds of ethanol solutions at different pH (approx. 3 or 7), and a base component of olanexidine gluconate hand rub formulation against 11 human norovirus genotypes by culture-independent methods. The infectivity of murine norovirus (MNV), a surrogate for human norovirus, was significantly reduced after use of the antiseptics. The olanexidine gluconate hand rub demonstrated the strongest virucidal efficacy against human norovirus among the five tested materials. This study showed that olanexidine gluconate has the potential to become a strong tool for the prevention of human norovirus infection.

Anti-inflammatory effects of olanexidine gluconate on oral epithelial cells

Background

Periodontitis is a biofilm-induced chronic inflammatory condition of the periodontium. Chemokines produced by the innate and acquired immune responses play a significant role in disease progression. Reducing biofilm formation and inflammatory response caused by chemokines is vital for preventing and treating periodontitis. Previously, we observed that treatment with 0.1% olanexidine gluconate (OLG) inhibited biofilm formation on saliva-coated hydroxyapatite. This study aimed to evaluate the anti-inflammatory effect of OLG on oral epithelial cells.

Methods

We examined if OLG could inhibit the inflammatory responses caused by Porphyromonas gingivalis (P. gingivalis) lipopolysaccharide (LPS) and heat-killed P. gingivalis in immortalized human oral keratinocytes (RT7).

Results

Treatment of RT7 with non-cytotoxic OLG concentrations significantly inhibited the production of inflammatory chemokines such as interleukin 8 (IL-8), C-C motif ligand 20 (CCL20), and growth-related oncogene protein-α (GRO-α), which are stimulated by P. gingivalis LPS in a concentration-dependent manner. Moreover, the inhibitory effects were observed regardless of the treatment time with P. gingivalis LPS (6, 12, or 24 h). OLG also significantly inhibited chemokine production stimulated by heat-killed P. gingivalis.

Conclusions

The findings of this study suggest that treatment with OLG inhibits chronic inflammatory reactions in oral mucosal cells, such as periodontitis, caused by oral bacteria.

Olanexidine gluconate versus povidone-iodine for preventing surgical-site infection in orthopaedic surgery: A retrospective study

BACKGROUND

Olanexidine gluconate (OLG) is a newly developed skin antiseptic, which is effective against a broad range of bacteria, including methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus. The purpose of this study was to evaluate the bactericidal efficacy and safety of OLG in orthopaedic surgery.

METHODS

This retrospective study included a total of 1103 patients who underwent clean orthopaedic surgery. They were divided into two groups: 556 patients who were treated with OLG (OLG group), and 547 patients who were treated with povidone-iodine (PVP-I) (PVP-I group). The efficacy and the safety outcomes were measured as the rate of surgical-site infection (SSI) within 30 days after surgery and the rate of adverse skin reaction, respectively.

RESULTS

There was no significant difference between the OLG group and PVP-I group (1.80% vs. 2.38%; p = 0.50) based on the overall rate of SSI. Also, there was no significant difference in both superficial incisional infections (1.08% vs. 2.01%; p = 0.21) and deep incisional infections (0.72% vs. 0.37%; p = 0.35). The overall rate of adverse skin reaction was significantly higher in the OLG group than in the PVP-I group (2.16% vs. 0.73%; p = 0.047).

CONCLUSIONS

This retrospective study demonstrated that OLG has an efficacy similar to PVP-I in preventing SSI in clean orthopaedic surgery. However, adverse skin reactions at the application site of OLG requires more attention.

Comparison of olanexidine versus povidone-iodine for preventing surgical site infection in gastrointestinal surgery: study protocol for a multicentre, single-blind, randomised controlled clinical trial

INTRODUCTION

The prevalence of surgical site infection (SSI) remains higher in gastrointestinal surgery than in other surgeries. Although several guidelines have indicated the efficacy of chlorhexidine and povidone-iodine in reducing the SSI rate, the optimal recommendation has still not been established. Therefore, it is necessary to determine the more effective antiseptic for surgical site preparation. Olanexidine (1.5% olanedine, Otsuka Pharmaceutical Factory, Tokushima, Japan), which is a new antiseptic in Japan, has antimicrobial activity against a wide range of bacteria, including Gram-positive and Gram-negative bacteria. Our study will contribute to determining a new antiseptic for use in gastrointestinal and other surgeries.

METHODS AND ANALYSIS

We propose a multicentre, randomised controlled clinical trial for comparing two treatments, that is, 1.5% olanexidine or 10% povidone-iodine, for surgical skin preparation to prevent SSI in clean-contaminated gastrointestinal surgeries with surgical wounds. Patients aged ≥20 years at the time of consent will be included. The primary outcome measure is the 30-day postoperative SSI rate. For the primary analysis, which is aimed at comparing the treatment effects, the adjusted risk ratio and its 95% CI will be estimated using the Mantel-Haenszel method.

ETHICS AND DISSEMINATION

The protocol was first approved by the Institutional Review Board of Keio University School of Medicine, followed by the institutional review board of each participating site. Participant recruitment began in June 2018. The final results will be published in international peer-reviewed medical journals.

TRIAL REGISTRATION NUMBER

UMIN 000031560; Pre-results.

Evaluation of fast-acting bactericidal activity and substantivity of an antiseptic agent, olanexidine gluconate, using an ex vivo skin model

PURPOSE

We assessed the fast-acting bactericidal activity and substantivity of olanexidine gluconate (OLG) to investigate its remaining bactericidal activity on the skin after rinsing and drying by using an ex vivo Yucatan micropig (YMP) skin model.

METHODOLOGY

The fast-acting bactericidal activity was evaluated in pigskin models inoculated with methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, vancomycin-resistant Enterococcus faecalis (VRE), Acinetobacter baumannii, Corynebacterium minutissimum and Cutibacterium acnes. To evaluate substantivity, the YMP skin piece first had 1.5 % OLG, chlorhexidine gluconate (CHG) formulations or 10 % povidone-iodine (PVP-I) applied to it, and was then rinsed with distilled water, incubated for 4, 6, 8 or 12 h and inoculated with the test bacteria (MRSA, S. epidermidis and VRE). The viable bacteria remaining at 1 min of exposure of bacteria were counted to measure the quantity of antiseptic molecules retaining bactericidal activity. To determine the factors contributing to the substantivity, the stratum corneum (SC) of the YMP skin that had had OLG or CHG applied to it was exfoliated using a tape-stripping method and the amount of antiseptic was quantitated.

RESULTS

OLG showed a fast-acting bactericidal activity that was similar to or stronger than that of CHG formulations up to a concentration of 1 % and PVP-I with a short exposure time of 30 s, and substantivity until 12 h after rinsing, whereas the other antiseptics hardly showed any substantivity. There was 2.8 times or more OLG in the SC than CHG.

CONCLUSION

OLG has fast-acting activity and substantivity, which are required properties for an antiseptic, and is useful for preventing infections.

Effects of olanexidine gluconate on preoperative skin preparation: an experimental study in cynomolgus monkeys

PURPOSE

To determine the bactericidal efficacy of a new topical antiseptic for preoperative skin preparation, olanexidine gluconate (development code: OPB-2045G), against transient or resident bacterial flora on the skin of cynomolgus monkeys.

METHODOLOGY

After measuring baseline bacterial counts on test sites marked on the abdomens, we applied olanexidine, chlorhexidine or povidone-iodine. After 10 min (fast-acting effect) and 6 h (long-lasting effect), bacterial counts were measured again and log10 reductions were calculated. In addition, we determined the bactericidal effects on the skin contaminated with blood before or after applying the antiseptics.

RESULTS

In the non-blood-contaminated condition, the mean log10 reductions of olanexidine at doses of 1-2 % were significantly higher than those of saline (negative control), but did not significantly differ from those of 0.5 % chlorhexidine and 10 % povidone-iodine at either time point. But olanexidine was significantly more effective at both time points than chlorhexidine and povidone-iodine when applied after the site was contaminated with blood. Olanexidine was also significantly more effective than chlorhexidine and as effective as or more effective than povidone-iodine at both time points when skin was contaminated with blood after the antiseptics were applied.

CONCLUSION

The bactericidal effects of olanexidine were comparable to those of commercial antiseptics such as chlorhexidine and povidone-iodine in non-blood-contaminated conditions. More importantly, the effect of olanexidine was hardly affected by blood unlike commercial antiseptics. Thus, it is considered that olanexidine has a favourable property for skin preparation in various types of surgical treatments.

Bactericidal Effects and Mechanism of Action of Olanexidine Gluconate, a New Antiseptic

Olanexidine gluconate [1-(3,4-dichlorobenzyl)-5-octylbiguanide gluconate] (development code OPB-2045G) is a new monobiguanide compound with bactericidal activity. In this study, we assessed its spectrum of bactericidal activity and mechanism of action. The minimal bactericidal concentrations of the compound for 30-, 60-, and 180-s exposures were determined with the microdilution method using a neutralizer against 320 bacterial strains from culture collections and clinical isolates. Based on the results, the estimated bactericidal olanexidine concentrations with 180-s exposures were 869 μg/ml for Gram-positive cocci (155 strains), 109 μg/ml for Gram-positive bacilli (29 strains), and 434 μg/ml for Gram-negative bacteria (136 strains). Olanexidine was active against a wide range of bacteria, especially Gram-positive cocci, including methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci, and had a spectrum of bactericidal activity comparable to that of commercial antiseptics, such as chlorhexidine and povidone-iodine. In vitro experiments exploring its mechanism of action indicated that olanexidine (i) interacts with the bacterial surface molecules, such as lipopolysaccharide and lipoteichoic acid, (ii) disrupts the cell membranes of liposomes, which are artificial bacterial membrane models, (iii) enhances the membrane permeability of Escherichia coli, (iv) disrupts the membrane integrity of S. aureus, and (v) denatures proteins at relatively high concentrations (≥160 μg/ml). These results indicate that olanexidine probably binds to the cell membrane, disrupts membrane integrity, and its bacteriostatic and bactericidal effects are caused by irreversible leakage of intracellular components. At relatively high concentrations, olanexidine aggregates cells by denaturing proteins. This mechanism differs slightly from that of a similar biguanide compound, chlorhexidine.