Bacterial Adhesion Rate Research Articles

Synthesis of efficient bacterial adhesion-resistant coatings by one-step polydopamine-assisted deposition of branched polyethylenimine-g-poly(sulfobetaine methacrylate) copolymers

Bacterial adhesion-resistant coatings were fabricated by one-step polydopamine-assisted deposition of zwitterionic branched polyethylenimine-g-poly(sulfobetaine methacrylate) copolymers on the substrate. The resistance activities for bacterial adhesion of coatings were evaluated by bacterial adhesion rate and SEM images. It turned out that such coatings resisted over 93% bacterial adhesion for 24 h. The coatings also exhibited a good performance to reduce protein absorption.

Surface Modification of Basalt Fiber with Organic/Inorganic Composites for Biofilm Carrier Used in Wastewater Treatment

Support carrier constitutes the technical core of biofilm processes in wastewater treatment. In this study, basalt fiber (BF) was modified by grafting an organic/inorganic composite, attached to which rich microorganisms were supposed to form biofilm for wastewater treatment. The modified BF (MBF) used as biofilm carriers were investigated in terms of hydrophilicity and surface roughness, which determined their bioaffinity. Fourier transforms infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS) were conducted to study the chemical components. Scanning electron microscopy (SEM) was carried out to observe BF surface morphology. The bioaffinity of BF and MBF was compared in terms of the rate of bacterial adhesion and the ratio of immobilization onto basalt fiber. The bioaffinity of MBF was significantly improved due to introduction of many hydrophilic groups onto BF surfaces, which were subsequently proved to facilitate biofilm formation. The results s...

Effect of 15% Carbamide Peroxide on the Surface Roughness and Adhesion of Streptococcus mutans to Microhybrid Composite Resin and Giomer

ABSTRACT Introduction Adhesion of bacteria, especially Streptococcus mutans (S. mutans), to the surface of tooth restorations is a factor in the etiology of secondary caries. Given the ever-increasing popularity of bleaching procedures, the aim of the present study was to evaluate adhesion of S. mutans and surface roughness (SR) of microhybrid composite resin and giomer subsequent to the application of 15% carbamide peroxide. Materials and methods Twenty disk-shaped samples were prepared from each material, measuring 8 mm in diameter and 2 mm in thickness. Then, the samples of each material were divided into two groups (n = 10): (a) microhybrid without bleaching; (b) microhybrid with bleaching; and (c) giomer without bleaching; and (d) giomer with bleaching. The samples in groups I and III were immersed in artificial saliva for 14 days without any bleaching procedure; the samples in groups II and IV underwent a bleaching procedure on their polished surfaces with 15% carbamide peroxide for 14 days (4 hours of bleaching and 20 hours of immersion in artificial saliva). The SR of all the samples was determined with the use of a profilometer. The samples were added to the culture medium after 4 hours of placement in a microbial suspension at 37°C; after 24 hours of incubation at 37°C, the bacterial counts, indicating the number of bacteria adhering to the surface, were determined by counting them in the plates containing the solid culture medium. Results The type of the restorative material had a significant effect on SR, with greater SR in giomer (p = 0.03). However, bleaching had no significant effect on SR (p = 0.099). In relation to the rate of bacterial adhesion (BA), both the types of the restorative materials and bleaching procedures were significantly effective; in this context, there was more BA in microhybrid composite resin samples that did not undergo bleaching (p < 0.001). Bleaching resulted in the adhesion of S. mutans to the surface of both materials decrease. Pearson's correlation coefficient did not reveal any correlation between BA and SR (p = 0.42). Conclusion The BA was higher in microhybrid composite resin, and SR was higher in giomer. The BA was higher in samples that did not undergo a bleaching procedure. Clinical significance There is no change in the SR of microhybrid composite resin and giomer after application of 15% carbamide peroxide; therefore, it is not necessary to polish or replace these restorative materials after bleaching. In addition, use of 15% carbamide peroxide does not increase caries risk. How to cite this article Mohammadi N, Mowlaie S, Savadi- Oskoee S, Ebrahimi ME, Rikhtegaran S, Rahbar M, Pirzadeh T. Effect of 15% Carbamide Peroxide on the Surface Roughness and Adhesion of Streptococcus mutans to Microhybrid Composite Resin and Giomer. World J Dent 2017;8(4):288-295.

Methods for increasing the rate of anammox attachment in a sidestream deammonification MBBR.

Deammonification (partial nitritation-anammox) is a proven process for the treatment of high-nitrogen waste streams, but long startup time is a known drawback of this technology. In a deammonification moving bed biofilm reactor (MBBR), startup time could potentially be decreased by increasing the attachment rate of anammox bacteria (AMX) on virgin plastic media. Previous studies have shown that bacterial adhesion rates can be increased by surface modification or by the development of a preliminary biofilm. This is the first study on increasing AMX attachment rates in a deammonification MBBR using these methods. Experimental media consisted of three different wet-chemical surface treatments, and also media transferred from a full-scale mainstream fully nitrifying integrated fixed-film activated sludge (IFAS) reactor. Following startup of a full-scale deammonification reactor, the experimental media were placed in the full-scale reactor and removed for activity rate measurements and biomass testing after 1 and 2 months. The media transferred from the IFAS process exhibited a rapid increase in AMX activity rates (1.1 g/m(2)/day NH(4)(+) removal and 1.4 g/m(2)/day NO(2)(-) removal) as compared to the control (0.2 g/m(2)/day NH(4)(+) removal and 0.1 g/m(2)/day NO(2)(-) removal) after 1 month. Two out of three of the surface modifications resulted in significantly higher AMX activity than the control at 1 and 2 months. No nitrite oxidizing bacteria activity was detected in either the surface modified media or IFAS media batch tests. The results indicate that startup time of a deammonification MBBR could potentially be decreased through surface modification of the plastic media or through the transfer of media from a mature IFAS process.

Studies of calcium-precipitating oral bacterial adhesion on TiN, TiO2 single layer, and TiN/TiO2 multilayer-coated 316L SS

Titanium nitride (TiN), titanium oxide (TiO2) single layer, and TiN/TiO2 multilayer coatings were deposited on a 316L stainless steel substrate using reactive magnetron sputtering process with the aim of preventing bacterial adhesion. The crystal structures of as-prepared coatings were evaluated using X-ray diffraction analysis. The cubic structure of TiN, anatase, and rutile structure of TiO2 was noticed. Atomic force microscopy images exhibited a relatively smooth surface for all coatings. The surface wettability studies confirmed that the coatings were hydrophilic in nature. The rate of bacterial adhesion was evaluated using scanning electron microscopy and epifluorescence microscopy. These results demonstrated that the coated substrates could help to effectively reduce the bacterial adhesion and biofilm formations.

Investigation of antibacterial and wettability behaviours of plasma-modified PMMA films for application in ophthalmology

The main objective of this research is the experimental investigation of the surface properties of polymethyl methacrylate (PMMA) such as wettability and the roughness effect on Escherichia coli (gram negative) cell adhesion. Radio frequency (RF; 13.56 MHz) oxygen plasma was used to enhance the antibacterial and wettability properties of this polymer for biomedical applications, especially ophthalmology. The surface was activated by O2 plasma to produce hydrophilic functional groups. Samples were treated with various RF powers from 10 to 80 W and different gas flow rates from 20 to 120 sccm. Optical emission spectroscopy was used to monitor the plasma process. The modified surface hydrophilicity, morphology and transparency characteristics were studied by water contact angle measurements, atomic force microscopy and UV–vis spectroscopy, respectively. Based on the contact angle measurements of three liquids, surface free energy variations were investigated. Moreover, the antibacterial properties were evaluated utilizing the method of plate counting of Escherichia coli. Also, in order to investigate stability of the plasma treatment, an ageing study was carried out by water contact angle measurements repeated in the days after the treatment. For biomedical applications, especially eye lenses, highly efficient antibacterial surfaces with appropriate hydrophilicity and transparency are of great importance. In this study, it is shown that the plasma process is a reliable and convenient method to achieve these purposes. A significant alteration in the hydrophilicity of a pristine PMMA surface was observed after treatment. Also, our results indicated that the plasma-modified PMMAs exhibit appropriate antibacterial performance. Moreover, surface hydrophilicity and surface charge have more influence on bacterial adhesion rate than surface roughness. UV–vis analysis results do not show a considerable difference for transparency of samples after plasma treatment.

The effect of electric fields on bacterial attachment to conductive surfaces

Bacterial adhesion has been studied in various conditions. The bactericidal effect of strong electric voltages has been mainly tested within the context of preventing device-related infections in hospital environments. Little evidence is found in the literature on the mechanism of bacterial deposition as a function of an applied electric field. In this study, we assumed that an electric field, which was applied perpendicularly to the flow of a bacterial suspension, might impact the electrostatic energy barrier between the negatively charged bacterial cell and the positively charged electrode substrate. Experiments were carried out with a QCM-D electro-chemical module which allowed monitoring the adhered mass as well as the dissipation factor, while a bacterial suspension was passed through the module in a diffusion dominated flow regime and while an electric field was applied perpendicularly to the flow of the suspension. A Pseudomonas fluorescens strain was used in order to detect and estimate any bacterial adhesion on the electrode surface. While the results confirmed that a decrease of the recorded resonance frequency was in direct proportion to the amount of adhered bacteria (estimated by a visual control of the bacterial signal on the electrode sensor at the end of each experiment), the change in the resonance frequency as a function of the applied electric potential was rather counter-intuitive: with negative potential the rate of bacterial adhesion was faster and steadier than with a positive electric potential, when the bacterial rate of adhesion tended to level off. Moreover, analyses of the measured dissipation to the measured frequency shifts (ΔD/Δf) during the deposition experiment, which indicate the fluidic character of the adhered layer of bacteria, revealed that with negative electric potential the bacterial cells were rigidly connected, while with positive electric potentials the cells were rather loosely bound to the electrode. The measured data suggested that the applied electric potential might have an impact on the conformation of the surface appendages on the bacterial cell surface of P. fluorescens, causing a state of steric repulsion with an extended conformation induced by positive electric potentials, and a state of entangled conformations induced by negative potentials, which allowed the cells to overcome the electrostatic energy barrier.

Adhesion of Pathogenic Bacteria to Food Contact Surfaces: Influence of pH of Culture.

The adhesion of Aeromonas hydrophila, Escherichia coli O157:H7, Salmonella Enteritidis, and Staphylococcus aureus to hydrophobic and hydrophilic surfaces in cultures with different pHs (6, 7, and 8) was studied. The results indicated that the type of material had no effect on the attachment capacity of microorganisms, while environmental pH influenced the adhesion of A. hydrophila, E. coli, and S. aureus to both solid substrates. The attachment of S. Enteritidis (P > .05) was not affected by the type of substrate or the culture pH, whereas E. coli displayed the weakest affinity for both polystyrene and glass surfaces. No correlation was established between the physicochemical properties of the materials, or the bacterial and the rate of bacterial adhesion, except for S. aureus. Photomicrographs have shown that surfaces were contaminated by small clusters of S. Enteritidis while S. aureus invaded the food contact surfaces in the form of small chains or cell aggregates.

Role of type 1 fimbriae and mannose in the development of Escherichia coli K12 biofilm: from initial cell adhesion to biofilm formation

The influence of type 1 fimbriae, mannose-sensitive structures, on biofilm development and maturation has been examined by the use of three isogenic Escherichia coli K12 strains: wild type, fimbriated, and non-fimbriated. Experiments with the three strains were done in minimal medium or Luria–Bertani broth supplemented with different concentrations of d-mannose. The investigation consisted of: (1) characterizing the bacterial surface of the three strains with respect to hydrophilicity and surface charge, (2) investigating the effect of type 1 fimbriae on bacterial adhesion rate and reversibility of initial adhesion on glass surfaces, and (3) verifying the role of type 1 fimbriae and exopolysaccharides (EPS) in biofilm maturation. The results suggest that type 1 fimbriae are not required for the initial bacterial adhesion on glass surfaces as the non-fimbriated cells had higher adhesion rates and irreversible deposition. Type 1 fimbriae, however, are critical for subsequent biofilm development. It was hypothesized that in the biofilm maturation step, the cells synthesize mannose-rich EPS, which functions as a ‘conditioning film’ that can be recognized by the type 1 fimbriae.

Effects of Mixtures of Tween80 and Cellulolytic Enzymes on Nutrient Digestion and Cellulolytic Bacterial Adhesion

: A series of in vitro and in vivo experiments were conducted to investigate the effects of the mixture of Tween 80 and cellulolytic enzymes (xylanase and cellulase) on total tract nutrient digestibility and rumen cellulolytic bacterial adhesion rates in Holstein steers. Ground timothy hay sprayed with various levels of Tween 80 and cellulolytic enzymes was used as substrates in an in vitro experiment to find out the best combinations for DM degradation. The application level of 2.5% (v/w) Tween 80 and the combination of 5 U xylanase and 2.5 U cellulase per gram of ground timothy hay (DM basis) resulted in the highest in vitro dry matter degradation rate (p<0.05). Feeding the same timothy hay to Holstein steers also improved in vivo nutrient (DM, CP, CF, NDF and ADF) digesibilities compared to non-treated hay (p<0.05). Moreover, Tween 80 and enzyme combination treatment increased total ruminal VFA and concentrations of propionic acid and isovaleric acid with decreased acetate to propionate ratio (p<0.001). However, adhesion rates of Fibrobacter succinogenes and Ruminococcus flavefaciens determined by Real Time PCR were not influenced by the treatment while that of Ruminococcus albus was decreased (p<0.05). The present results indicate that a mixture of Tween 80 and cellulolytic enzymes can improve rumen environment and feed digestibility with variable influence on cellulolytic bacterial adhesion on feed.

In vitro biocompatibility and bacterial adhesion of physico-chemically modified Ti6Al4V surface by means of UV irradiation

UV irradiation leads to a “spontaneous” wettability increase of the Ti6Al4V surface while preserving bulk properties of the alloy that are crucial for its performance as an orthopedic and dental implant. We hypothesized that UV treatment of Ti6Al4V may impair bacterial adhesion without compromising the good response of human bone-forming cells to this alloy. The in vitro biocompatibility of the Ti6Al4V surface, before and after UV irradiation, was analyzed by using human cells related to the osteoblastic phenotype. The adhesion processes of bacterial strains related to clinical orthopedic infections, i.e., Staphylococcus aureus and Staphylococcus epidermidis, were studied theoretically and in vitro, under dynamic and static conditions as well as in the presence or absence of shear forces. While human cell adhesion was not altered by UV irradiation of Ti6Al4V alloy, this treatment reduced not only initial bacterial adhesion rates but also the number of bacteria retained on the surface after the passage of two air–liquid interfaces on the previously adhered bacteria. This study proposes the use of UV treatment prior to implantation protocols as an easy, economic and effective way of reducing bacterial adhesion on the Ti6Al4V surface without compromising its excellent biocompatibility.

Bacterial adhesion to and viability on positively charged polymer surfaces

Secondary and tertiary amino groups were introduced into polymer chains grafted onto a polyethylene flat-sheet membrane to evaluate the effects of surface properties on the adhesion and viability of a strain of the Gram-negative bacterium Escherichia coli and a strain of the Gram-positive bacterium Bacillus subtilis. The characterization of the surfaces containing amino groups, i.e. ethylamino (EA) and diethylamino (DEA) groups, revealed that the membrane potentials are proportional to amino-group densities and contact angle hysteresis. A high bacterial adhesion rate constant k was observed at high membrane potential, which indicates that membrane potential could be used as an indicator for estimating bacterial adhesion to the EA and DEA sheets, especially in B. subtilis. The bacterial adhesion rate constant of E. coli markedly increased at a membrane potential higher than -7.8 mV, whereas that of B. subtilis increased at a membrane potential higher than -8.3 mV, at which the dominant effect on bacterial adhesion is expected to change. The viability experiments revealed that approximately 80% of E. coli cells adhering to the sheets with high membrane potential were inactivated after a contact time of 8 h, whereas 60% of B. subtilis cells were inactivated. Furthermore, E. coli viability significantly decreased at a membrane potential higher than -8 mV, whereas B. subtilis viability decreased as membrane potential increased, which reflects differences in cell wall structure between E. coli and B. subtilis.

Microbiological diagnosis of aortofemoral graft infections

Vascular surgery has benefitted from the introduction and development of new biomaterials used in grafting. However, these prosthetic materials are at risk of infection. 1-4 Such infections occur both early after implantation of grafts, and much later as a consequence of different mechanisms. 5 Early onset graft infections, occurring within 4 months of implantation, are often a consequence of inadequate aseptic surgical procedures or of inadequate patient selection procedures. 5-7 Late onset infections, occurring many years after implantation, are generally due to bacteria spreading from contiguous intestinal sites or through the blood stream. 8'9 Although virtually any microorganism can cause a vascular graft infection, the most frequently isolated bacteria are staphylococci (both Staphylococcus aureus and coagulase-negative Staphylococcus spp.) and enterobacteria (principally Escherichia coli), though enterococci and Pseudomonas aeruginosa are also frequently isolated. 1~'~°'1~ According to several in vitro findings the physical nature of different biomaterials shows some influence on bacterial adhesion rates, expanded polytetrafluoroethylene being less suitable for bacterial adhesion than dacron, though the significance of such findings for the in vivo susceptibility to colonisation is still not completely understood. ~2-14 Collagen or gelatin impregnated grafts also appear to be more resistant. Two principal characteristics of such infections contribute to their severity: the almost complete absence of specific clinical signs, particularly in the early phases (diagnosis is almost always possible when pus is already partially or totally surrounding the graft or causing a fistula), and their extreme resistance to chemotherapy, due to the bacterial production of esopolymeric substances. 1°'~5 Both these aspects point out the absolute necessity for diagnostic procedures that

Kinetics of Pseudomonas aeruginosa adhesion to 304 and 316-L stainless steel: role of cell surface hydrophobicity

Fifteen different isolates of Pseudomonas aeruginosa were used to study the kinetics of adhesion to 304 and 316-L stainless steel. Stainless steel plates were incubated with approximately 1.5 X 10(7) CFU/ml in 0.01 M phosphate-buffered saline (pH 7.4). After the plates were rinsed with the buffer, the number of adhering bacteria was determined by a bioluminescence assay. Measurable adhesion, even to the electropolished surfaces, occurred within 30 s. Bacterial cell surface hydrophobicity, as determined by the bacterial adherence to hydrocarbons test and the contact angle measurement test, was the major parameter influencing the adhesion rate constant for the first 30 min of adhesion. A parabolic relationship between the CAM values and the logarithm of the adhesion rate constants (In k) was established. No correlation between either the salt aggregation or the improved salt aggregation values and the bacterial adhesion rate constants could be found. Since there was no significant correlation between the bacterial electrophoretic mobilities and the In k values, the bacterial cell surface charge seemed of minor importance in the process of adhesion of P. aeruginosa to 304 and 316-L stainless steel.

Adhesion of coagulase-negative staphylococci to methacrylate polymers and copolymers.

Adhesion of coagulase-negative staphylococci (CNS) was studied onto a homologous series of methacrylate polymers and copolymers. The materials varied in wettability (contact angles) and were either positively or negatively charged (zeta-potential). Bacterial adhesion experiments performed in a parallel-plate perfusion system showed that positively charged TMAEMA-Cl copolymers significantly promoted the adhesion of CNS as compared with all other methacrylate (co)polymers tested. The bacterial adhesion rates onto the positively charged surfaces are diffusion-controlled, whereas those onto the surfaces with a negative zeta-potential are more surface-reaction-controlled due to the presence of a potential energy barrier. The bacterial adhesion rates onto various poly (alkyl methacrylates) were similar. The number of adhering bacteria onto the negatively charged MMA/MAA copolymer did not differ from that onto pMMA, indicating that sufficient sites on the copolymer surface with the same potential energy barrier as that on pMMA, were available for adhesion. Decreasing rates of adhesion of CNS were observed onto MMA/HEMA copolymers with increasing HEMA content coinciding with increasing hydrophilicity. Low plateau values for the bacterial adhesion were observed on 50MMA/50HEMA, pHEMA, and 85HEMA/15MAA, indicating that the adhesion onto these materials was reversible. Four CNS strains with different surface characteristics all showed higher numbers of adhering bacteria onto 85MMA/15TMAEMA-Cl than onto 85MMA/15MAA and pMMA.