Level Of Bacterial Adhesion Research Articles

Bacterial adhesion and microleakage of restorative materials for sealing accessory canals in implant prosthesis.

The level of bacterial adhesion and bacterial microleakage in four different materials utilised to seal the access passage of screw retained implant supported prosthesis (SRIP) is of interest to dentists. Four distinct categories were created from the samples on the basis of restorative materials used for sealing access passage in SRIP. Guttapercha and light cured acrylic resin were found to have comparatively low bacterial adhesion and bacterial microleakage in sealing accessory canals in screw retained implant supported prosthesis.

The trophoblast surface becomes refractory to adhesion by congenitally transmitted Toxoplasma gondii and Listeria monocytogenes during cytotrophoblast to syncytiotrophoblast development.

The placenta is a critical barrier against viral, bacterial, and eukaryotic pathogens. For most teratogenic pathogens, the precise molecular mechanisms of placental resistance are still being unraveled. Given the importance of understanding these mechanisms and challenges in replicating trophoblast-pathogen interactions using in vitro models, we tested an existing stem-cell-derived model of trophoblast development for its relevance to infection with Toxoplasma gondii. We grew human trophoblast stem cells (TSCT) under conditions leading to either syncytiotrophoblast (TSSYN) or cytotrophoblast (TSCYT) and infected them with T. gondii. We evaluated T. gondii proliferation and invasion, cell ultrastructure, as well as for transcriptome changes after infection. TSSYNs cells showed similar ultrastructure compared to primary cells and villous explants when analyzed by transmission electron microscopy and scanning electron microscopy (SEM), a resistance to T. gondii adhesion could be visualized on the SEM level. Furthermore, TSSYNs were highly refractory to parasite adhesion and replication, while TSCYTs were not. RNA-seq data on mock-treated and infected cells identified differences between cell types as well as how they responded to T. gondii infection. We also evaluated if TSSC-derived SYNs and CYTs had distinct resistance profiles to another vertically transmitted facultative intracellular pathogen, Listeria monocytogenes. We demonstrate that TSSYNs are highly resistant to L. monocytogenes, while TSCYTs are not. Like T. gondii, TSSYN resistance to L. monocytogenes was at the level of bacterial adhesion. Altogether, our data indicate that stem-cell-derived trophoblasts recapitulate resistance profiles of primary cells to T. gondii and highlight the critical importance of the placental surface in cell-autonomous resistance to teratogens.IMPORTANCECongenital toxoplasmosis can cause a devastating consequence to the fetus. To reach the fetus's tissues, Toxoplasma gondii must cross the placenta barrier. However, how this parasite crosses the placenta and the precise molecular mechanisms of placental resistance to this parasite are still unknown. In this study, we aimed to characterize a new cellular model of human trophoblast stem cells to determine their resistance, susceptibility, and response to T. gondii. Syncytiotrophoblast derived from trophoblast stem cells recapitulate the resistance profile similarly to placenta cells. We also showed that these cells are highly resistant to Listeria monocytogenes, at the level of bacterial adhesion. Our results suggest that resisting pathogen adhesion/attachment may be a generalized mechanism of syncytiotrophoblast resistance, and trophoblast stem cells represent a promising model to investigate cell-intrinsic mechanisms of resistance to pathogen adhesion and replication.

Exploring the mechanical strength, antimicrobial performance, and bioactivity of 3D-printed silicon nitride-PEEK composites in cervical spinal cages

 In this study, our goal was to assess the suitability of a polyether-ether-ketone (PEEK) and silicon nitride (Si3N4) polymer composite for antimicrobial three-dimensional (3D)-printed cervical cages. Generic cage designs (PEEK and 15 vol.% Si3N4-PEEK) were 3D-printed, including solid and porous cage designs. Cages were tested in static compression, compression shear, and torsion per ASTM F2077. For antibacterial testing, virgin and composite filament samples were inoculated with Staphylococcus epidermidis and Escherichia coli. In vitro cell testing was conducted using MC3T3-E1 mouse preosteoblasts, where cell proliferation, cumulative mineralization, and osteogenic activity were measured. The 3D-printed PEEK and Si3N4-PEEK cages exhibited adequate mechanical strength for all designs, exceeding 14.7 kN in compression and 6.9 kN in compression shear. Si3N4-PEEK exhibited significantly lower bacterial adhesion levels, with a 93.9% reduction (1.21 log), and enhanced cell proliferation when compared to PEEK. Si3N4-PEEK would allow for custom fabrication of 3D-printed spinal implants that reduce the risk of infection compared to unfilled PEEK or metallic alloys.  

High Adherence of Oral Streptococcus to Polylactic Acid Might Explain Implant Infections Associated with PLA Mesh Implantation.

The aim of this study was to evaluate and compare the biofilm formation properties of common pathogens associated with implant-related infections on two different implant material types. Bacterial strains tested in this study were Staphylococcus aureus, Streptococcus mutans, Enterococcus faecalis, and Escherichia coli. Implant materials tested and compared were PLA Resorb × polymer of Poly DL-lactide (PDLLA) comprising 50% poly-L-lactic acid and 50% poly-D-lactic acid) and Ti grade 2 (tooled with a Planmeca CAD-CAM milling device). Biofilm assays were done with and without saliva treatment to evaluate the effect of saliva on bacterial adhesion and to mimic the intraoral and extraoral surgical routes of implant placement, respectively. Five specimens of each implant type were tested for each bacterial strain. Autoclaved material specimens were first treated with 1:1 saliva-PBS solution for 30 min, followed by washing of specimens and the addition of bacterial suspension. Specimens with bacterial suspension were incubated for 24 h at 37 °C for biofilm formation. After 24 h, non-adhered bacteria were removed, and specimens were washed, followed by removal and calculation of adhered bacterial biofilm. S. aureus and E. faecalis showed more attachment to Ti grade 2, whereas S. mutans showed higher adherence to PLA in a statistically significant manner. The salivary coating of specimens enhanced the bacterial attachment by all the bacterial strains tested. In conclusion, both implant materials showed significant levels of bacterial adhesion, but saliva treatment played a vital role in bacterial attachment, therefore, saliva contamination of the implant materials should be minimized and considered when placing implant materials inside the body.

In vitro and in vivo methods to study bacterial colonization of hydrogel dermal fillers.

Preclinical in vitro and in vivo methods to study bacterial interactions with dermal fillers and infection pathogenesis are lacking. In this work, first in vitro methods to assess protein biofouling and effective pore size of commercial dermal fillers, including degradable hyaluronic acid (HA)-based fillers and other semi-degradable or permanent fillers (non-HA), were developed. The results were then related to Staphylococcus aureus (S. aureus) adhesion rates in vitro. HA fillers had less protein sorption than non-HA fillers and overall had smaller effective pore sizes. The properties correlated with levels of bacterial adhesion, where the control glass surface had the most rapid increase in bacterial cell adhesion, with a slope of 0.29 cm-2 min-1 , three unique non-HA fillers had intermediate adhesion with slopes of 0.11 and 0.06 cm-2 min-1 , and three unique HA fillers had the least adhesion with slopes of 0.02, 0.02, and 0.01 cm-2 min-1 . S. aureus had greater motility on the HA fillers than on non-HA fillers. Next, a mouse model for dermal filler biofilm and infection was developed. Mice were inoculated with a controlled amount of bioluminescent bacteria (Xen36 S. aureus) and polyacrylamide hydrogels of different stiffness were injected. In vivo bioluminescence was monitored longitudinally for 35 days to ensure that lasting colonization was established. The inoculum was optimized to achieve adequate bioluminescent signal, and bacterial bioburden over time and inter-animal variability in bioburden were determined. These in vitro and in vivo approaches can be used for future studies of antimicrobial interventions for dermal fillers.

Effectiveness of Chitosan Coating Catheter in Preventing Catheter- Associated Urinary Tract Infection (CAUTI)

Catheter-associated urinary tract infection (CAUTI) is a serious health issue that develops in hospitalized patients. The number of CAUTI cases could be reduced by preventing microbial adhesion and biofilm formation. Chitosan demonstrates antimicrobial activity against a variety of microorganisms. Coating the surfaces of silicon catheters has been shown to minimize or prevent bacterial adhesion and biofilm formation. In this study, we investigated the efficacy of chitosan, in different molecular sizes, as a polymer-coated silicon catheter. Chitosan of a high (HMw), medium (MMw), and low (LMw) molecular weight, at a pH value of 5.0-6.0, used to coat catheters, was examined using two methods, namely the crystal violet and sonication methods. The first method showed that clinical Klebsiella pneumoniae had a significantly (p<0.05) lower level of bacterial adhesion with MMw chitosan, and Klebsiella pneumoniae ATCC 13883 with LMw of chitosan. Using the sonication method, the MMw chitosan showed a decrease in bacterial viability for the Escherichia coli clinical isolate, Klebsiella pneumoniae reference strain, and Escherichia coli reference strain at to a greater extent than the HMw and LMw. Chitosan with three molecular weights (Mw) showed some antibacterial activity when the time-kill assay was applied. However, overall, HMw chitosan grades were not found to be effective as an antibacterial coating agent, although the MMw and LMw presented a potential antiadhesive polymer material to reduce CAUTI.

Potent Antibacterial and Antibiofilm Activities of a Synthetic Remineralizing Preparation of Nano-Hydroxyapatite Against Cariogenic Streptococcus mutans Using an Ex-vivo Animal Model

AimThe aim to this study is to evaluate the biocompatibility and antibiofilm actions of two nano-hydroxy apatite (NHA).MethodologyNano-hydroxy apatites are biomaterials use in direct contact with living tissues. Therefore, they should be tested for their safety beside assessment of their minimum inhibitory (MIC) and minimum bactericidal concentration (MBC) using broth microdilution method. One hundred and twenty extracted bovine incisors were collected and cleaned to ensure the absence of any defects. Enamel blocks with different size (2 × 2 × 3 mm) and (5 × 5 × 2 mm) were prepared from their labial surfaces using an isomet saw. Enamel blocks are used for detecting the suitable concentration will be used in the following experiments using energy dispersive X-ray analysis (EDX). The remaining enamel blocks divided into 5 equal groups to detect inhibitory effect against bacterial adhesion to the initial enamel caries like lesions using viable count technique beside the antibiofilm activity against mature biofilm of Streptococcus mutans (S. mutans) using confocal laser microscopy. The remaining enamel blocks were used as a representing data for detecting surface topography for each group by using the scanning electron microscopy (SEM).ResultThe data showed safety of NHA suspensions. Additionally, only NHA suspension of large nanoparticle size (NHA-LPS) had MIC of 1.25 mg/ml against S. mutans. Also, have the higher percentages of Ca and P in the enamel blocks. Furthermore, the lowest level of bacterial adhesion was recorded in (group III) treated by NHA-LPS which was non-significantly different with the positive control group V. Biofilm thickness in group IV treated with NHA-small particle size (SPS) recorded high biofilm thickness followed by group III. Interestingly, group III showed greater killing effect against mature biofilm which is slightly higher than the positive control group V. In group III, surface topography revealed very smooth enamel surface with closed pores. Accordingly, NHA-LPS suspension had antiadhesive, antibacterial, and antibiofilm effect against cariogenic S. mutans representing a promising possibility to be recommended for safe effective remineralization.

Antibacterial Polyelectrolytic chitosan derivatives conjugated natural rubber latex films with minimized bacterial adhesion

AbstractWater soluble polyelectrolytic derivatives of chitosan (CDs) with carboxyl (COO−) and quaternary ammonium (NH4+) groups were synthesized and characterized by NMR, FT‐IR, TGA and zeta potential analyses; while degree of substitution was determined by potentiometric titrations. Both CDs in the as‐synthesized form exhibited antibacterial zones against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The CD conjugated vulcanized natural rubber latex (NRL) films were investigated for understanding the level of bacterial adhesion and bactericidal properties as a function of the polyelectrolytic groups present. NRL Films modified at ambient conditions were found effective against Pseudomonas aeruginosa (P. aeruginosa). The biofilm assay results demonstrate that CD conjugated samples exhibit significantly reduced adhesion (63.8%) against P. aeruginosa. Further, alterations observed in cellular morphology of attached bacteria indicate that the modified surface of films is bacteriocidal while presence of significantly higher level of extra cellular polymer substances (EPS) were detected on control NRL films.

Antibacterial superhydrophobic polyvinyl chloride surfaces via the improved phase separation process using silver phosphate nanoparticles

This study aims to induce antibacterial and superhydrophobic properties on the surface of thermoplastic polyurethane (TPU) sheets via an improved phase separation process through application of polyvinyl chloride (PVC) thin films. Porous PVC thin films were produced using different amounts of ethanol as nonsolvent. However, the created porosity was not sufficient to achieve superhydrophobicity. To improve the phase separation process, the silver phosphate nanoparticles were first synthesized and then added to the solution. According to scanning electron microscopy and X-ray photoelectron spectroscopy results, the nanoparticles were majorly localized at the bulk of PVC films. A direct relationship was found between the level of porosity and superhydrophobicity. An exceedingly high amount of nanoparticles had a deteriorating influence on porosity and superhydrophobicity. The optimum sample was found to be durable against liquids with different pH values. In contrast to the good resistance of superhydrophobic sample at elevated temperatures (80 °C), a sticky behavior was obtained upon exposure to 120 °C. The level of bacterial adhesion for the superhydrophobic sample was drastically declined (>99%) with respect to the pure PVC film in case of S. aureus and E. coli bacteria after an incubation time of 24 h. In conclusion, the hybrid of superhydrophobic behavior and an antibacterial material such as silver phosphate nanoparticles exhibited a promising potential in achieving antibacterial surfaces.

Antimicrobial graphene nanoplatelets coatings for silicone catheters

Silicone rubber (SR) peritoneal dialysis (PD) catheters are prone to bacterial adhesion and biofilm formation, which contributes to development of infection and associated morbidity in PD patients. We herein evaluate whether surface immobilization of graphene nanoplatelets (GNP) provides antimicrobial properties to SR. Dip and spray coating were used to deposit a dispersion containing SR and GNP-M5 or its oxidized form (GNP-M5ox) on the surface of silicone. The antimicrobial effect of GNP exposure and oxidation towards Staphylococcus epidermidis was assessed. GNP was successfully exposed on the surface, and while dipping provided better adhesion of either GNP, spraying resulted in uniform and higher surface coverage. Spraying led to enhanced bacterial adhesion comparing to dip coated and uncoated SR, which are similar. However, independently of the technique, GNP-M5ox coatings induced higher bacterial death. As such, SR/GNP-M5ox coating performed by dipping revealed to be the most promising approach, preserving bacterial adhesion levels of silicone while increasing bacterial death to around 80%.For the first time, graphene-based materials antimicrobial activity was evaluated by quantification of bacterial adhesion and viability. The high antibacterial effect, associated with a stable and cytocompatible coating which does not delaminate from SR surface, demonstrates its potential use in silicone biomedical industry.

Combined soft lithographic transfer‐printing and patterning method of highly fluorinated polymers as a facile surface treatment protocol

ABSTRACTA combined soft lithographic transfer‐printing and patterning method of highly fluorinated polymers was investigated aiming to establish a facile surface treatment protocol for various substrates. Spin‐coated layers of poly(1H,1H,2H,2H‐perfluorodecyl methacrylate) (PFDMA) on patterned polydimethylsiloxane (PDMS) molds were transfer‐printed successfully on silicon, glass, aluminum substrates, resulting in the well‐controlled production of nano to micrometer‐scale periodic structures. With careful optimization of the dimension and density of the PFDMA patterns, it was possible to achieve a water contact angle as high as 175° on the transfer‐printed highly fluorinated polymer film. One of the advantages of the transfer‐patterning method is that highly fluorinated polymer films can be printed on curved surfaces while retaining their superhydrophobic and corrosion‐prevention character. In addition, the transfer‐printed PFDMA layers on the glass plates showed enhanced light transmission, which led to the extraction of 10% more light when they were applied to the emitting side of green organic light‐emitting devices. The micro‐patterned PFDMA surfaces also exhibited a significantly reduced level of bacterial adhesion when they were incubated in human bile juice. These results strongly suggest that the proposed facile transfer‐patterning protocol of highly fluorinated polymer films can be a suitable surface‐treatment technique for implantable electronic devices that exhibit improved device performance and anti‐biofouling nature. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45184.

The impacts of a fliD mutation on the biofilm formation of Helicobacter pylori

ObjectiveTo investigate the impact of the fliD gene on the biofilm formation of Helicobacter pylori (H. pylori). MethodsH. pylori fliD mutant was constructed using inverse PCR mutagenesis. The mobility of the bacteria and its adhesion ability to human epithelial cells were assessed using a motility assay and a fluorescein isothiocyanate staining adhesion assay, respectively. The formation of biofilm was evaluated using a pellicle assay and a crystal violet staining assay. The cyto-architecture of the biofilm was documented with scanning electron microscopy. ResultsIt was found that there was no significant difference in the levels of bacterial adhesion and the biofilm formation between the wild-type ATCC 43504 and the fliD mutant. Apart from a poor motility, the fliD mutant had a slightly delayed formation of its biofilm and an incomplete cyto-architecture of its biofilm. The bacterial cells residing in the biofilm of the fliD mutant showed a loose accumulation with less apparent cross-linking fibrils. Most of the mutant cells had truncated flagella. ConclusionsThis study provides the preliminary evidences that fliD potentially regulates biofilm formation and is required for the motility of H. pylori. Further studies need to be performed in order to develop fliD as a novel target for vaccine or antimicrobial agent in future.

Campylobacter jejuni outer membrane vesicle-associated proteolytic activity promotes bacterial invasion by mediating cleavage of intestinal epithelial cell E-cadherin and occludin.

Outer membrane vesicles (OMVs) play an important role in the pathogenicity of Gram-negative bacteria. Campylobacter jejuni produces OMVs that trigger IL-8, IL-6, hBD-3 and TNF-α responses from T84 intestinal epithelial cells and are cytotoxic to Caco-2 IECs and Galleria mellonella larvae. Proteomic analysis of 11168H OMVs identified the presence of three proteases, HtrA, Cj0511 and Cj1365c. In this study, 11168H OMVs were shown to possess proteolytic activity that was reduced by pretreatment with specific serine protease inhibitors. OMVs isolated from 11168H htrA, Cj0511 or Cj1365c mutants possess significantly reduced proteolytic activity. 11168H OMVs are able to cleave both E-cadherin and occludin, but this cleavage is reduced with OMVs pretreated with serine protease inhibitors and also with OMVs isolated from htrA or Cj1365c mutants. Co-incubation of T84 monolayers with 11168H OMVs results in a visible reduction in both E-cadherin and occludin. The addition of 11168H OMVs to the co-culture of live 11168H bacteria with T84 cells results in enhanced levels of bacterial adhesion and invasion in a time-dependent and dose-dependent manner. Further investigation of the cleavage of host cell structural proteins by C. jejuni OMVs should enhance our understanding of the interactions of this important pathogen with intestinal epithelial cells.

Bacteria and osteoblast adhesion to chitosan immobilized titanium surface: A race for the surface

In order to evaluate the anti-infective efficacy of the titanium implant materials, two co-culture systems, a low-bacteria/osteoblast (L-B) and a high-bacteria/osteoblast system (H-B), were established. Untreated (UN-Ti), sulfuric acid-treated (SA-Ti), and chitosan immobilized titanium (SA-CS-Ti) materials were developed and evaluated. Bacteria and osteoblast behaviors, including initial attachment (evaluated at 30mins), adhesion (evaluated at 4h), and osteoblast spreading on each material surface were evaluated using quantification assays, scanning electron microscopy (SEM), and confocal microscopy. Quantification analysis at 30mins showed significantly higher number of osteoblast present on SA-CS-Ti in both L-B (10,083±2626) and H-B (23,592±2233) than those on the UN-Ti (p<0.05). SEM observation and confocal microscopy results showed more surface area was occupied by adhered osteoblasts on SA-CS-Ti than UN-Ti and SA-Ti in both co-culture systems at 30mins. At all time points, SA-CS-Ti had the lowest level of bacterial adhesion compared to UN-Ti and SA-Ti in both co-culture systems. A significantly (p<0.05) lower number of bacteria were recovered from SA-CS-Ti (2233±681) in the H-B system compared to UN-Ti (5367±1662) and SA-Ti (4533±680) at 4h. Quantitative and qualitative co-culture results show the great potential of chitosan immobilization onto implant materials to prevent implant-associated infections.

Correction: Identification of a Predicted Trimeric Autotransporter Adhesin Required for Biofilm Formation of Burkholderia pseudomallei.

[This corrects the article DOI: 10.1371/journal.pone.0079461.].

Identification of a Predicted Trimeric Autotransporter Adhesin Required for Biofilm Formation of Burkholderia pseudomallei

The autotransporters are a large and diverse family of bacterial secreted and outer membrane proteins, which are present in many Gram-negative bacterial pathogens and play a role in numerous environmental and virulence-associated interactions. As part of a larger systematic study on the autotransporters of Burkholderia pseudomallei, the causative agent of the severe tropical disease melioidosis, we have constructed an insertion mutant in the bpss1439 gene encoding an unstudied predicted trimeric autotransporter adhesin. The bpss1439 mutant demonstrated a significant reduction in biofilm formation at 48 hours in comparison to its parent 10276 wild-type strain. This phenotype was complemented to wild-type levels by the introduction of a full-length copy of the bpss1439 gene in trans. Examination of the wild-type and bpss1439 mutant strains under biofilm-inducing conditions by microscopy after 48 hours confirmed that the bpss1439 mutant produced less biofilm compared to wild-type. Additionally, it was observed that this phenotype was due to low levels of bacterial adhesion to the abiotic surface as well as reduced microcolony formation. In a murine melioidosis model, the bpss1439 mutant strain demonstrated a moderate attenuation for virulence compared to the wild-type strain. This attenuation was abrogated by in trans complementation, suggesting that bpss1439 plays a subtle role in the pathogenesis of B. pseudomallei. Taken together, these studies indicate that BPSS1439 is a novel predicted autotransporter involved in biofilm formation of B. pseudomallei; hence, this factor was named BbfA, Burkholderia biofilm factor A.

Relationship between chemical components, bacterial adherence and in vitro fermentation of tropical forage legumes

Inclusion of forage legumes in diet may improve tropical ruminant systems productivity and sustainability. However, it is not well stablished which chemical components more impact their nutritional value. The relationship between chemical composition and in vitro fermentation of tropical forage legume was evaluated with the objective of obtaining indicators of their nutritional value. Samples of Crotalaria spectabilis, Cajanus cajan, Macrotyloma axillare, Mucuna aterrina, Stylosantis sp. and Canavalia ensiformis, cut from plants at growth age between 47 to 110 days, were analysed. Total gas production showed negative correlation (P&lt;0.05) with total N (R=-0.51), acid detergent fibre (ADF, R=-0.62) and acid detergent lignin (ADL, R=-0.65), and positive correlation with non-fibre carbohydrates (NFC, R=0.70). Gas production rate was negatively related (P&lt;0.05) to NDF (R=-0.73), ADF (R=-0.62) and ADL (R=-0.74). Ammonia concentration in the incubation medium was positively related (P&lt;0.05) to total (R=0.74) and soluble (R=0.56) N, and negatively related to NFC (R=-0.81). The level of bacterial adhesion on residue of incubation was negatively related (P&lt;0.05) to cell wall components, mainly to ADL (R=-0.57). The inclusion of polyehtylene glycol increased both gas volume and gas production rate whereas decreased ammonia concentration (P&lt;0.05). In conclusion, even at low concentrations tannins impact the in vitro fermentation of tropical legumes. However, among the analyzed chemical components, the ADL was the best indicator of the nutritional value of the tropical forage legumes.

Bacterial and Candida albicans Adhesion on Different Root Canal Filling Materials and Sealers

Introduction Microbial adhesion and subsequent biofilm formation on endodontic root canal filling materials and sealers lead to survival of microorganisms in treated root canals and subsequently to endodontic treatment failures. The present study focused on initial microbial adhesion to different endodontic filling materials. Methods The following endodontic biomaterials were tested: AH-Plus, Tubli Seal, gutta-percha, Real Seal SE, EndoREZ, Apexit Plus, GuttaFlow, and dentin. Samples of each material were prepared. Bovine dentin samples were used as a control. The initial adhesions of salivary bacteria as well as the subsequent single species were quantified by determination of colony-forming units (CFUs) and visualized by scanning electron microscopy and confocal microscopy (CLSM): Enterococcus faecalis, Streptococcus mutans, Streptococcus sanguis, Candida albicans, and Prevotella nigrescens. Results Initially adherent microorganisms could be detected and microscopically visualized on each of the materials tested. Considering the values of the CFUs and the covering grade as detected by CLSM, there were significant differences among the materials. Fewer bacteria tended to adhere to Apexit Plus, whereas Real Seal SE and the widely used gutta-percha showed the highest number of adherent bacteria. This tendency was not detected for C. albicans. Conclusions Endodontic microorganisms have a high affinity to root canal filling materials and sealers, especially to gutta-percha. Because of this high level of bacterial adhesion, subsequent biofilm formation on these materials could be suggested as leading to the persistence of microorganisms in root canals.

Bacterial Adhesion on Smooth and Rough Titanium Surfaces After Treatment With Different Instruments

Newly formed biofilm after implant debridement may challenge the long-term stability of peri-implant therapy. This in vitro study aimed to assess the roughness and adherence of Streptococcus sanguinis after treatment of smooth and rough titanium surfaces with an erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser, metal and plastic curets, and an air-powder abrasive system. Forty titanium disks with smooth-machined surfaces and 40 with sand-blasted and acid-etched surfaces were divided into the following treatment groups: Er:YAG laser; plastic curet; metal curet, and air-powder abrasive system. The surface roughness (roughness average [Ra]) before and after treatments was determined using a profilometer. S. sanguinis (American Type Culture Collection 10556) was grown on treated and untreated specimens, and the amounts of retained bacteria on the surfaces were measured by the culture method. Rough and smooth surfaces with and without a suspension of S. sanguinis were also analyzed using scanning electron microscopy (SEM). For smooth surfaces, the roughest surfaces were produced by metal curets (repeated-measures analysis of variance [ANOVA] and Tukey test; P <0.05). The rough-surface profile was not altered by any of the treatments (repeated-measures ANOVA; P >0.05). Rough surfaces treated with metal curets and air-powder abrasion showed the lowest level of bacterial adhesion (two-way ANOVA and Tukey test; P <0.05). SEM analysis revealed distinct surface profiles produced by all devices. Metal curets are not recommended for smooth titanium surface debridement due to severe texture alteration. Rough surfaces treated with a metal curet and the air-powder abrasive system were less susceptible to bacterial adhesion, probably due to texture modification and the presence of abrasive deposits.

Impact of surface energy and roughness on cell distribution and viability

The aim of this study was to assess the respective impacts of the surface energy and surface roughness of bare and coated steels on biofouling and sanitisation. Bioadhesion of Staphylococcus aureus CIP 53.154 was studied on two stainless steel surfaces with smooth or specific micro-topography. Two coatings were also studied: silicon oxide (hydrophilic) and polysiloxane (hydrophobic). On smooth surfaces, adhesion was reduced on an apolar coating and cell viability increased with the surface polarity. A specific micro-topography decreased the level of bacterial adhesion on bare surfaces by a factor ten. On this surface, only single adherent cells were observed, contrasting with cells in clusters on smoother surfaces. As a consequence, cell repartition influenced bacterial viability. Most isolated adherent cells were dead whereas cells in clusters were still alive. In addition, the quaternary ammonium chloride used in sanitisation, acted at once both as a tensio-active molecule and a biocide. It only displaced adherent cells but did not remove them.