Chlorhexidine Acetate Research Articles

Inhibitory Effects and Mechanism of the Combined Use of α-Helical Peptides HPRP-A1/HPRP-A2 and Chlorhexidine Acetate Against Bacterial and Fungal Biofilms

Drug resistance is an increasing problem in the treatment of vaginitis bacterial vaginosis and vulvovaginal candidiasis caused by biofilm-forming bacteria and fungi. In this study, the antimicrobial activities of the synergistic effects coordinated by antimicrobial peptides HPRP-A1, HPRP-A2, and chlorhexidine acetate (CHA), against biofilms caused by Gram-negative and Gram-positive bacteria, and one fungus Candida albicans, were investigated in vitro and in mouse and rat infection models. The minimal biofilm inhibitory concentration and the fractional biofilm inhibitory concentration of HPRP-A1, HPRP-A2 alone and in combination with CHA were determined by classical methods. The crystal violet staining assay was used to determine the biomass of agents on biofilms. The MTT assay was used to determine the metabolic activity of agents on biofilms. Different microscopy assays were used to observe the morphological characteristics of bacterial and fungal biofilms after drug treatments. The extracellular polysaccharide was detected by a phenol–sulfuric acid method. The combined uses of HPRP-A1, HPRP-A2 and CHA exerted strong synergistic effects to inhibit the formation of bacterial and fungal biofilms and disrupt the construction of biofilms in vitro and in vivo. In animal vaginitis models, the drug combination reduced 99.9% of the number of bacterial and fungal CFU, and showed significant therapeutic effects against biofilm vaginitis. The mechanism of membrane disruption coordinated by the combination of drugs depends not only on the inhibition of extracellular polysaccharides secreted by bacterial and fungal cells, but also on the ability of the peptides to penetrate the cell membrane.

Hierarchically electrospraying a PLGA@chitosan sphere-in-sphere composite microsphere for multi-drug-controlled release.

Sequential administration and controlled release of different drugs are of vital importance for regulating cellular behaviors and tissue regeneration, which usually demands appropriate carriers like microspheres (MS) to control drugs releases. Electrospray has been proven an effective technique to prepare MS with uniform particle size and high drug-loading rate. In this study, we applied electrospray to simply and hierarchically fabricate sphere-in-sphere composite microspheres, with smaller poly(lactic-co-glycolic acid) MS (∼8–10 μm in diameter) embedded in a larger chitosan MS (∼250–300 μm in diameter). The scanning electron microscopy images revealed highly uniform MS that can be accurately controlled by adjusting the nozzle diameter or voltage. Two kinds of model drugs, bovine serum albumin and chlorhexidine acetate, were encapsulated in the microspheres. The fluorescence-labeled rhodamine-fluoresceine isothiocyanate (Rho-FITC) and ultraviolet (UV) spectrophotometry results suggested that loaded drugs got excellent distribution in microspheres, as well as sustained, slow release in vitro. In addition, far-UV circular dichroism and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) results indicated original secondary structure and molecular weight of drugs after electrospraying. Generally speaking, our research proposed a modified hierarchically electrospraying technique to prepare sphere-in-sphere composite MS with two different drugs loaded, which could be applied in sequential, multi-modality therapy.

Functional Synergy Of Antimicrobial Peptides And Chlorhexidine Acetate Against Gram-Negative/Gram-Positive Bacteria And A Fungus In Vitro And In Vivo.

Background and purposeTo reduce the resistance and allergic reaction to chlorhexidine acetate (CHA) in the current treatment of (Bacterial vaginosis) BV and (vulvovaginal candidiasis) VVC in female vaginitis. In this study, the antimicrobial activities and mechanism of action of the synergistic effects of antimicrobial peptides (AMPs) HPRP-A1 and HPRP-A2, and CHA, against Gram-negative and Gram-positive bacteria, and one fungus Candida albicans (C. albicans) were investigated in vitro and in mouse and rat vaginitis infection models in vivo.ResultsHPRP-A1, HPRP-A2 and CHA showed significant synergistic effects on the antimicrobial activities against different Gram-negative and Gram-positive bacteria and C. albicans. The combined application of HPRP-A2 and CHA exhibited strong synergistic effects in the mouse and rat vaginitis models caused by bacteria or C. albicans.ConclusionThis study may prompt the development of new drug combinations against vaginitis infections, including mixed bacterial and fungal infections and multi-drug-resistant infections.

Dynamic covalent constructed self-healing hydrogel for sequential delivery of antibacterial agent and growth factor in wound healing

The conventional injectable hydrogels as wound dressing materials frequently encounter bacterial infection and lack self-healing ability. Besides, the hydrogels injected into the irregular wound sites are easily damaged by external forces, which further hinder wound healing. To make up for these deficiencies, we developed a novel hydrogel with the unique properties including dynamic covalent based self-healing, antibacterial and sequential drug release. This injectable and self-healing hydrogel was constructed via the dynamic reaction of aminated gelatin (NGel), adipic acid dihydrazide (ADH) and oxidized dextran (ODex). After injection or damage, the broken hydrogel pieces performed excellent self-healing capability to generate an integral hydrogel owing to dynamic imine and acylhydrazone bonds. Meanwhile, bFGF@PLGA microspheres and chlorhexidine acetate (CHA) were embedded into the hydrogels. This bFGF@PLGA/CHA/hydrogel presented a good biodegradability, and it could retain the morphological stability after swelling. Moreover, bFGF@PLGA/CHA/hydrogels achieved the sequential release of CHA and bFGF during the drug release assay. When topically applied onto the wound skin of rats, the hydrogels can effectively prevent infection at the early stages due to the rapid release of CHA, then further accelerate cell proliferation and wound healing through the sustained release of bFGF. These results indicate that the proposed self-healing hydrogel with sequential release properties is a highly promising dressing material for wound healing.

Resistance mechanisms and molecular epidemiology of chlorhexidine acetate-resistant Klebsiella pneumoniae clinical isolates

Objective To investigate the chlorhexidine acetate-resistance in Klebsiella pneumoniae (K.pneumoniae) clinical isolates and to analyze the possible mechanisms and molecular epidemiology of resistant isolates. Methods A total of 332 K. pneumoniae clinical isolates were collected in the First Affiliated Hospital of Wenzhou Medical University in 2015. Standard agar dilution was used to screen chlorhexidine acetate-resistant isolates. The minimum inhibition concentrations (MIC) of chlorhexidine acetate to resistant isolates with and without the presence of carbonyl cyanide m-chlorophenyl hydrazone (CCCP), which was an efflux pump inhibitor, were analyzed. Efflux pump genes of cepA, qacE and qacΔE1 that carried by and expressed in those isolates were detected by polymerase chain reaction (PCR) and quantitative real-time PCR (RT-qPCR), respectively. The biofilm formation ability was measured by crystal violet staining. The homology among the chlorhexidine acetate-resistant isolates was investigated with multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). Results Twenty-five K. pneumoniae strains were resistant to chlorhexidine acetate. The MIC values of chlorhexidine acetate for them were reduced by at least four-fold in the presence of CCCP. Strains carrying the genes of cepA, qacE and qacΔE1 accounted for 100%, 40% and 40%, respectively. The expression of the efflux pump genes in the chlorhexidine acetate-resistant isolates was higher than that in the susceptible isolates. The biofilm formation ability of the chlorhexidine acetate-resistant isolates was better than that of the susceptible isolates. Furthermore, negative, weak-positive and positive biofilm formation ability was observed in four (16%), 20 (80%) and one (4%) strains, respectively. The results of MLST and PFGE showed that the 25 chlorhexidine acetate-resistant isolates belonged to 19 different sequence types (ST) with diverse PFGE patterns. Conclusions This study suggested that active efflux was the main mechanism of chlorhexidine acetate resistance in K. pneumoniae. The 25 chlorhexidine acetate-resistant K. pneumoniae strains possessed different biofilm formation ability and shared low homology. Key words: Chlorhexidine acetate; Klebsiella pneumoniae; Resistance mechanism; Molecular epidemiology

Antibacterial activity, cell toxicity, and mechanical property of ultra-high molecular weight polyethylene/chlorhexidine acetate–montmorillonite nanocomposite

Nanocomposites have been extensively used in many fields. Their properties can be improved or enhanced by the components in the nanocomposites. In this study, we reported the antibacterial activity, cell toxicity, and mechanical property of a three-component nanocomposite which consisted of ultra-high molecular weight polyethylene (UHMWPE), chlorhexidine acetate (CA), and montmorillonite (MMT). This nanocomposite (UHMWPE/CA-MMT) maintained good short-term resistance to bacterial adhesion, and its long-term resistance to bacterial adhesion was significantly improved as the interlayer space in montmorillonite prevented effectively the agglomeration and precipitation of chlorhexidine acetate after the intercalation of chlorhexidine acetate into montmorillonite. Also, its cell toxicity was reduced as the interlayer space in montmorillonite inhibited the release rate of chlorhexidine acetate. In addition, the mechanical property of UHMWPE/CA-MMT was improved because of the synergistic optimization of these three components. These findings suggested that this three-component nanocomposite UHMWPE/CA-MMT may be a promising biomaterial.

Thermal stability and thermal oxidation kinetics of PU/CA‐MMT composites

ABSTRACTIn this work, we prepared three composites polyurethane (PU)/chlorhexidine acetate (CA), PU/montmorillonite (MMT), and PU/CA‐MMT, and investigated their kinetics of thermal degradation at different heating rates at atmosphere. These materials had good thermal stability and aging resistance. The thermal stability of PU/CA (Tonset: 237.3°C) was not obviously enhanced by the addition of only CA when compared with that of PU (Tonset: 232.3°C), while the thermal stability of PU/MMT (Tonset: 273.4°C) was considerably enhanced by the addition of MMT due to the high thermal stability of MMT. CA‐MMT filler was dispersed and exfoliated in PU more easily than CA or MMT in PU, so the composite PU/CA‐MMT possessed the best thermal stability (Tonset: 285.8°C). In addition, PU/CA‐MMT also had the best resistance to bacterial adhesion and antibacterial ability. The analysis with Flynn‐Wall‐Ozawa method showed that the activation energy of thermal oxidation of PU increased when CA‐MMT was added and thus its anti‐aging ability was enhanced, and the thermal oxidation of these four materials was first‐order reaction. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47002.

The effect of chlorhexidine acetate flushing oral care in patients with endotracheal intubation

Objective To study the clinical effect of chlorhexidine acetate solution for oral care in patients with endotracheal intubation. Methods From February 2017 to August 2017, 160 patients with tracheal intubation in our department were divided into the observation group (80 cases) and the control group (80 cases) by random number table method. The observation group was treated with chlorhexidine acetate solution, and the control group used the compound Borax solution for oral care. The oral condition score, the positive rate of oral bacterial culture, the incidence rate of ventilator-associated pneumonia were compared between two groups. Results In the observation group, the oral condition score and the positive rate of oral bacterial culture were 10.29±2.04 and 16.25% (13/80) on the 3rd day after theoral care. In the control group, the oral condition score and the positive rate of oral bacterial culture were 12.79±1.97 and 31.25%(25/80) on the 3rd day after the oral care. There were statistically significant differences between the two groups (t=-7.895, P<0.01; χ2=4.970, P<0.05). The incidence and occurrence time of ventilator-associated pneumonia in the observation group were 7.50% (6/80), (9.33±1.37) d. The incidence and occurrence time of ventilator-associated pneumonia in the control group were 18.75% (15/80), (5.87±1.06) d. The difference between the two groups was statistically significant (χ2= 4.440, P<0.05; t=6.248, P<0.01). Conclusions The chlorhexidine acetate flushing oral care can significantly improve dental status, reduce the positive rate of oral bacterial culture and the incidence of ventilator-associated pneumonia, and prolong the occurrence time of ventilator-associated pneumonia in patients with endotracheal intubation. Key words: Pneumonia, ventilator-associated; Endotracheal intubation; Chlorhexidine; Flushing oral care

Anticoagulant polyurethane substrates modified with poly(2-methacryloyloxyethyl phosphorylcholine) via SI-RATRP.

A novel catalyst system of Reverse Atom Transfer Radical Polymerization (RATRP) to prepare Polyurethane (PU) films modified by poly(2-methacryloyloxyethyl phosphorylcholine) (pMPC) was studied in this article. In this system, PU film was pretreated by LaCl3/CA ethanol solution to obtain a hydrated surface allowing more initiators to be immobilized on it. Moreover, complexes composed of silane coupling agent 3-chloropropyltrimethoxysilane (CPTM), chlorhexidine acetate (CA) and lanthanum(III) worked as ligands of copper ions as a whole during RATRP process. PU films before and after modification were characterized by X-ray photoelectron spectroscopy (XPS) and static contact angle (SCA) to confirm that pMPC chains were successfully grafted from the substrates. Results of Plasma recalcification time assay, platelet adhesion test indicated excellent blood compatibility. Furthermore, the antibacterial activity of the material have been improved which proved by adhesion test of E.coil.

Study on montmorillonite-chlorhexidine acetate-terbinafine hydrochloride intercalation composites as drug release systems.

This paper focuses on the intercalation of chlorhexidine acetate (CA) and terbinafine hydrochloride (TBH) into montmorillonite as sustained release drug carriers. The intercalation compounds were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetric analysis (TGA). The basal spacing of montmorillonite increased from 1.23 to 2.97 nm. It was confirmed that CA and TBH molecules were well-stabilized in the interlayer space of clay via mono-, double or triplicate layer stacking. The adsorption amounts and molecular structures of CA and TBH appeared to depend on the cation exchange capacity of MMT, which in turn, tailored the drug release patterns. In vitro release tests of MMT–CA–TBH in 0.9 wt% NaCl solution at 37 °C show a biphasic and sustained profile of CA and TBH ion release. After release, dissolution–diffusion kinetic models were fitted. The mechanism of MMT–CA–TBH release is probably due to surface diffusion and bulk diffusion via ionic exchange of MMT ions on or in the MMT with ions in the NaCl solution. The in vitro release experiments revealed that CA and TBH were released from MMT steadily, depending on the cooperation between the drugs themselves and the electrostatic interactions between the drugs and MMT. It was found that the cross-linking ratio increased due to a decrease in the free volume available for diffusion.

A novel method to detect bacterial resistance to disinfectants

In clinical practice, the important hygienic prevention of bacterial pathogen spread is disinfection of potentially contaminated area. Benzalkonium bromide and chlorhexidine acetate are commonly used disinfectants with a broad spectrum of anti-microbial effect. It is vital to inhibit the spread of pathogen in hospital. However, a large number of pathogens with the decreased antiseptic susceptibility have been isolated from clinical samples which showed an increased minimal inhibitory concentration (MIC) against those antiseptics. These resistant pathogens are the major causes for nosocomial cross-infections in hospital. The present study demonstrated the utility of Oxford plate assay system in determining the potential disinfectant resistance of bacteria. The microbiological assay is based on the inhibitory effect of tested disinfectants upon the strains of Staphylococcus aureus and Escherichia coli. Statistical analysis of the bioassay results indicated the linear correlation (r = 0.87–0.99, P < 0.01) between the diameter of growth inhibition zone and the log dosage of the tested disinfectants. Moreover, comparison of inhibitory efficacy of benzalkonium bromide upon 29 S. aureus strains isolated from clinical samples by both Oxford plate method and broth dilution method showed that the diameter of growth inhibition zone has significantly negative correlation with the minimal inhibitory concentration (MIC) (r = −0.574, P < 0.001). These results suggest that the Oxford plate is a simple and time-saving method in detecting potential clinical disinfectant resistance and its usefulness for routine surveillance of pathogenic resistance to disinfectants warrants further investigation.

Comparative Evaluation of Root Surface Changes by Air-Polishing using Glycine and Chlorhexidine Acetate Powder: An in-vitro Study

Background: Biofilm removal is the central part of the etiotropic and maintenance phase of periodontal therapy. Commercially available injection water jets such as Prophy-Jet allows an efficient and convenient biofilm removal as an adjunct to mechanical periodontal therapy. But, due to the abrasive nature of traditionally used air polishing powders such as sodium bicarbonate, there is a continuous research going on for less abrasive materials.&#x0D; Aims: To compare the effectiveness of air polishing using glycine powder and chlorhexidine acetate powder on tooth surface as compared to ultrasonic scaling and also to evaluate the time taken for stain removal.&#x0D; Materials and Methods: Thirty fully erupted, single rooted teeth extracted due to poor periodontal prognosis were used in this in-vitro study. The sample teeth were divided into 3 equal groups and stained in coffee solution. The test Groups A and B underwent air-polishing with glycine powder and chlorhexidine acetate powder respectively. Group C was control group and underwent ultrasonic scaling. Time taken for stain removal was recorded. The sample teeth were also evaluated under a stereo-microscope and digital micrometer preprocedurally and post-procedurally to measure surface changes.&#x0D; Results: The study showed statistically significant results (p&lt;0.05) when measurements of changes in surface roughness of samples treated with glycine powder air-polishing were compared with ultrasonic scaling and chlorhexidine acetate powder air-polishing were compared with ultrasonic scaling. Surface texture loss as well as time taken for stain removal was minimum with glycine powder and maximum with ultrasonic scaling.&#x0D; Conclusion: Air-polishing with glycine powder was least abrasive on root surface followed by chlorhexidine acetate powder air-polishing. This is because of the lower particle size of glycine which also covers larger area in lesser time.

Nasal decontamination for the prevention of surgical site infection in Staphylococcus aureus carriers.

Surgical site infection rates in the month following surgery vary from 1% to 5%. Due to the large number of surgical procedures conducted annually, the costs of these surgical site infections (SSIs) can be considerable in financial and social terms. Nasal decontamination using antibiotics or antiseptics is performed to reduce the risk of SSIs by preventing organisms from the nasal cavity being transferred to the skin where a surgical incision will be made. Staphylococcus aureus (S aureus) colonises the nasal cavity and skin of carriers and can cause infection in open or unhealed surgical wounds. S aureus is the leading nosocomial (hospital-acquired) pathogen in hospitals worldwide. The potential effectiveness of nasal decontamination of S aureus is thought to be dependent on both the antibiotic/antiseptic used and the dose of application; however, it is unclear whether nasal decontamination actually reduces postoperative wound infection in S aureus carriers. To assess the effects of nasal decontamination on preventing surgical site infections (SSIs) in people who are S aureus carriers undergoing surgery. In September 2016 we searched the Cochrane Wounds Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library), Ovid MEDLINE, Ovid MEDLINE (In-Process & Other Non-Indexed Citations), Ovid Embase, and EBSCO CINAHL Plus. We also searched three clinical trial registries and the references of included studies and relevant systematic reviews. There were no restrictions based on language, date of publication or study setting. Randomised controlled trials (RCTs) which enrolled S aureus carriers with any type of surgery and assessed the use of nasal decontamination with antiseptic/antibiotic properties were included in the review. Two review authors independently performed study selection, data extraction, risk of bias assessment and GRADE assessment. We located two studies (291 participants) for inclusion in this review. The trials were clinically heterogeneous with differences in duration of follow-up, and nasal decontamination regimens. One study compared mupirocin (2% contained in a base of polyethylene glycol 400 and polyethylene glycol 3350) with a placebo in elective cardiac surgery patients; and one study compared Anerdian (iodine 0.45% to 0.57% (W/V), chlorhexidine acetate 0.09% to 0.11% (W/V)) with no treatment also in cardiac surgery patients. The trials reported limited outcome data on SSI, adverse events and secondary outcomes (e.g. S aureus SSI, mortality). Mupirocin compared with placeboThis study found no clear difference in SSI risk following use of mupirocin compared with placebo (1 trial, 257 participants); risk ratio (RR) 1.60, 95% confidence interval (CI) 0.79 to 3.25 based on 18/130 events in the mupirocin group and 11/127 in the control group; low-certainty evidence (downgraded twice due to imprecision). Anerdian compared with no treatmentIt is uncertain whether there is a difference in SSI risk following treatment with Anerdian compared with no treatment (1 trial, 34 participants); RR 0.89, 95% CI 0.06 to 13.08 based on 1/18 events in the Anerdian group and 1/16 in the control group; very low certainty evidence (downgraded twice due to imprecision and once due to risk of bias). There is currently limited rigorous RCT evidence available regarding the clinical effectiveness of nasal decontamination in the prevention of SSI. This limitation is specific to the focused question our review addresses, looking at nasal decontamination as a single intervention in participants undergoing surgery who are known S aureus carriers. We were only able to identify two studies that met the inclusion criteria for this review and one of these was very small and poorly reported. The potential benefits and harms of using decontamination for the prevention of SSI in this group of people remain uncertain.

0.2% chlorhexidine acetate as skin disinfectant prevents skin lesions in extremely preterm infants: a preliminary report

ObjectiveThe skin disinfectant ‘0.5% chlorhexidine gluconate in 70% alcohol’ (0.5% CHG-70% alc) may cause skin lesions in extremely preterm infants (gestational age <26 weeks). In April 2013, 0.2% chlorhexidine gluconate...

PLLA microcapsules combined with silver nanoparticles and chlorhexidine acetate showing improved antibacterial effect

In this study, composite antibacterial microcapsules combining of two antibacterial agents: chlorhexidine acetate and silver nanoparticle were prepared. The chlorhexidine acetate was encapsulated inside of the microcapsules and nano-sized silver particles were modified on the surface of microcapsules by electrostatic adsorption methods. Results show that this method decreases the silver usage dramatically, and promises a sustained antibacterial effect >30days. These microcapsules can also be modified on the surface of polymer films easily, which demonstrated the potential in functionalizing the implanted materials with antibacterial property.

Chlorhexidine-Loaded Amorphous Calcium Phosphate Nanoparticles for Inhibiting Degradation and Inducing Mineralization of Type I Collagen.

A major shortcoming of contemporary dentin adhesives is their limited durability. Exposed collagen fibrils within the bonding interface are degraded by matrix metalloproteinases (MMPs), resulting in aging of the resin-dentin bond. In this study, chlorhexidine-loaded amorphous calcium phosphate (ACP) nanoparticles were synthesized to induce the mineralization of collagen fibrils. The nanoparticles sustainably released chlorhexidine to inhibit MMPs during mineralization. Three types of ACP nanoparticles were prepared: N-ACP containing no chlorhexidine, C-ACP containing chlorhexidine acetate, and G-ACP containing chlorhexidine gluconate, which had a higher drug-loading than C-ACP. Scanning and transmission electron microscopy indicated that the synthesized nanoparticles had diameters of less than 100 nm. Some had diameters of less than 40 nm, which was smaller than the width of gap zones in the collagen fibrils. Energy dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, and high performance liquid chromatography confirmed the presence of chlorhexidine in the nanoparticles. X-ray diffraction confirmed that the nanoparticles were amorphous. The drug loading was 0.11% for C-ACP and 0.53% for G-ACP. In vitro release profiles indicated that chlorhexidine was released sustainably via first-order kinetics. Released chlorhexidine inhibited the degradation of collagen in human dentine powder, and its effect lasted longer than that of pure chlorhexidine of the same concentration. The ACP could induce the mineralization of self-assembled type I collagen fibrils. The chlorhexidine-loaded ACP nanoparticles sustainably released chlorhexidine and ACP under appropriate conditions. This is useful for inhibiting degradation and inducing the mineralization of dentine collagen fibrils.

Application of chlorhexidine acetate disinfectant in pin site care of patients with calcaneal traction

Objective To explore the application effect of chlorhexidine acetate disinfectant in pin site care of the patients with calcaneal traction. Methods From January 2014 to December 2015, 85 cases of patients with calcaneal traction were selected as the research object by purpose sampling method, and were divided into the control group (n=42) and the intervention group (n=43) according to admission time. Patients in two group all received closed nursing for pin site care. Patients in the control group used povidone iodine disinfectant, while patients in the intervention group used chlorhexidine acetate disinfectant. We estimated the infection rate of the patients in two groups. Results During the period of calcaneal traction, there was no pin site infection over level IV happened in two groups. In the first day after calcaneal traction, there was no difference in the infection rate between two groups (P>0.05) . In the third day, the fifth day after calcaneal traction and the day before internal fixation, the incidence rate and the level of pin-site infection in the intervention group were lower than those in the control group (Z=-3.214, -2.662, -3.094, P<0.05) . Conclusions Chlorhexidine acetate disinfectant can decrease the infection rate of pin site in patients with calcaneal traction under closed nursing. It provides an effective nursing method for preventing the infection of pin site. Key words: Hospital, orthopedic department; Traction; Disinfection; Infection; Chlorhexidine acetate disinfectant solution

Sequential delivery of chlorhexidine acetate and bFGF from PLGA-glycol chitosan core-shell microspheres

Wound treatment should meet the challenge both of preventing infection and promoting wound healing. To design a sequential delivery system for wound healing, PLGA-glycol chitosan (GC) core-shell microspheres containing chlorhexidine acetate (CHA) at the GC shell and bFGF in the core of PLGA microspheres were fabricated using emulsion-solvent evaporation method. SEM showed that the microspheres were all spherical in shape with a smooth surface. The average size of PLGA-GC microspheres increased due to the GC coating on the surface. The results of release profiles and fluorescence images indicated that PLGA-GC microspheres had an ability to deliver drugs in sequence. The CHA was rapidly released, whereas the proteins presented a sustained release. The release behavior could be modulated by changing the GC amount. Antibacterial assay and cell proliferation tests suggested that the released CHA and bFGF retained their antimicrobial activity and bioactivity during preparation. The microspheres exhibited non-cytotoxicity against 3T3 cells and had a good biocompatibility. These results demonstrated that PLGA-GC core-shell microspheres could be a promising controlled release system of delivering drugs and proteins in sequence for wound healing.

Characterization and antibacterial activity of chlorhexidine loaded silver-kaolinite

Chlorhexidine acetate-loaded silver-kaolinite (CA-Ag-Kaol) was prepared and characterised, and its application as an antibacterial agent was studied. CA-Ag-Kaol was prepared by the adsorption of chlorhexidine acetate (CA) (0.5mmol/L) on Ag (50% of the Cation Exchange Capacity (CEC) of kaolinite) on kaolinite. Kaolinite (Kaol), silver-kaolinite (Ag-Kaol), CA-modified kaolinite (CA-Kaol) and CA-Ag-Kaol were characterised by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field-emission scanning-electron microscopy (FESEM), energy dispersive X-ray (EDX) spectroscopy, zeta potential analysis and dispersion behavior measurements. The modification of kaolinite with cationic silver and chlorhexidine ions did not change the structure of kaolinite, and the characterization of the kaolinite samples revealed the successful loading of cationic silver and chlorhexidine ions on the kaolinite. The antibacterial assay of the samples was carried out against Escherichia coli ATCC 11229, Pseudomonas aeruginosa ATCC 15442, Staphylococcus aureus ATCC 6538 and Enterococcus faecalis ATCC 29212 using the disc diffusion technique (DDT) and the minimum inhibition concentration (MIC) technique. Based on the antibacterial assay, CA-Ag-Kaol showed better antibacterial activity than Ag-Kaol and CA-Kaol, and it performed well in both distilled water and a 0.9% saline solution. Gram-positive bacteria were more susceptible to the antibacterial behavior of Ca-Ag-Kaol than Gram-negative bacteria. In conclusion, silver-kaolinite that has been loaded with chlorhexidine acetate can be used as an effective antibacterial agent because of its high antibacterial activity against wide spectrum of bacteria in solutions containing electrolytes (saline solution).

Enhanced efficacy and anti-biofilm activity of novel nanoemulsions against skin burn wound multi-drug resistant MRSA infections

Multi-drug resistant MRSA (methicillin-resistant Staphylococcus aureus) is a global problem for human health, especially skin burn wound patients. Therefore, we estimated the antibacterial and anti-biofilm activity of a chlorhexidine acetate nanoemulsion (CNE) by previously ourselves designed against skin burn wound MRSA infections. Compared with its water solution (CHX), CNE showed a better and faster action against MRSA both in vitro and in vivo. Importantly, CNE was more effective at inhibiting biofilm formation and clearing the biofilm. We also found that the cell walls and membranes of MRSA were severely disrupted after treatment with CNE. Moreover, the relative electrical conductivity and the leakage of alkaline phosphates, K+, Mg2+, DNA and protein obviously increased because the cell wall and membrane were damaged. These data show that novel CNE is a promising potential antimicrobial candidate, especially for skin burn wound MRSA infections.