Insights into the Cytotoxicity and Irritant Potential of Chlorhexidine Digluconate: An In Vitro and In Ovo Safety Screening

Chlorhexidine (CHX) represents one of the most commonly used antiseptics in dentistry and other medical-pharmaceutical fields due to its broad-spectrum antimicrobial activity. However, the potential toxic events arising from its common use in practice has become a subject of increasing concern. Thus, the present study was designed to investigate the potential toxicity of CHX digluconate at concentrations covering its antibacterial properties (0.0002-0.2%) in HGF primary gingival fibroblasts, HaCaT immortalized human keratinocytes, and JB6 Cl 41-5a epidermal cells, as well as its irritant action in ovo. Our results indicate that CHX exerted a concentration- and time-dependent cytotoxicity in all cell lines, which was evidenced by the reduction in cell viability, number, and confluence, damaged cell membrane integrity, impaired cell morphology, and specific apoptotic nuclear shape. The highest cytotoxicity was caused by CHX digluconate 0.02% and 0.2%, concentrations, at which an irritant effect on the chorioallantoic membrane was also observed. The novel findings revealed in this research contribute to the overall safety profile of CHX and stand as a basis for further investigations in this regard.

Identification of mechanisms modulating chlorhexidine and octenidine susceptibility in Proteus mirabilis

AIMS

We aimed to identify mechanisms underlying the tolerance of Proteus mirabilis-a common cause of catheter associated urinary tract infection-to the clinically used biocides chlorhexidine (CHD) and octenidine (OCT).

METHODS AND RESULTS

We adapted three clinical isolates to grow at concentrations of 512 µg ml-1 CHD and 128 µg ml-1 OCT. Genetic characterization and complementation studies revealed mutations inactivating the smvR repressor and increasing smvA efflux expression were associated with adaptation to both biocides. Mutations in mipA (encoding the MltA interacting protein) were less prevalent than smvR mutations and only identified in CHD adapted populations. Mutations in the rppA response regulator were exclusive to one adapted isolate and were linked with reduced polymyxin B susceptibility and a predicted gain of function after biocide adaptation. Biocide adaptation had no impact on crystalline biofilm formation.

CONCLUSIONS

SmvR inactivation is a key mechanism in both CHD and OCT tolerance. MipA inactivation alone confers moderate protection against CHD, and rppA showed no direct role in either CHD or OCT susceptibility.

Chlorhexidine digluconate mouthwash alters the oral microbial composition and affects the prevalence of antimicrobial resistance genes

Introduction

Chlorhexidine (CHX) is a commonly used antiseptic in situations of limited oral hygiene ability such as after periodontal surgery. However, CHX is also considered as a possible factor in the emergence of cross-resistance to antibiotics. The aim of this study was to analyze the changes in the oral microbiota and the prevalence of antimicrobial resistance genes (ARGs) due to CHX treatment.

Materials and methods

We analyzed the oral metagenome of 20 patients who applied a 0.2% CHX mouthwash twice daily for 4 weeks following periodontal surgical procedures. Saliva and supragingival plaque samples were examined before, directly after 4 weeks, and another 4 weeks after discontinuing the CHX treatment.

Results

Alpha-diversity decreased significantly with CHX use. The Bray-Curtis dissimilarity increased in both sample sites and mainly streptococci showed a higher relative abundance after CHX treatment. Although no significant changes of ARGs could be detected, an increase in prevalence was found for genes that encode for tetracycline efflux pumps.

Conclusion

CHX treatment appears to promote a caries-associated bacterial community and the emergence of tetracycline resistance genes. Future research should focus on CHX-related changes in the microbial community and whether the discovered tetracycline resistance genes promote resistance to CHX.

Impact of postoperative skin disinfection with chlorhexidine on bacterial colonisation following shoulder arthroplasty surgery: a controlled randomised study

Background

Surgical site infections are a significant threat to patient safety. Shoulder arthroplasty carries an increased risk due to foreign implants. Skin preparation in general is a key preoperative preventive intervention, and the use of chlorhexidine can have a prolonged effect on bacterial colonisation. There is a lack of evidence regarding whether postoperative disinfection has an impact on bacterial colonisation during the first 48 hours after surgery. Our hypothesis was that applying postoperative antiseptic with 5 mg/ml chlorhexidine in 70% ethanol would lead to reduced bacterial colonisation with Staphylococcus aureus, coagulase-negative staphylococcus and Cutibacterium acnes around the surgical wound within the initial 48 hours after elective shoulder surgery, compared with the use of sodium chloride.

Methods

A single-blinded, controlled study was conducted at a county hospital in Sweden. Swabs from the skin were collected four times: at baseline, preoperatively, after the intervention and after 48 hours.

Results

Our hypothesis was not confirmed. Although not statistically significant, the chlorhexidine group had a higher prevalence of bacterial colonisation of clinically relevant bacteria.

Conclusions

Our study could not confirm that postoperative disinfection with chlorhexidine reduces bacterial colonisation compared with sodium chloride. The results highlight the complexity of SSIs and the importance of evidence-based preventive skin preparation to ensure patient safety. Further research is needed, considering the study's limitations, to explore and evaluate the effectiveness of different skin cleansing solutions and preventive strategies in diverse surgical contexts.

Unveiling potential repurposed drug candidates for Plasmodium falciparum through in silico evaluation: A synergy of structure-based approaches, structure prediction, and molecular dynamics simulations

The rise of drug resistance in Plasmodium falciparum, rendering current treatments ineffective, has hindered efforts to eliminate malaria. To address this issue, the study employed a combination of Systems Biology approach and a structure-based pharmacophore method to identify a target against P. falciparum. Through text mining, 448 genes were extracted, and it was discovered that plasmepsins, found in the Plasmodium genus, play a crucial role in the parasite's survival. The metabolic pathways of these proteins were determined using the PlasmoDB genomic database and recreated using CellDesigner 4.4.2. To identify a potent target, Plasmepsin V (PF13_0133) was selected and examined for protein-protein interactions (PPIs) using the STRING Database. Topological analysis and global-based methods identified PF13_0133 as having the highest centrality. Moreover, the static protein knockout PPIs demonstrated the essentiality of PF13_0133 in the modeled network. Due to the unavailability of the protein's crystal structure, it was modeled and subjected to a molecular dynamics simulation study. The structure-based pharmacophore modeling utilized the modeled PF13_0133 (PfPMV), generating 10 pharmacophore hypotheses with a library of active and inactive compounds against PfPMV. Through virtual screening, two potential candidates, hesperidin and rutin, were identified as potential drugs which may be repurposed as potential anti-malarial agents.

Antibacterial Activity of Various Morphologies of Films Based on Guanidine Derivatives of Pillar[5]arene: Influence of the Nature of One Substitute on Self-assembly

The progress of the pillar[5]arene chemistry allowed us to set out a new concept on application of the supramolecular assemblies to create antimicrobial films with variable surface morphologies and biological activities. Antibacterial films were derived from the substituted pillar[5]arenes containing nine pharmacophoric guanidine fragments and one thioalkyl substituent. Changing the only thioalkyl fragment in the macrocycle structure made it possible to control the biological activity of the resulting antibacterial coating. Pretreatment of the surface with aqueous solution of the amphiphilic pillar[5]arenes reduced the biofilm thickness by 56 ± 10% of Gram-positive Staphylococcus aureus in the case of the pillar[5]arene containing a thiooctyl fragment and by 52 ± 7% for the biofilm of Gram-negative Klebsiella pneumoniae in the case of pillar[5]arene containing a thiooctadecyl fragment. Meanwhile, the cytotoxicity of the synthesized macrocycles was examined at a concentration of 50 μg/mL, which was significantly lower than that of bis-guanidine-based antimicrobial preparations.

Unlocking the mechanism of action: a cost-effective flow cytometry approach for accelerating antimicrobial drug development

Antimicrobial resistance is one of the greatest challenges to global health. While the development of new antimicrobials can combat resistance, low profitability reduces the number of new compounds brought to market. Elucidating the mechanism of action is crucial for developing new antimicrobials. This can become expensive as there are no universally applicable pipelines. Phenotypic heterogeneity of microbial populations resulting from antimicrobial treatment can be captured through flow cytometric fingerprinting. Since antimicrobials are classified into limited groups, the mechanism of action of known compounds can be used for predictive modeling. We demonstrate a cost-effective flow cytometry approach for determining the mechanism of action of new compounds. Cultures of Actinomyces viscosus and Fusobacterium nucleatum were treated with different antimicrobials and measured by flow cytometry. A Gaussian mixture mask was applied over the data to construct phenotypic fingerprints. Fingerprints were used to assess statistical differences between mechanism of action groups and to train random forest classifiers. Classifiers were then used to predict the mechanism of action of cephalothin. Statistical differences were found among the different mechanisms of action groups. Pairwise comparison showed statistical differences for 35 out of 45 pairs for A. viscosus and for 32 out of 45 pairs for F. nucleatum after 3.5 h of treatment. The best-performing random forest classifier yielded a Matthews correlation coefficient of 0.92 and the mechanism of action of cephalothin could be successfully predicted. These findings suggest that flow cytometry can be a cheap and fast alternative for determining the mechanism of action of new antimicrobials.IMPORTANCEIn the context of the emerging threat of antimicrobial resistance, the development of novel antimicrobials is a commonly employed strategy to combat resistance. Elucidating the mechanism of action of novel compounds is crucial in this development but can become expensive, as no universally applicable pipelines currently exist. We present a novel flow cytometry-based approach capable of determining the mechanism of action swiftly and cost-effectively. The workflow aims to accelerate drug discovery and could help facilitate a more targeted approach for antimicrobial treatment of patients.

Emergence and clonal expansion of a qacA-harbouring sequence type 45 lineage of methicillin-resistant Staphylococcus aureus

The past decade has seen an increase in the prevalence of sequence type (ST) 45 methicillin-resistant Staphylococcus aureus (MRSA), yet the underlying drivers for its emergence and spread remain unclear. To better understand the worldwide dissemination of ST45 S. aureus, we performed phylogenetic analyses of Australian isolates, supplemented with a global population of ST45 S. aureus genomes. Our analyses revealed a distinct lineage of multidrug-resistant ST45 MRSA harbouring qacA, predominantly found in Australia and Singapore. Bayesian inference predicted that the acquisition of qacA occurred in the late 1990s. qacA was integrated into a structurally variable region of the chromosome containing Tn552 (carrying blaZ) and Tn4001 (carrying aac(6')-aph(2")) transposable elements. Using mutagenesis and in vitro assays, we provide phenotypic evidence that qacA confers tolerance to chlorhexidine. These findings collectively suggest both antimicrobial resistance and the carriage of qacA may play a role in the successful establishment of ST45 MRSA.

Novel anionic surfactant-modified chlorhexidine and its potent antimicrobial properties

Chlorhexidine dodecyl sulfate (CHX-DS) was synthesized and characterized via single-crystal X-ray diffraction (SC-XRD), 1H nuclear magnetic resonance (NMR) spectroscopy, 1H nuclear Overhauser effect spectroscopy (NOESY), and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR). The solid-state structure, comprising a 1 : 2 stoichiometric ratio of chlorhexidine cations [C22H30Cl2N10]2+ to dodecyl sulfate anions [C12H25SO4]-, is the first report of chlorhexidine isolated with a surfactant. CHX-DS exhibits broad-spectrum antibacterial activity and demonstrates superior efficacy for reducing bacteria-generated volatile sulfur compounds (VSCs) as compared to chlorhexidine gluconate (CHG). The minimum inhibitory concentrations (MICs) of CHX-DS were 7.5, 2.5, 2.5, and 10 μM for S. enterica, E. coli, S. aureus, and S. mutans, respectively. Furthermore, MIC assays for E. coli and S. mutans demonstrate that CHX-DS and CHX exhibit a statistically significant efficacy enhancement in 2.5 μM treatment as compared to CHG. CHX-DS was incorporated into SBA-15, a mesoporous silica nanoparticle (MSN) framework, and its release was qualitatively measured via UV-vis in aqueous media, which suggests its potential as an advanced functional material for drug delivery applications.

Haemostatic discs demonstrate physical efficacy against microbes commonly associated with central-line-associated bloodstream infections

BACKGROUND

Vascular access devices form an essential component in the management of acute and chronic medical conditions. Introduction and ongoing management of these devices are linked with bundles of care aimed at reducing associated risks including bleeding and infection.

AIM

To evaluate the antimicrobial potential of the potassium ferrate haemostatic disc on Gram-positive (Staphylococcus aureus) and Gram-negative (Klebsiella pneumoniae, Pseudomonas aeruginosa) bacteria and on Candida albicans.

METHODS

The impact of the potassium ferrate disc was compared with the often-used chlorhexidine gluconate (CHG) impregnated disc to evaluate the potential efficacy of the potassium ferrate disc as an alternative to CHG in cases with an increased risk of active bleeding.

RESULTS

In the presence of anticoagulated blood, we observed an inhibitory effect of the haemostatic disc on microbial growth for microbial strains commonly associated with vascular access device related infections.

CONCLUSION

Our results indicate that the potassium ferrate disc may provide dual clinical benefits with both haemostatic and antimicrobial action observed during in-vitro testing.

Novel surface biochemical modifications of urinary catheters to prevent catheter-associated urinary tract infections

More than 70% of hospital-acquired urinary tract infections are related to urinary catheters, which are commonly used for the treatment of about 20% of hospitalized patients. Urinary catheters are used to drain the bladder if there is an obstruction in the tube that carries urine out of the bladder (urethra). During catheter-associated urinary tract infections, microorganisms rise up in the urinary tract and reach the bladder, and cause infections. Various materials are used to fabricate urinary catheters such as silicone, polyurethane, and latex. These materials allow bacteria and fungi to develop colonies on their inner and outer surfaces, leading to bacteriuria or other infections. Urinary catheters could be modified to exert antibacterial and antifungal effects. Although so many research have been conducted over the past years on the fabrication of antibacterial and antifouling catheters, an ideal catheter needs to be developed for long-term catheterization of more than a month. In this review, we are going to introduce the recent advances in fabricating antibacterial materials to prevent catheter-associated urinary tract infections, such as nanoparticles, antibiotics, chemical compounds, antimicrobial peptides, bacteriophages, and plant extracts.

Clinical Efficacy of Different Concentrations of Povidone Iodine in the Management of Peri-Implant Mucositis

Mechanical plaque control is the first line of management of peri-implant diseases. Povidone iodine is one of the broad spectrum and potent antiseptics available at various concentrations. The aim of the study was to assess and compare the efficacy of various concentrations of povidone iodine in the management of peri-implant mucositis. In the present double blinded, parallel designed, randomized clinical trial, a total of 60 patients with peri-implant mucositis (20 participants in each group [Group 1 (povidone iodine 0.1%), Group 2 (povidone iodine 2%) and Group 3 (povidone iodine 010%)] were enrolled. Scaling and root planing was done and then the peri-implant sulcus was irrigated with respective irrigant and repeated once in a week for 4 weeks. Loe and Silness Gingival Index (GI) and Mombelli Modified sulcular bleeding index (BI) were recorded at baseline and after a month and compared. Statistical analysis was done using One-way ANOVA and Tukey's HSD post hoc test. A statistically significant difference (P = 0.000) observed between the three concentrations when compared after 1 month. Also, a statistically significant difference between Group 1 and Group 3 and Group 2 and Group 3 was observed in terms of post GI (P = 0.000) and post BI (P = 0.000) but statistically no significant difference was observed between Group 1 and Group 2 in terms of post GI (P = 0.171) and post BI (P = 0.338). The 2% and 10% povidone iodine showed significant improvement in gingival index and bleeding index and hence it could be an effective adjunct to scaling and root planing in the management of peri-implant mucositis.

Chlorhexidine-based versus non-chlorhexidine dressings to prevent catheter-related bloodstream infections: An evidence-based review

In patients with central venous catheters (CVCs) in situ, the development of catheter-related bloodstream infections (CRBSIs) is often linked with increased morbidity and mortality. Sterile gauze or transparent polyurethane dressings are conventionally used as extraluminal barriers; however, antimicrobial chlorhexidine CVC dressings could potentially reduce infection risk. This short evidence-based review examined the literature comparing the effectiveness of chlorhexidine-based CVC dressings against non-chlorhexidine dressings in reducing CRBSI occurrence. Four systematic reviews with meta-analysis were reviewed, all of which reported a statistically significant reduction in CRBSI occurrence on using chlorhexidine-based dressings. Further research is needed to determine the cost-effectiveness of chlorhexidine-based CVC dressings and their effectiveness in reducing CRBSIs in different catheter types and entry sites because infection risk is not uniform.

Patch Testing to Chlorhexidine Digluconate, 1% Aqueous: North American Contact Dermatitis Group Experience, 2015-2020

Background: Chlorhexidine is an antiseptic that may cause allergic contact dermatitis. Objectives: To describe the epidemiology of chlorhexidine allergy and characterize positive patch test reactions. Methods: This retrospective study analyzed patients patch tested to chlorhexidine digluconate 1% aqueous by the North American Contact Dermatitis Group, 2015-2020. Results: Of 14,731 patients tested to chlorhexidine digluconate, 107 (0.7%) had an allergic reaction; of these, 56 (52.3%) reactions were currently clinically relevant. Most (59%) reactions were mild (+), followed by strong (++, 18.7%) and very strong (+++, 6.5%). Common primary dermatitis anatomic sites in chlorhexidine-positive patients were hands (26.4%), face (24.5%), and scattered/generalized distribution (17.9%). Compared with negative patients, chlorhexidine-positive patients were significantly more likely to have dermatitis involving the trunk (11.3% vs 5.1%; P = 0.0036). The most commonly identified source category was skin/health care products (n = 41, 38.3%). Only 11 (10.3%) chlorhexidine reactions were occupationally related; of these, 81.8% were in health care workers. Conclusions: Chlorhexidine digluconate allergy is uncommon, but often clinically relevant. Involvement of the hands, face, and scattered generalized patterns was frequent. Occupationally related reactions were found predominantly in health care workers.

Theranostic gold-in-gold cage nanoparticles enable photothermal ablation and photoacoustic imaging in biofilm-associated infection models

Biofilms are structured communities of microbial cells embedded in a self-produced matrix of extracellular polymeric substances. Biofilms are associated with many health issues in humans, including chronic wound infections and tooth decay. Current antimicrobials are often incapable of disrupting the polymeric biofilm matrix and reaching the bacteria within. Alternative approaches are needed. Here, we described a complex structure of a dextran-coated gold-in-gold cage nanoparticle that enabled photoacoustic and photothermal properties for biofilm detection and treatment. Activation of these nanoparticles with a near infrared laser could selectively detect and kill biofilm bacteria with precise spatial control and in a short timeframe. We observed a strong biocidal effect against both Streptococcus mutans and Staphylococcus aureus biofilms in mouse models of oral plaque and wound infections, respectively. These effects were over 100 times greater than those seen with chlorhexidine, a conventional antimicrobial agent. Moreover, this approach did not adversely affect surrounding tissues. We concluded that photothermal ablation using theranostic nanoparticles is a rapid, precise, and nontoxic method to detect and treat biofilm-associated infections.

Comparing the efficacy of chlorhexidine and povidone-iodine in preventing surgical site infections: A systematic review and meta-analysis

Surgical site infections (SSIs) post-surgery impact patient health and raise healthcare costs. This meta-analysis examines the efficacy of antiseptics, chlorhexidine and povidone-iodine, in reducing SSIs, including various types, to settle ongoing debates on their comparative effectiveness. A systematic literature search conforming to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines was executed on four established databases without temporal restrictions. Only randomized controlled trials (RCTs) including patients aged 18 years or older undergoing clean or potentially contaminated surgeries were included. Two independent evaluators carried out study selection, data extraction and quality assessment, adhering to Cochrane Collaboration's risk of bias tool. Statistical analyses were performed using chi-square tests and the I2 index to evaluate heterogeneity, and meta-analyses were conducted employing either fixed-effects or random-effects models as warranted by the heterogeneity assessments. A total of 16 RCTs were included after rigorous selection from an initial pool of 1742 articles. The studies demonstrated low levels of heterogeneity, supporting the use of a fixed-effects model. Chlorhexidine exhibited statistically lower rates of overall SSIs (RR 0.75; 95% CI 0.64-0.88; p < 0.001), superficial SSIs (RR 0.62; 95% CI 0.47-0.82; p < 0.001) and deep SSIs compared to povidone-iodine. The study furnishes compelling evidence in favour of chlorhexidine as a more efficacious antiseptic agent over povidone-iodine in minimizing the risk of various types of SSIs.

Ozonated Oil in Liposome Eyedrops Reduces the Formation of Biofilm, Selection of Antibiotic-Resistant Bacteria, and Adhesion of Bacteria to Human Corneal Cells

The recent attention to the risk of potential permanent eye damage triggered by ocular infections has been leading to a deeper investigation of the current antimicrobials. An antimicrobial agent used in ophthalmology should possess the following characteristics: a broad antimicrobial spectrum, prompt action even in the presence of organic matter, and nontoxicity. The objective of this study is to compare the antimicrobial efficacy of widely used ophthalmic antiseptics containing povidone-iodine, chlorhexidine, and liposomes containing ozonated sunflower oil. We determined the minimum inhibitory concentration (MIC) on various microbial strains: Staphylococcus aureus (ATCC 6538), methicillin-resistant Staphylococcus aureus (ATCC 33591), Staphylococcus epidermidis (ATCC 12228), Pseudomonas aeruginosa (ATCC 9027), and Escherichia coli (ATCC 873). Furthermore, we assessed its efficacy in controlling antibiotic resistance, biofilm formation, and bacterial adhesion. All three antiseptic ophthalmic preparations showed significant anti-microbicidal and anti-biofilm activity, with the liposomes containing ozonated sunflower oil with the highest ability to control antibiotic resistance and bacteria adhesion to human corneal cells.

Study of Combined Effect of Bacteriophage vB3530 and Chlorhexidine on the Inactivation of Pseudomonas aeruginosa

BACKGROUND

Chlorhexidine (CHG) is a disinfectant commonly used in hospitals. However, it has been reported that the excessive use of CHG can cause resistance in bacteria to this agent and even to other clinical antibiotics. Therefore, new methods are needed to alleviate the development of CHG tolerance and reduce its dosage. This study aimed to explore the synergistic effects of CHG in combination with bacteriophage against CHG-tolerant Pseudomonas aeruginosa (P. aeruginosa) and provide ideas for optimizing disinfection strategies in clinical environments as well as for the efficient use of disinfectants.

METHODS

The CHG-tolerant P. aeruginosa strains were isolated from the First Affiliated Hospital of Wenzhou Medical University in China. The bacteriophage vB3530 was isolated from the sewage inlet of the hospital, and its genome was sequenced. Time-killing curve was used to determine the antibacterial effects of vB3530 and chlorohexidine gluconate (CHG). The phage sensitivity to 16 CHG-tolerant P. aeruginosa strains and PAO1 strain was detected using plaque assay. The emergence rate of resistant bacterial strains was detected to determine the development of phage-resistant and CHG-tolerant strains. Finally, the disinfection effects of the disinfectant and phage combination on the surface of the medical devices were preliminarily evaluated.

RESULTS

The results showed that (1) CHG combined with bacteriophage vB3530 significantly inhibited the growth of CHG-resistant P. aeruginosa and reduced the bacterial colony forming units (CFUs) after 24 h. (2) The combination of CHG and bacteriophage inhibited the emergence of phage-resistant and CHG-tolerant strains. (3) The combination of CHG and bacteriophage significantly reduced the bacterial load on the surface of medical devices.

CONCLUSIONS

In this study, the combination of bacteriophage vB3530 and CHG presented a combined inactivation effect to CHG-tolerant P. aeruginosa and reduced the emergence of strains resistant to CHG and phage. This study demonstrated the potential of bacteriophage as adjuvants to traditional disinfectants. The use of bacteriophage in combination with commercial disinfectants might be a promising method for controlling the spread of bacteria in hospitals.

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.

Mutanase from Trichoderma harzianum inductively Produced by Mutan: Short-Term Treatment to Degrade Mature Streptococcus mutans Biofilm

This study aimed to evaluate the disruptive effect of fungal mutanase against cariogenic biofilm after short-term treatment. For that, mature Streptococcus mutans biofilms (n = 9) were exposed to active or inactivated enzymes produced by Trichoderma harzianum for 1 min, two times per day. Biofilms were analyzed by amount of matrix water-insoluble polysaccharides, bacterial viability, acidogenicity, and morphology by scanning electron microscopy (SEM). The group treated with active enzymes (AE) had a significantly lower amount of insoluble polysaccharides (893.30 ± 293.69) when compared to the negative control group (NaCl, 2192.59 ± 361.96), yet no significant difference was found when comparing to the positive control group (CHX, 436.82 ± 151.07). Also, there was no significant effect on bacteria metabolism and viability (P-value < 0.05). Data generated by the quantitative analysis were confirmed through scanning electron microscopy images. Thus, fungal mutanase degraded the biofilm after a short-term treatment without interfering with bacterial viability and metabolism. Such findings offer insight to the development of routine oral care products containing this input.

Targeted screening and identification of chlorhexidine as a pro-myogenic circadian clock activator

BACKGROUND

The circadian clock is an evolutionarily conserved mechanism that exerts pervasive temporal control in stem cell behavior. This time-keeping machinery is required for orchestrating myogenic progenitor properties in regenerative myogenesis that ameliorates muscular dystrophy. Here we report a screening platform to discover circadian clock modulators that promote myogenesis and identify chlorhexidine (CHX) as a clock-activating molecule with pro-myogenic activities.

METHODS

A high-throughput molecular docking pipeline was applied to identify compounds with a structural fit for a hydrophobic pocket within the key circadian transcription factor protein, Circadian Locomotor Output Cycles Kaput (CLOCK). These identified molecules were further screened for clock-modulatory activities and functional validations for pro-myogenic properties.

RESULTS

CHX was identified as a clock activator that promotes distinct aspects of myogenesis. CHX activated circadian clock that reduced cycling period length and augmented amplitude. This action was mediated by the targeted CLOCK structure via augmented interaction with heterodimer partner Bmal1, leading to enhanced CLOCK/Bmal1-controlled transcription with upregulation of core clock genes. Consistent with its clock-activating function, CHX displayed robust effects on stimulating myogenic differentiation in a clock-dependent manner. In addition, CHX augmented the proliferative and migratory activities of myoblasts.

CONCLUSION

Our findings demonstrate the feasibility of a screening platform to discover clock modulators with myogenic regulatory activities. Discovery of CHX as a pro-myogenic molecule could be applicable to promote regenerative capacities in ameliorating dystrophic or degenerative muscle diseases.

Exploring the Potential of Bee-Derived Antioxidants for Maintaining Oral Hygiene and Dental Health: A Comprehensive Review

Honey bee products comprise various compounds, including honey, propolis, royal jelly, bee pollen, bee wax and bee venom, which have long been recognized for their pharmacological and health-promoting benefits. Scientists have discovered that periodontal disorders stem from dental biofilm, an inflammatory response to bacterial overgrowth produced by dysbiosis in the oral microbiome. The bee products have been investigated for their role in prevention of oral diseases, which are attributed to a myriad of biologically active compounds including flavonoids (pinocembrin, catechin, caffeic acid phenethyl ester (CAPE) and galangin), phenolic acids (hydroxybenzoic acid, hydroxycinnamic acid, p-coumaric, ellagic, caffeic and ferulic acids) and terpenoids. This review aims to update the current understanding of role of selected bee products, namely, honey, propolis and royal jelly, in preventing oral diseases as well as their potential biological activities and mechanism of action in relation to oral health have been discussed. Furthermore, the safety of incorporation of bee products is also critically discussed. To summarize, bee products could potentially serve as a therapy option for people suffering from a variety of oral disorders.

In vitro and in vivo evaluation of chlorhexidine salts as potential alternatives to potassium dichromate for Eimeria maxima M6 oocyst preservation

Introduction

Coccidiosis caused by the Eimeria spp., an Apicomplexan protozoon, is a major intestinal disease that affects the poultry industry. Although most cases of coccidiosis are subclinical, Eimeria infections impair bird health and decrease overall performance, which can result in compromised welfare and major economic losses. Viable sporulated Eimeria oocysts are required for challenge studies and live coccidiosis vaccines. Potassium dichromate (PDC) is typically used as a preservative for these stocks during storage. Although effective and inexpensive, PDC is also toxic and carcinogenic. Chlorhexidine (CHX) salts may be a possible alternative, as this is a widely used disinfectant with less toxicity and no known carcinogenic associations.

Methods

In vitro testing of CHX gluconate and CHX digluconate exhibited comparable oocyst integrity and viability maintenance with equivalent bacteriostatic and bactericidal activity to PDC. Subsequent use of CHX gluconate or digluconate-preserved Eimeria oocysts, cold-stored at 4°C for 5 months, as the inoculum also resulted in similar oocyst shedding and recovery rates when compared to PDC-preserved oocysts.

Results and discussion

These data show that using 0.20% CHX gluconate could be a suitable replacement for PDC. Additionally, autofluorescence was used as a method to evaluate oocyst viability. Administration of artificially aged oocysts exhibiting >99% autofluorescence from each preserved treatment resulted in no oocyst output for CHX salt groups.

Impact on S. aureus and E. coli Membranes of Treatment with Chlorhexidine and Alcohol Solutions: Insights from Molecular Simulations and Nuclear Magnetic Resonance

Membranes form the first line of defence of bacteria against potentially harmful molecules in the surrounding environment. Understanding the protective properties of these membranes represents an important step towards development of targeted anti-bacterial agents such as sanitizers. Use of propanol, isopropanol and chlorhexidine can significantly decrease the threat imposed by bacteria in the face of growing anti-bacterial resistance via mechanisms that include membrane disruption. Here we have employed molecular dynamics simulations and nuclear magnetic resonance to explore the impact of chlorhexidine and alcohol on the S. aureus cell membrane, as well as the E. coli inner and outer membranes. We identify how sanitizer components partition into these bacterial membranes, and show that chlorhexidine is instrumental in this process.

Theranostic gold in a gold cage nanoparticle for photothermal ablation and photoacoustic imaging of skin and oral infections

Biofilms are structured communities of microbial cells embedded in a self-produced matrix of extracellular polymeric substances. Biofilms are associated with many health issues in humans, including chronic wound infections and tooth decay. Current antimicrobials are often incapable of disrupting the polymeric biofilm matrix and reaching the bacteria within. Alternative approaches are needed. Here, we describe a unique structure of dextran coated gold in a gold cage nanoparticle that enables photoacoustic and photothermal properties for biofilm detection and treatment. Activation of these nanoparticles with a near infrared laser can selectively detect and kill biofilm bacteria with precise spatial control and in a short timeframe. We observe a strong biocidal effect against both Streptococcus mutans and Staphylococcus aureus biofilms in mouse models of oral plaque and wound infections respectively. These effects were over 100 times greater than that seen with chlorhexidine, a conventional antimicrobial agent. Moreover, this approach did not adversely affect surrounding tissues. We conclude that photothermal ablation using theranostic nanoparticles is a rapid, precise, and non-toxic method to detect and treat biofilm-associated infections.

Effect of combined boric acid and chlorhexidine mouthwashes on postoperative complications and periodontal healing after impacted third molar surgery: a-double blind randomized study

OBJECTIVES

This study aimed to evaluate the effects of different concentrations of boric acid (BA) combined with chlorhexidine (CHX) mouthwash on postoperative complications and periodontal healing following impacted third molar surgery.

MATERIALS AND METHODS

A total of 80 patients were randomly divided into eight groups. The patients in the study groups received different concentrations of BA ranging from 0.1% to 2.5% combined with CHX or 2% BA mouthwash alone. The control group received CHX mouthwash alone. The scores of self-reported pain and jaw dysfunction, trismus, edema, number of analgesics used, and periodontal parameters were compared between the groups.

RESULTS

2.5% BA + CHX group had significantly lower pain and facial swelling values during the follow-up period. 2% BA + CHX group reported significantly lower jaw dysfunction scores on the fourth and fifth postoperative days. The control group showed significantly higher values for pain, jaw dysfunction, and facial swelling than other groups. No significant differences were found between the groups regarding trismus, analgesic use, and periodontal variables.

CONCLUSIONS

The combination of higher concentrations of BA with CHX was more effective in reducing pain, jaw dysfunction, and swelling following impacted third molar surgery than CHX mouthwash alone.

CLINICAL RELEVANCE

The combination of BA and CHX showed better results than the gold standard CHX mouthwash in reducing postoperative complications related to surgical removal of impacted third molars without any adverse effects. This new combination can be an effective alternative to traditional mouthwashes after impacted third molar surgery to ensure oral hygiene.

Povidone-Iodine Adverse Effects and Alternatives for Ocular Procedures

Purpose: Povidone-iodine (PVI), also known as Betadine, is a widely used antiseptic agent used in several fields of medicine. In ophthalmology, it is applied as a preoperative antiseptic to prevent infectious complications that can result from surgical procedures. PVI's safety and efficacy have been extensively studied and represented in the literature; however, the incidence of adverse effects has been reported in conjunction. The aim of this paper is to compile information regarding PVIs use, safety profile, adverse effects, and possible alternatives through a review of the existing literature. Methods: Literature was compiled utilizing the database PubMed and Google Scholar using specified keywords with a total of 86 reviewed articles, after excluding search results that did not meet the inclusion criteria. Results: While the allergic potential to PVI is a highly contested topic, there are several nonallergic adverse effects of PVI that should not be overlooked. These effects include chemical burn, cytotoxic effects, and general patient discomfort. In light of these adverse effects, alternatives to PVI may be considered. However, there has been little research identifying feasible alternatives in preoperative intraocular procedures. Alternatives including chlorhexidine, polyhexamethylene biguanide (polyhexanide), and octenidine were identified as potential substitutes for PVI. Conclusions: Further study is needed to provide robust evidence regarding the efficacy profiles of these alternatives in comparison with PVI and to demonstrate comparable tolerance to PVI in intraocular procedures.

Short-term effects of Chlorhexidine mouthwash and Listerine on oral microbiome in hospitalized patients

Introduction

Chlorhexidine (CHX) and essential oil containing mouthwashes like Listerine^® can improve oral hygiene via suppressing oral microbes. In hospitalized patients, CHX mouthwash reduces the incidence of ventilator-associated pneumonia. However, CHX use was also associated with increased mortality, which might be related to nitrate-reducing bacteria. Currently, no study determines oral bacteria targeted by essential oils mouthwash in hospitalized patients using a metagenomic approach.

Methods

We recruited 87 hospitalized patients from a previous randomized control study, and assigned them to three mouthwash groups: CHX, Listerine, and normal saline (control). Before and after gargling the mouthwash twice a day for 5-7 days, oral bacteria were examined using a 16S rDNA approach.

Results

Alpha diversities at the genus level decreased significantly only for the CHX and Listerine groups. Only for the two groups, oral microbiota before and after gargling were significantly different, but not clearly distinct. Paired analysis eliminated the substantial individual differences and revealed eight bacterial genera (including Prevotella, Fusobacterium, and Selenomonas) with a decreased relative abundance, while Rothia increased after gargling the CHX mouthwash. After gargling Listerine, seven genera (including Parvimonas, Eubacterium, and Selenomonas) showed a decreased relative abundance, and the magnitudes were smaller compared to the CHX group. Fewer bacteria targeted by Listerine were reported to be nitrate-reducing compared to the CHX mouthwash.

Discussion

In conclusion, short-term gargling of the CHX mouthwash and Listerine altered oral microbiota in our hospitalized patients. The bacterial genera targeted by the CHX mouthwash and Listerine were largely different and the magnitudes of changes were smaller using Listerine. Functional alterations of gargling CHX and Listerine were also different. These findings can be considered for managing oral hygiene of hospitalized patients.

Assessment of Alcohol Exposure From Alcohol-Based Disinfectants Among Premature Infants in Neonatal Incubators in Japan

IMPORTANCE

The risk of premature infants in neonatal incubators exposed to evaporated alcohol from alcohol-based disinfectants (ABDs) is unknown.

OBJECTIVE

To assess alcohol concentrations in the peripheral blood of premature infants and neonatal incubators.

DESIGN, SETTING, AND PARTICIPANTS

A quality improvement study comparing 2 different populations before and after introduction of ABD practice (ABD-PRAC) was conducted in a neonatal intensive care unit of a single tertiary hospital in Japan. Participants included premature infants who were born before 34 weeks of gestational age and received medical care in neonatal incubators. The study consisted of 3 periods: (1) September 1, 2020, to August 1, 2021 (prospective observation of pre-ABD-PRAC, (2) August 2 to August 22, 2021 (introduction of ABD-PRAC to medical staff and parents in the neonatal intensive care unit), and (3) August 23, 2021, to March 31, 2022 (prospective observation of post-ABD-PRAC). No follow-up studies were initiated.

INTERVENTIONS

An ABD-PRAC that aimed to reduce alcohol evaporation from ABDs inside neonatal incubators was instituted: (1) place alcohol preps in the incubator just before use and remove them from the incubator as soon as possible and (2) withhold placing hands into the incubators until 60 seconds after using ABDs for disinfection (applied only to family members).

MAIN OUTCOMES AND MEASURES

Blood alcohol concentration and evaporated alcohol concentrations in neonatal incubators.

RESULTS

Disinfectant practice was assessed among 28 infants during the pre-ABD-PRAC (17 infants [10 girls]; median gestational age at birth, 29.4 [IQR, 26.3-30.3] weeks) and post-ABD-PRAC (11 infants [3 girls]; median gestational age at birth, 30.0 [IQR, 25.3-32.2] weeks) study periods. The median blood alcohol concentration was 7.0 (IQR, 5.4-9.3) mg/dL pre-ABD-PRAC and 4.2 (IQR, 2.5-7.2) mg/dL post-ABD-PRAC. The median evaporated alcohol concentration inside neonatal incubators during pre-ABD-PRAC during the day was 23.6 (IQR, 15.9-36.5) ppm and, at night, was 13.2 (IQR, 8.9-19.4) ppm; during post-ABD-PRAC, the concentration was 9.4 (IQR, 6.0-16.0) ppm during the day and 5.7 (IQR, 3.6-9.7) ppm at night. The introduction of ABD-PRAC at 22 weeks' corrected gestational age was associated with a lower blood alcohol concentration in premature infants: regression coefficient value, -8.3 (95% CI, -12.0 to -4.7).

CONCLUSIONS AND RELEVANCE

In this study, alcohol evaporated from ABDs was absorbed by premature infants in neonatal incubators. The findings suggest that introduction of ABD-PRAC was associated with lower alcohol concentrations in neonatal incubators and in the blood of premature infants.

Combination of Cetylpyridinium Chloride and Chlorhexidine Acetate: A Promising Candidate for Rapid Killing of Gram-Positive/Gram-Negative Bacteria and Fungi

Combined use of the present antimicrobial drugs has been proved to be an alternative approach for antimicrobial agents' development since the co-existed of the drugs working in different mechanism have been demonstrated potentially enhance their antimicrobial activity. In this work, antibacterial and antifungal activity of the cetylpyridinium chloride (CPC)/chlorhexidine acetate (CHA) combination was evaluated for the first time, while a universal concentration for the rapid killing of gram-positive/gram-negative bacteria and fungi was also proposed. The minimum inhibitory concentrations (MIC) of CPC and CHA used alone or in combination were first measured, showing that the combined treatment decreased the MIC against tested gram-positive/gram-negative bacteria and fungi to 1/8-1/2. Growth curve assays demonstrated CPC and CHA had dynamic combined effects against the tested microorganisms at the concentration equal to MIC. Besides, combined use of these two drugs could also enhance their biocidal activity, which was illustrated by fluorescence microscopy and SEM images, as well as soluble protein measurement. More importantly, in vitro acute eye and skin irritation tests showed short-term contact with CPC/CHA combination would not cause any damage to mammalian mucosa and skin. In a word, CPC/CHA combination exhibited broad-spectrum antibacterial and antifungal activity against tested gram-positive/gram-negative bacteria and fungi while without any acute irritation to mammalian mucosa and skin, providing a new perspective on the selection of personal disinfectants.

Caries Management with Non-Metallic Nanomaterials: A Systematic Review

BACKGROUND

Non-metallic nanomaterials do not stain enamel or dentin. Most have better biocompatibility than metallic nanomaterials do for management of dental caries.

OBJECTIVE

The objective of this study is to review the types, properties and potential uses of non-metallic nanomaterials systematically for managing dental caries.

METHODS

Two researchers independently performed a literature search of publications in English using PubMed, Scopus and Web of Science. The keywords used were (nanoparticles OR nanocomposites OR nanomaterials) AND (caries OR tooth decay). They screened the titles and abstracts to identify potentially eligible publications of original research reporting non-metallic nanomaterials for caries management. Then, they retrieved and studied the full text of the identified publications for inclusion in this study.

RESULTS

Out of 2497 resulting publications, this study included 75 of those. The non-metallic nanomaterials used in these publications were categorized as biological organic nanomaterials (n=45), synthetic organic nanomaterials (n=15), carbon-based nanomaterials (n=13) and selenium nanomaterials (n=2). They inhibited bacteria growth and/or promoted remineralization. They could be incorporated in topical agents (29/75, 39%), dental adhesives (11/75, 15%), restorative fillers (4/75, 5%), dental sealant (3/75, 4%), oral drugs (3/75, 4%), toothpastes (2/75, 3%) and functional candies (1/75, 1%). Other publications (22/75, 29%) do not mention specific applications. However, most publications (67/75, 89%) were in vitro studies. Six publications (6/75, 8%) were animal studies, and only two publications (2/75, 3%) were clinical studies.

CONCLUSION

The literature showed non-metallic nanomaterials have antibacterial and/or remineralising properties. The most common type of non-metallic nanomaterials for caries management is organic nanomaterials. Non-metallic nanomaterials can be incorporated into dental sealants, toothpaste, dental adhesives, topical agents and even candies and drugs. However, the majority of the publications are in vitro studies, and only two publications are clinical studies.

Advancements in antimicrobial nanoscale materials and self-assembling systems

Antimicrobial resistance is directly responsible for more deaths per year than either HIV/AIDS or malaria and is predicted to incur a cumulative societal financial burden of at least $100 trillion between 2014 and 2050. Already heralded as one of the greatest threats to human health, the onset of the coronavirus pandemic has accelerated the prevalence of antimicrobial resistant bacterial infections due to factors including increased global antibiotic/antimicrobial use. Thus an urgent need for novel therapeutics to combat what some have termed the 'silent pandemic' is evident. This review acts as a repository of research and an overview of the novel therapeutic strategies being developed to overcome antimicrobial resistance, with a focus on self-assembling systems and nanoscale materials. The fundamental mechanisms of action, as well as the key advantages and disadvantages of each system are discussed, and attention is drawn to key examples within each field. As a result, this review provides a guide to the further design and development of antimicrobial systems, and outlines the interdisciplinary techniques required to translate this fundamental research towards the clinic.

Oral cleaning habits and the copy number of periodontal bacteria in pregnant women and its correlation with birth outcomes: an epidemiological study in Mibilizi, Rwanda

BACKGROUND

Since 1996, many studies have reported that periodontal disease during pregnancy may be a risk factor for preterm birth and low birth weight; however, in Africa, periodontal disease is considered a non-high-priority disease. In addition, there are few dental facilities in rural Rwanda; thus, the oral condition of pregnant women has not been investigated. The objective of this study was to assess the tooth brushing habits of pregnant women in rural Rwanda and evaluate whether periodontal bacteria in the oral cavity of pregnant women are related to birth outcomes or oral cleaning habits.

METHODS

A questionnaire survey and saliva collection were conducted for pregnant women in the catchment area population of Mibilizi Hospital located in the western part of Rwanda. Real-time PCR was performed to quantitatively detect total bacteria and 4 species of periodontal bacteria. The relationship of the copy number of each bacterium and birth outcomes or oral cleaning habits was statistically analyzed.

RESULTS

Among the participants, high copy numbers of total bacteria, Tannerella forsythia, and Treponema denticola were correlated with lower birth weight (p = 0.0032, 0.0212, 0.0288, respectively). The sex ratio at birth was higher in women who had high copy numbers of Porphyromonas gingivalis and T. denticola during pregnancy (p = 0.0268, 0.0043). Furthermore, regarding the correlation between oral cleaning habits and the amount of bacteria, the more frequently teeth were brushed, the lower the level of P. gingivalis (p = 0.0061); the more frequently the brush was replaced, the lower the levels of P. gingivalis and T. forsythia (p = 0.0153, 0.0029).

CONCLUSIONS

This study suggested that improving tooth brushing habits may reduce the risk of periodontal disease among pregnant women in rural Rwanda. It also indicated that the amount of bacteria is associated with various birth outcomes according to the bacterial species. Both access to dental clinics and the oral cleaning habits of pregnant women should be important considerations in efforts to alleviate reproductive-related outcomes in rural Africa.

Antimicrobial persistence of two alcoholic preoperative skin preparation solutions

BACKGROUND

Normal skin flora and suboptimal skin antisepsis are the primary drivers of healthcare-associated infections (HAIs). Antimicrobial persistence of preoperative skin preparation is necessary to limit microorganisms on the skin and help minimize their entry into an incision or device-insertion site after application.

AIM

To assess the antimicrobial persistence of two preoperative skin preparation solutions.

METHODS

A randomized, single-centre, partially blinded, clinical study was conducted in 103 healthy volunteers to evaluate the persistent antimicrobial properties of BD ChloraPrep™ (2% w/v chlorhexidine gluconate [CHG] + 70% v/v isopropyl alcohol [IPA]) and BD PurPrep™ (8.3% w/w povidone-iodine [PVP-I] + 72.5% w/w IPA) skin preparations out to 7 days and 96 hours, respectively, on abdomen and groin testing sites. An additional 32 healthy volunteers participated in a neutralization procedure to ensure the study recovery solution was non-toxic to microorganisms, and a spore-recovery procedure to demonstrate that microorganisms could be successfully recovered from the PVP-I+IPA film-forming product.

RESULTS

Both CHG+IPA and PVP-I+IPA produced a mean bacterial log₁₀ reduction >2 and >3 on the abdomen and groin, respectively, 10 minutes after application. CHG+IPA maintained antimicrobial persistence out to 7 days post-application, while PVP-I+IPA maintained antimicrobial persistence out to 96 hours post-application, the longest timepoint selected for this product.

CONCLUSION

CHG+IPA and PVP-I+IPA were both found to be effective persistent antiseptic skin preparations. Overall, skin irritation was uncommon, and only 1 adverse event occurred following product application, which was not considered product related but was considered procedure related.

Irrigation Solutions and Antibiotic Powders: Should I Use Them in Primary and Revision Total Joint Arthroplasty?

BACKGROUND

The prevention and treatment of periprosthetic joint infection is of utmost importance to orthopedic surgeons. Irrigation solutions have become a popular additive to the prevention and treatment armamentarium.

METHODS

This symposium summarizes the mechanism of action, basic science, and clinical research to date on the use of irrigation solutions. The four most commonly used irrigation solutions, povidone iodine, chlorhexidine, hydrogen peroxide, and acetic acid, are discussed. In addition, the role of antibiotic powers is reviewed.

RESULTS

Each solution has its risks and benefits that must be weighed by the surgeon. There is no clear irrigation solution that is superior. The role of additive antibiotic powder (vancomycin) remains controversial.

CONCLUSION

More rigorous prospective clinical trials are needed to determine the optimal irrigation solution for the prevention and treatment of periprosthetic joint infection.

Antimicrobial tolerance and its role in the development of resistance: Lessons from enterococci

Bacteria have developed resistance against every antimicrobial in clinical use at an alarming rate. There is a critical need for more effective use of antimicrobials to both extend their shelf life and prevent resistance from arising. Significantly, antimicrobial tolerance, i.e., the ability to survive but not proliferate during antimicrobial exposure, has been shown to precede the development of bona fide antimicrobial resistance (AMR), sparking a renewed and rapidly increasing interest in this field. As a consequence, problematic infections for the first time are now being investigated for antimicrobial tolerance, with increasing reports demonstrating in-host evolution of antimicrobial tolerance. Tolerance has been identified in a wide array of bacterial species to all bactericidal antimicrobials. Of particular interest are enterococci, which contain the opportunistic bacterial pathogens Enterococcus faecalis and Enterococcus faecium. Enterococci are one of the leading causes of hospital-acquired infection and possess intrinsic tolerance to a number of antimicrobial classes. Persistence of these infections in the clinic is of growing concern, particularly for the immunocompromised. Here, we review current known mechanisms of antimicrobial tolerance, and include an in-depth analysis of those identified in enterococci with implications for both the development and prevention of AMR.

S, Pande A, Pandey PK. Anti-oomycete Activity of Chlorhexidine Gluconate: Molecular Docking and in vitro Studies

Saprolegniosis is one of the most catastrophic oomycete diseases of freshwater fish caused by the members of the genus Saprolegnia. The disease is responsible for huge economic losses in the aquaculture industry worldwide. Until 2002, Saprolegnia infections were effectively controlled by using malachite green. However, the drug has been banned for use in aquaculture due to its harmful effect. Therefore, it has become important to find an alternate and safe anti-oomycete agent that is effective against Saprolegnia. In this study, we investigated the anti-oomycete activity of chlorhexidine gluconate (CHG) against Saprolegnia. Before in vitro evaluation, molecular docking was carried out to explore the binding of CHG with vital proteins of Saprolegnia, such as S. parasitica host-targeting protein 1 (SpHtp1), plasma membrane ATPase, and TKL protein kinase. In silico studies revealed that CHG binds with these proteins via hydrogen bonds and hydrophobic interactions. In an in vitro study, the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of CHG against S. parasitica were found to be 50 mg/L. Further, it was tested against S. australis, another species of Saprolegnia, and the MIC and MFC were found to be 100 and 200 mg/L, respectively. At 500 mg/L of CHG, there was complete inhibition of the radial growth of Saprolegnia hyphae. In propidium iodide (PI) uptake assay, CHG treated hyphae had bright red fluorescence of PI indicating the disruption of the cell membrane. The results of the present study indicated that CHG could effectively inhibit Saprolegnia and hence can be used for controlling Saprolegniasis in cultured fish.

Continuous antimicrobial mechanism of dispersible hydroxyapatite nanoparticles doped with zinc ions for percutaneous device coatings

Percutaneous devices-indwelling catheters-related infections are serious clinical incidents. It is accordingly necessary to develop anti-infective coating materials suitable for the devices for long-term effectiveness. In our research group, highly dispersible and crystalline hydroxyapatite (HAp) nanoparticles doped with metallic or halogen ions possessing antibacterial activities have been developed. In this study, antibacterial, dispersible, and crystalline zinc (Zn)-doped hydroxyapatite [Zn(15)-HAp] nanoparticles substituted with 13.5% Zn content [Zn/(Zn + Ca) × 100] were prepared by a wet chemical method using an anti-sintering agent through calcination. Antibacterial activities of Zn(15)-HAp nanoparticles were evaluated using Escherichia coli (E. coli) and Staphylococcus aureus. The survival rates of the bacteria on Zn(15)-HAp nanoparticles were significantly lower than that on normal HAp (nHAp) coated surfaces, while no influences were observed on proliferation of L929 cells. Even after soaking Zn(15)-HAp nanoparticles in PBS for 2 weeks, the antibacterial activities against E. coli were maintained at a similar level to a 20 min soaking. The bacterial death was related to not only ion-exchange phenomenon between Zn and magnesium ions but also accumulation of reactive oxygen species (ROS) in the cells. Allergic-like reactions-anaphylactoid reactions-might not readily occur with Zn(15)-HAp nanoparticles because the amounts of histamine released from HMC-1 cells co-cultured with nanoparticles were not significantly different to that of nHAp, but were statistically much lower than that of chlorhexidine.

Evidence on the Use of Mouthwash for the Control of Supragingival Biofilm and Its Potential Adverse Effects

Antimicrobial mouthwash improves supragingival biofilm control when used in conjunction with mechanical removal as part of an oral hygiene routine. Mouthwash is intended to suppress bacterial adhesion during biofilm formation processes and is not aimed at mature biofilms. The most common evidence-based effects of mouthwash on the subgingival biofilm include the inhibition of biofilm accumulation and its anti-gingivitis property, followed by its cariostatic activities. There has been no significant change in the strength of the evidence over the last decade. A strategy for biofilm control that relies on the elimination of bacteria may cause a variety of side effects. The exposure of mature oral biofilms to mouthwash is associated with several possible adverse reactions, such as the emergence of resistant strains, the effects of the residual structure, enhanced pathogenicity following retarded penetration, and ecological changes to the microbiota. These concerns require further elucidation. This review aims to reconfirm the intended effects of mouthwash on oral biofilm control by summarizing systematic reviews from the last decade and to discuss the limitations of mouthwash and potential adverse reactions to its use. In the future, the strategy for oral biofilm control may shift to reducing the biofilm by detaching it or modulating its quality, rather than eliminating it, to preserve the benefits of the normal resident oral microflora.

The Application of Small Molecules to the Control of Typical Species Associated With Oral Infectious Diseases

Oral microbial dysbiosis is the major causative factor for common oral infectious diseases including dental caries and periodontal diseases. Interventions that can lessen the microbial virulence and reconstitute microbial ecology have drawn increasing attention in the development of novel therapeutics for oral diseases. Antimicrobial small molecules are a series of natural or synthetic bioactive compounds that have shown inhibitory effect on oral microbiota associated with oral infectious diseases. Novel small molecules, which can either selectively inhibit keystone microbes that drive dysbiosis of oral microbiota or inhibit the key virulence of the microbial community without necessarily killing the microbes, are promising for the ecological management of oral diseases. Here we discussed the research progress in the development of antimicrobial small molecules and delivery systems, with a particular focus on their antimicrobial activity against typical species associated with oral infectious diseases and the underlying mechanisms.

Functional screening of a human saliva metagenomic DNA reveal novel resistance genes against sodium hypochlorite and chlorhexidine

Objective

Many sections of the health care system are facing a major challenge making infectious disease problematic to treat; antimicrobial resistance (AMR). Identification and surveillance of the resistome have been highlighted as one of the strategies to overcome the problem. This study aimed to screen for AMR genes in an oral microbiota, a complex microbial system continuously exposed to antimicrobial agents commonly used in dental practice.

Materials and methods

As a significant part of the oral microbiome cannot be conventionally cultured, a functional metagenomic approach was chosen. The human oral metagenomic DNA was extracted from saliva samples collected from 50 healthy volunteers in Norway. The oral metagenomic library was then constructed by ligating partially digested oral metagenome into pSMART BAC vector and introducing into Escherichia coli. The library was screened against antimicrobials in dental practices. All resistant clones were selected and analyzed.

Results

Screening of the oral metagenomic library against different antimicrobials detected multiple clones with resistance against chlorhexidine, triclosan, erythromycin, tetracycline, and sodium hypochlorite. Bioinformatic analysis revealed both already known resistance genes, including msr, mef(A), tetAB(46), and fabK, and genes that were not previously described to confer resistance, including recA and accB conferring resistance to sodium hypochlorite and chlorhexidine, respectively.

Conclusion

Multiple clones conferring resistance to antimicrobials commonly used in dental practices were detected, containing known and novel resistant genes by functional-based metagenomics. There is a need for more studies to increase our knowledge in the field.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-02000-5.

Reduced Susceptibility to Biocides among Enterococci from Clinical and Non-Clinical Sources

BACKGROUND

Wide use of biocidal agents such as benzalkonium chloride (BCC) and chlorhexidine digluconate (CHX) in hospitals and non-hospital environments, has raised concerns over the emergence of non-susceptible strains. Efflux pumps are of known main mechanisms in biocide tolerance which have been rarely addressed in enterococci - members of gut microbiota which can cause serious problems particularly in hospitalized patients. The purpose of this study was to investigate the susceptibility of enterococci from different sources (clinical and fecal isolates) toward BCC and CHX, and its correlation with efflux associated genes. Also, possible link between biocide tolerance and antibiotic resistance was examined.

MATERIALS AND METHODS

One hundred and four enterococcus isolates including clinical (n = 54) and fecal isolates (n = 50) were studied for susceptibility toward BCC, CHX, ciprofloxacin, gentamicin and vancomycin. Twelve efflux associated genes were investigated by polymerase chain reaction assay.

RESULTS

In clinical isolates, reduced susceptibility to CHX and resistance to gentamicin and ciprofloxacin were significantly higher than fecal isolates. Vancomycin resistance was associated with increasing minimum inhibitory concentration of CHX. Among all investigated genes, only three ones, efrA, efrB and emeA were detected which were significantly associated with reduced susceptibility to CHX and were more frequent among clinical isolates. Also, high level resistance to gentamicin was significantly associated with the presence of efrA/B as well as with reduced susceptibility to CHX.

CONCLUSION

As expected, reduced susceptibility to CHX, was significantly higher in clinical isolates. However, the presence of a vancomycin-resistant enterococci among fecal isolates of healthy people which showed resistance/tolerance to studied antimicrobial agents, was unexpected and highlights the need to investigate other non-hospital environments to avoid dissemination of antimicrobial resistance. Correlation between reduced susceptibility to CHX and high level resistance to gentamicin, substantiates monitoring of biocide tolerance particularly in the healthcare settings to control the establishment of antimicrobial resistant strains.

In vitro study examining the effectiveness of antiseptic prophylaxis for antibiotic-resistant bacterial endophthalmitis

PURPOSE

To assess the effectiveness of current antiseptic agents on multidrug-resistant (MDR) isolates in an in vitro setting.

SETTING

Department of Microbiology, The National Maternity Hospital, Dublin, Ireland.

DESIGN

Organisms were selected based on current review of endophthalmitis literature: methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant Staphylococcus epidermidis (MRSE), Pseudomonas aeruginosa, carbapenem-resistant and extended-spectrum β-lactamase Klebsiella pneumoniae, and vancomycin-resistant (VRE) Enterococcus faecalis.

METHODS

Samples were exposed to povidone-iodine (PVI) 5% and chlorhexidine (CHX) 0.05% for 0.5 minutes, 1 minute, 3 minutes, and 5 minutes. After inactivation, organisms were incubated under standard conditions and growth assessed after 16 hours.

RESULTS

MRSA and MRSE responded to 3-minute PVI exposure. CHX eradicated MRSA growth after 5 minutes but failed to completely suppress MRSE. Pseudomonas and Klebsiella required 3-minute CHX exposure and 5-minute PVI exposure for complete clearance. Eradication of enterococci (VRE positive and negative) was not achieved at 10 minutes of CHX or PVI exposure. Comparison of PVI vs CHX showed a benefit for PVI in MRSA (P < .01) and MRSE (P < .001) eradication at 3 minutes.

CONCLUSIONS

Current recommendations of 3 minutes of antisepsis prior to intraocular surgery are not sufficient for complete eradication of MDR organisms from the ocular surface. A bespoke approach is suggested to patients at risk for carriage of MDR organisms to minimize the risk of endophthalmitis.

Effectiveness of mouthwash against viruses: 2020 perspective. A systematic review

INTRODUCTION

Antiseptic mouthwash is widely recommended to treat various oral diseases as well as to improve oral health. Most of the dental procedures lead to the generation of aerosols. These aerosols have a high potential to transmit disease. Preprocedural oral rinse with antimicrobial agents in the form of mouthwashes reduces the bacterial and viral load many folds. The purpose of this review was to summarize the effectiveness of mouthwash against viruses affecting human beings.

EVIDENCE ACQUISITION

Search engines like PubMed, Google Scholar, and others were used to search the electronic database. Articles were identified in which the effectiveness of antiseptic mouth rinse against the virus was tested. A comprehensive search strategy was designed to select the articles and then independently screened for eligibility.

EVIDENCE SYNTHESIS

A total of 9624 articles out of the 13 titles met the eligibility criteria. The selected papers were included in the present manuscript according to their relevance to the topic. Authors searched the most used chemicals as mouthwashes but records of three types of mouthwash tested against various types of viruses i.e. chlorhexidine gluconate, Povidone-iodine and essential oil containing mouthwash (Listerine) were found.

CONCLUSIONS

Povidone-iodine mouth rinse is effective in reducing viral load either in-vitro or in-vivo conditions. Chlorhexidine gluconate mouthwash and essential oils have shown its effectiveness in a few studies. Insufficient evidence is available to support the claim that oral antiseptics can reduce the risk of developing viral loads in humans or the rate of progression of diseases caused by viruses.

What Is the Optimal Irrigation Solution in the Management of Periprosthetic Hip and Knee Joint Infections?

BACKGROUND

Thorough irrigation and debridement using an irrigation solution is a well-established treatment for both acute and chronic periprosthetic joint infections (PJIs). In the absence of concrete data, identifying the optimal irrigation agent and protocol remains challenging.

METHODS

A thorough review of the current literature on the various forms of irrigations and their additives was performed to evaluate the efficacy and limitations of each solution as pertaining to pathogen eradication in the treatment of PJI. As there is an overall paucity of high-quality literature comparing irrigation additives to each other and to any control, no meta-analyses could be performed. The literature was therefore summarized in this review article to give readers concise information on current irrigation options and their known risks and benefits.

RESULTS

Antiseptic solutions include povidone-iodine, chlorhexidine gluconate, acetic acid, hydrogen peroxide, sodium hypochlorite, hypochlorous acid, and preformulated commercially available combination solutions. The current literature suggests that intraoperative use of antiseptic irrigants may play a role in treating PJI, but definitive clinical studies comparing antiseptic to no antiseptic irrigation are lacking. Furthermore, no clinical head-to-head comparisons of different antiseptic irrigants have identified an optimal irrigation solution.

CONCLUSION

Further high-quality studies on the optimal irrigation additive and protocol for the management of PJI are warranted to guide future evidence-based decisions.

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.

Review of Pre-Operative Skin Preparation Options Based on Surgical Site in Orthopedic Surgery

Background: Surgical site infections (SSIs) are a primary contributor to surgical morbidity and mortality, causing a substantial financial burden on the healthcare system. Specifically, Cutibacterium acnes contributes greatly to infections in the shoulder and spine regions. Prevention of infection is crucial to improve patient outcomes and reduce costs. This article reviews current surgical skin preparation solutions, the unique distribution of organisms at common orthopedic surgical sites, and recommends solutions based on surgical location. Methods: A search of electronic databases (PubMed, MEDLINE, and Embase) was conducted for relevant literature until December 2020. Sources were compiled based on title and abstract, then full texts were read for possible inclusion. This review summarizes the most recent publications in the field of SSIs and preparation solutions. Results: The mechanism and efficacy of alcohol-, iodine-, and chlorhexidine-based preparations were reviewed, along with experimental preparations. This article identifies common colonization patterns for the shoulder, elbow, hip, knee, spine, foot, and ankle, and discusses recommendations for preparations based on current evidence. Recommendations: For shoulder and elbow operations, we recommend ChloraPrep™ (CareFusion, BD, El Paso, TX), DuraPrep™ (3M Health Care, St. Paul, MN), or Betadine^® applied with 4 × 4 gauze sponge, three-day pre-operative benzyl peroxide, and application of 3% hydrogen peroxide before skin preparation. For the hip and knee, we recommend application of 2% chlorhexidine gluconate (CHG) cloth the night before and morning of surgery and either DuraPrep or iodine-alcohol skin prep prior to surgery. For spine surgeries, we recommended ChloraPrep. For foot and ankle, our recommendations are: ChloraPrep or DuraPrep, submersion of foot in 70% ethanol/10% isopropyl alcohol for five minutes prior to procedure, application with a bristled brush, and a second vigorous scrub with 4 × 4 soaked gauze. Conclusions: The current surgical skin preparations have both benefits and drawbacks. We recommend that orthopedic surgeons choose a skin preparation based on surgical site and prevalence of unique skin flora there.