Chlorhexidine Diacetate Research Articles

The Development of a Biomimetic Model of Bacteria Migration on Indwelling Urinary Catheter Surfaces.

The aim of this study was to develop a novel biomimetic in vitro extraluminal migration model to observe the migration of bacteria along indwelling urinary catheters within the urethra and assess the efficacy of a prototype chlorhexidine diacetate (CHX) coating to prevent this migration. The in vitro urethra model utilised chromogenic agar. A catheter was inserted into each in vitro urethra. One side of the urethra was then inoculated with bacteria to replicate a contaminated urethral meatus. The models were then incubated for 30 days (d), with the migration distance recorded each day. Four indwelling catheter types were used to validate the in vitro urethra model and methodology. Using the biomimetic in vitro urethra model, E. coli and S. aureus migrated the entire length of a control catheter within 24-48 h (h). In the presence of a prototype CHX coating, full migration of the channel was prevented for 30 d. The results of this study support the hypothesis that catheter-associated urinary tract infections (CAUTIs) could be prevented by targeting catheter-mediated extraluminal microbial migration from outside of the urinary tract into the bladder.

Evaluation of biofilm formation and expression of psl, pel, alg genes of Pseudomonas aeruginosa in exposure to detergents.

Pseudomonas aeruginosa has been in the center of attention for several years as an opportunistic human pathogen implicated in many severe acute and chronic infections particularly in immunocompromised patients. Its high persistence and resistance against many antimicrobial agents are mostly attributed to biofilm formation. Biofilms are microbial communities mainly consisting of extracellular polymeric substances that encapsulate bacteria together and protect them from extracellular stresses. This cell aggregation is a stress response that P. aeruginosa employes as a survival strategy during growth with the toxic detergents. This process has shown to involve several operons such as psl, pel, and alg. Here we used P. aeruginosa strain PAO1 in control group, 40 P. aeruginosa strains from sink and 40 strains from surface of public places. Biofilm formation and gene expression were measured before and after exposure to sub minimum inhibitory concentration (sub-MIC) of biocides chlorhexidine diacetate and benzalkonium chloride. The qRT-PCR and biofilm formation results demonstrated an increase in biofilm formation ability and gene expression of pslA/B and pelA/B in two groups collected from sinkand surface in contrast to the control group. A remarkable increase was observed in the biofilm formation and expression of pslA in the bacterial strain collected from the sink after exposure tobiocides chlorhexidine diacetate. Both Pel and Psl appeared to have redundant functions as structuralscaffolds in biofilms. Sub-MIC levels of detergents can improve biofilm formation ability of P.aeruginosa and therefore trigger resistance.

Cell death of Acanthamoeba castellanii following exposure to antimicrobial agents commonly included in contact lens disinfecting solutions.

Several antimicrobial agents are commonly included in contact lens disinfectant solutions including chlorhexidine diacetate (CHX), polyhexamethylene biguanide (PHMB) or myristamidopropyl dimethylamine (MAPD); however, their mode of action, i.e. necrosis versus apoptosis is incompletely understood. Here, we determined whether a mechanism of cell death resembling that of apoptosis was present in Acanthamoeba castellanii of the T4 genotype (NEFF) following exposure to the aforementioned antimicrobials using the anticoagulant annexin V that undergoes rapid high affinity binding to phosphatidylserine in the presence of calcium, making it a sensitive probe for phosphatidylserine exposure. The results revealed that under the conditions employed in this study, an apoptotic pathway of cell death in this organism at the tested conditions does not occur. Our findings suggest that necrosis is the likely mode of action; however, future mechanistic studies should be accomplished in additional experimental conditions to further comprehend the molecular mechanisms of cell death in Acanthamoeba.

LDPE/PCL nanofibers embedded chlorhexidine diacetate for potential antimicrobial applications

In this study, we described the process of developing antimicrobial nanofibers using a solution-based electrospinning technique. The nanofibers were composed of a 40:60 blend of low-density polyethylene (LDPE) and polycaprolactone (PCL), loaded with chlorhexidine diacetate (CHD).The diameter of the nanofibers was measured for LDPCL (235 nm), but it changed to 148, 194, and 325 nm for LDPCL-CHD 1%, 3%, and 5%, respectively. The hydrophilic properties of the nanofibers were significantly improved by incorporating CHD. Also, the contact angle was reduced from 116 ± 5° to 37 ± 2°. The CHD was released from the nanofibers by an initial immediate release and then by extended-release. The released CHD from the nanofibers was found to effectively reduce the formation of biofilms when exposed to microorganisms such as S. aureus and E. coli compared to the control group (LDPCL). The drug-loaded nanofibers were found to be non-cytotoxic when incubated with L929 fibroblast cells for the duration of 24 and 72 h. The study findings suggest that antimicrobial nanofibers have potential applications in preventing implant-related infections caused by (S. aureus and E. coli).

The Antibacterial and Antifungal Activity of Chlorhexidine Diacetate Incorporated into Acrylic Resins Used in Provisional Restorations.

The surface of provisional restorations applied before conventional or implant- supported fixed restorations may cause bacterial or fungal biofilm formation. The aim of this study was to evaluate the antimicrobial activity of acrylic resins used in provisional restorations modified with chlorhexidine diacetate. 120 cylindrical, auto-polymerized resin samples modified with chlorhexidine diacetate were prepared at concentrations of 0 (control), 1, 3, 5 wt %. The antimicrobial activity was examined against Streptococcus mutans, Enterococcus faecalis, and Candida albicans using Crystal Violet quantification, MTT assay, and Scanning Electron Microscopy. Data were analyzed by ANOVA and paired sample t-tests (α=0.05). The addition of chlorhexidine diacetate influenced the growth rate and metabolic activity of microorganisms. The antimicrobial effect against C. albicans and S. mutans statistically increased with the percentage of chlorhexidine diacetate. E. faecalis bacteria were less affected by chlorhexidine diacetate compared to other pathogens. It has been shown that the effectiveness of CHDA in inhibiting the proliferation of microorganisms correlated positively with increasing concentration levels. More research is needed to confirm the impact of different chlorhexidine concentrations on the mechanical properties, clinical efficacy, and antimicrobial properties of CDHA.

Antibacterial and Biocompatible Polyethylene Composites with Hybrid Clay Nanofillers.

Low-density polyethylene is one of the basic polymers used in medicine for a variety of purposes; so, the relevant improvements in functional properties are discussed here, making it safer to use as devices or implants during surgery or injury. The objective of the laboratory-prepared material was to study the antimicrobial and biocompatible properties of low-density polyethylene composites with 3 wt. % hybrid nanoclay filler. We found that the antimicrobial activity was mainly related to the filler, i.e., the hybrid type, where inorganic clay minerals, vermiculite or montmorillonite, were intercalated with organic chlorhexidine diacetate and subsequently decorated with Ca-deficient hydroxyapatite. After fusion of the hybrid nanofiller with polyethylene, intense exfoliation of the clay layers occurred. This phenomenon was confirmed by the analysis of the X-ray diffraction patterns of the composite, where the original basal peak of the clays decreased or completely disappeared, and the optimal distribution of the filler was observed using the transmission mode of light microscopy. Functional property testing showed that the composites have good antibacterial activity against Staphylococcus aureus, and the biocompatibility prediction demonstrated the formation of Ca- and P-containing particles through an in vitro experiment, thus applicable for medical use.

Effectiveness of chlorhexidine diacetate and povidone-iodine in antiseptic preparation of the canine external ear canal prior to total ear canal ablation with bulla osteotomy procedure: A preliminary study.

This article is a preliminary study to compare the ability of 0.05% chlorhexidine diacetate (CD) and 1% povidone-iodine (PI) solutions to reduce bacterial contamination on the canine external ear canal during initial patient preparation and comparison of the incidence of immediate tissue reactions. The study is a multi-institutional, randomised, clinical prospective study. Dogs (n = 19) undergoing total ear canal ablation with bulla osteotomy (TECABO). The external ear of each dog was cleaned with the assigned antiseptic solution. Culture of the ear was performed by standard techniques to semi-quantitatively evaluate bacterial growth and to identify bacterial organisms pre- and post-antiseptic use. Both antiseptic groups showed a significant reduction in bacterial growth score (BGS) between pre- and post-antiseptic use (CD p = 0.009, PI p = 0.005). There was no difference in the reduction of BGS between CD and PI solutions (p = 0.53). Minor adverse skin reactions occurred in 25% of cases. There was no significant difference in the occurrence of adverse skin reactions between antiseptics (p = 0.63). CD and PI were similarly able to decrease the number of bacteria on the external ear following initial preparation. No difference in the incidence of adverse tissue reactions was found. Properly diluted aqueous formulations of either antiseptic may be used for safe preparation limited to the external ear canal of dogs. Additional studies evaluating outcomes such as duration of bacterial inhibition and incidence of surgical site infections are needed to fully elucidate differences between CD and PI antiseptics prior to TECABO.

Effects of thyme on halitosis in gingivitis patients: Can thyme mouthwash prevent halitosis-A randomized trial.

Bad breath is a condition that negatively affects people's social interactions and quality of life. The aim of this study was to evaluate the effect of thyme mouthwash on intraoral halitosis, gingival index (GI) and plaque index (PI) in patients with gingivitis. In this retrospective study, 60 gingivitis patients (30 women/30 men) received initial periodontal treatment followed by oral hygiene instructions (OHI) and then were divided into four groups: The control group (C) received only OHI, while chlorhexidine (CHX) mouthwash was prescribed to the CHX group, Zinc acetate and CHX diacetate mouthwash was prescribed to the zinc acetate and CHX diacetate (ZnA) group, and the thyme (T) group was instructed to use thyme mouthwash. GI, PI and volatile sulfur compound (VSC) values were recorded at baseline and at the first week of treatment. The initial values of the recorded parameters did not differ significantly between the groups. In all groups, VSCs, GI and PI decreased after treatment (p=0.001). There was no significant difference between the PI values of the groups after treatment (p=0.188). On the contrary, the GI and VSC values after treatment were significantly different between the groups (p=0.001). GI values were highest in the control group and lowest in the CHX group. In terms of VSCs, a significant difference was found between groups T and C, and between groups T and ZnA (p=0.001). This study showed that the use of thyme mouthwash after periodontal treatment was effective in improving bad breath and gingivitis in gingivitis patients.

Resilient liner modified by antimicrobials for denture stomatitis treatment: A randomized controlled trial

ObjectivesThis randomized clinical trial evaluated the effectiveness of an interim denture resilient liner (Trusoft) modified with minimum inhibitory concentrations (MICs) of antimicrobial agents for Candida albicans biofilm in the denture stomatitis (DS) treatment. MethodsForty participants with DS and maxillary complete denture (MCD) wearers were randomly assigned to one of the treatments for 14 days (n=10): nystatin oral suspension (Control-100,000IU/mL; 4 × /day), MCD relined with Trusoft either without (Tru) or with nystatin (Ny) or chlorhexidine diacetate (Chx) at MICs. Cytological smears and mycological quantitative cultures were taken from the palate and denture before treatment (baseline), at the end of treatment (day 14), and at follow-up (days 30, 45, and 60). Photographs of the palate were made at each visit. Data were analyzed by the Cochran and χ2 tests, ANOVA and the Tukey test or the Friedman and Kruskal-Wallis tests (α=0.05). ResultsPalatal smears of the Ny and Chx groups exhibited no mycelial Candida (0%) on day 14, and, at the 60-day follow-up, it was observed for only 1 participant from Chx group. MCD smears showed reduction in mycelial forms for all groups on day 14 (P<0.05), but this difference was maintained at follow-up only for the relined dentures (P<0.05). Unlike Tru and the control groups, Ny and Chx groups evidenced a significant reduction in CFU/mL values and DS severity throughout the trial (P<0.05). ConclusionsThe addition of nystatin and chlorhexidine at MICs to an interim resilient liner is a promising treatment for DS, with better results than those for conventional therapy with nystatin suspension, including the follow-ups. Clinical significanceCompared with conventional topical antifungal therapy, modifying a denture reline material with antimicrobials provided a therapeutic option for denture stomatitis. This non-invasive, straightforward therapeutic approach can be easily adopted by dentists and has the advantage of not requiring patient compliance while maintaining therapeutic concentrations on the denture base.

Profile of MDP-chlorhexidine for universal dentin bonding systems: A calcium-competition interference?

10-methacryloyloxy-decyl-dihydrogen phosphate (10-MDP) mostly changed the bonding concept by chemically interacting with hydroxyapatite. Currently, multimode simplified universal dentin bonding systems (UDBSs) contains 10-MDP, and its use in etch-and rinse mode renewed the concern on the employment of antienzymatic agents as chlorhexidine (CHX). This study aimed to investigate the effect of MDP-CHX interaction on bonding properties. The following DBSs were tested: MP-Adper Scotchbond Multipurpose, SU-Adper Scothbond Universal, CSE-Clearfil SE Bond, and CPB–Clearfill Protect Bond. The degree of conversion (DC) was assessed by a drop of each DBS (≈3.0 μL, n = 3) combined with chlorhexidine diacetate (0, 0.2, and 2%) and hydroxyapatite (HAP) (0, 0.1%) using Fourier Transform Infrared Spectroscopy (FTIR). Bond strength (BS) was tested using 144 human third molars, randomized according to DBS/CHX groups (n = 12), and submitted to the microtensile test (μTBS) at 24-h, 6-month, and 12-month periods. Failure mode of interfaces, FTIR profile, and Scanning Electronic Microscopy (SEM) were assessed. DC and BS data were statistically analyzed by three-way and Repeated Measures ANOVA followed by Tukey tests (p < 0.05). Results: CHX decreased DC values of MDP-based systems, while HAP/CHX recovered DC values compared with control. CHX reduced BS values for CSE (MDP-based), while improved BS values for MP (MDP-free). MDP-based system associated particularly with 2% CHX should be avoided even for multimode simplified DBS, as both ingredients may compete for calcium, reducing their benefits.

Cover Image

The cover image is based on the Research Article Prevention ofmedical device infections viamulti-action nitric oxide and chlorhexidine diacetate releasing medical grade silicone biointerfaces by ElizabethBrisbois et al., https://doi.org/10.1002/jbm.a.37372.

Assembly and Functional Role of PACE Transporter PA2880 from Pseudomonas aeruginosa.

ABSTRACTThe recently identified proteobacterial antimicrobial compound efflux (PACE) transporters are multidrug transporters energized by the electrochemical gradient of protons. Here, we present the results of phylogenetic and functional studies on the PACE family transporter PA2880 from Pseudomonas aeruginosa. A phylogenetic analysis of the PACE family revealed that PA2880 and AceI from Acinetobacter baumannii are classified into evolutionarily distinct clades, although they both transport chlorhexidine. We demonstrate that PA2880 mainly exists as a dimer in solution, which is independent of pH, and its dimeric state is essential for its proper function. Electrogenicity studies revealed that the chlorhexidine/H+ antiport process is electrogenic. The function of several highly conserved residues was investigated. These findings provide further insights into the functional features of PACE family transporters, facilitating studies on their transport mechanisms.IMPORTANCE Pseudomonas aeruginosa is a pathogen that causes hospital-acquired (nosocomial) infections, such as ventilator-associated pneumonia and sepsis syndromes. Chlorhexidine diacetate is a disinfectant used for bacterial control in various environments potentially harboring P. aeruginosa. Therefore, investigation of the mechanism of the efflux of chlorhexidine mediated by PA2880, a PACE family transporter from P. aeruginosa, is of significance to combat bacterial infections. This study improves our understanding of the transport mechanism of PACE family transporters and will facilitate the effective utilization of chlorhexidine for P. aeruginosa control.

Prevention of medical device infections via multi-action nitric oxide and chlorhexidine diacetate releasing medical grade silicone biointerfaces.

The presence of bacteria and biofilm on medical device surfaces has been linked to serious infections, increased health care costs, and failure of medical devices. Therefore, antimicrobial biointerfaces and medical devices that can thwart microbial attachment and biofilm formation are urgently needed. Both nitric oxide (NO) and chlorhexidine diacetate (CHXD) possess broad-spectrum antibacterial properties. In the past, individual polymer release systems of CHXD and NO donor S-nitroso-N-acetylpenicillamine (SNAP) incorporated polymer platforms have attracted considerable attention for biomedical/therapeutic applications. However, the combination of the two surfaces has not yet been explored. Herein, the synergy of NO and CHXD was evaluated to create an antimicrobial medical-grade silicone rubber. The 10wt% SNAP films were fabricated using solvent casting with a topcoat of CHXD (1, 3, and 5wt%) to generate a dual-active antibacterial interface. Chemiluminescence studies confirmed the NO release from SNAP-CHXD films at physiologically relevant levels (0.5-4× 10-10 mol min-1 cm-2 ) for at least 3 weeks and CHXD release for at least 7 days. Further characterization of the films via SEM-EDS confirmed uniform distribution of SNAP and presence of CHXD within the polymer films without substantial morphological changes, as confirmed by contact angle hysteresis. Moreover, the dual-active SNAP-CHXD films were able to significantly reduce Escherichia coli and Staphylococcus aureus bacteria (>3-log reduction) compared to controls with no explicit toxicity towards mouse fibroblast cells. The synergy between the two potent antimicrobial agents will help combat bacterial contamination on biointerfaces and enhance the longevity of medical devices.

Chlorhexidine versus organoselenium for inhibition of S. mutans biofilm, an in vitro study

BackgroundChemical Plaque control by antimicrobial agent application can defend the teeth against caries. S. mutans is considered the main etiologic factor for caries. This was an in vitro study to compare between the efficacy of chlorhexidine diaceteate varnish, and an organoselenium sealant, to prevent S. mutans biofilm formation on human teeth.MethodsFourty five premolars extracted for orthodontic purposes were randomly divided into 3 groups of 15 teeth each. One control group and two test groups, chlorhexidine diaceteate varnish and an organoselenium sealant. The teeth were autoclaved before S. mutans biofilm was induced on to each in their respective groups. The reading T1 was taken for each tooth to assess the number of S. mutans attached in order to compare for differences in surface area among the 3 groups. The respective test materials were applied onto the teeth and biofilm induced onto them in their respective groups. The reading T2 was taken for the 2 test groups. The 3 groups were then subjected to aging for a period equivalent to 5 months before the biofilm was induced to take the reading T3 for the number of S. mutans. We used vortexing of the teeth to disrupt the biofilm at time points T1, T2 and T3. S. mutans count was then done using PCR.ResultsThere were significantly lower S. mutans counts in the control group as compared to the chlorhexidine diacetate group at T3.There were no other statistically significant differences found.ConclusionBoth organoselenium and Chlorhexidine diacetate do not inhibit S. mutans biofilm attachment onto the teeth.

Antimicrobial Efficacy of Glass Ionomer Cement in Incorporation with Biogenic Zingiber officinale Capped Silver-Nanobiotic, Chlorhexidine Diacetate and Lyophilized Miswak.

In the present study, Zingiber officinale is used for the synthesis of Zingiber officinale capped silver nanoparticles (ZOE-AgNPs) and compares the antimicrobial efficacy and compressive strength of conventional glass ionomer cement (GIC) combined with ZOE-AgNPs, lyophilized miswak, and chlorhexidine diacetate (CHX) against oral microbes. Five groups of the disc-shaped GIC specimens were prepared. Group A: lyophilized miswak and GIC combination, Group B: ZOE-AgNPs and GIC combinations, Group C: CHX and GIC combination, Group D: ZOE-AgNPs + CHX + GIC; Group E: Conventional GIC. Results confirmed the successful formation of ZOE-AgNPs that was monitored by UV-Vis sharp absorption spectra at 415 nm. The X-ray diffractometer (XRD) and transmission electron microscope (TEM) results revealed the formation of ZOE-AgNPs with a mean size 10.5–14.12 nm. The peaks of the Fourier transform infrared spectroscopy (FTIR) were appearing the involvement of ZOE components onto the surface of ZOE-AgNPs which played as bioreducing, and stabilizing agents. At a 24-h, one-week and three-week intervals, Group D showed the significantly highest mean inhibitory zones compared to Group A, Group B, and Group C. At microbe-level comparison, Streptococcus mutans and Staphylococcus aureus were inhibited significantly by all the specimens tested except group E when compared to Candida albicans. Group D specimens showed slightly higher (45.8 ± 5.4) mean compressive strength in comparison with other groups. The combination of GIC with ZOE-AgNPs and chlorhexidine together enhanced its antimicrobial efficacy and compressive strength compared to GIC with ZOE-AgNPs or lyophilized miswak or chlorhexidine combination alone. The present study revealed that The combination of GIC with active components of ZOE-AgNPs and chlorhexidine paves the way to lead its effective nano-dental materials applications.

Antimicrobial agents in dental restorative materials: Effect on long-term drug release and material properties.

The present study reports on the long-term drug release and mechanical properties of bioactive dental filling materials based on chlorhexidine diacetate (CHX) or octinidine (di)hydrochloride (ODH) incorporated in a composite based on dimethacrylates or an ormocer. CHX or ODH were added to a nano-hybrid ormocer (O) and a nano-hybrid composite (C) with the amount of 2wt% to achieve four matrix-drug combinations: O-CHX, O-ODH, C-CHX, and C-ODH. Drug extraction and release were measured using high-performance liquid chromatography with diode-array detection (HPLC-DAD), while drug distribution was assessed by using energy dispersive X-ray spectroscopy (EDX). Drug release in water at 37°C was observed over 87 d. To determine the material properties, the water absorption, water solubility, flexural strength and hardness were measured and compared to the reference materials. Persistent drug release over 87 d was observed for both ODH-based systems and both ormocer-systems, with the longest duration of activity seen for the O-ODH combination. Persistent drug release was achieved via the loosening of the polymer network indicated via decreasing polymerization enthalpies, enhanced water absorption, and water solubility. As a consequence, the flexural strengths of the materials were reduced. However, surface hardness was hardly reduced. ODH seems to be more adequate than CHX for the design of bioactive dental filling materials based on nano-hybrid ormocer and composites.

Antimicrobial agents in dental restorative materials: Effect on polymerization, short-term drug release and biological impact.

With the aim to design bioactive dental restorative material, the present study investigated the influence of the antimicrobial agents chlorhexidine diacetate (CHX) and octinidine (di)hydrochloride (ODH) when incorporated in two different materials. Selected parameters were polymerization enthalpy, short-term drug release, and the effect on Streptococcus mutans as well as human gingival fibroblasts. Samples were made by mixing a nano-hybrid ormocer (O) and a methacrylate-based nano-hybrid composite (C), each with a mass fraction of 2% CHX or ODH. Release profiles and concentrations of active agents from the resins were assessed, and the cell proliferation of human gingival fibroblasts as well as Streptococcus mutans cultured with the eluates were evaluated. The influence on polymerization was assessed by means of differential scanning calorimetry. Both drugs, especially ODH, showed a decreasing effect on polymerization enthalpies associated with a lowered crosslinking degree. At the same time ODH appeared to be released more persistently than CHX. Moreover, ODH was more efficient with regard to bacteria growth inhibition but also more cytotoxic in terms of reduction of cell viability. ODH is deemed more appropriate for application in a dental resin-based drug delivery system, because of the more persistent drug release than seen for CHX.

Influence of Cavity Size on the Survival of Single Surface Atraumatic Restorative Treatment Using Glass Ionomer Cement with or without Chlorhexidine Diacetate—A Randomized Trial

The purpose of the present study was to assess the influence of cavity size on the survival of conventional and CHX modified GIC in single surface primary molars receiving Atraumatic Restorative Treatment (ART). A randomized controlled trial with a split-mouth design was conducted on 90 children with symmetrical bilateral single surface carious lesions on primary molars. The teeth were randomly allotted to the conventional GIC group (group 1, n = 90) and CHX modified GIC group (group 2, n = 90). Both groups received atraumatic restorative treatment under rubber dam isolation. The cavity size was measured in terms of depth, mesiodistal, and buccolingual dimensions. The survival of ART restorations was measured after 6, 12, 18, and 24 months. The difference in proportion was tested using the Kruskal–Wallis H test, and survival curve estimation was carried out using the Kaplan–Meier method. The overall survival of all ART restorations was 83.3% at 24 months for the total sample. The survival of conventional GIC at 24 months was 83.9%, and for CHX-modified GIC was 82.7% (p &gt; 0.05). The collective overall success of 65.1% was seen in the cavity volume category of 10–29.9 mm3. CHX modified GIC showed high survival percentage (60%) with depth &gt;3 mm. To conclude, no significant difference was observed in the overall survival percentage of conventional and CHX modified GIC. Survival percentage was highest for cavities with a volume of 10–19.9 mm3.

Synthesis, Drug Release, and Antibacterial Properties of Novel Dendritic CHX-SrCl2 and CHX-ZnCl2 Particles.

This work demonstrated for the first time the synthesis of novel chlorhexidine particles containing strontium and zinc, to provide an effective, affordable, and safe intervention in the treatment of recurrent infections found in Medicine and Dentistry. The CHX-SrCl2 and CHX-ZnCl2 particles were synthesized by co-precipitation of chlorhexidine diacetate (CHXD) and zinc chloride or strontium chloride, where particle size was manipulated by controlling processing time and temperature. The CHX-ZnCl2 and CHX-SrCl2 particles were characterized using SEM, FTIR, and XRD. UV-Vis using artificial saliva (pH 4 and pH 7) was used to measure the drug release and ICP-OES ion release. The antibacterial properties were examined against P. gingivalis, A. actinomycetemcomitans, and F. nucleatum subsp. Polymorphum, and cytotoxicity was evaluated using mouse fibroblast L929 cells. The novel particles were as safe as commercial CHXD, with antibacterial activity against a range of oral pathogens. UV-Vis results run in artificial saliva (pH 4 and pH 7) indicated a higher release rate in acidic rather than neutral conditions. The CHX-ZnCl2 particles provided the functionality of a smart Zinc and CHX release, with respect to environmental pH, allowing responsive antibacterial applications in the field of medicine and dentistry.

Effect of topical medication on the nasomaxillary skin-fold microbiome in French bulldogs.

Host-microbe interactions may influence dermatitis pathogenesis in the nasomaxillary folds of French bulldogs, which is often complicated by secondary bacterial and fungal infections. To assess the skin-fold microbiome in systemically healthy French bulldogs and to determine the influence of topical medications on this microbiome. Nineteen healthy French bulldogs. Next-generation DNA sequencing was applied to characterise the microbiome composition in the nasomaxillary folds of systemically healthy French bulldogs. Subsequently, the effect of two topical products on the fold microbiome was assessed. Seven dogs were treated with a protease product (Kalzyme; enzyme) that inhibits biofilm formation without biocidal activity, six dogs were treated with a 2% chlorhexidine diacetate solution (Nolvasan; CHX) with biocidal activity, and six dogs were untreated. Dogs were randomly assigned to each group, and the investigator was blinded. The primary skin bacterial phyla inhabiting the folds at inclusion were Firmicutes, Actinobacteria and Proteobacteria. The primary skin fungal phyla were Ascomycota and Basidiomycota. Topical treatment increased the diversity of bacterial and fungal compositions over time (increase in microbial diversity score: enzyme 38%, chlorhexidine 11%, control <5%) and the relative abundance of pathogens reduced significantly (enzyme, P = 0.028; CHX, P = 0.048). A clear correlation (r2 = 0.83) was observed between the abundance of clinically relevant pathogens and microbial diversity. The nasomaxillary skin-fold microbiome of healthy French bulldogs contained a high abundance of clinically relevant pathogens (mean 36.4%). Topical therapy with enzyme increased microbial diversity of skin folds and reduced the relative abundance of pathogens.