Inhibition Of Bacterial Attachment Research Articles

Biomimetic PMMA coating surface and its application on inhibition of bacterial attachment and anti-biofilm performance

In this study, poly(methyl methacrylate) (PMMA) coating with biomimetic hydrophobic surface was fabricated through the nano-casting technique to transfer the surface of natural Xanthosoma sagittifolium leaf (XSL) to polymer surface and apply it in the inhibition of bacterial attachment and the anti-biofilm performance.First, poly(dimethyl siloxane) (PDMS) was used as a negative template to transfer the pattern of natural XSL surface. Subsequently, the commercial PMMA powder was dissolved in toluene and then dropped onto the PDMS template, resulting in the successful pattern transfer of natural XSL surface in producing an artificial biomimetic PMMA coating surface. Next, the surface morphology of biomimetic coating, denoted by Bio-PMMA, was investigated by SEM, containing micron-sized papillae decorated with many nano-scaled creases. Compared with that of non-Bio-PMMA coating, the contact angle(CA) of Bio-PMMA coating was found to increase significantly (increased from 68°±0.8° to 121°±0.6°), reflecting an increase of 53°±0.8° in CA, indicating that the original hydrophilic surface of PMMA can be converted to a hydrophobic surface when replicating the XSL template.In the research of anti-biofilm applications on artificial biomimetic PMMA coating, three types of bacteria (i.e., Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa) were observed to study short-term anti-bacterial attachment and conducted long-term anti-biofilm test via SEM. Crystal violet and a Microplate reader were used for bacterial qualitative and quantitative analysis, respectively. The results showed that Bio-PMMA coating surface with micro papillae and folded micro-nanostructures inhibited the growth of bacteria and effectively delayed the formation of biofilm, and the hydrophobicity of the surface also helped to prevent the adhesion of bacteria, thus inhibiting the adhesion of bacteria with good long-term anti-biofilm performance.

Essential oils from Artemisia species inhibit biofilm formation and the virulence of Escherichia coli EPEC 2348/69

Enteropathogenic Escherichia coli E2346/69 (EPEC) has caused foodborne outbreaks worldwide and the bacterium forms antimicrobial-tolerant biofilms. The anti-biofilm formation of various components of essential oils extracted from selected medicinal plants were investigated and tested on EPEC and wild strains of E. coli. Oils extracted from the family Asteraceae and their major common constituents at 0.031 and 0.062% (V/v) were found to significantly inhibit biofilm formation without affecting the growth of planktonic cells. In addition, three plants belonging to this family (Artemisia herba alba, Artemisia campestris and Artemisia absinthium) played important roles in the antimicrobial activity. Interestingly, their essential oils reduced the ability of E. coli (the EPEC and K12 strains) to form a biofilm. The crystal violet reduction assay showed that the plant extracts tested reduced biofilm formation with the inhibition of bacterial attachment up to 45% for EPEC and 70% for E. coli K-12 after 24 h treatment at 0.62 mg ml−1, demonstrating that Artemisia oils had a high anti-biofilm activity on the bacteria tested. The results indicate that the locus of enterocyte effacement (LEE) acquired by horizontal transfer promotes the formation of the attaching and effacing (A/E) lesion and increases the capacity of the photogen strain (EPEC) to form a biofilm. The chemical composition of the volatile compounds was obtained by gas chromatography-mass spectrometry analysis, which showed that the essential oils consisted of thirty-four compounds. Chamazulene (39.21%), β-pinene (32.07%), and α-thujone (29.39%) were the main constituents of the essential oils of A. herba alba, A. absinthium and A. campestris, respectively.

Antibacterial Properties of Polysulfone Membranes Blended with Arabic Gum.

Polysulfone (PS) membranes blended with different loadings of arabic gum (AG) were synthesized using phase inversion method and the antibacterial properties of the synthesized membranes were tested using a number Gram-negative (Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacterial species. It was shown that AG addition to the dope polymer solutions essentially changed porous structure, hydrophilicity and zeta potential of the cast PS/AG membranes. These changes were due to the amphiphilic properties of AG macromolecules that contained negatively charged hydrophilic residues. A pronounced decrease in bacterial attachment was seen in the field emission scanning electron microscopy (FESEM) images for PS/AG membrane samples compared to both commercial (Microdyn-Nadir) and bare PS (without AG) membranes. AG loading dependent trend was observed where the prevention of bacterial colonization on the membrane surface was strongest at the highest (7 wt. %) AG loading in the casting solution. Possible mechanisms for the prevention of bacterial colonization were discussed. Significantly, the inhibition of bacterial attachment and growth on PS/AG membranes was observed for both Gram-positive and Gram-negative bacterial models, rendering these novel membranes with strong biofouling resistance attractive for water treatment applications.

Inhibition of bacterial attachment and biofilm formation by a novel intravenous catheter material using an in vitro percutaneous catheter insertion model.

IntroductionDespite sterile barrier precautions and vigorous skin antisepsis, percutaneous insertion of intravenous catheters has been shown to result in attachment to the catheter surface of bacteria residing in the deep structures of the skin. Such attachment poses the risk of biofilm formation and eventual catheter-related bloodstream infection (CRBSI). This study was undertaken to assess whether the non-coated surface treatment of a unique catheter material (ChronoFlex C® with BioGUARD™) could inhibit bacterial attachment and biofilm formation.MethodsA novel in vitro model and fluorescence microscopy were used to compare two intravascular catheter materials with respect to bacterial attachment and biofilm formation. The control material was a commonly used polyurethane. The study material was a unique copolymer, treated so as to remove surface additives, alter hydrophobicity and create surface micro-patterning. Outcomes were assessed using both a membrane potential indicator and a cell death reporter with appropriate fluorescent channels. Thus, bacterial cells attached to the catheter surface (living and dead) were imaged without mechanical disruption.ResultsBoth bacterial attachment and biofilm formation are significantly inhibited by the study catheter material. In fact, over 5 times more bacteria were able to attach and grow on the control polyurethane material than on the study material (P=0.0020). Moreover, those few bacteria that were able to attach to the study material had a 1.5 times greater likelihood of dying.ConclusionUsing a novel in vitro percutaneous catheter insertion model, ChronoFlex C with BioGUARD is proven to significantly inhibit bacterial attachment and biofilm formation as compared with a commonly used polyurethane catheter material.

Inhibition of Bacterial Attachment on Surfaces by Immobilization of Tobramycin-Loaded Liposomes.

Stainless steel surfaces were processed by gold deposition in order to immobilize tobramycin-loaded liposomes which were functionalized on their surface with thiol-groups (through maleimide (MAL) derivatization with thiols). After optimizing the tobramycin loading in liposomes (LIPs), and the immobilization of THIOL-MAL-functionalized LIPs on gold-sputtered surfaces, the coated surfaces were challenged with two reference Staphylococcus epidermidis strains: ATCC 35984 (slime-positive) and ATCC 12228 (slime-negative), in order to measure the degree of surface protection from biofilm formation. Moreover, the effect of the reference and two well characterized clinical S. epidermidis strains on the integrity of LIPs (composed of PC or DSPC) was evaluated, in order to investigate whether specific interactions between LIPs and bacteria occur, and if they are affected by LIP membrane composition and/or bacterial strain type. Bacteria growth on surfaces is substantially inhibited by TOBR-loaded-LIP immobilization, especially in the case of the non-biofilm forming bacterial strain. Gold sputtered surfaces were moderately (albeit significantly) protected, from both reference strains tested (compared to bare surfaces). Interestingly, LIP integrity is significantly decreased in the presence of bacteria (at specific lipid/bacteria ratios); the biofilm-forming bacteria being most potent for LIP disruption, whereas, less rigid liposomal membranes (PC) are affected more compared to rigid (DSPC) ones. The clinical strains are also reactive against LIP. This interaction indicates a potential for triggered release of LIP-encapsulated drugs in presence of biofilm-forming bacteria, therefore LIP encapsulation/immobilization may be envisioned as a potential platform technology for triggered antimicrobial therapy.

Soybean Extracts Facilitate Bacterial Agglutination and Prevent Biofilm Formation on Orthodontic Wire

Soybean is an essential food ingredient that contains a class of organic compounds known as isoflavones. It is also well known that several plant agglutinins interfere with bacterial adherence to smooth surfaces. However, little is known about the effects of soybean extracts or genistein (a purified isoflavone from soybean) on bacterial biofilm formation. We evaluated the effects of soybean (Glycine max) extracts, including fermented soybean and genistein, on streptococcal agglutination and attachment onto stainless steel orthodontic wire. After cultivating streptococci in biofilm medium containing soybean extracts and orthodontic wire, the viable bacteria attached to the wire were counted. Phase-contrast microscopy and scanning electron microscopy (SEM) analyses were conducted to evaluate bacterial agglutination and attachment. Our study showed that soybean extracts induce agglutination between streptococci, which results in bacterial precipitation. Conversely, viable bacterial counting and SEM image analysis of Streptococcus mutans attached to the orthodontic wire show that bacterial attachment decreases significantly when soybean extracts were added. However, there was no significant change in pre-attached S. mutans biofilm in response to soybean. A possible explanation for these results is that increased agglutination of planktonic streptococci by soybean extracts results in inhibition of bacterial attachment onto the orthodontic wire.

Real-time PCR method for the quantification ofBurkholderia cepaciacomplex attached to lung epithelial cells and inhibition of that attachment

To develop a rapid method to quantify the attachment of the cystic fibrosis pathogen, Burkholderia multivorans, to lung epithelial cells (16HBE14o(-)) using real-time PCR with a view to monitoring potential inhibition of lung cell attachment. Mammalian and bacterial DNA were purified from bacteria attached to lung epithelial cells. The relative amount of bacteria attached was determined by amplification of the recA gene relative to the human GAPDH gene, in the presence of SYBR Green. The method was thoroughly validated and shown to correlate well with traditional plating techniques. Inhibition of bacterial attachment with simple sugars was then evaluated by real-time PCR. Of the sugars examined, pre-incubation of B. multivorans with lactose, mannose and xylitol all decreased bacterial adherence to 16HBE14o(-) cells, while glucose and galactose had no significant effect. Pre-incubation with lactose had the greatest effect, resulting in reduced adhesion to 35% of untreated controls. This method can be used to quickly and effectively screen novel agents with higher affinities for bacterial adhesins. This method will enable the rapid development of novel agents to inhibit colonization by this pathogen from the environment.

Protection of catheter surfaces from adhesion of Pseudomonas aeruginosa by a combination of silver ions and lectins

A catheter surface was modified by coating a cellulose acetate polymer. Adhesion of Pseudomonas aeruginosa ATCC 27853 to the surface was investigated by exposing bacterial cultures to three treatments: polymer impregnated with silver ions (Ag+), polymer surfaces coated with lectins and a combination of Ag+ and a lectin coating. The effective concentration of Ag+ providing protection against bacterial biofilm development was 100μg/ml and higher. Lectins alone at 10% also showed inhibition of bacterial attachment. However, the best result was achieved against bacterial adhesion and growth on surfaces using a combination of 100 μg Ag+/ml and a lectin coating as a surface treatment. This surface treatment was also effective against both fresh culture and a two-week-old culture containing P. aeruginosa producing exopolymers. Our results suggest that Ag+impregnation combined with a lectin coating warrants further investigation as a potential means of protecting catheters.

Immunological aspects of the potential role of dietary carbohydrates and lectins in human health.

Little is known regarding the immunobiology of dietary carbohydrate intake and its relevance to human health, although foodstuffs contain many simple and complex carbohydrates. Lectins, immunoglobulins, viruses, bacteria and host cells interact with each other forming a delicate equilibrium within the alimentary canal which may be perturbed by saccharide intake. The ways in which these components may interact at different sites within the alimentary canal are discussed, as are the possible influences on mucosal immunity and the induction of oral tolerance. The possible systemic influences of absorbed saccharides at loci remote from the gut are considered in terms of inhibition of dietary and endogenous lectins, inhibition of bacterial attachment, and alteration of leukocyte homing behaviour. Finally, possible means by which dietary carbohydrates might modify various specific diseases are considered. It is probable that dietary carbohydrates can alter the equilibria between lectins, secretory IgA and micro-organisms in the alimentary canal, and this consideration could be exploited to promote health. The possible effects of dietary saccharides on allergy/oral tolerance or on recognition events at gut-remote sites warrant further investigation.

Factors affecting bio‐oxidation of sulfide minerals at high concentrations of solids: A review

Bio-oxidation has proved to be a viable process for the oxidative pretreatment of refractory gold-bearing sulfides. Generally, the oxidation rate is maximal at 20% solids for high sulfide content materials [ca. 30% sulfur]. Low grade ores [1% sulfur] have been successfully oxidized at 55% solids, indicating a link between the sulfide grade of the material and the optimal solids concentration for operation. Concentrations of high solids have been reported to lower oxidation rates, increase lag times, and decrease the ultimate extent of oxidation. This review discusses the various factors that have been proposed as causes of these phenomena. The factors include oxygen and carbon dioxide availability, low bacteria-solids ratio; mechanical damage or inhibition of the bacteria, inhibition of bacterial attachment, and the buildup of toxic leach products or other detrimental substances such as some flotation reagents.

Antibacterial mechanisms of antibody to mannose-sensitive pili of Escherichia coli.

To identify mechanisms whereby antibody to mannose-sensitive pili of Escherichia coli might enhance host defenses, we evaluated the activity of antibody to pili in four antibacterial immune processes. Antiserum to pili and Fab' fragments of IgG antibody to pili inhibited the ability of homologous piliated organisms to adhere to buccal epithelial cells. However, this antiserum did not enhance intravascular clearance, complement-dependent bacteriolysis, or opsonophagocytosis. The addition of antiserum to pili to polymorphonuclear leukocytes and piliated E. coli reduced the rate of killing from 52% to 5%. The addition of complement restored the rate to 52%, but this was much less than the 99% rate achieved with polymorphonuclear leukocytes and either fresh serum or antibody to the whole bacteria. These observations suggest that the principal anti-bacterial property of antibody to mannose-sensitive pili of E. coli is inhibition of bacterial attachment. Whether the anti-opsonic effect of antibody to pili is detrimental to host defense remains to be determined.

Effects of Methylcellulose on Fibrolytic Bacterial Detachment and In vitro Degradation of Rice Straw.

Two in vitro experiments were conducted to evaluate the effect of methylcellulose (MC) on i) bacterial detachment from rice straw as well as ii) inhibition of bacterial attachment and fiber digestibility. To evaluate the effect of MC on fibrolytic bacterial detachment (Exp 1), in vitro bacterial cultures with 0.1% (w/v) MC solution were compared with cultures without MC after 8 h incubation. The effect of MC on inhibition of bacterial attachment was determined by comparing with real-time PCR the populations of F. succinogenes, R. flavefaciens and R. albus established on rice straw pre-treated with 0.1% MC with those on untreated straw after incubation for 0, 6 and 12 h (Exp 2). The major fibrolytic bacterial attachment on rice straw showed significantly lower populations with either the addition of MC to the culture or pre-treated rice straw compared to controls (p<0.05). Also, the digestibility of rice straw with MC was significantly lower compared with control (p<0.05). The F. succinogenes population did not show detachment from rice straw, but showed an inhibition of attachment and proliferation on rice straw in accordance with a decrease of fiber digestion. The detachments of Ruminococcus species co-existed preventing the proliferations with subsequent reduction of fiber degradation by MC during the incubation. Their detachments were induced from stable colonization as well as the initial adhesion on rice straw by MC in in vitro ruminal fermentation. Furthermore, the detachment of R. albus was more sensitive to MC than was R. flavefaciens. These results showed the certain evidence that attachment of major fibrolytic bacteria had an effect on fiber digestion in the rumen, and each of fibrolytic bacteria, F. succinogenes, R. flavefaciens and R. albus had a specific mechanism of attachment and detachment to fiber.