Poly(Allylamine Hydrochloride) and ZnO Nanohybrid Coating for the Development of Hydrophobic, Antibacterial, and Biocompatible Textiles.

In healthcare facilities, infections caused by Staphylococcus aureus (S. aureus) from textile materials are a cause for concern, and nanomaterials are one of the solutions; however, their impact on safety and biocompatibility with the human body must not be neglected. This study aimed to develop a novel multilayer coating with poly(allylamine hydrochloride) (PAH) and immobilized ZnO nanoparticles (ZnO NPs) to make efficient antibacterial and biocompatible cotton, polyester, and nylon textiles. For this purpose, the coated textiles were characterized with profilometry, contact angles, and electrokinetic analyzer measurements. The ZnO NPs on the textiles were analyzed by scanning electron microscopy and inductively coupled plasma mass spectrometry. The antibacterial tests were conducted with S. aureus and biocompatibility with immortalized human keratinocyte cells. The results demonstrated successful PAH/ZnO coating formation on the textiles, demonstrating weak hydrophobic properties. Furthermore, PAH multilayers caused complete ZnO NP immobilization on the coated textiles. All coated textiles showed strong growth inhibition (2-3-log reduction) in planktonic and adhered S. aureus cells. The bacterial viability was reduced by more than 99%. Cotton, due to its better ZnO NP adherence, demonstrated a slightly higher antibacterial performance than polyester and nylon. The coating procedure enables the binding of ZnO NPs in an amount (<30 µg cm-2) that, after complete dissolution, is significantly below the concentration causing cytotoxicity (10 µg mL-1).

Antibacterial evaluation of different prosthetic liner textiles coated by CuO nanoparticles.

Prosthetic liners are mainly used as an interface between residual limbs and prosthetic sockets to minimize physical and biological damage to soft tissue. However, the closed and moist conditions within liners and the amputee's skin provide a suitable environment for bacterial growth to cause infections. This study aimed to coat a comprehensive variant material with copper oxide nanoparticles (CuO NPs) and compare their surface analysis and antibacterial properties. These materials were covered with CuO NPs solution at a concentration of 70 µg mL-1 to achieve this purpose. After drying, their surface characteristics were analyzed by measuring zeta potential, contact angle, surface roughness, and fiber arrangement. Cu-released concentration from the coatings into the acetate buffer solution by inductively coupled plasma mass spectrometry indicated that lycra and nylon quickly released Cu ions to concentrations up to ∼0.2 µg mL-1 after 24 h, causing low metabolic activity of human bone-marrow mesenchymal stem cells (bMSC) in the indirect assay. Antibacterial activity of the coated specimens was evaluated by infecting their surfaces with the Gram-positive bacteria Staphylococcus epidermidis, reporting a significant ∼40 % reduction of metabolic activity for x-dry after 24 h; in addition, the number of viable bacterial colonies adhered to the surface of this material was reduced by ∼23 times in comparison with non-treated x-dry that were visually confirmed by scanning electron microscope. In conclusion, CuO NPs x-dry shows optimistic results to pursue further experiments due to its slow speed of Cu release and prolonged antibacterial activity, as well as its compatibility with human cells.

Antifungal Effect of Polymethyl Methacrylate Resin Base with Embedded Au Nanoparticles.

Full and partial restorations in dentistry must replicate the characteristics of the patient's natural teeth. Materials must have good mechanical properties and be non-toxic and biocompatible. Microbes, which can form biofilms, are constantly in contact with restorations. In this study, we investigate how well Candida albicans adheres to a polymethyl methacrylate (PMMA) resin base with gold (Au) nanoparticles. We synthesized Au nanoparticles and characterized them. The average size of Au nanoparticles embedded in PMMA was 11 nm. The color difference ΔE between PMMA and PMMA/Au composites was 2.7 and was still esthetically acceptable to patients. PMMA/Au surfaces are smoother and more hydrophilic than pure PMMA surfaces, and the isoelectric point of both types of surfaces was 4.3. Above the isoelectric point, PMMA/Au surfaces are more negatively charged than PMMA surfaces. The added Au nanoparticles decreased the tensile strength, while the hardness did not change significantly. Adhesion measurements showed that PMMA surfaces modified with Au nanoparticles reduced the extent of microbial adhesion of Candida albicans.

The occurrence of antibiotic-resistant bacteria on the clothes of nursery teachers in daycare centres.

AIMS: Childcare facilities act as microenvironments that facilitate and promote the selection, spread and transmission of antibiotic-resistant micro-organisms in the community. We focused on the study of antimicrobial resistance and genetic predispositions for ß-lactamase production in bacterial isolates from nursery teachers' clothing. METHODS AND RESULTS: Antimicrobial resistance of bacterial strains belonging to Enterobacteriaceae, Enterococcus, Staphylococcus spp., Pseudomonas spp. and Bacillus spp. isolated from 80 samples of nursery teachers' clothing was determined. The selected ESßL genes were found in 30 (44.1%) of 68 strains examined. The CTX-M type ESßL determinants were detected in 15.4%, 71.5% and 42.5% of the Enterobacteriaceae, Pseudomonas and Bacillus isolates, respectively. The OXA-type coding genes were detected only in strains of the genera Pseudomonas (57.1%) and Bacillus (48.6%). Thus, most B. cereus strains were sensitive to the recommended antibiotics used to treat infections caused by these bacteria. Methicillin resistance was phenotypically confirmed in 27 (14.6%) of 185 staphylococcal isolates. Four isolates (2.2%) were identified as MRSA. Vancomycin resistance was not observed in any of the staphylococcal and enterococci strains. CONCLUSIONS: This study has shown that potential pathogens have been isolated from the clothing of nursery teachers, posing a risk of transmission to children. These clothes should be maintained and properly laundered to avoid cross-contamination and the spread of multidrug-resistant (MDR) bacteria in childcare centres. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides insight into the route of transmission of MDR micro-organisms through the clothing of nursery teachers, to which greater importance should be given in the future. Proper procedures for the cleaning and use of clothing in daycare centres should be clarified and standardized.

Biophysical Properties of Foamed and Solid Polymers Used in Orthotics and Prosthetics.

Orthotic and prosthetic materials should have good mechanical and antibacterial properties. Therefore, in our study, we consider four common foamed closed-cells and two solid polymeric materials regarding their mechanical behaviour and tendency for bacterial adhesion. For all materials, the surface roughness, hydrophobicity, zeta potential, tensile properties, hardness and CIE color parameters were measured. We found that foamed polymeric materials have higher roughness, higher hydrophobicity, lower Young's modulus, lower maximum tensile strength and lower hardness than solid materials. Bacterial adhesion test measurements based on observation by scanning electron microscopy show much a lower adhesion extent of S. aureus on solid materials than on foamed materials. The measured biophysical properties could be the key data for users to select the optimal materials.

Bacterial Adhesion of Streptococcus mutans to Dental Material Surfaces.

The aim of this study was to investigate and understand bacterial adhesion to different dental material surfaces like amalgam, Chromasit, an Co-Cr alloy, an IPS InLine ceramic, yttrium stabilized tetragonal polycrystalline zirconia (TPZ), a resin-based composite, an Au-Pt alloy, and a tooth. For all materials, the surface roughness was assessed by profilometry, the surface hydrophobicity was determined by tensiometry, and the zeta potential was measured by electrokinetic phenomena. The arithmetic average roughness was the lowest for the TPZ ceramic (Ra = 0.23 µm ± 0.02 µm), while the highest value was observed for the Au-Pt alloy (Ra = 0.356 µm ± 0.075 µm). The hydrophobicity was the lowest on the TPZ ceramic and the highest on the Co-Cr alloy. All measured streaming potentials were negative. The most important cause of tooth caries is the bacterium Streptococcus mutans, which was chosen for this study. The bacterial adhesion to all material surfaces was determined by scanning electron microscopy. We showed that the lowest bacterial extent was on the amalgam, whereas the greatest extent was on tooth surfaces. In general, measurements showed that surface properties like roughness, hydrophobicity and charge have a significant influence on bacterial adhesion extent. Therefore, dental material development should focus on improving surface characteristics to reduce the risk of secondary caries.

Bacterial adhesion on orthopedic implants.

Orthopedic implants are routinely used for fixation of fractures, correction of deformities, joint replacements, and soft tissue anchorage. Different biomaterials have been engineered for orthopedic implants. Previously, they were designed merely as mechanical devices, now new strategies to enhance bone healing and implant osteointegration via local delivery of molecules and via implant coatings are being developed. These biological coatings should enhance osteointegration and reduce foreign body response or infection. This article reviews current and future orthopedic implants, materials and surface characteristics, biocompatibility, and mechanisms of bacterial adhesion. Additionally, the review is addressing implant-related infection, the main strategies to prevent it and suggest possible future research that may control implant related-infection.

Bacterial adhesion rate on food grade ceramics and Teflon as kitchen worktop surfaces.

Here we present a research of bacterial adhesion to two most often used materials in modern kitchens, namely food grade ceramics and Teflon. To test the bacterial adhesion on kitchen worktops Escherichia coli, Pseudomonas aeruginosa and Campylobacter jejuni were used as the most common foodborne contaminants. Contact angle, roughness and streaming potential measurements were used for surface characterization. Crystal violet staining and scanning electron microscopy were applied for bacterial adhesion analysis. We showed that the adhesion of tested bacteria strains was lower on the Teflon surface compared to the ceramics. The hydrophobicity of the surface substantially contributed to the bacterial adhesion rate. On the other hand, the surface roughness and charge did not play a crucial role in the adhesion process.

Characterization of Borrelia burgdorferi sensu lato isolates by pulsed-field gel electrophoresis after MluI restriction of genomic DNA.

At least three Borrelia species (Borrelia afzelii, Borrelia garinii and Borrelia burgdorferi sensu stricto) cause disease in humans, but Borrelia spielmanii, Borrelia valaisiana, Borrelia lusitaniae and Borrelia bissettii have also been reported to be rare or potential causes of human disease in Europe. Pulsed-field gel electrophoresis after MluI restriction of the genomic DNA (MluI large restriction fragment patterns, LRFPs) represents one of several approaches that have been used to assess Borrelia genotypic characteristics. The aim of the present report was to analyze the value of MluI-LRFP for identification of B. burgdorferi sensu lato at a species level and for further species subtype delineation. Results of the present study are based on 1487 B. afzelii strains, 285 B. garinii strains, 29 B. burgdorferi sensu stricto strains, 23 B. valaisiana strains, 8 B. spielmanii strains and 3 B. lusitaniae strains. Using MluI-LRFP, we were able to delineate all Borrelia species included in the study. Each of the six examined Borrelia species displayed unique MluI-LRFPs that enabled straightforward separation of strains into particular species, and also of strains within species. The subtypes of B. afzelii (Mla2 and Mla3), B. spielmanii (Mls1 and Mls2) and B. lusitaniae (Mll1 and Mll2) uncovered in the present analysis have not been reported previously. MluI-LRFP represents a highly specific and reproducible method for Borrelia identification.

Sensitivity of culture and polymerase chain reaction for the etiologic diagnosis of erythema migrans.

Skin biopsy samples from 150 patients with typical cutaneous manifestation of Lyme borreliosis, erythema migrans, were cultivated for the presence of Borrelia burgdorferi sensu lato in modified Kelly Pettenkofer (MKP) medium and analysed with two different polymerase chain reactions using either flagellin or nested OspA primers. Cultivation was successful in 75 of 150 (50%) skin samples. Out of 70 strains that were typed using PFGE, B. afzelii was identified in 60 (86%), B. garinii in 10 (14%) specimens, while no B. burgdorferi sensu stricto strains were found. B. burgdorferi sensu lato DNA was detected with polymerase chain reaction in 28% and 61% of skin samples, using flagellin and nested OspA primers, respectively. Concordant results in all three procedures employed in the present study were found in 62 (41%) specimens: 25/150 (17%) were positive with all three methods and 37/150 (25%) samples were completely negative.