Evaluation of in Vitro Bactericidal Activity of 1.5% Olanexidine Gluconate, a Novel Biguanide Antiseptic Agent

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.

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.

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.

In vitro growth-inhibitory effects of Portulaca oleracea L. formulation on intestinal pathogens

Introduction

Empirical evidence suggests that Portulaca oleracea L. treats enteric infections, including dysentery, cholera, and acute infectious gastroenteritis.

Aim

The aim of this study is to clarify the growth-inhibitory effects of Portulaca oleracea L. extract against 56 strains of intestinal pathogens.

Methodology

‘Gogyo-so-cha (GSC)’ was used as the P. oleracea L. formulation. A growth curve analysis was used to measure the growth-inhibitory effects of GSC, and Shiga toxin induction was measured using the latex agglutination test.

Results

GSC demonstrated strong bactericidal effects against Shigella dysenteriae and Vibrio cholerae strains from various isolates. GSC demonstrated weak or no bactericidal effects against intestinal commensal bacteria, including Enterococcus spp. and Escherichia coli. GSC did not induce Shigella toxins.

Conclusion

GSC significantly inhibited the growth of intestinal pathogens, including S. dysenteriae and V. cholerae, without adversely affecting the intestinal flora, supporting the usage of GSC in traditional Chinese medicine. Taken together, GSC would be of immense value in the developing world, where diarrhoeal infectious diseases continue to pose a major health risk.

Amiodarone that has antibacterial effect against human pathogens may represent a novel catheter lock

Infection is one of the most feared hospital-acquired complications. Infusion therapy is frequently administered through a central line. Infusions facilitating bacterial growth may be a source of central line-associated bloodstream infections. On the other hand, medications that kill bacteria may protect against this kind of infection and may be used as a catheter lock.In this study, we examined the impact of amiodarone on bacterial growth. Amiodarone is used for controlling cardiac arrhythmias and can be administered as an infusion for weeks. Standard microbiological methods have been used to study the growth of laboratory strains and clinical isolates of Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and multidrug-resistant Acinetobacter baumannii in amiodarone. The minimum inhibitory concentration (MIC) of amiodarone was determined. Bacterial growth from in use amiodarone syringes and giving sets was also investigated.Most examined strains were killed within 1 min in amiodarone. The other strains were killed within 1 h. The MICs of amiodarone were <0.5-32 μg/mL.Amiodarone infusion is unlikely to be responsible for bloodstream infections as contaminating bacteria are killed within 1 h. Amiodarone may also protect against central line infections if used as a catheter lock.

A case of allergic contact dermatitis caused by Olanedine solution-A diagnostic patch-testing method involving dried filter paper

BACKGROUND

Olanedine solution is a new antiseptic, and several cases of allergic contact dermatitis caused by the agent were reported in 2018; however, these cases were diagnosed based on positive results in 2-day closed patch testing of Olanedine solution "as is."

OBJECTIVES

To present another case of Olanedine-induced allergic contact dermatitis and to analyze the optimal patch-testing method for this condition.

METHODS

A 34-year-old Japanese female patient and 25 healthy control subjects were patch tested using wet filter paper, which had been treated with 15 μL Olanedine solution, and dried filter paper, which had been treated with 15 μL Olanedine solution and then dried.

RESULTS

The patient and all of the control subjects exhibited false-positive reactions due to irritation in the 2-day closed patch tests with wet filter paper containing Olanedine solution "as is." The tests with dried filter paper produced a positive reaction on day 7 in the patient, and negative reactions in all control subjects.

CONCLUSIONS

It is preferable to perform 2-day closed patch tests using filter paper with the test solution "as is," which had been dried before application in order to correctly diagnose antiseptic-induced allergic contact dermatitis.

Carbon-carbon Bond Cleavage Catalyzed by Human Cytochrome P450 Enzymes: α-ketol as the Key Intermediate Metabolite in Sequential Metabolism of Olanexidine

BACKGROUND

Carbon-carbon bond cleavage of a saturated aliphatic moiety is rarely seen in xenobiotic metabolism. Olanexidine (Olanedine®), containing an n-octyl (C₈) side chain, was mainly metabolized to various shortened side chain (C₄ to C₆) acid-containing metabolites in vivo in preclinical species. In liver microsomes and S9, the major metabolites of olanexidine were from multi-oxidation on its n-octyl (C₈) side chain. However, the carbon-carbon bond cleavage mechanism of n-octyl (C₈) side chain, and enzyme(s) responsible for its metabolism in human remained unknown.

METHODS

A pair of regioisomers of α-ketol-containing C₈ side chain olanexidine analogs (3,2-ketol olanexidine and 2,3-ketol olanexidine) were synthesized, followed by incubation in human liver microsomes, recombinant human cytochrome P450 enzymes or human hepatocytes, and subsequent metabolite identification using LC/UV/MS.

RESULTS

Multiple shortened side chain (C₄ to C₆) metabolites were identified, including C₄, C₅ and C₆- acid and C₆-hydroxyl metabolites. Among 19 cytochrome P450 enzymes tested, CYP2D6, CYP3A4 and CYP3A5 were identified to catalyze carbon-carbon bond cleavage.

CONCLUSION

3,2-ketol olanexidine and 2,3-ketol olanexidine were confirmed as the key intermediates in carbon-carbon bond cleavage. Its mechanism is proposed that a nucleophilic addition of iron-peroxo species, generated by CYP2D6 and CYP3A4/5, to the carbonyl group caused the carbon-carbon bond cleavage between the adjacent hydroxyl and ketone groups. As results, 2,3-ketol olanexidine formed a C₆ side chain acid metabolite. While, 3,2-ketol olanexidine formed a C₆ side chain aldehyde intermediate, which was either oxidized to a C₆ side chain acid metabolite or reduced to a C₆ side chain hydroxyl metabolite.