Inhibition Of Bacterial Adhesion Research Articles

Lactobacillus plantarum surface layer adhesive protein protects intestinal epithelial cells against tight junction injury induced by enteropathogenic Escherichia coli

Lactobacillus plantarum (LP) has previously been used for the treatment and prevention of intestinal disorders and disease. However, the role of the LP surface layer adhesive protein (SLAP) in inhibition of epithelial cell disruption is not fully understood. The aim of the present study was to investigate the protective effects of purified SLAP on Caco-2 cells infected with enteropathogenic Escherichia coli (EPEC). The role of ERK in LP-mediated inhibition of tight junction (TJ) injury was also evaluated in order to determine the molecular mechanisms underlying the protective effects of LP in epithelial cells. SLAP was extracted and purified from LP cells using a porcine stomach mucin-Sepharose 4B column. SLAP-mediated inhibition of bacterial adhesion was measured using a competition-based adhesion assay. Expression of TJ-associated proteins, maintenance of TJ structure, and levels of extracellular signal regulated kinase (ERK) and ERK phosphorylation were assessed in SLAP-treated cells by a combination of real-time PCR, western blotting, and immunofluorescence microscopy. Cell permeability was analyzed by measurement of trans-epithelial electrical resistance (TER) and dextran permeability. The effect of SLAP on levels of apoptosis in epithelial cells was assessed by flow cytometry. Results from these experiments revealed that treatment with SLAP decreased the level of adhesion of EPEC to Caco-2 cells. SLAP treatment also enhanced expression of TJ proteins at both the mRNA and protein levels and affected F-actin distribution. Although ERK levels remained unchanged, ERK phosphorylation was increased by SLAP treatment. Caco-2 cells treated with SLAP exhibited increased TER and decreased macromolecular permeability, which was accompanied by a decrease in the level of apoptosis. Together, these results suggest that LP-produced SLAP protects intestinal epithelial cells from EPEC-induced injury, likely through a mechanism involving ERK activation.

Bacterial adhesion inhibition of the quaternary ammonium functionalized silica nanoparticles

Quaternary ammonium compounds have been considered as excellent antibacterial agents due to their effective biocidal activity, long term durability and environmentally friendly performance. In this work, 3-(trimethoxysilyl)-propyldimethyloctadecylammonium chloride as a quaternary ammonium silane was applied for the surface modification of silica nanoparticles. The quaternary ammonium silane provided silica surface with hydrophobicity and antibacterial properties. In addition, the glass surface which was coated with the surface modified silica nanoparticles presented bacterial growth inhibition activity. For comparison of bacterial growth resistance, hydrophobic silane (alkyl functionalized silane) modified silica nanoparticles and pristine silica nanoparticles were prepared. As a result of bacterial adhesion test, the quaternary ammonium functionalized silica nanoparticles exhibited the enhanced inhibition performance against growth of Gram-negative Escherichia coli (96.6%), Gram-positive Staphylococcus aureus (98.5%) and Deinococcus geothermalis (99.6%) compared to pristine silica nanoparticles. These bacteria resistances also were stronger than that of hydrophobically modified silica nanoparticles. It could be explained that the improved bacteria inhibition performance originated from the synergistic effect of hydrophobicity and antibacterial property of quaternary ammonium silane. Additionally, the antimicrobial efficacy of the fabricated nanoparticles increased with decreasing size of the nanoparticles.

Inhibition of bacterial adherence on the surface of biliary stent materials modified with chitosan

Bacterial infection plays an important role in the initiation of biliary sludge formation. Bacterial adherence and biofilm formation on the surface of a material have been considered as one of the main factors of stent re-occlusion in clinic. This work reported preventing bacterial adherence and bacterial biofilm formation on the surface of biliary stent material using chitosan film. The chitosan film was deposited on 316 L stainless steel (SS) plate by electrophoresis method and was characterized by X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). The ability of inhibiting bacterial adherence was investigated by incubating in human fresh bile adding E. coli and Enterobacter at 37±1 °C. Scanning electron microscopy (SEM) and fluorescence staining were used for observing bacterial colonization and biofilm formation. The results show that chitosan film was uniformly deposited on material surface, and the composition of the film did not change through cross-linking, but the crystallinity of chitosan film become well. Comparing to un-modified sample, the E. coli and Enterococcus adhesion amount and colonization on the surface of modified sample were significantly decreased by fluorescence staining and SEM. It is suggested that chitosan could be applied to biliary stent in clinical because of its antimicrobial activities.

Glyco-pseudopolyrotaxanes: Carbohydrate Wheels Threaded on a Polymer String and Their Inhibition of Bacterial Adhesion

We report glyco-pseudopolyrotaxanes composed of cucurbit[6]uril-based mannose wheels (ManCB[6]) threaded on polyviologen (PV), which not only effectively induce bacterial aggregation, but also exhibit high inhibitory activity against bacterial binding to host cells. Three glyco-pseudopolyrotaxanes (1-3), which have 10, 5, and 3 ManCB[6] wheels, respectively, on a PV string, were prepared and characterized. Bacterial aggregation assays and hemagglutination inhibition assays illustrated the specific and multivalent interaction between the glyco-pseudopolyrotaxanes and E. coli ORN178. Compound 3 was especially effective at inducing bacterial aggregation and showed 300 times higher inhibitory potency than monomeric methyl-α-mannoside (Me-αMan) for ORN178-induced hemagglutination. Furthermore, we demonstrated their inhibitory activities for the adhesion of ORN178 bacteria to urinary epithelial cells as a model of urinary tract infection. Our findings suggest that these supramolecular carbohydrate clusters are potentially useful in antiadhesion therapy.

An in vitro assessment of titanium functionalized with polysaccharides conjugated with vascular endothelial growth factor for enhanced osseointegration and inhibition of bacterial adhesion

The long-term success of orthopedic implants may be compromised by defective osseointegration and bacterial infection. An effective approach to minimize implant failure would be to modify the surface of the implant to make it habitable for bone-forming cells and anti-infective at the same time. In this in vitro study, the surfaces of titanium (Ti) substrates were functionalized by first covalently grafting either dopamine followed by carboxymethyl chitosan (CMCS) or hyaluronic acid-catechol (HAC). Vascular endothelial growth factor (VEGF) was then conjugated to the polysaccharide-grafted surface. Antibacterial assay with Staphylococcus aureus ( S. aureus) showed that the polysaccharide-modified substrates significantly decrease bacterial adhesion. The CMCS-functionalized Ti demonstrated better antibacterial property than the HAC-functionalized Ti since CMCS is bactericidal while HA only inhibits the adhesion of bacteria without killing them. Osteoblast attachment, as well as alkaline phosphatase (ALP) activity and calcium deposition were enhanced by the immobilized VEGF on the polysaccharide-grafted Ti. Thus, Ti substrates modified with polysaccharides conjugated with VEGF can promote osteoblast functions and concurrently reduce bacterial adhesion. Since VEGF is also known to enhance angiogenesis, the VEGF-polysaccharide functionalized substrates will have promising applications in the orthopedic field.

Surface hydrophilization of microporous polypropylene membrane by grafting zwitterionic polymer for anti-biofouling

The anti-biofouling properties, i.e. the resistance to protein adsorption and the inhibition of bacterial adhesion (biofilm formation) are of vital importance to separation membranes. Surface hydrophilization is thought to be the most common approach to improve these performances for hydrophobic polymer membranes, such as microporous polypropylene membrane (MPPM). In this work, MPPM was highly hydrophilized by the UV-induced grafting of polysulfobetaine methacrylate (polySBMA), an outstanding representative of zwitterionic anti-/non-fouling polymers. A sequential grafting strategy was improved by combining the conventional benzophenone entrapment and covalent immobilization methods. FT-IR/ATR, XPS and FESEM were used to characterize the detailed surface structures of MPPM. The hydrophilization effect was evaluated by water contact angle (WCA) and pure water flux measurements. Besides, both protein filtration and initial adhesion of bacteria were performed to investigate the anti-biofouling properties of the modified MPPM. The surface hydrophobicity of the bacteria was also measured and correlated with the adhesion results. It is found that the improved strategy allows the grafting to take place on the external surface and the grafting density to be well controlled by modulating the SBMA concentration. The surface hydrophilicity of MPPM is significantly enhanced, characterized by a decrease of WCA from 145 to ∼15° and an increase of flux by 4 times. These hydrophilized MPPM has strong resistance to protein fouling, having a flux recovery ratio higher than 95% under optimized conditions. The initial adhesion of bacteria on the MPPM can be completely suppressed when the grafting density reaches 560 μg/cm 2, regardless of the bacterial surface hydrophobicity.

Studies on novel silicone/phosphorus/sulphur containing nano-hybrid epoxy anticorrosive and antifouling coatings

The objective of the present work is the development and characterization of silicone, phosphorous and sulphur containing nano-coatings using diglycidyl ether of bisphenol-A type epoxy resin (DGEBA) as base material, tris (p-isocyanatophenyl) thio phosphate (DESMODUR) as modifier and POSS-NH 2 (polyhedraloligomeric silsesquioxane) as nano-reinforcement. The nano-coatings were cured by Aradur 140 (polyamidoimidazoline) and XY 54 (polyamidoamine) curatives. The corrosion and fouling resistant properties of these coatings were evaluated by potentiodynamic polarization, electrochemical impedance, salt-spray and antifouling tests. It was interesting to observe that the molecular structure of curing agents as well as the nano-reinforcing effect of POSS-NH 2 significantly influenced their corrosion and fouling protection behaviour. For example, coating system ‘1’ alone retained an impedance value of 10 9 ohm cm 2 even after 30 days of immersion indicating no deterioration on the coating. However the impedance values of other specimens decreased from 10 9 to 10 7 and 10 6 ohm cm 2. This observation clearly indicates the synergistic effect of curing agent and nano-reinforcing effect of POSS-NH 2 towards corrosion resistance. Similar observation was made from the antifouling study, with a marked inhibition of bacterial adhesion on such coated panels.

Inhibition of bacterial adhesion on well ordered comb-like polymer surfaces

The surfaces of comb-like poly(oxyethylene) derivatives with n-alkylsulfonyl side groups were more effective at reducing Pseudomonas aeruginosa adhesion than the surfaces of common materials such as polystyrene, poly(methyl methacrylate), poly(dimethylsiloxane), fluorinated polyacrylate, and glass. When the comb-like poly(oxyethylene) was mixed with polystyrene and poly(methyl methacrylate), the topology and roughness of the surfaces varied according to the mixture compositions. However the surface energies of the mixtures were close to that of the comb-like poly(oxyethylene) in the range of 21–23 mN/m and bacterial adhesion resistances of the mixture surfaces were also comparable to that of the pure comb-like poly(oxyethylene) surface.

Effects of a partially digested whey protein concentrate on Salmonella enterica serotype Typhimurium adhesion to Caco-2 cells : Prevention of Salmonella adhesion to Caco-2 cells using whey

The effect of a partially lipase-digested whey protein concentrate (WPD) containing free fatty acids on the adherence of Salmonella enterica serovar Typhimurium to Caco-2 cells was investigated. A short concurrent exposure of the Caco-2 monolayers and WPD caused dose-dependent inhibition of bacterial adhesion. Pre-treatment of S. Typhimurium with WPD resulted in inhibition of adhesion equivalent to that with concurrent administration, whereas treatment with WPD did not significantly inhibit adhesion. WPD was not bactericidal towards S. Typhimurium at up to 50 mg ml −1 for up to 1 h, but was bacteriostatic over 12 h. High concentrations of WPD (>20 mg ml −1) were cytotoxic to newly-confluent cell monolayers, depending on the duration of exposure. Lactoferrin (LF), caseinoglycomacropeptide (CGMP), and gamma globulins all significantly inhibited S. Typhimurium adhesion.

A kit for the investigation of live Escherichia colicell adhesion to glycosylated surfaces

A combination of microtiter plate functionalization techniques and two facile bacterial adhesion inhibition assays form a flexible toolbox for the investigation of bacterial adhesion mechanisms on glycosylated surfaces.

Bovine Muc1 inhibits binding of enteric bacteria to Caco-2 cells

Inhibition of bacterial adhesion to intestinal epithelial receptors by the consumption of natural food components is an attractive strategy for the prevention of microbial related gastrointestinal illness. We hypothesised that Muc1, a highly glycosylated mucin present in cows' milk, may be one such food component. Purified bovine Muc1 was tested for its ability to inhibit binding of common enteric bacterial pathogens to Caco-2 cells grown in vitro. Muc1 caused dose-dependent binding inhibition of Escherichia coli, Salmonella enterica serovar Typhimurium (S. Typhimurium), Staphylococcus aureus and Bacillus subtilis. This inhibition was more pronounced for the Gram negative compared with Gram positive bacteria. It was also demonstrated that Muc1, immobilised on a membrane, bound all these bacterial species in a dose-dependent manner, although there was greater interaction with the Gram negative bacteria. A range of monosaccharides, representative of the Muc1 oligosaccharide composition, were tested for their ability to prevent binding of E. coli and S. Typhimurium to Caco-2 cells. Inhibition was structure dependent with sialic acid, L(-) fucose and D(+) mannose significantly inhibiting binding of both Gram negative species. N-acetylglucosamine and N-acetylgalactosamine significantly inhibited binding of E. coli whilst galactose, one of the most abundant Muc1 monosaccharides, showed the strongest inhibition against S. Typhimurium. Treatment with sialidase significantly decreased the inhibitory properties of Muc1, demonstrating the importance of sialic acid in adhesion inhibition. It is concluded that bovine Muc1 prevents binding of bacteria to human intestinal cells and may have a role in preventing the binding of common enteropathogenic bacteria to human intestinal epithelial surfaces.

UP-3.156: Preparation and Characterization of Phosphomycin Loaded Double-J Stents

Urethral stents are frequently used in the urinary tract disorders. Encrustation, bacterial adhesion and catheter associated urinary tract infections (CAUTI) are the potential complications of long term usage of urethral stents.Aim of the presented study was the modification of double-J stent surfaces for the inhibition of bacterial adhesion and encrustation.

Streptomycessp. ST8 extracts attenuate growth, acid production, adhesion, biofilm formation, and water-insoluble glucan synthesis ofStreptococcus mutans

The purpose of this study was to evaluate the inhibitory effects of crude extract of endophytic Streptomyces sp . ST8 against Streptococcus mutan s, which is one of the major causes of dental caries and oral diseases. The extract from culture filtrate of endophytic Streptomyces sp. ST8 by ethylacetate has activity against S. mutans ATCC25175 and 104B. The extract at such concentrations (0.05-5 mg/ml) demonstrated inhibition of bacterial adherence on glass surfaces and saliva-coated hydroxyapatite. The crude extract also decreased the activity of glucosyltransferase and glucan-binding lectin from both strains. These results suggest that the crude extract of endophytic Streptomyces sp. ST8 may be a new potential source for pharmaceutical products used for prevention and/or treatment of dental caries and periodontal disease. Key words: adherence, biofilm production, glucan-binding lectin, glucosyltransferase, endophytic Streptomyces, Streptococcus mutans

Patterned macroarray plates in comparison of bacterial adhesion inhibition of tantalum, titanium, and chromium compared with diamond‐like carbon

Staphylococcus aureus device-related infection is a common complication in implantology. Bacterial adhesion on implant surfaces is the initial step in the infective process. The aim was to develop a method suitable for quantitative bacterial adherence studies and to test a new diamond-like carbon (DLC) coating against commonly used metallic biomaterials with regards to Staphylococcus aureus adhesion. Patterned silicon chips with spots of tantalum, titanium, chromium, and DLC were produced using ultraviolet lithography and physical vapor deposition. These patterned chips were used as such or glued to array plates, pretreated with serum and exposed to S. aureus (S-15981) for 90 min, followed by acridine orange staining and fluorescence microscopy. An adhesion index showed that the ranking order of the biomaterials was titanium, tantalum, chromium, and DLC, with the DLC being clearly most resistant against colonization with S. aureus. Micropatterned surfaces are useful for quantitative comparison of bacterial adherence on different biomaterials. In the presence of serum, DLC is superior in its ability to resist adhesion and colonization by S. aureus compared with the commonly used biomaterial metals tantalum, titanium, and chromium.

Titanium with Surface-Grafted Dextran and Immobilized Bone Morphogenetic Protein-2 for Inhibition of Bacterial Adhesion and Enhancement of Osteoblast Functions

Failure of bone and joint implants has been attributed mainly to poor bonding of the implant to bone tissue, and to bacterial infection. The probability of successful osseointegration or implant infection depends on the race for the surface between tissue cells and bacteria. One promising strategy to enhance tissue integration is to develop a selective biointeractive surface that increases bone cell (osteoblast) function while decreasing bacterial adhesion. In this in vitro study, the surface of titanium alloy substrates was first functionalized by covalently grafted oxidized dextran, which is known to have activity against bacterial adhesion. Bone morphogenetic protein-2 (BMP-2) was then covalently linked to dextran-grafted surfaces through a chemical conjugation process. The composition and properties of the surface were investigated by X-ray photoelectron spectroscopy and by measuring the surface density of BMP-2 using an enzyme-linked immunosorbent assay. Bacterial adhesion was assayed with Staphylococcus aureus and Staphylococcus epidermidis. Bacterial adhesion on both the dextran and dextran-BMP-2-functionalized surfaces was significantly decreased compared to that on the pristine substrates. Further, the dextran-BMP-2 modified substrates with a surface protein density of >50 ng/cm(2) or higher significantly promoted osteoblast spreading, alkaline phosphatase activity, and calcium mineral deposition. Thus, the results from this study suggest that surface grafting of dextran in conjunction with the bone growth factor BMP-2 on metal surfaces can enhance tissue integration of implants through the dual functions of reducing bacterial adhesion and promoting osteoblast functions.

Effect of cefuroxime and moxifloxacin on Staphylococcus epidermidis adherence to intraocular lenses

Objective: To investigate and compare the effect of cefuroxime and moxifloxacin on adhesion of Staphylococcus epidermidis to intraocular lenses (IOLs). Design: Experimental study Methods: The 3-pieced hydrophobic acrylic lenses were contaminated with S. epidermidis (American Type Culture Collection 35983) solutions containing 10 8 colony-forming units. IOLs were inoculated into test tubes containing tryptic soy broth after being held in antibiotic solutions for 15 minutes. Sonication and vortex procedures were performed in order to remove all the remaining bacteria. From each tube 10 μL and 100 μL was taken and inoculated into sheep blood agar. The colonies were counted overnight. The statistical analyses were made using oneway ANOVA, Tukey Honestly Significant Differences test (HSD) and independent t tests, and a p value less than 0.05 was considered statistically significant. Results: Overall, the mean numbers of colony-forming units on the lenses that were held in control, cefuroxime, moxifloxacin 0.5 mg/0.1 mL and moxifloxacin 0.1 mg/0.1 mL solutions were 1398 (SE 10.01 × 10 3), 29.9 (SE 1.16 × 10 3), 0.23 (SD 0.04 × 10 3), and 0.41 (SD 0.05 × 10 3), respectively. The evaluation using one-way ANOVA and Tukey HSD tests revealed significant statistical differences among the groups ( p = 0.000).The evaluation using independent t tests revealed significant statistical differences between the 2 moxifloxacin groups ( p < 0.05). Conclusion: Our results suggest that moxifloxacin and cefuroxime significantly inhibit bacterial adherence to IOLs. The effect of moxifloxacin on inhibition of bacterial adherence was significantly greater than that of cefuroxime. For this reason moxifloxacin might be considered as a better prophylactic agent.

Effect of Molecules Secreted by Lactobacillus acidophilus Strain La-5 on Escherichia coli O157:H7 Colonization

The probiotic bacterium Lactobacillus acidophilus strain La-5 is a gut-colonizing microorganism that, when established, becomes an important part of the gastrointestinal (GI) tract microbiota. It has been shown to be effective against enterohemorrhagic Escherichia coli (EHEC) O157:H7 infection. We have previously shown that molecules released by probiotic strain La-5 influence the transcription of EHEC genes involved in colonization and quorum sensing. In this work, we report on the ability of these molecules to prevent the adherence of EHEC to epithelial cells and on its capacity to concentrate F-actin at adhesion sites. With a fluorescein-labeled phallotoxin, it was shown that La-5 cell-free spent medium (CFSM) fractions remarkably reduced attaching and effacing lesions in HeLa cells. We also observed a significant inhibition of bacterial adhesion to Hep-2 cells when they were treated with the same La-5 CFSM fractions. In order to observe if La-5 CFSM fractions exhibited the same effect in vivo, we studied the ability of luminescent EHEC constructs (LEE1::luxCDABE) to adhere to intestinal epithelial cells of specific-pathogen-free ICR mice following intragastric inoculation. Colonization of the GI tract by luminescent EHEC O157:H7 was monitored in real time with a slow-scan charge-coupled device camera. At the same time, fecal shedding of EHEC was studied. Following oral gavage of the La-5 active fraction, we observed a reduced amount of bioluminescence signal along with a decrease in fecal shedding by mice, indicating an effect on the ability of the organism to colonize the GI tract. Our results confirm past evidence of the possibility of blocking or interfering with EHEC's virulence by active molecules contained in the probiotic CFSM and identify novel therapeutic alternatives to antibiotic treatments in the fight against food-borne pathogens.

Nanostructured Materials for Inhibition of Bacterial Adhesion in Orthopedic Implants: A Minireview

Orthopedic implants may fail owing to different reasons: poor osseointegration at the tissue-implant interface, generation of wear debris, stress and strain imbalance between implant and surrounding tissues, and infections. To ensure success in orthopedics, implant materials must not evoke an undesirable inflammatory response, they must be habitable by bone-forming cells (favoring adhesion of osteoblasts), hinder formation of soft connective tissue (hindering adhesion of fibroblasts), and be anti-infective (discouraging bacterial adhesion). Recent studies have suggested that nanophase materials have a better efficacy as bone implants in favoring osseointegration compared to conventional orthopedic implant materials. This minireview discusses studies on nanophase materials as bone implants, focusing on the effect of these materials in inhibiting bacterial adhesion for the prevention of implant infections.

Cranberry Derived Proanthocyanidins Reduce Bacterial Adhesion to Selected Biomaterials

Catheter associated urinary tract infections (CAUTI) linked with the uropathogens Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) account for the majority of nosocomial infections acquired in the clinical environment. Because these infections develop following initial adhesion of the bacterial pathogens to the catheter surface, there is increased interest in developing effective methods to inhibit attachment of cells to biomaterials used in the manufacture of indwelling devices. High molecular weight proanthocyanidins (PAC) extracted from the North American cranberry (Vaccinium macrocarpon) were examined for their potential to reduce the initial adhesion of uropathogenic bacteria (E. coli CFT073 and E. faecalis 29212) to two model biomaterials, poly(vinyl chloride) (PVC) and polytetrafluoroethylene (PTFE). Well-controlled experiments conducted in a parallel-plate flow chamber (PPFC) demonstrated decreased attachment of both bacteria to PVC and PTFE when either the bacteria, biomaterial or both surfaces were treated with PAC. Most significant inhibition of bacterial adhesion was observed for the condition where both the bacteria and biomaterial surfaces were coated with PAC. Additional experiments conducted with nonbiological model particles demonstrate comparable extents of adhesion inhibition, supporting a nonbiospecific mechanism of PAC action. The results of this study are promising for the implementation of PAC in the clinical milieu for prevention of device associated infection as the proposed functional modification is independent of antibacterial mechanisms that may give rise to resistant strains.

Characterization of Chitosan Coated Magnetoelastic Materials for Use in Percutaneous Implants

There are upwards of 250,000 cases of infections due to the use of percutaneous devices in the US every year, with an estimated cost of $25,000 per incident. Improving the longevity of these devices is thus of significant clinical and economic importance. Current antimicrobial and junctional healing approaches do not allow for in situ modulation of therapeutic effects. In this work we are developing bioactive vibrational magnetoelastic (ME) materials for use as a remotely activated tunable coating promoting cell differentiation and inhibition of bacterial adhesion at the tissue-implant interface. ME sensors are currently used as an in situ method of measuring biological processes. The objective of this study was to develop an ME antimicrobial coating conducive to cell growth and characterize the antimicrobial and cell inductive response towards frequency-amplitude modulated vibrations. A thin film of Chitosan, a natural polymer with antimicrobial properties, was applied to the material using spin coating and quantified with profilometry and scanning electron microscopy. Custom built activation coils were constructed measuring resonant frequencies and amplitudes of coated and uncoated ME material. Based upon collected data a representative curve was created modeling the changes in resonant frequency and amplitude. Tunable vibrations induced a 30% decrease in bacterial adhesion when compared to non-vibrated controls. Currently we are testing the effectiveness of these coatings at promoting epithelial cell differentiation in addition to inhibition of bacteria adhesion.