Antimicrobial Protection Research Articles

Green Nanosilver as Reinforcing Eco-Friendly Additive to Epoxy Coating for Augmented Anticorrosive and Antimicrobial Behavior

Epoxy resin GY250 representing diglycidyl ethers of bisphenol-A (DGEBA) was reinforced with 1, 3 and 5 wt % of surface functionalized silver nanoparticles (F-AgNPs) which were synthesized using Couroupita guianensis leaves extract with a view of augmenting the corrosion control property of the epoxy resin and also imparting antimicrobial activity to epoxy coatings on mild steel. Corrosion resistance of the coatings was evaluated by EIS, potentiodynamic polarization studies and cross scratch tests. AFM, SEM, HRTEM and EDX were utilized to investigate the surface topography, morphology and elemental composition of the coatings on MS specimens. Results showed that the corrosion resistance, hardness and T-g of the DGEBA/F-AgNPs coatings increased at 1 wt % of F-AgNPs. The DGEBA/F-AgNPs coatings also offered manifold antimicrobial protection to the MS surfaces by inhibiting the growth of biofilm forming bacteria like P. aeruginosa, B. subtilis, the most common human pathogen E. coli and the most virulent human pathogenic yeast C. albicans.

Comparative proteomic analysis of egg white proteins during the rapid embryonic growth period by combinatorial peptide ligand libraries

Egg white proteins provide essential nutrients and antimicrobial protection during embryonic development. Although various biological functions of major egg white proteins have been investigated via embryogenesis, understanding of global changes in low-abundance proteins has been limited. In the current study, a proteomic analysis of low-abundance egg white proteins was conducted using combinatorial peptide ligand libraries (CPLL), two-dimensional gel electrophoresis (2-DE), and matrix-assisted laser desorption/ionization-time-of-flight with two mass analyzers for tandem mass spectrometry (MALDI-TOF MS/MS) during the rapid embryonic growth period. Significant increases in the relative abundance of 88 protein spots (P ≤ 0.05), of which 47 spots were found to correspond to 10 proteins from 8 protein families were identified over 16 d incubation. During this developmental process, the protein concentration increased and the amount of albumin solid material decreased in the residual egg white. Clusterin precursors were observed over a wide range of pH values and the tenp protein increased continuously during embryonic development. Low-abundance proteins were identified in a comparison of optimal incubation conditions to the altered conditions of 2 control groups to better understand the function of these proteins in egg whites. Collectively, these findings provide insight into the supportive role of the egg white during embryonic development, enabling a broader understanding of chick embryogenesis.

Antimicrobial properties of silver nanoparticles misting on cotton fabrics

The purpose of this research was to investigate whether silver nanoparticles (AgNPs) misting could be an effective disinfection and protection method for cotton fabric. The study showed that the disinfection resulted in the reduction of microorganism number by 32–100%, depending on the strain. Fabric humidity of not less than 84% ensures high effectiveness of the process. It was proved that vegetative cells are more susceptible to nanoparticles than spores. The antimicrobial protection of cotton fabric results in the 33–93% reduction of microorganism number. The application of AgNPs does not influence significantly the optical and mechanical parameters of cotton fabric, even after accelerated light ageing. The AgNPs misting is safe for personnel. The AgNPs misting can be considered as an alternative for currently used disinfection methods of ancient textiles.

Probiotic potential of nutritionally improved Lactobacillus plantarum DGK-17 isolated from Kimchi – A traditional Korean fermented food

The aim of the study was to evaluate the functional properties of the Lactic acid bacterium Lactobacillus plantarum DGK-17 isolated from Kimchi-a traditional fermented Korean food, and to assess its antimicrobial and cell-invasion protection activity. Nutritionally improved DGK-17 showed antimicrobial activity, checked via agar well diffusion assay against several pathogenic microorganisms and showed enhanced antimicrobial activity against target microbes Pseudomonas aeruginosa 03K711 and Klebsiella pneumoniae 05K279. Bactericidal activity of DGK-17 Cell-free Culture Supernatant (CFCS) was evident from the decreased growth of P. aeruginosa 03K711 and K. pneumoniae 05K279. Altered membrane integrity was observed in scanning electron microscopy which indicated that CFCS acts on cell membrane of bacteria leading to a cell burst. CFCS also acts on DNA as shown by the DNA damage study. Our auto-aggregation, co-aggregation and adhesion studies indicated that DGK-17 prevents colonization of pathogenic bacteria thereby limiting their infection. Also, DGK-17 is able to survive under low pH and high bile salt conditions – a simulated gastric juice environment. Efficacy of DGK-17 to protect HCT 116 colon cells against P. aeruginosa (03K711) and K. pneumoniae (05K279) invasion suggests its role in protection of host cells from such infections. Finally we conclude that L. plantarum DGK-17 has a strong probiotic potential, antimicrobial activity and a potential for invasion protection.

The human counterpart of mouse B-1 cells.

B-1 cells represent a subpopulation of B cells that has been extensively studied in mice and shown to spontaneously generate natural antibody that provides antimicrobial protection and helps dispose of cellular debris. Mouse B-1 cells originate from distinct progenitors and express additional immune properties that include phagocytosis, antigen presentation, immune suppression, and polarization of T cell differentiation. Confusion regarding the existence of human B-1 cells with mouse B-1-like properties has recently been addressed by identification of a new phenotypic profile. Human B-1 cells spontaneously secrete antibody and are distinct from other circulating B cell populations by multiple criteria. A number of laboratories have recently reported on changes to the human B-1 cell population in human disease.

Evaluation of Ceftaroline Alone and in Combination against Biofilm-Producing Methicillin-Resistant Staphylococcus aureus with Reduced Susceptibility to Daptomycin and Vancomycin in an In Vitro Pharmacokinetic/Pharmacodynamic Model.

Annually, medical device infections are associated with >250,000 catheter-associated bloodstream infections (CLABSI), with up to 25% mortality. Staphylococcus aureus, a primary pathogen in these infections, is capable of biofilm production, allowing organism persistence in harsh environments, offering antimicrobial protection. With increases in S. aureus isolates with reduced susceptibility to current agents, ceftaroline (CPT) offers a therapeutic alternative. Therefore, we evaluated whether CPT would have a role against biofilm-producing methicillin-resistant S. aureus (MRSA), including those with decreased susceptibilities to alternative agents. In this study, we investigated CPT activity alone or combined with daptomycin (DAP) or rifampin (RIF) against 3 clinical biofilm-producing MRSA strains in an in vitro biofilm pharmacokinetic/pharmacodynamic (PK/PD) model. Simulated antimicrobial regimens were as follows: 600 mg of CPT every 8 h (q8h) (free maximum concentration of drug [fCmax], 17.04 mg/liter; elimination half-life [t1/2], 2.66 h), 12 mg/kg of body weight/day of DAP (fCmax, 14.7 mg/liter; t1/2, 8 h), and 450 mg of RIF q12h (fCmax, 3.5 mg/liter; t1/2, 3.4 h), CPT plus DAP, and CPT plus RIF. Samples were obtained and plated to determine colony counts. Differences in log10 CFU/cm(2) were evaluated by analysis of variance with Tukey's post hoc test. The strains were CPT and vancomycin susceptible and DAP nonsusceptible (DNS). CPT displayed activity throughout the experiment. DAP demonstrated initial activity with regrowth at 24 h in all strains. RIF was comparable to the drug-free control, and little benefit was observed when combined with CPT. CPT plus DAP displayed potent activity, with an average log10 CFU/cm(2) reduction of 3.33 ± 1.01 from baseline. CPT demonstrated activity against biofilm-producing DNS MRSA. CPT plus DAP displayed therapeutic enhancement over monotherapy, providing a potential option for difficult-to-treat medical device infections.

The effect of BCG on iron metabolism in the early neonatal period: A controlled trial in Gambian neonates

Bacillus Calmette-Guerin (BCG) vaccination has been reported to protect neonates from non-tuberculous pathogens, but no biological mechanism to explain such effects is known. We hypothesised that BCG produces broad-spectrum anti-microbial protection via a hepcidin-mediated hypoferraemia, limiting iron availability for pathogens.To test this we conducted a trial in 120 Gambian neonates comparing iron status in the first 5-days of life after allocation to: (1) All routine vaccinations at birth (BCG/Oral Polio Vaccine (OPV)/Hepatitis B Vaccine (HBV)); (2) BCG delayed until after the study period (at day 5); and (3) All routine vaccinations delayed until after the study period.Vaccine regime at birth did not significantly impact on any measured parameter of iron metabolism. However, the ability to detect an effect of BCG on iron metabolism may have been limited by short follow-up time and high activation of the inflammatory-iron axis in the study population.

Bactericidal/Permeability-increasing protein fold-containing family member A1 in airway host protection and respiratory disease.

Bactericidal/permeability-increasing protein fold-containing family member A1 (BPIFA1), formerly known as SPLUNC1, is one of the most abundant proteins in respiratory secretions and has been identified with increasing frequency in studies of pulmonary disease. Its expression is largely restricted to the respiratory tract, being highly concentrated in the upper airways and proximal trachea. BPIFA1 is highly responsive to airborne pathogens, allergens, and irritants. BPIFA1 actively participates in host protection through antimicrobial, surfactant, airway surface liquid regulation, and immunomodulatory properties. Its expression is modulated in multiple lung diseases, including cystic fibrosis, chronic obstructive pulmonary disease, respiratory malignancies, and idiopathic pulmonary fibrosis. However, the role of BPIFA1 in pulmonary pathogenesis remains to be elucidated. This review highlights the versatile properties of BPIFA1 in antimicrobial protection and its roles as a sensor of environmental exposure and regulator of immune cell function. A greater understanding of the contribution of BPIFA1 to disease pathogenesis and activity may clarify if BPIFA1 is a biomarker and potential drug target in pulmonary disease.

Multilayer hydrogel coatings to combine hemocompatibility and antimicrobial activity

While silver-loaded catheters are widely used to prevent early-onset catheter-related infections [1], long term antimicrobial protection of indwelling catheters remains to be achieved [2] and antiseptic functionalization of coatings often impairs their hemocompatibility characteristics. Therefore, this work aimed to capitalize on the antimicrobial properties of silver nanoparticles, incorporated in anticoagulant poly(ethylene glycol) (PEG)-heparin hydrogel coatings [3] on thermoplastic polyurethane materials. For prolonged antimicrobial activity, the silver-containing starPEG-heparin hydrogel layers were shielded with silver-free hydrogel layers of otherwise similar composition. The resulting multi-layered gel coatings showed long term antiseptic efficacy against Escherichia coli and Staphylococcus epidermidis strains in vitro, and similarly performed well when incubated with freshly drawn human whole blood with respect to hemolysis, platelet activation and plasmatic coagulation. The introduced hydrogel multilayer system thus offers a promising combination of hemocompatibility and long-term antiseptic capacity to meet an important clinical need.

Phytochemical and Spectral Studies of Synthesis sulfur Nanoparticles using Sophora japonica Pods Extract

This study aims to investigate the aqueous extract of Sophora japonica pods for the presence of various phytochemicals and to synthesize sulfur nanoparticles. The presence of various phytochemicals viz. polyphenols, alkaloids, terpenoids, flavonoids, and tannins were investigated by standard biochemical methods. A rapid, green and novel approach for synthesis sulfur nanoparticles (SNPs) from sodium thiosulfate in the presence of Sophora japonica pods aqueous extract in one-pot reaction at ambient temperature. The resulting sulfur nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that sulfur nanoparticles were successfully synthesized in sphere shape, and with an average particle size 5-100 nm. The effect of plant pods extract concentration on particle size of sulfur nanoparticles shows that can significantly reduce the particle size without changing the shape. The results revealed that the aqueous extract of Sophora japonica pods act as capping, dispersing and stabilizing agent for sulfur nanoparticles. This method is a novel approach for production nanosized sulfur particles, which could be applied to prepare sulfur nanoparticles for application in antimicrobial activity, fertilizers, and plant protection.

Development of a microarray-based tool to characterize vaginal bacterial fluctuations and application to a novel antibiotic treatment for bacterial vaginosis.

The healthy vaginal microbiota is generally dominated by lactobacilli that confer antimicrobial protection and play a crucial role in health. Bacterial vaginosis (BV) is the most prevalent lower genital tract infection in women in reproductive age and is characterized by a shift in the relative abundances of Lactobacillus spp. to a greater abundance of strictly anaerobic bacteria. In this study, we designed a new phylogenetic microarray-based tool (VaginArray) that includes 17 probe sets specific for the most representative bacterial groups of the human vaginal ecosystem. This tool was implemented using the ligase detection reaction-universal array (LDR-UA) approach. The entire probe set properly recognized the specific targets and showed an overall sensitivity of 6 to 12 ng per probe. The VaginArray was applied to assess the efficacy of rifaximin vaginal tablets for the treatment of BV, analyzing the vaginal bacterial communities of 22 BV-affected women treated with rifaximin vaginal tablets at a dosage of 25 mg/day for 5 days. Our results showed the ability of rifaximin to reduce the growth of various BV-related bacteria (Atopobium vaginae, Prevotella, Megasphaera, Mobiluncus, and Sneathia spp.), with the highest antibiotic susceptibility for A. vaginae and Sneathia spp. Moreover, we observed an increase of Lactobacillus crispatus levels in the subset of women who maintained remission after 1 month of therapy, opening new perspectives for the treatment of BV.

Immunological role of vitamin D at the maternal-fetal interface.

During pregnancy, immune activity is tightly regulated so that antimicrobial protection of the mother and fetus is balanced with the need for immune tolerance to prevent fetal rejection. In this setting, the maternal-fetal interface, in the form of the uterine decidua, provides a heterogeneous immune cell population with the potential to mediate diverse activities throughout pregnancy. Recent studies have suggested that vitamin D may be a key regulator of immune function during pregnancy, with the fetal-maternal interface representing a prominent target. Among its non-classical actions are potent immunomodulatory effects, including induction of antibacterial responses and modulation of T-lymphocytes to suppress inflammation and promote tolerogenesis. Thus, vitamin D may play a pivotal role in normal decidual immune function by promoting innate responses to infection, while simultaneously preventing an over-elaboration of inflammatory adaptive immunity. Research to date has focused upon the potential role of vitamin D in preventing infectious diseases such as tuberculosis, as well as possibly suppressing of autoimmune disease. Nevertheless, vitamin D may also influence facets of immune function not immediately associated with primary innate responses. This review summarises our current understanding of decidual immune function with respect to the vitamin D metabolism and signalling, and as to how this may be affected by variations in maternal vitamin D status. There has recently been much interest in vitamin D supplementation of pregnant women, but our knowledge of how this may influence the function of decidua remains limited. Further insight into the immunomodulatory actions of vitamin D during pregnancy will help shed light upon this.

CXCL9 contributes to antimicrobial protection of the gut during citrobacter rodentium infection independent of chemokine-receptor signaling.

Chemokines have been shown to be effective bactericidal molecules against a variety of bacteria and fungi in vitro. These direct antimicrobial effects are independent of their chemotactic activities involving immunological receptors. However, the direct biological role that these proteins may play in host defense, particularly against intestinal pathogens, is poorly understood. Here, we show that CXCL9, an ELR- chemokine, exhibits direct antimicrobial activity against Citrobacter rodentium, an attaching/effacing pathogen that infects the gut mucosa. Inhibition of this antimicrobial activity in vivo using anti-CXCL9 antibodies increases host susceptibility to C. rodentium infection with pronounced bacterial penetration into crypts, increased bacterial load, and worsened tissue pathology. Using Rag1-/- mice and CXCR3-/- mice, we demonstrate that the role for CXCL9 in protecting the gut mucosa is independent of an adaptive response or its immunological receptor, CXCR3. Finally, we provide evidence that phagocytes function in tandem with NK cells for robust CXCL9 responses to C. rodentium. These findings identify a novel role for the immune cell-derived CXCL9 chemokine in directing a protective antimicrobial response in the intestinal mucosa.

Antimicrobial Packaging for Extending the Shelf Life of Bread—A Review

Antimicrobial packaging is an important form of active packaging that can release antimicrobial substances for enhancing the quality and safety of food during extended storage. It is in response to consumers demand for preservative-free food as well as more natural, disposable, biodegradable, and recyclable food-packaging materials. The potential of a combination of allyl isothiocyanate and potassium sorbate incorporated into polymers in providing the needed natural antimicrobial protection for bread products is discussed. The role of double extrusion process as a means for obtaining a homogeneous mix of the sorbate into the polymer (polyethylene or ethylenevinyalcohol), is highlighted.

Electrospun Microfiber Membranes Embedded with Drug-Loaded Clay Nanotubes for Sustained Antimicrobial Protection

Guided tissue regeneration/guided bone regeneration membranes with sustained drug delivery were developed by electrospinning drug-loaded halloysite clay nanotubes doped into poly(caprolactone)/gelatin microfibers. Use of 20 wt % nanotube content in fiber membranes allowed for 25 wt % metronidazole drug loading in the membrane. Nanotubes with a diameter of 50 nm and a length of 600 nm were aligned within the 400 nm diameter electrospun fibers, resulting in membranes with doubling of tensile strength along the collector rotating direction. The halloysite-doped membranes acted as barriers against cell ingrows and have good biocompatibility. The metronidazole-loaded halloysite nanotubes incorporated in the microfibers allowed for extended release of the drugs over 20 days, compared to 4 days when directly admixed into the microfibers. The sustained release of metronidazole from the membranes prevented the colonization of anaerobic Fusobacteria, while eukaryotic cells could still adhere to and proliferate on the drug-loaded composite membranes. This indicates the potential of halloysite clay nanotubes as drug containers that can be incorporated into electrospun membranes for clinical applications.

Nanotitania/mulberry fibers as novel textile with anti-yellowing and intrinsic antimicrobial properties

The present work for the first time introduces a new class of textile consisting of mulberry fibers uniformly laden with titania nanorods. This unique natural-synthetic composite textile is self-cleaning and environmental friendly. The utilized composite was characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction pattern (XRD), electron probe microanalysis (EPMA), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and UV–vis diffused reflectance spectrum (UV-DRS). The SEM images clearly show homogeneous distribution of titania nanorods on the surface of mulberry fibers (MF). XRD and FTIR results confirm the presence of titania in the composite materials. Antimicrobial potential and UV protection due to presence of titania nanorods on MFs was investigated in this study. Results of this investigation indicated that MFs-TiO2 composite exhibit admirable antibacterial activity. From the antimicrobial kinetic test on E. coli, it was established that the composite textile possess improved bactericidal activity than pure mulberry textile. Moreover, titania present on the mulberry fibers impart anti-yellowing, self-cleaning properties, which were endorsed due to the scattering effect of UV radiation by titania nanorods. Thus our study provides the clue/grounds to select mulberry fibers/titania composite as a material of choice for fabrication of promising antimicrobial future textile.

NK1.1+ CD8+ T cells escape TGF-β control and contribute to early microbial pathogen response.

Following microbial pathogen invasion, one of the main challenges for the host is to rapidly control pathogen spreading to avoid vital tissue damage. Here we report that an effector CD8(+) T-cell population that expresses the marker NK1.1 undergoes delayed contraction and sustains early anti-microbial protection. NK1.1(+) CD8(+) T cells are derived from CD8(+) T cells during priming, and their differentiation is inhibited by transforming growth factor-β signalling. After their own contraction phase, they form a distinct pool of KLRG1 CD127 double-positive memory T cells and rapidly produce both interferon-γ and granzyme B, providing significant pathogen protection in an antigen-independent manner within only a few hours. Thus, by prolonging the CD8(+) T-cell response at the effector stage and by expressing exacerbated innate-like features at the memory stage, NK1.1(+) cells represent a distinct subset of CD8(+) T cell that contributes to the early control of microbial pathogen re-infections.

Monotreme lactation protein is highly expressed in monotreme milk and provides antimicrobial protection.

Monotremes (platypus and echidna) are the descendants of the oldest ancestor of all extant mammals distinguished from other mammals by mode of reproduction. Monotremes lay eggs following a short gestation period and after an even briefer incubation period, altricial hatchlings are nourished over a long lactation period with milk secreted by nipple-less mammary patches located on the female’s abdomen. Milk is the sole source of nutrition and immune protection for the developing young until weaning. Using transcriptome and mass spectrometry analysis of milk cells and milk proteins, respectively, a novel Monotreme Lactation Protein (MLP) was identified as a major secreted protein in milk. We show that platypus and short-beaked echidna MLP genes show significant homology and are unique to monotremes. The MLP transcript was shown to be expressed in a variety of tissues; however, highest expression was observed in milk cells and was expressed constitutively from early to late lactation. Analysis of recombinant MLP showed that it is an N-linked glycosylated protein and biophysical studies predicted that MLP is an amphipathic, α-helical protein, a typical feature of antimicrobial proteins. Functional analysis revealed MLP antibacterial activity against both opportunistic pathogenic Staphylococcus aureus and commensal Enterococcus faecalis bacteria but showed no effect on Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis, and Salmonella enterica. Our data suggest that MLP is an evolutionarily ancient component of milk-mediated innate immunity absent in other mammals. We propose that MLP evolved specifically in the monotreme lineage supporting the evolution of lactation in these species to provide bacterial protection, at a time when mammals lacked nipples.

Influence of the Temperature on the Efficiency of Cellulose Treatment Using Copolymer Chitosan-Eugenol

In order to achieve effective antimicrobial protection of textile materials against microorganisms, a natural compound called chitosan has become very interesting. In regard to the antimicrobial protection of textile materials, functionalization with chitosan does not affect some other properties, such as antioxidative or any other action. For this reason, it seems appropriate for chitosan to be combined with any natural antimicrobial active compound, such as eugenol, an extract of clove oil. During this research viscose as a representative of cellulose fibers was used, because it can be functionalized relatively easily. In terms of functionalization, the drying temperature of viscose, after antimicrobial compound application onto substrate, as well as the successful synthesis of copolymer chitosan/eugenol is also important. FTIR spectroscopy was used to evaluate the efficiency of synthesizing a chitosan/eugenol graft copolymer. The spectrophotometric method Acid Orange 7 was chosen as a means for determining the proportion of available antimicrobial active amino groups. In addition, microbiological testing of selected pathogenic micro-organisms was also performed. The results were compared with the results for viscose functionalized by a 1% solution of chitosan.

Rehabilitación bucal bajo anestesia general en pacientes cardiópatas. Experiencia de cuatro años en el Instituto Nacional de Pediatría

Objective. To analyze presurgical and transurgical conditions of cardiac patients previously treated for oral rehabilitation under general anesthesia. Materials and methods. The records of operated cardiac patients who were previously treated for rehabilitation of the oral cavity under general anesthesia were reviewed. The nature of the cardiopathy was recorded. Results. Both operated patients and those in waiting-list for cardiac surgery were rehabilitated of the oral cavity; some patients with cardiac surgery did not have rehabilitation of the oral cavity. Conclusions. Ideally any child who requires cardiac surgery should be free of oral cavity infections. Therefore a narrower communication between (among) the Services of Cardiovascular Surgery and Stomatology is required for the benefit of the patient. If a cardiac patient is in need of surgery and has dental caries, it is important to value risk/benefit of the operation taking into consideration the number and extention of the dental lesions. Cardiac surgery can be performed by an adequate antimicrobial protection. On the contrary, it is not mandatory to put risk the life of the patient with a surgery that can be postponed after dental infections are eliminated, bearing in mind that a