Concentrations Of Chlorhexidine Research Articles

Assessment of antimicrobial activity of bioflavonoid CITROX and chlorhexidine combination against P. gingivalis (in vitro)

The aim of the study - evaluation of the antiseptic properties of the combination of chlorhexidine and bioflavonoid CITROX against P. gingivalis. Clinical isolates of microbial cultures from the collection of the Department of Microbiology, Immunology, Virology of the Moscow State Medical University named after A.I. Evdokimov: P. gingivalis. Primary seeding of the studied material was carried out on nutrient media produced by Himedia Laboratories Pvt. Limited (India): Colombian agar with the addition of 5% defibrinated blood and a selective additive for the isolation of non-spore anaerobes. To conduct the experiment, a thermostatic rotary system - RTS-1 (Biosan, Latvia) was used, which performs a modern type of mixing due to the formation of a vortex-type diffusing effect. The interpretation of the results was carried out by changing the optical density index (the indicator in McFarland units) at a wavelength of λ = 850 nm. The combination of CITROX + chlorhexidine 0.05% more effectively suppresses the growth of periodotopathogenic bacteria than chlorhexidine 0.05%, prolonging the adaptive phase (lag phase) of the growth of P.gingivalis bacteria and can be considered as an alternative to chlorhexidine without additives. Prolongation of the lag phase increases the time until the first clinical symptoms appear, as a result, the body has more time to form an immune response. The combination of the complex of bioflavonoids CITROX and chlorhexidine bigluconate in concentrations of 0.05% and 0.2% is active against P. gingivalis and can be considered as an alternative to chlorhexidine without additives. The inclusion of CITROX in the rinse aid reduces the concentration of chlorhexidine in the rinse aid, which can lead to a decrease in the severity of undesirable effects and be considered as an alternative remedy in the treatment of periodontal diseases.

Assessment of Self Disinfecting Capacity and Dimensional Stability of Irreversible Hydrocolloid Impression Material Mixed With Different Concentrations of Chlorhexidine Solution-An Invitro Study

Introduction: Impression materials are used to record the anatomical topography of oral tissues. Irreversible hydrocolloid is an impression material routinely used in dentistry. However, it retains bacteria, 2 to 3 times higher than other impression material. Spraying and immersion technique has been employed for disinfection of irreversible hydrocolloid with varying degree of success. Thus the need of impression material that has self-disinfecting capacity seems to be very important to have infection control in dentistry. Materials and Methods: This invitro study was done in two parts. Assessment of self-disinfecting capacity of irreversible hydrocolloid impression material mixed with different concentrations of chlorhexidine solution and dimensional stability of irreversible hydrocolloid impression material mixed with different concentrations of chlorhexidine solution. For assessment of self-disinfecting capacity, irreversible hydrocolloid was mixed with various concentrations of chlorhexidine (0.05%, 0.1%, 0.2%) and distilled water. Total 64 culture plates were prepared, n=16 for each group of microorganisms (E. coli, S. aureus, Pseudomonas, Klebsiella). Inhibition zones were measured for each microorganism. For dimensional stability, the specimens were divided into four groups similar to specimen for self-disinfecting ability. Total 56 samples were prepared, n=14 for each group. Interpretation (IP), Mesiodistal (MD), Buccolingual (BL), Occlusogingival (OG) dimensions were measured by digital Vernier caliper. One-way analysis of variance was done for assessment of self-disinfecting capacity and for dimensional stability. Dunnett comparison test was performed to test the significance between test and control. P value was calculated under the predetermined level of significance (0.05). Results: Zones of inhibition were observed around test specimens (groups 0.05, 0.1, 0.2), but not around control specimen (Group d/w). There was a significant difference in the mean diameters of the inhibition zones between test groups and control which was statistically highly significant (p < 0.001). In the test for dimensional stability, no significant differences were detected among groups for all the measured dimensions (p> 0.05). Conclusion: Irreversible hydrocolloid impression material mixed with chlorhexidine exhibits varying degrees of self-disinfecting activity without influencing the dimensional stability of set material.

Effect of chlorhexidine cleansing on healthcare-associated infections in neonates: a systematic review and meta-analysis

BackgroundHealthcare-associated infections (HAIs) have a significant impact on neonatal morbidity, mortality and long-term prognosis, which have a high incidence in neonates. Many studies have shown that chlorhexidine cleansing is effective...

Sub-Inhibitory Concentrations of Chlorhexidine Induce Resistance to Chlorhexidine and Decrease Antibiotic Susceptibility in Neisseria gonorrhoeae.

Objectives: Chlorhexidine digluconate (chlorhexidine) and Listerine® mouthwashes are being promoted as alternative treatment options to prevent the emergence of antimicrobial resistance in Neisseria gonorrhoeae. We performed in vitro challenge experiments to assess induction and evolution of resistance to these two mouthwashes and potential cross-resistance to other antimicrobials.Methods: A customized morbidostat was used to subject N. gonorrhoeae reference strain WHO-F to dynamically sustained Listerine® or chlorhexidine pressure for 18 days and 40 days, respectively. Cultures were sampled twice a week and minimal inhibitory concentrations (MICs) of Listerine®, chlorhexidine, ceftriaxone, ciprofloxacin, cefixime and azithromycin were determined using the agar dilution method. Isolates with an increased MIC for Listerine® or chlorhexidine were subjected to whole genome sequencing to track the evolution of resistance.Results: We were unable to increase MICs for Listerine®. Three out of five cultures developed a 10-fold increase in chlorhexidine MIC within 40 days compared to baseline (from 2 to 20 mg/L). Increases in chlorhexidine MIC were positively associated with increases in the MICs of azithromycin and ciprofloxacin. Low-to-higher-level chlorhexidine resistance (2–20 mg/L) was associated with mutations in NorM. Higher-level resistance (20 mg/L) was temporally associated with mutations upstream of the MtrCDE efflux pump repressor (mtrR) and the mlaA gene, part of the maintenance of lipid asymmetry (Mla) system.Conclusion: Exposure to sub-lethal chlorhexidine concentrations may not only enhance resistance to chlorhexidine itself but also cross-resistance to other antibiotics in N. gonorrhoeae. This raises concern regarding the widespread use of chlorhexidine as an oral antiseptic, for example in the field of dentistry.

Minimum inhibitory concentrations of chlorhexidine- and lactic acid-based teat disinfectants: An intervention trial assessing bacterial selection and susceptibility

Teat disinfection is a recommended preventive tool to improve udder health and to prevent new intramammary infections. However, side effects are discussed, such as bacterial selection of less-susceptible bacteria with the application of certain teat disinfectants. The objective of this study was to assess the species composition and bacterial in vitro susceptibility by means of an interventive trial. For this purpose, 3 different postmilking teat treatments (disinfection with 0.215% chlorhexidine or 3.5% lactic acid, or control group with no dipping) were applied to 28 cows in a 6-d intervention approach using a split-udder design. Milk samples were taken before and after intervention. Bacteria were cultured and differentiated to species or genus level by MALDI-TOF mass spectrometry. Minimum inhibitory concentrations (MIC) were determined, and MIC changes over time were recorded. Susceptibilities to chlorhexidine and lactic acid were compared between species of the genera Staphylococcus, Streptococcus, Corynebacterium, and others. Species composition changed during the intervention. Under the treatment of chlorhexidine and lactic acid, the proportion of coagulase-negative staphylococci (CNS) decreased. An increased proportion of species belonging to the genus Corynebacterium was observed especially under the application of lactic acid. Although both teat disinfectants were basically effective, isolates differed in their susceptibility to both teat disinfectants. Populations of CNS, Staphylococcus aureus, and Corynebacterium spp. showed significantly lower absolute MIC values for chlorhexidine. Compared with other species, Corynebacterium spp. showed the lowest susceptibility for chlorhexidine as well as for lactic acid. A significant increase in MIC values after 6 d of intervention was observed with the lactic acid treatment in all isolates, as well as in CNS. This increase can be interpreted as either adaptation of isolates or displacement of more-susceptible species by less-susceptible species. Further studies using long-term intervention might reveal more pronounced effects on MIC values and species composition.

The effect of different concentrations of chlorhexidine on microbial colonization: A double-blinded randomized controlled study.

Study aims were to determine the most effective chlorhexidine concentration to be used in reducing microbial colonization in patients under mechanical ventilation and to examine the effect of oral care using different concentrations on the integrity of the oral mucous membranes. This research was a randomized controlled double-blinded experimental study. The sample of study consisted of the 116 adult patients who remained intubated. Oral care was given to patients 4 times/day as per nurse protocol. Every morning during for 4 days, the intraoral mucosa of all groups of patients was assessed. Microbial colonization samples from oral mucosa were taken in the morning before oral care. A determination of the species of microorganisms in these samples was made. A statistically significant difference was found with regard to the reproduction of microorganisms between the oral mucosa samples taken from patients using 2% and 1% chlorhexidine solutions (P < 0.001). In the cultures taken from patients on the first and fourth days of intubation, a total of 36 different microorganisms were seen to be reproducing. It was concluded that the most effective oral solution for the prevention of microbial colonization in patients under mechanical ventilation was chlorhexidine 1%.

Differences in chlorhexidine mouthrinses formulations influence the quantitative and qualitative changes in in-vitro oral biofilms.

Chlorhexidine mouthrinses are marketed in different formulations. This study aimed at investigating qualitative and quantitative changes in in-vitro multispecies oral biofilms, induced by different chlorhexidine-containing mouthrinses. Earlier studies comparing chlorhexidine mouthrinses are either clinical studies or in-vitro studies assessing the antimicrobial efficacy of the mouthrinses. However, no clear investigations are available regarding ecological impact of different chlorhexidine formulations on in-vitro multispecies oral biofilms after rinsing with different chlorhexidine formulations. Nine commercially available chlorhexidine mouthrinses were selected. Multispecies oral communities (14species) were grown for 48h in a Biostat-B Twin bioreactor. After that, they were used to develop biofilms on the surface of hydroxyapatite disks in 24-well pates for 48h. Biofilms were then rinsed once or multiple times with the corresponding mouthrinse. Biofilms were collected before starting the rinsing experiment and every 24h for 3days and vitality quantitative PCR was performed. The experiment was repeated 3 independent times on 3 different days and the results were analyzed using a linear mixed model. The mouthrinses provoked different effects in terms of change in total viable bacterial load (VBL), ecology, and community structure of the multispecies biofilms. There was no relation between chlorhexidine concentrations, presence, or absence of cetylpyridinium chloride and/or alcohol, and the observed effects. Some tested chlorhexidine mouthrinses (MC, HG, HH, and HI) strongly lowered the total VBL (≈1007 Geq/ml), but disrupted biofilm symbiosis (≥40% of the biofilms communities are pathobionts). On the other hand, other tested chlorhexidine mouthrinses (MD, ME, and HF) had limited impact on total VBL (≥1010 Geq/ml), but improved the biofilm ecology and community structure (≤10% of the biofilms communities are pathobionts). Not all chlorhexidine mouthrinses have the same effect on oral biofilms. Their effect seems to be strongly product dependent and vary according to their compositions and formulations.

Low Concentrations of Chlorhexidine Inhibit the Formation and Structural Integrity of Enzyme-Treated Multispecies Oral Biofilms

The self-produced matrix of biofilms, consisting of extracellular polymeric substances, plays an important role in biofilm adhesion to surfaces and the structural integrity of biofilms. In dentistry, biofilms cause multiple diseases such as caries, periodontitis, and pulpitis. Disruption of these biofilms adhering to dental hard tissues may pose a major challenge since biofilms show higher tolerance to antimicrobials and antibiotics than planktonic cells. In this study, the effect of low concentrations of chlorhexidine (CHX) on enzyme-treated multispecies oral biofilm was investigated in an in vitro model. Six-species biofilms were enzymatically treated by anaerobic growth in a medium containing DNase I and proteinase K. Biofilms were exposed to a low concentration of CHX at defined time points. After 64h, biofilms were either harvested and quantified by cultural analyses or stained for confocal laser scanning microscopy (CLSM) analyses using either Live/Dead kit or different fluorescent dyes. A mixture of YoPro1 and SYTOX™ Green, Fluorescent Brightener 28 (Calcofluor), and SYPRO™ Ruby Protein Gel Stain was used to stain total DNA, exopolysaccharides, and extracellular proteins, respectively. Extracellular DNA (eDNA) was visualized via an indirect immunofluorescence assay (Mouse anti-DNA IgG, Goat anti-Mouse IgG, Streptavidin-Cy3). Overall, the total colony-forming units significantly decreased after combined treatment with a low concentration of CHX and enzymes compared to the group treated with CHX alone (p<0.001). These findings also apply to five species individually (Streptococcus mutans, Streptococcus oralis, Actinomyces oris, Veillonella dispar, and Candida albicans) occurring in the biofilms, with Fusobacterium nucleatum being the only exception. Furthermore, CLSM images showed less dense biofilms and a reduction in cell numbers after combined treatment compared to the group without enzymes. The combination of enzymes capable of disturbing the matrix integrity with antimicrobial agents thus appears to be a promising approach for biofilm disruption and killing.

Enhanced Antimicrobial Action of Chlorhexidine Loaded in Shellac Nanoparticles with Cationic Surface Functionality.

We report on an active nanocarrier for chlorhexidine (CHX) based on sterically stabilized shellac nanoparticles (NPs) with dual surface functionalization, which greatly enhances the antimicrobial action of CHX. The fabrication process for the CHX nanocarrier is based on pH-induced co-precipitation of CHX-DG from an aqueous solution of ammonium shellac and Poloxamer 407 (P407), which serves as a steric stabilizing agent. This is followed by further surface modification with octadecyl trimethyl ammonium bromide (ODTAB) through a solvent change to yield cationic surface functionality. In this study, we assessed the encapsulation efficiency and release kinetics of the novel nanocarrier for CHX. We further examined the antimicrobial effects of the CHX nanocarriers and their individual components in order to gain better insight into how they work, to improve their design and to explore the impacts of their dual functionalization. The antimicrobial actions of CHX loaded in shellac NPs were examined on three different proxy microorganisms: a Gram-negative bacterium (E. coli), a yeast (S. cerevisiae) and a microalgae (C. reinhardtii). The antimicrobial actions of free CHX and CHX-loaded shellac NPs were compared over the same CHX concentration range. We found that the non-coated shellac NPs loaded with CHX showed inferior action compared with free CHX due to their negative surface charge; however, the ODTAB-coated, CHX-loaded shellac NPs strongly amplified the antimicrobial action of the CHX for the tested microorganisms. The enhancement of the CHX antimicrobial action was thought to be due to the increased electrostatic adhesion between the cationic surface of the ODTAB-coated, CHX-loaded shellac NPs and the anionic surface of the cell walls of the microorganisms, ensuring direct delivery of CHX with a high concentration locally on the cell membrane. The novel CHX nanocarriers with enhanced antimicrobial action may potentially find applications in dentistry for the development of more efficient formulations against conditions such as gingivitis, periodontitis and other oral infections, as well as enabling formulations to have lower CHX concentrations.

Antibacterial and Antifungal Capacity of Three Commercially Available Mouthwashes with Different Concentrations of Chlorhexidine

Chlorhexidine was introduced almost seven decades ago and has a myriad of applications in dentistry. Few studies have evaluated the antimicrobial and antifungal capacity of different concentrations of chlorhexidine mouthwashes. Therefore, the aim of this study, was to evaluate in vitro, the antibacterial and antifungal capacity of three commercially available mouthwashes in Costa Rica, with different concentrations of chlorhexidine, 0.12%, 0.06%, and 0.03%. The experimental method selected was the Kirby-Bauer method to evaluate the antibacterial and antifungal effect of each compound by measuring the inhibitory effect on Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Candida albicans strains, exposed to the antiseptic solutions. All samples showed some degree of antibacterial and antifungal effect. Even though we provide in vitro results, our findings are of relevance since all the species used in our experiment are microorganisms that may be present in dental plaque. Our results further support evidence that oral hygiene regimens may include mouthwashes with low doses of chlorhexidine and maintain reasonable antibacterial and antifungal efficacy.

Oral mucosal mouthwash with chlorhexidine does not reduce the incidence of ventilator-associated pneumonia in critically ill children: A randomised controlled trial

BackgroundVentilator-associated pneumonia (VAP) is one of the most frequently encountered causes of hospital-acquired infection and results in high morbidity among intubated patients. Few trials have investigated the efficacy of oral care with chlorhexidine (CHX) mouthwash for the prevention of VAP in the paediatric population. ObjectivesThe objective of this study was to assess the efficacy of CHX mouthwash in the prevention of VAP and to determine risk factors for VAP in children aged 1 month to 18 years admitted to the paediatric intensive care unit (PICU). MethodsThis was a prospective, randomised, controlled, double-blind trial performed in the PICU. Patients were randomised into two groups receiving CHX (0.12%) (n = 88) or placebo (0.9% NaCl) (n = 86) and were followed up for VAP development. The main outcome measures were incidence of VAP, duration of hospital stay, duration of PICU stay, duration of ventilation, mortality, and the characteristics of organisms isolated in cases with VAP. Results:No difference was observed in the incidence of VAP and the type and distribution of organisms in the two groups (p > 0.05). In the CHX and placebo groups, we identified 21 and 22 patients with VAP, respectively. Incidence per 1000 ventilation days was 29.5 events in the CHX group and 35.1 events in the placebo group. Gram-negative bacteria were most common (71.4% in CHX vs. 54.5% in placebo). The use of 0.12% CHX did not influence hospital stay, PICU stay, ventilation, and mortality (p > 0.05). Multivariate analysis identified duration of ventilation as the only independent risk factor for VAP (p = 0.001). ConclusionThe use of 0.12% CHX did not reduce VAP frequency among critically ill children. The only factor that increased VAP frequency was longer duration on ventilation. It appears that low concentration of CHX is not effective for VAP prevention, especially in the presence of multiresistant bacteria. ClinicalTrials.gov IdentifierNCT04527276.

Investigating the Antioxidant and Cytocompatibility of Mimusops elengi Linn Extract over Human Gingival Fibroblast Cells.

Background—chlorhexidine (CHX) is most commonly used as a chemical plaque control agent. Nevertheless, its adverse effects, including teeth discoloration, taste alteration and calculus build-up, limit its use and divert us to medicinal herbs. The purpose of the study was to evaluate the phytochemical composition, antioxidant potential, and cytotoxic effects of Mimusops elengi Linn extract (ME) over normal human cultured adult gingival fibroblasts (HGFs). Methods—in vitro phytochemical screening, total flavonoid content, antioxidant potential by DPPH and Nitric Oxide (NO) radical scavenging activity, and cytotoxic effects of ME extracts over HGF were explored. The viability of HGF cells was determined using 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT), neutral red uptake, and trypan blue assay after treatment with different concentrations of CHX and ME (0.3125 to 10 µg/mL). Results—ME showed some alkaloids, glycosides, saponins and flavonoids exhibited relatively moderate-to-good antioxidant potential. Increasing the concentration of CHX and ME from 0.3125 to 10 µg/mL reduced cell viability from 29.71% to 1.07% and 96.12% to 56.02%, respectively. At higher concentrations, CHX reduced the viability of cells by 52.36-fold compared to ME, revealed by MTT assay. At 10 µg/mL concentration, the mean cell viability of CHX and ME-treated cells was 2.24% and 57.45%, respectively, revealed by a neutral red assay. The viability of CHX- and ME-treated HGF cells estimated at higher concentrations (10 µg/mL) using trypan blue assay was found to be 2.18% and 47.36%, respectively. A paired t-test showed significance (p < 0.05), and one-way ANOVA difference between the mean cell viability of CHX- and ME-treated cells at different concentrations. One-way ANOVA confirmed the significant difference between the viability of CHX- and ME-treated cells. Conclusions—The cytoprotective and antioxidant effects of ME emphasize its potential benefits. Therefore, it could emerge as a herbal alternative and adjunct to conventional oral hygiene methods, that can diminish periodontal tissue destruction.

Chlorhexidine leads to the evolution of antibiotic-resistant Pseudomonas aeruginosa.

Antimicrobial resistance is a major public-health concern. We evaluate chlorhexidine role in selection of resistant Pseudomonas aeruginosa mutants and their antibiotic cross-resistance. Mutation frequency and mutation rate after short-term exposure to sub-inhibitory concentrations of chlorhexidine were compared to those after spontaneous chlorhexidine-exposure, in P. aeruginosa PAO1 strain. Chlorhexidine-resistant mutants were generated, either by serial passage in increasing chlorhexidine concentrations or by single exposure to lethal chlorhexidine concentration. The generated mutants were tested for cross-resistance to different antibiotics, by determination of minimum inhibitory concentrations (MIC). The accompanied phenotypic changes in membrane permeability, outer membrane proteins (OMP), and efflux function were evaluated. The effect of exposure to chlorhexidine on MexAB-OprM, MexEF-oprN, and MexXY efflux pumps expression was investigated. No significant change was recorded between the mutation frequencies and mutation rates after short-term exposure to sub-inhibitory concentrations of chlorhexidine and after spontaneous chlorhexidine-exposure, in P. aeruginosa PAO1 strain. Twelve stable mutants, with ≥ eight-fold increase in chlorhexidine MIC, were generated. Several mutants showed increase in the MIC of colistin, cefepime, ceftazidime, meropenem, ciprofloxacin, and amikacin; seven mutants expressed meropenem cross-resistance. This was accompanied by decreased outer membrane permeability and changes in OMP. Using efflux pump inhibitor, chlorhexidine resistance was reverted in most isolates. Exposure to sub-inhibitory concentration of chlorhexidine induced the expression of MexXY efflux pump. Some resistant mutants had overexpressed MexXY efflux pump. Chlorhexidine can select P. aeruginosa strains with antibiotic cross-resistance. This necessitates implementing special protocols for chlorhexidine use and re-evaluation of its benefit versus risk in personal-care products.

Efficacy of 0.05% Chlorhexidine and 0.05% Cetylpyridinium Chloride Mouthwash to Eliminate Living Bacteria on In Situ Collected Biofilms: An In Vitro Study.

Chlorhexidine (CHX) mouthwashes are frequently used as an adjunctive measure for the treatment of periodontitis and peri-implantitis, as well as in patients on maintenance therapy. However, their prolonged use is associated with several side effects. This study aimed at evaluating if a mouthwash with a reduced concentration of CHX combined with cetylpyridnium chloride (CPC) was as effective as a conventional CHX mouthwash in the reduction in living cells in oral biofilms attached to hydroxyapatite (HA) and micro-rough titanium (Ti) surfaces. Four healthy volunteers wore a customized acrylic appliance containing HA and Ti discs for in situ plaque accumulation. Biofilms were grown on the discs for 24 or 48 h and then randomly exposed for 60 s to: 0.05% CHX + 0.05% CPC, 0.1% CHX (positive control) or sterile saline (negative control). Viability assay and live-dead staining were performed to quantify bacterial viability and to distinguish live and dead cells, respectively. At both time points, contrary to saline, CHX, both alone and in combination with CPC, exhibited high antibacterial properties and induced a significant reduction in biofilm viability. This study demonstrates the potential of mouthwashes containing a low concentration of CHX combined with CPC as effective antibacterial agents for long-term applications with reduced undesired side effects.

Successful control of Serratia marcescens outbreak in a neonatal unit of a tertiary-care hospital in Spain

ObjectiveSerratia marcescens is a Gram-negative bacterium that is found in hospital environments and commonly associated with outbreaks in neonatal units. One S. marcescens isolate was detected from a bloodstream culture from a neonate in our hospital that was followed by an outbreak. The aim of this study was to describe the molecular epidemiology of a S. marcescens outbreak in the neonatal unit. MethodsIn order to investigate the outbreak, weekly surveillance rectal swabs were submitted for culture from all patients admitted in this unit from August to September 2018. Environmental samples were obtained from potential sources in September 2018. Typing of isolates was performed by pulsed field gel electrophoresis (PFGE). In addition, we studied the in vitro activity of chlorhexidine against S. marcescens. ResultsDuring this period, 146 infants were hospitalised in our neonatal unit, of which 16 patients had a S. marcescens-positive sample. A total of 36 environmental surveillance samples were collected, and one sample from a stethoscope from an incubator of a colonized baby was positive for S. marcescens. All the 18 isolates, including the isolate from the stethoscope, belonged to a single PFGE cluster. We found that very low concentrations of chlorhexidine, even with application times close to 0 achieved significant reductions in the amount of S. marcescens. ConclusionA unique clone of S. marcescens caused this outbreak, including isolates from patients and from one stethoscope. The outbreak was controlled with the early implementation of specific control measures.

Does a diluted chlorhexidine-based orthodontic mouthwash cause less discoloration compared to chlorhexidine mouthwash in fixed orthodontic patients? A randomized controlled trial

Chlorhexidine gluconate is currently the most effective oral antimicrobial agent against microorganisms, but discoloration of the teeth prevents its long-term use and can reduce patient cooperation. In this study, the effect of chlorhexidine and a diluted chlorhexidine-based, fluoride, cetylpyridinium and vitamin added mouth rinse (Orthokin) on stain index in fixed orthodontic patients was compared. This study was performed as a double blind randomized controlled trial on 50 patients undergoing fixed orthodontic treatment in the age group of 14-30 years. The patients were categorized as two groups of chlorhexidine and Orthokin mouth rinses and were asked to use mouthwash for eight weeks. Groups were matched according to colouring food consumption. Extrinsic staining index was assessed by modified Loben technique. Data was analysed by SPSS software. P value was set to be 0.05. In the chlorhexidine group, the stain extent index and overall stain index were increased significantly at 8 weeks (P<0.001 and P=0.002, respectively). However, the increase in stain intensity index was insignificant (P=0.07). In Orthokin group, the changes in stain extent, stain intensity and overall stain were insignificant (P=0.66, P=1.000, P=0.47, respectively). According to the results of the present study, chlorhexidine mouthwash causes more staining of teeth compared to Orthokin mouthwash. It seems that lower concentrations of chlorhexidine can be prescribed to orthodontic patients. Although these compounds are effective in sense of oral hygiene, they do not cause significant discoloration.

Phenotypic and Multi-Omics Characterization of Escherichia coli K-12 Adapted to Chlorhexidine Identifies the Role of MlaA and Other Cell Envelope Alterations Regulated by Stress Inducible Pathways in CHX Resistance.

Chlorhexidine (CHX) is an essential medicine used as a topical antiseptic in skin and oral healthcare treatments. The widespread use of CHX has increased concerns regarding the development of antiseptic resistance in Enterobacteria and its potential impact on cross-resistance to other antimicrobials. Similar to other cationic antiseptics, resistance to CHX is believed to be driven by three membrane-based mechanisms: lipid synthesis/transport, altered porin expression, and increased efflux pump activity; however, specific gene and protein alterations associated with CHX resistance remain unclear. Here, we adapted Escherichia coli K-12 BW25113 to increasing concentrations of CHX to determine what phenotypic, morphological, genomic, transcriptomic, and proteomic changes occurred. We found that CHX-adapted E. coli isolates possessed no cross-resistance to any other antimicrobials we tested. Scanning electron microscopy imaging revealed that CHX adaptation significantly altered mean cell widths and lengths. Proteomic analyses identified changes in the abundance of porin OmpF, lipid synthesis/transporter MlaA, and efflux pump MdfA. Proteomic and transcriptomic analyses identified that CHX adaptation altered E. coli transcripts and proteins controlling acid resistance (gadE, cdaR) and antimicrobial stress-inducible pathways Mar-Sox-Rob, stringent response systems. Whole genome sequencing analyses revealed that all CHX-resistant isolates had single nucleotide variants in the retrograde lipid transporter gene mlaA as well as the yghQ gene associated with lipid A transport and synthesis. CHX resistant phenotypes were reversible only when complemented with a functional copy of the mlaA gene. Our results highlight the importance of retrograde phospholipid transport and stress response systems in CHX resistance and the consequences of prolonged CHX exposure.

InVitro Comparison of the Acanthamoeba Cysticidal Activity of Povidone Iodine, Natamycin, and Chlorhexidine.

PurposeAcanthamoeba keratitis often is refractory to medical and surgical therapy, primarily because of the remarkable resilience of Acanthamoeba cysts. In this study, we directly compared the cysticidal activity and potency of several candidate medical therapies in vitro.DesignExperimental study.ParticipantsIn vitro Acanthamoeba specimens obtained from 9 patients with keratitis seen at the Francis I. Proctor Foundation from 2008 through 2012.MethodsThe minimum cysticidal concentration (MCC) of povidone iodine, natamycin, and chlorhexidine was investigated using an established assay technique. The relative potency of each agent was estimated starting with concentrations commonly used in clinical practice and determining the number of two-fold dilutions required to reach the MCC. Statistical comparisons of relative potency were performed using bootstrap simulations and permutation tests.Main Outcome MeasuresMinimum cysticidal concentration and the number of two-fold dilutions required to reach the MCC.ResultsThe MCC for chlorhexidine ranged from 3.1 to 25 μg/ml (median, 12.5 μg/ml; interquartile range [IQR], 6.25–12.5 μg/ml), the MCC for natamycin ranged from 390.6 to 3125 μg/ml (median, 390.6 μg/ml; IQR, 390.6–781.2 μg/ml), and the MCC for povidone iodine ranged from 0.3 to 78.1 μg/ml (median, 2.4 μg/ml; IQR, 0.6–9.8 μg/ml). Doses commonly used in clinical practice (povidone iodine 1%, natamycin 5%, and chlorhexidine 0.04%) were approximately 12, 7, and 5 two-fold dilutions higher than the drug’s corresponding median MCC, respectively (P < 0.001, comparing 3 drugs). Povidone iodine 1% had the highest potency of the 3 medications tested, requiring more dilutions than natamycin 5% (P < 0.001) and chlorhexidine 0.04% (P < 0.001) to reach the MCC.ConclusionsAll 3 medications demonstrated in vitro cysticidal activity in each of the 9 isolates. The potency of 1% povidone iodine was greater than standard formulations of natamycin or chlorhexidine. Although its clinical efficacy is yet to be determined, povidone iodine may be considered as a potential adjuvant treatment in cases of recalcitrant Acanthamoeba keratitis.

The assortment analysis of chlorhexidine-containing medicines and procurement data of state and municipal organizations

Chlorhexidine is an effective cationic antiseptic and disinfectant that has been used in medical practice for decades. It is generally recommended to use different concentrations of aqueous or alcoholic solutions of chlorhexidine for different therapeutic purposes.&#x0D; Objective. To determine the proportions of different chlorhexidine concentrations in medicines purchased by state and municipal organizations and to identify possible issue of chlorhexidine formulations utilization in the suboptimal or insufficient concentrations.&#x0D; Results. The vast majority of the chlorhexidine-containing medicines found in the State Register of Medicines of Ukraine are 0.05% solutions for external use, 0.05% gels for dental and urological use and vaginal suppositories (pessaries) with 16 mg of chlorhexidine in one dose. While the most common representatives of chlorhexidine-containing medicines abroad are solutions with a concentration of 4% and 2%, as well as mouthwashes with a concentration of 0.12%. The highest share - 96% - among the procurements of chlorhexidine-containing medicines by state and municipal organizations is 0.05% aqueous solution for external use. Instructions for medical use of 0.05% aqueous chlorhexidine solution for external use contain indications that are not supported by international documents: WHO Model List of Essential Medicines and British National Formulary.&#x0D; Conclusions. The obtained results suggest probable cases of irrational use of chlorhexidine medicines in medical practice in Ukraine. The consequences of such cases are not limited to the failure to achieve therapeutic goals or to the development of nosocomial infection, but includes also the selection of chlorhexidine-resistant strains of microorganisms.&#x0D; Key words: chlorhexidine; assortment analysis; medicinal procurements study; suboptimal concentration; rational pharmacotherapy

Benefits of Polyamide Nanofibrous Materials: Antibacterial Activity and Retention Ability for Staphylococcus Aureus.

Although nanomaterials are used in many fields, little is known about the fundamental interactions between nanomaterials and microorganisms. To test antimicrobial properties and retention ability, 13 electrospun polyamide (PA) nanomaterials with different morphology and functionalization with various concentrations of AgNO3 and chlorhexidine (CHX) were analyzed. Staphylococcus aureus CCM 4516 was used to verify the designed nanomaterials’ inhibition and permeability assays. All functionalized PAs suppressed bacterial growth, and the most effective antimicrobial nanomaterial was evaluated to be PA 12% with 4.0 wt% CHX (inhibition zones: 2.9 ± 0.2 mm; log10 suppression: 8.9 ± 0.0; inhibitory rate: 100.0%). Furthermore, the long-term stability of all functionalized PAs was tested. These nanomaterials can be stored at least nine months after their preparation without losing their antibacterial effect. A filtration apparatus was constructed for testing the retention of PAs. All of the PAs effectively retained the filtered bacteria with log10 removal of 3.3–6.8 and a retention rate of 96.7–100.0%. Surface density significantly influenced the retention efficiency of PAs (p ≤ 0.01), while the effect of fiber diameter was not confirmed (p ≥ 0.05). Due to their stability, retention, and antimicrobial properties, they can serve as a model for medical or filtration applications.