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Bacterial Adhesion (bacterial + adhesion)

Distribution by Scientific Domains

Medical Sciences	41%
Life Sciences	37%
Chemistry	12%

Selected Abstracts

Oral bacterial adhesion forces to biomaterial surfaces constituting the bracket,adhesive,enamel junction in orthodontic treatment

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2009
Li Mei
Bacterial adhesion to biomaterial surfaces constituting the bracket,adhesive,enamel junction represents a growing problem in orthodontics, because bacteria can adversely affect treatment by causing demineralization of the enamel surface around the brackets. It is important to know the forces with which bacteria adhere to the surfaces of these junction materials, as the strength of these forces will determine how easy it will be to remove the bacteria. We compared the adhesion forces of five initially colonizing and four cariogenic strains of bacteria to an orthodontic adhesive, stainless steel, and enamel, with and without a salivary conditioning film. Adhesion forces were determined using atomic force microscopy and a bacterial probe. In the absence of a salivary conditioning film, the strongest bacterial adhesion forces occurred to the adhesive surface (,2.9 to ,6.9 nN), while adhesion forces to the enamel surfaces were lowest (,0.8 to ,2.7 nN). In the presence of a salivary conditioning film, adhesion forces were reduced strongly, to less than 1 nN, and the differences between the various materials were reduced. Generally, however, initial colonizers of dental hard surfaces presented stronger adhesion forces to the different materials (,4.7 and ,0.6 nN in the absence and presence of a salivary conditioning film, respectively) than cariogenic strains (,1.8 and ,0.5 nN). [source]

Bacterial adhesion to diamond-like carbon as compared to stainless steel

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2009
Antti Soininen
Abstract Recent studies suggest that diamond-like carbon (DLC) coatings are suitable candidates for application on biomedical devices and implants, due to their high hardness, low friction, high wear and corrosion resistance, chemical inertness, smoothness, and tissue and blood compatibility. However, most studies have neglected the potential susceptibility of DLC coatings to bacterial adhesion, which is the first step in the development of implant-related infections. This study compares adhesion of seven bacterial strains, commonly implicated in implant-related infections, to tetrahedral amorphous carbon, with their adhesion to AISI 316L surgical steel. The results show that bacterial adhesion to DLC was similar to the adhesion to commonly used stainless steel. This suggests that DLC coating can be advantageously used on implants made of AISI 316L or other materials without increasing the risk to implant-related infections. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [source]

Influence of probiotic vaginal lactobacilli on in vitro adhesion of urogenital pathogens to vaginal epithelial cells

LETTERS IN APPLIED MICROBIOLOGY, Issue 2 2006
G. Zárate
Abstract Aims:, Lactobacilli, the predominant micro-organisms of the vaginal microbiota, play a major role in the maintenance of a healthy urogenital tract by preventing the colonization of pathogenic bacteria. The aim of the present study was to assess the ability of four vaginal Lactobacillus strains, previously selected for their probiotic features, to block in vitro the adherence of three human urogenital pathogens to vaginal epithelial cells (VEC). Methods and Results:, Three types of assays were performed in order to determine the inhibitory effect of lactobacilli on adhesion of urogenital pathogens to VEC: blockage by exclusion (lactobacilli and VEC followed by pathogens), competition (lactobacilli, VEC and pathogens together) and displacement (pathogens and VEC followed by the addition of lactobacilli). Bacterial adhesion to VEC was quantified by microscopy (×1000) after Gram's stain. All the strains were able to inhibit by exclusion and competition the adhesion of Staphylococcus aureus to VEC but none was able to decrease the attachment of Escherichia coli by neither of the mechanisms assayed. Only Lactobacillus acidophillus CRL 1259 and Lactobacillus paracasei CRL 1289 inhibited the attachment of Group B streptococci (GBS) to VEC by exclusion and competition respectively. Conclusions:,Lactobacillus of vaginal origin were able to inhibit the attachment of genitouropathogenic Staph. aureus and GBS to the vaginal epithelium. Significance and Impact of the Study:, The results support the probiotic potential of these Lactobacillus strains as anti-infective agents in the vagina and encourage further studies about their capacity to prevent and manage urogenital tract infections in females. [source]

The affinity of the FimH fimbrial adhesin is receptor-driven and quasi-independent of Escherichia coli pathotypes

MOLECULAR MICROBIOLOGY, Issue 6 2006
Julie Bouckaert
Summary Type-1 fimbriae are important virulence factors for the establishment of Escherichia coli urinary tract infections. Bacterial adhesion to the high-mannosylated uroplakin Ia glycoprotein receptors of bladder epithelium is mediated by the FimH adhesin. Previous studies have attributed differences in mannose-sensitive adhesion phenotypes between faecal and uropathogenic E. coli to sequence variation in the FimH receptor-binding domain. We find that FimH variants from uropathogenic, faecal and enterohaemorrhagic isolates express the same specificities and affinities for high-mannose structures. The only exceptions are FimHs from O157 strains that carry a mutation (Asn135Lys) in the mannose-binding pocket that abolishes all binding. A high-mannose microarray shows that all substructures are bound by FimH and that the largest oligomannose is not necessarily the best binder. Affinity measurements demonstrate a strong preference towards oligomannosides exposing Man,1-3Man at their non-reducing end. Binding is further enhanced by the ,1-4-linkage to GlcNAc, where binding is 100-fold better than that of ,- d -mannose. Man,1-3Man,1-4GlcNAc, a major oligosaccharide present in the urine of ,-mannosidosis patients, thus constitutes a well-defined FimH epitope. Differences in affinities for high-mannose structures are at least 10-fold larger than differences in numbers of adherent bacteria between faecal and uropathogenic strains. Our results imply that the carbohydrate expression profile of targeted host tissues and of natural inhibitors in urine, such as Tamm-Horsfall protein, are stronger determinants of adhesion than FimH variation. [source]

Rhinovirus enhances various bacterial adhesions to nasal epithelial cells simultaneously

THE LARYNGOSCOPE, Issue 7 2009
Jong Hwan Wang MD
Abstract Objectives/Hypothesis: Viral upper respiratory tract infections are often followed by secondary bacterial infections in the form of acute rhinosinusitis. We investigate the effect of rhinovirus infection on the expression of cell adhesion molecules and bacterial adherence to primary human nasal epithelial cells. Methods: Cells were infected with rhinovirus serotype 16 (RV-16), and then Staphylococcus aureus, Streptococcus pneumoniae, or Hemophilus influenzae were added to the culture. Rhinovirus-induced expression of fibronectin, platelet-activating factor receptor, and carcinoembryonic antigen-related cell adhesion molecule, was assayed by confocal microscopy, real-time polymerase chain reaction, and Western blot analysis. Bacterial adhesion to cells was assessed by confocal microscopy and the fluorescence intensity of adherent bacteria was analyzed using Image-Pro Plus 5.1 (Media Cybernetics, Inc., Bethesda, MD). Results: RV-16 infection significantly increased the gene and protein expression of fibronectin, platelet-activating factor receptor, and carcinoembryonic antigen-related cell adhesion molecule in nasal epithelial cells. Compared with rhinovirus-uninfected control cells, the adhesion of S. aureus, S. pneumoniae, and H. influenzae increased significantly to 2.53-fold, 1.51-fold, and 2.74-fold of control levels, respectively, in rhinovirus-infected nasal epithelial cells. Conclusions: These findings suggest that increased expression of host cell adhesion molecules may be the mechanism accounting for the increase in susceptibility to bacterial rhinosinusitis associated with rhinovirus-induced upper respiratory infections. Laryngoscope, 2009 [source]

Electric field induced desorption of bacteria from a conditioning film covered substratum

BIOTECHNOLOGY & BIOENGINEERING, Issue 4 2001
Albert T. Poortinga
Abstract Desorption of three oral bacterial strains from a salivary conditioning film on an indium tin oxide electrode during application of a positive (bacterial adhesion to the anode) or a negative electric current was studied in a parallel plate flow chamber. Bacterial adhesion was from a flowing suspension of high ionic strength, after which the bacterial suspension was replaced by a low ionic strength solution without bacteria and currents ranging from ,800 to +800 ,A were applied. Streptococcus oralis J22 desorbed during application of a positive and negative electric current with a desorption probability that increased with increasing electric current. Two actinomyces strains, however, could not be stimulated to desorb by the electric currents applied. The desorption forces acting on adhering bacteria are electroosmotic in origin and working parallel to the electrode surface in case of a positive current, whereas they are electrophoretic and electrostatic in origin and working perpendicular to the surface in case of a negative current. By comparison of the effect of positive and negative electric currents, it can be concluded that parallel forces are more effective in stimulating bacterial desorption than perpendicular forces. The results of this study point to a new pathway of cleaning industrial and biomedical surfaces without the use of detergents or biocides. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 395,399, 2001. [source]

Physical Properties of Biopolymers Assessed by Optical Tweezers: Analysis of Folding and Refolding of Bacterial Pili

CHEMPHYSCHEM, Issue 2 2008
Magnus Andersson
Abstract Bacterial adhesion to surfaces mediated by specific adhesion organelles that promote infections, as exemplified by the pili of uropathogenic E. coli, is studied mostly at the level of cell,cell interactions and thereby reflects the averaged behavior of multiple pili. The role of pilus rod structure has therefore only been estimated from the outcome of experiments involving large numbers of organelles at the same time. It has, however, lately become clear that the biomechanical behavior of the pilus shafts play an important, albeit hitherto rather unrecognized, role in the adhesion process. For example, it has been observed that shafts from two different strains, even though they are similar in structure, result in large differences in the ability of the bacteria to adhere to their host tissue. However, in order to identify all properties of pilus structures that are of importance in the adhesion process, the biomechanical properties of pili must be assessed at the single-molecule level. Due to the low range of forces of these structures, until recently it was not possible to obtain such information. However, with the development of force-measuring optical tweezers (FMOT) with force resolution in the low piconewton range, it has lately become possible to assess forces mediated by individual pili on single living bacteria in real time. FMOT allows for a more or less detailed mapping of the biomechanical properties of individual pilus shafts, in particular those that are associated with their elongation and contraction under stress. This Mi- nireview presents the FMOT technique, the biological model system, and results from assessment of the biomechanical properties of bacterial pili. The information retrieved is also compared with that obtained by atomic force microscopy. [source]

The acyltransferase gene bus-1 exhibits conserved and specific expression in nematode rectal cells and reveals pathogen-induced cell swelling

DEVELOPMENTAL DYNAMICS, Issue 12 2008
Maria J. Gravato-Nobre
Abstract Susceptibility to the rectal pathogen Microbacterium nematophilum provides a means of examining hindgut differentiation in C. elegans. Mutants of bus - 1 are resistant to infection with this pathogen. We show here that bus - 1 encodes a predicted acyltransferase expressed in rectal epithelial cells (K, F, and U), suggesting its involvement in regional surface modification. bus - 1 reporter genes were used to show spatial regulation by hindgut developmental control genes: egl - 38, mab - 9, and mab - 23. A bus - 1::GFP reporter reveals the conspicuous rectal epithelial swelling induced by M. nematophilum. The C. briggsae ortholog of bus - 1 exhibits conserved function and rectal expression, but it is expressed in vulval as well as rectal cells, correlated with pathogen adhesion to both vulval and rectal cells in this species. Another acyltransferase affecting bacterial adhesion, bus - 18/acl - 10, was also identified, which also shows strong rectal expression, but it is expressed in additional epithelial tissues and is required for general surface integrity. Developmental Dynamics 237:3762,3776, 2008. © 2008 Wiley-Liss, Inc. [source]

Induction of neutralizing antibodies in mice immunized with an amino-terminal polypeptide of Streptococcus mutans P1 protein produced by a recombinant Bacillus subtilis strain

FEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 2 2010
Milene B. Tavares
Abstract The oral pathogen Streptococcus mutans expresses a surface protein, P1, which interacts with the salivary pellicle on the tooth surface or with fluid-phase saliva, resulting in bacterial adhesion or aggregation, respectively. P1 is a target of protective immunity. Its N-terminal region has been associated with adhesion and aggregation functions and contains epitopes recognized by efficacious antibodies. In this study, we used Bacillus subtilis, a gram-positive expression host, to produce a recombinant N-terminal polypeptide of P1 (P139,512) derived from the S. mutans strain UA159. Purified P139,512 reacted with an anti-full-length P1 antiserum as well as one raised against intact S. mutans cells, indicating preserved antigenicity. Immunization of mice with soluble and heat-denatured P139,512 induced antibodies that reacted specifically with native P1 on the surface of S. mutans cells. The anti-P139,512 antiserum was as effective at blocking saliva-mediated aggregation of S. mutans cells and better at blocking bacterial adhesion to saliva-coated plastic surfaces compared with the anti-full-length P1 antiserum. In addition, adsorption of the anti-P1 antiserum with P139,512 eliminated its ability to block the adhesion of S. mutans cells to abiotic surfaces. The present results indicate that P139,512, expressed and purified from a recombinant B. subtilis strain, maintains important immunological features of the native protein and represents an additional tool for the development of anticaries vaccines. [source]

Physicochemical properties of Shiga toxigenic Escherichia coli

JOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2005
L. Rivas
Abstract Aims:, To investigate the physicochemical surface properties, such as cellular surface charge, hydrophobicity and electron donor/acceptor potential of a selection of Shiga toxigenic Escherichia coli (STEC) isolates grown in broth and agar culture. Methods and Results:, Cellular surface charge was determined using zeta potential measurements. Hydrophobicity of the isolates was determined using bacterial adhesion to hydrocarbons assay, hydrophobic interaction chromatography and contact angle measurements. Microbial adhesion to solvents was used to determine the electron donor/acceptor characteristics. No differences of surface charge measurements were found between broth and agar grown cultures. Isolates belonging to serogroup O157 and serotypes O26:H11 and O111:H- were significantly (P < 0·05) less negatively charged than other STEC serotypes tested. All strains were hydrophilic with most methods and demonstrated a lower hydrophobicity in agar culture compared with broth culture. All strains demonstrated a strong microbial adhesion to chloroform indicating that STEC possess an electron donor and basic character. A relationship between serogroup O157 and other STEC serotypes was apparent using principal-component analysis (PCA). Conclusions:, Combining the results for physicochemical properties using PCA differentiated between strains belonging to the O157 serogroup and other STEC/non-STEC strains. PCA found similar results for broth and agar grown cultures. Significance and Impact of the Study:, Particular serotypes of STEC possess similar physicochemical properties which may play a role in their pathogenicity or potential attachment to various surfaces. [source]

Bacterial adhesion to diamond-like carbon as compared to stainless steel

Initial biofilm formation of Streptococcus sobrinus on various orthodontics appliances

JOURNAL OF ORAL REHABILITATION, Issue 11 2004
D. Steinberg
summary, Biofilms accumulate on hard and soft surface in the oral cavity. Accumulation of biofilms on orthodontic appliance bear scientific and clinical interest. The objection of this study was to examine the formation of dental biofilm by Streptococcus sobrinus on different types of orthodontics appliances, using a model consisting of host and bacterial constituents. The adsorption pattern of saliva to the orthodontics appliances was determined by means of gel electrophoresis coupled with computerized densitometry techniques. The amount of salivary proteins adsorbed onto the surfaces was measured using the Bradford method. Sucrose-dependent bacterial adhesion to the saliva-coated orthodontics appliances was tested by radioactive-labelled S. sobrinus. Our results show different adsorption patterns of salivary proteins to the various orthodontic appliances as modules, brackets, springs and intra oral elastics. Modules and brackets demonstrated the most affinity to salivary proteins. A surface dependent adhesion profile was recorded, showing a high affinity of albumin and amylase to modules. Bacterial accumulation was the highest on modules compared with springs which demonstrated the least bacterial adhesion. Our study demonstrates the specificity of biofilm formation on the different orthodontic appliances. Formation of a variety of dental biofilms has a significant impact on the progression of dental diseases associated with orthodontic treatment. [source]

Trichoderma enzymes promote Fibrobacter succinogenes S85 adhesion to, and degradation of, complex substrates but not pure cellulose,

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2004
Diego P Morgavi
Abstract The effects of an enzyme preparation from Trichoderma longibrachiatum (TE) on adhesion and growth of the fibrolytic rumen bacterium Fibrobacter succinogenes S85 was studied to gain a better understanding of the action of feed enzyme additives on fibre digestion by ruminants. Adhesion experiments were performed on crystalline cellulose, corn silage and alfalfa hay. Adhesion of F succinogenes to cellulose was negatively related to the concentration of TE (p < 0.05). At the highest concentration used, TE reduced adhesion to cellulose from 65 to 39%. For corn silage and alfalfa hay, TE stimulated adhesion at low levels (p < 0.05) but this effect was lost at higher levels. Culture experiments were performed on crystalline cellulose and corn silage. The presence of TE in media containing cellulose failed to increase substrate disappearance or gas production although it increased numbers of non-adherent bacteria (p < 0.05). When corn silage was used, the addition of TE increased NDF disappearance (p < 0.05) at 24 and 48 h (33 and 52% in controls versus 53 and 65% in TE treatments). Growth rate and gas production were also stimulated (p < 0.05). We conclude that, for cellulose, the hydrolytic enzymes in TE obstructed available binding sites decreasing bacterial adherence. Fibrobacter succinogenes digested cellulose efficiently and addition of exogenous cellulases did not further increase substrate disappearance. However, for complex plant substrates, low concentration of TE increased bacterial adhesion and plant (corn) fiber degradation. For the Department of Agriculture and Agri-Food, Government of Canada, © Minister of Public Works and Government Services Canada 2004. Published for SCI by John Wiley & Sons, Ltd. [source]

Sialidase of Streptococcus intermedius: a putative virulence factor modifying sugar chains

MICROBIOLOGY AND IMMUNOLOGY, Issue 10 2010
Ayuko Takao
ABSTRACT A sialidase gene of Streptococcus intermedius was cloned. It was most similar to nanA, a major sialidase gene in Streptococcus pneumoniae, and was expressed in Escherichia coli. Since the gene-knockout S. intermedius strain lost detectable sialidase activity, the gene might code, either solely or mainly, the glycosidase in the bacterial genome. Polymerase chain reaction using the primers for the nanA homologue in S. intermedius (described as nanA below) showed that this sialidase gene was commonly distributed within the isolates of S. intermedius, but not found in the strains of other species among the anginosus group. In biofilm formation assay under cultivation with mucin, the nanA -deleted S. intermedius maintained the amount of biofilm for 72 hr, while that of the parent strain decreased during incubation from 24 to 72 hr. Since sialidase activity in the parent strain increased during that time period, sialidase might contribute to the degradation of biofilm under sialic acid-rich conditions. When S. intermedius was added into the HepG2 hepatoma culture, the calculated disassociation constant (Kd) of EDTA-releasable bacterial adhesion to the cells was higher in the nanA -deleted strain than in the parent. Furthermore, the rate constant, assuming endocytosis of the bacterium mediated by ASGP-R in HepG2 cells, seemed to be increased by sialidase pretreatment of the bacterial cells before addition to the cell culture. According to the results, modification of sugar chains by sialidase on the bacterial surface and in the surrounding environment might influence both bacterial interaction and host,bacterial interaction in S. intermedius. [source]

Host collagen signal induces antigen I/II adhesin and invasin gene expression in oral Streptococcus gordonii

MOLECULAR MICROBIOLOGY, Issue 2 2003
Catherine Heddle
Summary Microbial interactions with host molecules, and programmed responses to host environmental stimuli, are critical for colonization and initiation of pathogenesis. Bacteria of the genus Streptococcus are primary colonizers of the human mouth. They express multiple cell-surface adhesins that bind salivary components and other oral bacteria and enable the development of polymicrobial biofilms associated with tooth decay and periodontal disease. However, the mechanisms by which streptococci invade dentine to infect the tooth pulp and periapical tissues are poorly understood. Here we show that production of the antigen I/II (AgI/II) family polypeptide adhesin and invasin SspA in Streptococcus gordonii is specifically upregulated in response to a collagen type I signal, minimally the tri-peptide Gly-Pro-Xaa (where Xaa is hydroxyproline or alanine). Increased AgI/II polypeptide expression promotes bacterial adhesion and extended growth of streptococcal cell chains along collagen type I fibrils that are characteristically found within dentinal tubules. These observations define a new model of host matrix signal-induced tissue penetration by bacteria and open the way for novel therapy opportunities for oral invasive diseases. [source]

Effects of zinc and copper on adhesion and hemagglutination of Prevotella intermedia and Prevotella nigrescens

MOLECULAR ORAL MICROBIOLOGY, Issue 6 2005
M. Tamura
This study investigated the mechanism of protein attachment to the surface of the putative periodontal pathogens Prevotella intermedia and Prevotella nigrescens in artificial gingival crevicular fluid, and ways to increase protein attachment to the bacterial cells. The effects of cations on protein attachment, bacterial adhesion, and hemagglutination were examined, and cation-binding components on both bacterial species were identified. The presence of cations, especially zinc, copper and cerium, increased attachment of human serum proteins to both bacterial species. In contrast, the presence of hydrophobic inhibitors or sugars had little effect. Protein attachment was reduced by heat treatment of the bacterial cells. Pretreatment of bacteria with human serum proteins inhibited adhesion of both species to buccal epithelial cells and hemagglutination. These effects were enhanced by the presence of zinc and copper during pretreatment. Using a chelating column, specific zinc- and copper-binding proteins were identified on the surfaces of both bacterial species. [source]

Inhibitory effects of cranberry juice on attachment of oral streptococci and biofilm formation

MOLECULAR ORAL MICROBIOLOGY, Issue 3 2004
A. Yamanaka
Cranberry juice is known to inhibit bacterial adhesion. We examined the inhibitory effect of cranberry juice on the adhesion of oral streptococci strains labeled with [3H]-thymidine to saliva-coated hydroxyapatite beads (s-HA). When the bacterial cells were momentarily exposed to cranberry juice, their adherence to s-HA decreased significantly compared with the control (P < 0.01). Their hydrophobicity also decreased dependently with the concentration of cranberry juice. We also evaluated the inhibitory effect of cranberry juice on biofilm formation. By using a microplate system, we found that the high molecular mass constituents of cranberry juice inhibited the biofilm formation of the tested streptococci. The inhibitory activity was related to the reduction of the hydrophobicity. The present findings suggest that cranberry juice component (s) can inhibit colonization by oral streptococci to the tooth surface and can thus slow development of dental plaque. [source]

Cheese Consumption and the Development and Progression of Dental Caries

NUTRITION REVIEWS, Issue 4 2002
Shelby Kashket Ph.D.
Whereas research into the causes of dental decay has focused on the harmful relationship between dental plaque bacteria and foods, studies into the protective effects of foods have been infrequent and limited in number. Recent investigations showed that milk and cheese could reduce the effects of metabolic acids, and could help restore the enamel that is lost during eating. Postulated mechanisms involve buffering, salivary stimulation, reduction of bacterial adhesion, reduction of enamel demineralization, and/or promotion of remineralization by casein and ionizable Ca and P. Given this information, consumers may be motivated to use milk and cheese to reduce, or reverse the cariogenic effects of many other foods. [source]

A new look at bacterial adhesion and its effects on metabolic activity

BIOTECHNOLOGY & BIOENGINEERING, Issue 5 2010
Article first published online: 19 FEB 2010
No abstract is available for this article. [source]

Electric field induced desorption of bacteria from a conditioning film covered substratum

Characterization of the Biomechanical Properties of T4 Pili Expressed by Streptococcus pneumoniae,A Comparison between Helix-like and Open Coil-like Pili

CHEMPHYSCHEM, Issue 9-10 2009
Mickaël Castelain Dr.
Abstract Adhesion strategies: Open coil-like T4 pili use different adhesion strategies in the presence of external forces (see figure) compared to the helix-like P pili. When exposed to significant forces, bacteria expressing helix-like pili remain attached by distributing the external force among a multitude of pili, whereas bacteria expressing open coil-like pili sustain large forces primarily by their multitude of binding adhesins. Bacterial adhesion organelles, known as fimbria or pili, are expressed by Gram-positive as well as Gram-negative bacteria families. These appendages play a key role in the first steps of the invasion and infection processes, and they therefore provide bacteria with pathogenic abilities. To improve the knowledge of pili-mediated bacterial adhesion to host cells and how these pili behave under the presence of an external force, we first characterize, using force measuring optical tweezers, open coil-like T4 pili expressed by Gram-positive Streptococcus pneumoniae with respect to their biomechanical properties. It is shown that their elongation behavior can be well described by the worm-like chain model and that they possess a large degree of flexibility. Their properties are then compared with those of helix-like pili expressed by Gram-negative uropathogenic Escherichia coli (UPEC), which have different pili architecture. The differences suggest that these two types of pili have distinctly dissimilar mechanisms to adhere and sustain external forces. Helix-like pili expressed by UPEC bacteria adhere to host cells by single adhesins located at the distal end of the pili while their helix-like structures act as shock absorbers to dampen the irregularly shear forces induced by urine flow and to increase the cooperativity of the pili ensemble, whereas open coil-like pili expressed by S. pneumoniae adhere to cells by a multitude of adhesins distributed along the pili. It is hypothesized that these two types of pili represent different strategies of adhering to host cells in the presence of external forces. When exposed to significant forces, bacteria expressing helix-like pili remain attached by distributing the external force among a multitude of pili, whereas bacteria expressing open coil-like pili sustain large forces primarily by their multitude of binding adhesins which presumably detach sequentially. [source]

Serotype and adhesion of Pseudomonas aeruginosa isolated from contact lens wearers

CLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 3 2001
Sophy J Thuruthyil PhD
ABSTRACT The purpose of the present study was to correlate the serotypes of Pseudomonas aeruginosa to the bacterial adhesion to contact lenses and human corneal epithelial cells. Twenty-three strains isolated from contact lens wearers were used for the study. The bacterial serotypes were examined with a P. aeruginosa antisera kit. The attachment of bacteria on contact lenses or human corneal epithelial cells was determined by counting the number of adhered bacteria after incubation of the bacteria with contact lenses or corneal epithelial cells. The 23 ocular isolates belonged to seven serotypes. Strains of serotypes I, G and E were the three dominant serogroups and were more adhesive to contact lenses compared with other groups of the bacteria. The bacterial serotypes and the clinical sequelae were not strongly related. These results indicate that the surface characteristics of bacterial serotypes are related to the bacterial adhesion to the surface, but the pathogenesis of the bacteria may result from multiple factors. [source]