Anti-adherence Activity Research Articles

Evaluation of the antibacterial effect of (R)-(+)-Limonene against Enterococcus faecalis and Enterobacter cloacae strains isolated from food

The aim of this study was to evaluate the potential antibacterial and anti-adherent activities of the monoterpene (R)-(+)-limonene, as well as its synergistic potential with synthetic antimicrobials against strains of Enterococcus faecalis and Enterobacter cloacae. The antibacterial properties of (R)-(+)-limonene were assessed using the broth microdilution technique to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Additionally, the infusion disc method was employed to explore the association of the compound with antimicrobials, and the test tube method was used to determine the minimum inhibitory concentration of adherence (MICA). It was observed that the MIC for (R)-(+)-limonene was 1000 μg mL-1 for five of the six E. faecalis strains tested, while for E. cloacae, the MIC exceeded 1000 μg mL-1 for all strains tested. Identical values were recorded for the MBC in E. faecalis. In terms of its combination with synthetic antimicrobials, (R)-(+)-limonene demonstrated a synergistic effect with gentamicin and ciprofloxacin for most strains. Regarding the MICA, both (R)-(+)-limonene and 0.12% chlorhexidine digluconate failed to inhibit biofilm formation at the tested concentrations. Given the need for new therapeutic alternatives for treating bacterial infections, this study revealed that the tested monoterpene exhibited moderate bactericidal effects against E. faecalis strains and no antibacterial effect against E. cloacae strains. However, when combined with various classes of antimicrobials, (R)-(+)-limonene showed synergistic effects with gentamicin and ciprofloxacin for most strains. This suggests that (R)-(+)-limonene holds promise for enhancing the treatment of bacterial infections and could support conventional therapies. Nonetheless, further in vitro, ex vivo, and in vivo studies are necessary to confirm and elucidate its efficacy and mechanisms.

Assessment of the Antifungal Activity of PMMA-MgO and PMMA-Ag Nanocomposite

Orthodontic acrylic resin is used in the construction of orthodontic appliances. It lacks antimicrobial properties and is prone to microbial infection. So, the infection associated with it can be reduced via modification of orthodontic acrylic resin with nanoparticles (NPs) incorporation. The study directed to evaluate the antifungal properties of modified orthodontic acrylic resin incorporated with magnesium oxide (MgO)-NPs and silver (Ag)-NPs. NPs were mixed with polymethylmethacrylate (PMMA) in ethanol-assisted mixing method. Disc samples (10 mm in diameter and 2 mm thick) of PMMA-MgO, PMMA-Ag nanocomposites and PMMA alone (as control) were prepared. Then, C. albicans was isolated and identified clinically through taking swabs from acrylic denture base orthodontic appliances, cultured on a Sabouraud Dextrose Agar medium, followed by transferring on HiCrome™ candida Differential agar which is a selective and differential medium to distinguish distinct Candida species. The polymerase chain reaction was performed and the amplicon was separated by 2% gel electrophoresis and then visualised by ethidium bromide. DNA sequencing was performed on the sample at Sanger sequencing/ ABI 3500. Antifungal activity of PMMA-MgO and PMMA-Ag (1%, 3% and 5% of NPs) was conducted through disc diffusion assay and colony forming unit counts. The result showed a decrease in the number of adhered Candida albicans (C. albicans) of all concentrations of both nanocomposite and the decrease was statistically significant (P<0.05) in all experimental groups except MgO-NPs 1% and 3%. Increasing the concentration of NPs was associated with decrease in the adhered C. albicans. It was concluded that PMMA-MgO and PMMA-Ag nanocomposites showed anti-adherence activities against clinically isolated C. albicans in concentration dependent manner.

Biological Activities of Virgin Coconut and Virgin Olive Oil Mixture against Oral Primary Colonizers: An In Vitro Study.

This study aimed to explore the potential synergistic interaction of virgin coconut oil (VCO) and virgin olive oil (VOO) mixture against Streptococcus sanguinis, Streptococcus mutans, and Lactobacillus casei in a single and mixture species through the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), antiadherence, and antibiofilm activities. The broth microdilution technique was used to individually determine the MIC of both oils and an oil mixture (in the ratio of 1:1) in a 96-well microtiter plate. As for the MBC, the subcultured method was used. The fractional inhibitory concentration index (ΣFIC) was determined to identify the interaction types between both oils. The oil mixture at its MIC was then tested on its antibiofilm and antiadherence effect. The MIC of the oil mixture against the tested microbiota was 50-100%. The oil mixture was bactericidal at 100% concentration for all the mentioned microbes except S. mutans. The ΣFIC value was 2 to 4, indicating that the VCO and VOO acted additively against the microbiota. Meanwhile, the oil mixture at MIC (50% for S. sanguinis and L. casei; 100% for S. mutans and mixture species) exhibited antiadherence and antibiofilm activity toward the microbiota in mixture species. The oil mixture possesses antibacterial, antibiofilm, and antiadherence properties toward the tested microbiota, mainly at 50-100% concentration of oil mixture. There was no synergistic interaction found between VCO and VOO. Children and individuals with special care may benefit from using the oil mixture, primarily to regulate the biofilm formation and colonization of the bacteria. Furthermore, the oil mixture is natural and nontoxic compared to chemical-based oral healthcare products. How to cite this article: Ng YM, Sockalingam SNMP, Shafiei Z, et al. Biological Activities of Virgin Coconut and Virgin Olive Oil Mixture against Oral Primary Colonizers: An In Vitro Study. J Contemp Dent Pract 2024;25(3):260-266.

Cellulose Nanocrystals Show Anti-Adherent and Anti-Biofilm Properties against Oral Microorganisms.

Cellulose nanocrystals (CNCs) are cellulose-derived nanomaterials that can be easily obtained, e.g., from vegetable waste produced by circular economies. They show promising antimicrobial activity and an absence of side effects and toxicity. This study investigated the ability of CNCs to reduce microbial adherence and biofilm formation using in vitro microbiological models reproducing the oral environment. Microbial adherence by microbial strains of oral interest, Streptococcus mutans and Candida albicans, was evaluated on the surfaces of salivary pellicle-coated enamel disks in the presence of different aqueous solutions of CNCs. The anti-biofilm activity of the same CNC solutions was tested against S. mutans and an oral microcosm model based on mixed plaque inoculum using a continuous-flow bioreactor. Results showed the excellent anti-adherent activity of the CNCs against the tested strains from the lowest concentration tested (0.032 wt. %, p < 0.001). Such activity was significantly higher against S. mutans than against C. albicans (p < 0.01), suggesting a selective anti-adherent activity against pathogenic strains. At the same time, there was a minimal, albeit significant, anti-biofilm activity (0.5 and 4 wt. % CNC solution for S. mutans and oral microcosm, respectively, p = 0.01). This makes CNCs particularly interesting as anticaries agents, encouraging their use in the oral field.

Yarrowia lipolytica CMGB32 Biosurfactants Produced Using n-Hexadecane: Developing Strategies for Environmental Remediation

The yeast Yarrowia lipolytica degrades petroleum compounds, including alkanes, via the monoterminal oxidation pathway, the hydrophobic carbon substrate assimilation is mediated by biosurfactants, and extracellular amphiphilic molecules are produced by the yeast cell. This study focuses on the ability of the strain Y. lipolytica CMGB32 to degrade n-hexadecane by producing biosurfactants with high potential for bioremediation. The hydrocarbon-degrading potential of the yeast strain was observed via a 2,6-dichlorophenolindophenol (DCPIP) test in Bushnell–Hass medium with 1% n-hexadecane, and cell hydrophobicity was expressed as microbial adhesion to hydrocarbons (MATH). Biosurfactant production on yeast peptone (YP) with 1% n-hexadecane was estimated after 72 h using the emulsification index (E24%) against toluene. Crude biosurfactant (cell-free broth) stability tests were performed at different temperatures (4 °C, 70 °C) and NaCl concentrations (2–10%). The effects of a biosurfactant on synthetic wastewater remediation comprised the growth curves (OD measurements) of natural heavy metal degrader Rhodotorula mucilaginosa, determination of nutrients (spectrophotometrically), physico-chemical parameters, and removal capacity of lead and cadmium ions (via inductively coupled plasma mass spectrometry—ICP-MS). The antimicrobial and anti-adherence activities of 20 mg/mL and 40 mg/mL of the biosurfactant against pathogenic Candida krusei strains involved growth observations and the crystal violet microtiter method. The DCPIP decolorization occurred after six days, corresponding to the maximum growth phase of the Y. lipolytica culture. After 72 h, the cells presented high hydrophobicity (82.61% MATH) and stable biosurfactant production (E24% 47%). The crude biosurfactant (5%) increased the growth of R. mucilaginosa strains cultivated on synthetic wastewater cultures contaminated with Pb2+ and Cd2+, increased the conductivity and COD (86%) of the samples, and determined Pb2+ (66%) and Cd2+ (42%) ions reduction. The concentrated biosurfactant inhibited C. krusei growth (70%) and biofilm adherence. In conclusion, Y. lipolytica CMGB32 shows important potential for development of biosurfactant-based technologies for the remediation of heavy-metal- and emerging pathogen-contaminated wastewaters.

Chemical Characterization and Biological Properties Assessment of Euphorbia resinifera and Euphorbia officinarum Moroccan Propolis.

Although the plants of the genus Euphorbia are largely exploited by therapists in Morocco, the composition and antibacterial activities of propolis from these plants are still unknown. To address this gap, this study aimed to characterize the pollen type, the volatile compounds, and the phenolic and mineral profiles of three Euphorbia propolis samples collected in Morocco and evaluate their antimicrobial activities. The minimum inhibitory concentration of the propolis samples was determined by the microdilution method, and the anti-adherence activity was evaluated by the crystal violet assay. The examination of anti-quorum-sensing proprieties was performed using the biosensor Chromobacterium violaceum CV026. Pollen analysis revealed that Euphorbia resinifera pollen dominated in the P1 sample (58%), while E. officinarum pollen dominated in the P2 and P3 samples (44%). The volatile compounds were primarily composed of monoterpene hydrocarbons, constituting 35% in P1 and 31% in P2, with α-pinene being the major component in both cases, at 16% in P1 and 15% in P2. Calcium (Ca) was the predominant mineral element in both E. resinifera (P1) and E. officinarum (P2 and P3) propolis samples. Higher levels of phenols, flavonoids and dihydroflavonoids were detected in the E. officinarum P2 sample. The minimum inhibitory concentration (MIC) value ranged from 50 to 450 µL/mL against Gram-positive and Gram-negative bacteria. Euphorbia propolis displayed the ability to inhibit quorum sensing in the biosensor C. violaceum CV026 and disrupted bacterial biofilm formation, including that of resistant bacterial pathogens. In summary, the current study evidences the potential use of E. officinarum propolis (P2 and P3) to combat important features of resistant pathogenic bacteria, such as quorum sensing and biofilm formation.

Evaluation of the antibacterial, modulatory and anti-adherent properties of oregano (Origanum vulgare) essential oil against food pathogenic bacteria

There are over 250 types of foodborne diseases, the majority of which are infections caused by bacteria. Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus saprophyticus are considered contaminants of meat products. The use of natural products as antimicrobials to combat these diseases can be an effective and economical approach. This study proposes to assess the antibacterial, modulatory, and anti-adherent activity of the essential oil of Origanum vulgare against strains of Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus saprophyticus isolated from meat products. The assay was conducted in duplicate. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined using the broth microdilution technique. MIC represents the lowest concentration of the product capable of inhibiting the growth of the bacterial strain, whereas MBC represents the lowest concentration capable of inhibiting total growth. The study of association of the product with antimicrobials was undertaken by disk diffusion using ampicillin, gentamicin, ceftazidime, and ciprofloxacin, resulting in synergistic, antagonistic, or indifferent effects. Anti-adherent activity was determined in the presence of sucrose, as the lowest concentration of the agent in contact with sucrose that prevented adherence to the glass tube. Oregano oil exhibited strong inhibitory and bactericidal activity against Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus saprophyticus, with MIC values ranging from 32 to 512 μg mL-1 and MBC values ranging from 128 to 512 μg mL-1. Origanum vulgare oil showed varied interactions when associated with antimicrobials, with modulations for synergism (37.5%), indifference (50%), and antagonism (12.5%). Regarding anti-adherent activity, the test product effectively inhibited the adherence of P. aeruginosa bacterial strains in the presence of sucrose (1:8) but had no effect against K. pneumoniae or S. saprophyticus. Therefore, oregano oil proves to be an antibacterial and modulating agent against different bacteria isolated from meat products. Additionally, it displays anti-adherent properties against P. aeruginosa, making it a natural product that could serve as an interesting alternative in efforts to combat foodborne diseases.

Comparative evaluation of anti-biofilm and anti- adherence potential of plant extracts against Streptococcus mutans: A therapeutic approach for oral health

Dental caries predominantly attributed to the cariogenic nature of Streptococcus mutans, continue to pose a substantial global challenge to oral health. In response to this challenge, this study aimed to evaluate the effectiveness of leaf extracts (LEs) and essential oils (EOs) derived from different medicinal plants in inhibiting the growth of Streptococcus mutans biofilm. In vitro and in silico approaches were employed to identify active compounds and assess their inhibitory effects on S. mutans. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were measured to determine the anti-biofilm and anti-adherence activity against S. mutans. Biofilm viability (CFU/mL) and extracellular polymeric substance (EPS) concentration were quantified. GC-MS analysis was utilized to identify active compounds in the most effective plant extracts exhibiting anti-S. mutans activity. A high-throughput screening focused on the interaction between these compounds and the target enzyme SortaseA (SrtA) using molecular docking was performed. Results indicated that Cymbopogon citratus displayed the highest efficacy in reducing S. mutans biofilm formation and adhesion activity, achieving 90 % inhibition at an MIC value of 12 μg/mL. Among the 12 bioactive compounds identified, trans-Carvyl acetate exhibited the lowest binding energy with SrtA (-6.0 Kcal/mole). Trans-Carvyl acetate also displayed favorable pharmacokinetic properties. This study provides novel insights into the anti-S. mutans properties of C. citratus and suggests its potential as a therapeutic approach for oral health. Further research is needed to explore the combined effect of plant extracts for enhanced protection against dental caries.

Chitosan-Coated Silver Nanoparticles Inhibit Adherence and Biofilm Formation of Uropathogenic Escherichia coli.

Urinary tract infections are commonly caused by uropathogenic Escherichia coli (UPEC), which usually presents multiple virulence and resistance mechanisms, making it difficult to treat. It has been demonstrated that silver and polymeric nanoparticles had potential against these pathogens. In this study, we synthesized thiol chitosan-coated silver nanoparticles (SH-Cs-AgNPs) and evaluated their antibacterial, antibiofilm and antiadherence activity against clinical isolates of UPEC. The SH-Cs-AgNPs showed a spherical shape with a size of 17.80 ± 2.67 nm and zeta potential of 18 ± 2 mV. We observed a potent antibacterial and antibiofilm activity as low as 12.5 μg/mL, as well as a reduction in the adherence of UPEC to mammalian cells at concentrations of 1.06 and 0.53 μg/mL. These findings demonstrate that SH-Cs-AgNPs have potential as a new therapeutic compound against infections caused by UPEC.

Evaluation of the Anti-Bacterial and Anti-Adherent Activity of Pogostemon Cablin’s Essential Oil Against Klebsiella Pneumoniae

Klebsiella pneumoniae is an example of a microorganism that does not belong to the oral biofilm in a state of health but is present in cases of infection, especially nosocomial infections. The high virulence and resistance of this bacterium to various forms of antimicrobial treatment represent a major concern in the hospital environment, as it is responsible for a high number of deaths of hospitalized patients under mechanical ventilation, so the search for new drugs that are effective in treating this bacterium is extremely important. Natural products, especially essential oils, have considerable therapeutic activities in antimicrobial treatments. A good example is Pogostemon cablin, which has antimicrobial, anti-adherent, and anti-inflammatory activities, among others. Thus, this research aimed to analyze the possible antimicrobial potential of the essential oil extracted from Pogostemon cablin against strains of Klebsiella pneumoniae, using the Minimum Inhibitory Concentration (MIC), which was determined using the microdilution technique in plates containing 96 sterile holes with positive control, the antimicrobial chloramphenicol. The Minimum Bactericidal Concentration (MBC) was read 48 hours after the MIC, using plates with 96 holes. After the reading, it was found that the essential oil of Pogostemon cablin had a 50% MIC of 512 μg/mL against the Klebsiella pneumoniae strains tested, making it a strong bacteriostatic. It was therefore possible to observe the antibacterial potential of Pogostemon cablin essential oil against the K. pneumoniae strains tested.

Resveratrol and Resveratrol-Loaded Galactosylated Liposomes: Anti-Adherence and Cell Wall Damage Effects on Staphylococcus aureus and MRSA.

Antibiotic resistance due to bacterial biofilm formation is a major global health concern that makes the search for new therapeutic approaches an urgent need. In this context,, trans-resveratrol (RSV), a polyphenolic natural substance, seems to be a good candidate for preventing and eradicating biofilm-associated infections but its mechanism of action is poorly understood. In addition, RSV suffers from low bioavailability and chemical instability in the biological media that make its encapsulation in delivery systems necessary. In this work, the anti-biofilm activity of free RSV was investigated on Staphylococcus aureus and, to highlight the possible mechanism of action, we studied the anti-adherence activity and also the cell wall damage on a MRSA strain. Free RSV activity was compared to that of RSV loaded in liposomes, specifically neutral liposomes (L = DOPC/Cholesterol) and cationic liposomes (LG = DOPC/Chol/GLT1) characterized by a galactosylated amphiphile (GLT1) that promotes the interaction with bacteria. The results indicate that RSV loaded in LG has anti-adherence and anti-biofilm activity higher than free RSV. On the other side, free RSV has a higher bacterial-growth-inhibiting effect than encapsulated RSV and it can damage cell walls by creating pores; however, this effect can not prevent bacteria from growing again. This RSV ability may underlie its bacteriostatic activity.

Evaluation of the Antibacterial and Anti-Adherent Activities of Eucalyptus globulus and Eucalyptus citriodora Essential Oils against Pseudomonas aeruginosa Strains

Biofilm can be defined as a complex sessile microbiological ecosystem formed by one or more species of bacteria, fungi or protozoa. Among the microorganisms capable of forming biofilms is Pseudomonas aeruginosa, a gram-negative bacterium with extensive virulence factors and high resistance to antimicrobials, making it difficult to treat infections caused by it. In this sense, phytotherapy and essential oils are promising therapeutic alternatives to multi-resistant microorganisms. The aim of this study was to evaluate the antibacterial and anti-adherent activities of Eucalyptus globulus and Eucalyptus citriodora essential oils against clinical strains of P. aeruginosa, and to compare their antibiofilm effects with 0.12% chlorhexidine digluconate. To determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the oils, the broth microdilution technique was used in 96-well plates. To determine the Minimum Adherence Inhibitory Concentration (MAIC), the inclined glass tube technique was used in the presence of 5% sucrose, using proportions corresponding to the pure essential oil up to a dilution of 1:1024, and its positive control was 0.12% chlorhexidine digluconate. It was therefore concluded that the essential oils under study had an antibacterial effect against the strains tested, varying between bactericidal and bacteriostatic action, as well as demonstrating an effective anti-adherence effect that was superior to the positive control.

Assessment of the Antiadertional Potential of Pogostemon cablin Essential Oil against Staphylococcus aureus

Nosocomial pneumonia, an infection of the lung parenchyma caused by bacterial species, corresponds to a morbidity responsible for reducing the quality of life and further compromising the hospitalized patient. Among the bacteria that cause this infection is Staphylococcus aureus, which has proved resistant to the drugs used in its treatment. Therefore, the need for new studies is urgent and phytotherapy has been gaining space. The objective of this research was to evaluate the anti-adherent activity of Pogostemon cablin essential oil against a strain of Staphylococcus aureus. To obtain the Minimum Inhibitory Adherence Concentration (MIC), Muller Hinton broth with 5% sucrose was used, the Sa 101 strain of the bacterial species under study, as well as, the positive control with 0.12% chlorhexidine. The material was incubated at 37 °C for 24 hours for reading using fuchsin. Through analysis, it was found that the oil studied was able to inhibit the adhesion of bacteria to the wall of the tube at a concentration of 1:2, showing positive activity against the formation of biofilm by Staphylococcus aureus, although the result found is lower than that of chlorhexidine, which inhibited at a ratio of 1:8. It is concluded that Pogostemon cablin oil showed anti-adherent activity against the strain under study, however, inferior when compared to the positive control.

Could Helium Plasma Treatment be a Novel Approach to Prevent the Biofilm Formation of Candida albicans?

There is no definitive method to prevent Candida albicans (C. albicans) biofilm formation on polymethyl methacrylate (PMMA) surfaces. The objective of this study was to evaluate the effect of Helium plasma treatment (before the application of removable dentures to the patient) to prevent or reduce C. albicans ATCC 10,231 the anti-adherent activity, viability, and biofilm formation on PMMA surfaces. One hundred disc-shaped PMMA samples (2mm × 10mm) were prepared. The samples were randomly divided into 5 surface groups and treated with different concentrations of Helium plasma: G I: Control group (untreated), G II: 80% Helium plasma-treated group, G III: 85% Helium plasma-treated group, G IV: 90% Helium plasma-treated group, G V: 100% Helium plasma-treated group. C. albicans viability and biofilm formations were evaluated using 2 methods: MTT (3-(4,5-dimethyl thiazolyl-2)-2, 5-diphenyltetrazolium bromide) assays and Crystal Violet (CV) staining. The surface morphology and C. albicans biofilm images were observed with scanning electron microscopy. The Helium plasma-treated PMMA groups (G II, G III, G IV, G V) observed a significant reduction in C. albicans cell viability and biofilm formation compared with the control group. Treating PMMA surfaces with different concentrations of Helium plasma prevents C. albicans viability and biofilm formation. This study suggests that Helium plasma treatment might be an effective strategy in modifying PMMA surfaces to prevent denture stomatitis formation.

Anti-adherent activity of nano-coatings deposited by thermionic vacuum arc plasma on C. albicans biofilm formation.

The purpose of this study was to analyze the anti-adherent activity of nano-coatings deposited by Thermionic Vacuum Arc plasma on C. albicans ATCC 10231 biofilm. A total of 80 disc-shaped (2 × 10 mm) polymethymethacrylate samples were prepared and divided into four groups with 10 samples in each group (Control, ZnO, SnO2, Ag) (n = 10). Using thermionic vacuum arc plasma, they were coated with ZnO, SnO2, and Ag. 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Crystal Viole (CV) assays were conducted for biofilm quantification. Scanning electron microscopy (SEM) was used to observe biofilm images of C. albicans biofilm. MTT and CV mean values differ statistically significantly between all groups (p ⩽ 0.05). The SnO2 group had the lowest mean value, whereas the control group received the highest value. SnO2 coating shown greater anti-adherent activity than either metal oxides. C. albicans biofilm formation on denture base surfaces is reduced following Thermionic Vacuum Arc plasma coating with SnO2.

Anti-adherence Activity of Monomicrobial and Polymicrobial Food-Derived Enterococcus spp. Biofilms Against Pathogenic Bacteria.

Enterococcus species are commensal organisms of the gastrointestinal tract and can also be isolated from traditional food products. They are used as probiotics in animals and less often in humans. This study aimed to investigate the antibacterial and anti-adhesive activities of twelve food-origin Enterococcus spp. biofilms on stainless steel AISI 316L against foodborne pathogens, including Listeria monocytogenes CECT4032, Pseudomonas aeruginosa ATCC27853, and Escherichia coli ATCC25922. The antimicrobial and co-aggregation abilities of Enterococcus spp. were evaluated using spots-agar test and spectrophotometry aggregation assay, respectively. The anti-adhesive activity of selected strains on pathogenic bacteria was tested using serial dilution technique. Enterococci strains in planktonic mode showed strong inhibition activity against different pathogens tested with a significant difference in co-aggregation capacity. Moreover, L. monocytogenes and E. coli presented a low auto-aggregation rate compared to P. aeruginosa, which showed an amount of 11.25%. Scanning electron microscopy (SEM) revealed that biofilm biomass of Enterococcus spp. increased after 10 days. The thick layer of enterococci biofilms on AISI 316L caused a low adhesion of L. monocytogenes, resulting in a reduction of approximately 2.8 log CFU/cm² for some selected strains. Additionally, Enterococcus monocultures' biofilms were more efficient than polymicrobial cultures (a cocktail of enterococci strains) in controlling pathogen adhesion. These results indicate that monocultures of Enterococcus spp. biofilms could be used to prevent the adhesion of pathogenic bacteria on AISI 316L.

Inhibition of Adherence and Biofilm Formation of Pseudomonas aeruginosa by Immobilized ZnO Nanoparticles on Silicone Urinary Catheter Grafted by Gamma Irradiation.

Nosocomial infections caused by microbial biofilm formation on biomaterial surfaces such as urinary catheters are complicated by antibiotic resistance, representing a common problem in hospitalized patients. Therefore, we aimed to modify silicone catheters to resist microbial adherence and biofilm formation by the tested microorganisms. This study used a simple direct method to graft poly-acrylic acid onto silicone rubber films using gamma irradiation to endow the silicone surface with hydrophilic carboxylic acid functional groups. This modification allowed the silicone to immobilize ZnO nanoparticles (ZnO NPs) as an anti-biofilm. The modified silicone films were characterized by FT-IR, SEM, and TGA. The anti-adherence ability of the modified silicone films was evidenced by the inhibition of biofilm formation by otherwise strong biofilm-producing Gram-positive, Gram-negative, and yeast clinical isolates. The modified ZnO NPs grafted silicone showed good cytocompatibility with the human epithelial cell line. Moreover, studying the molecular basis of the inhibitory effect of the modified silicone surface on biofilm-associated genes in a selected Pseudomonas aeruginosa isolate showed that anti-adherence activity might be due to the significant downregulation of the expression of lasR, lasI, and lecB genes by 2, 2, and 3.3-fold, respectively. In conclusion, the modified silicone catheters were low-cost, offering broad-spectrum anti-biofilm activity with possible future applications in hospital settings.

The anti-adherence activity and bactericidal effect of GO against Streptococcus mutans from Iraqi dental patients.

The high rate of microbes and their biological activity in the patient's mouth is a concern in the domains of dental caries and periodontal disease. The study aimed to shed light on the relationship between graphene oxide's nanoparticles (nGOs) antimicrobial properties and the growth of dental pathogenic bacteria. The forty swab samples were frequently collected from the patient's cavity mouth between November 2019 and January 2020, from patients who visited dentist clinics in Baghdad by taking swabs from mouth cavities with various dental caries with two age groups (5-17) and (18-60) from male and female to streaking them on Brain-Heart Infusion (BHI) agar, then identified by re-streaking on Mitis Salivarius Bacitracin (MSB) agar. All isolates were confirmed as Streptococcus mutans after API 20 Strep method. As well as the Colony Forming Units (CFU) were then determined after diluting the bacterial cell suspensions to obtain cell samples containing 1.5 × 108CFU/ ml. The collagen-binding adhesin (cnm) and glucosyltransferases (gtf) of S. mutans genes were identified using polymerase chain reaction (PCR) method before and after exposure to the nGOs, which were prepared in different pulse laser energy (500, 600, and 700mJ) with presence and absence of the magnetic field, and the data have been analyzing. After counting the CFU, the nGOs shows high effectiveness inhibiting the growth of S. mutans. This research provides definitive answers about the relationship between nGOs, antibacterial caries, and periodontal disease.

Differences in In Vitro Bacterial Adherence between Ti6Al4V and CoCrMo Alloys.

Prosthetic joint infection is an uncommon entity, but it supposes high costs, both from the economic side to the health systems and from the emotional side of the patient. The evaluation of the bacterial adherence to different materials frequently involved in joint prostheses allows us to better understand the mechanisms underlying this and provide information for the future development of prevention strategies. This study evaluated the bacterial adherence of four different species (Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa) on Ti6Al4V and CoCrMo. The topography, surface contact angles, and linear average roughness were measured in the samples from both alloys. The interaction with the surface of both alloys was significantly different, with the CoCrMo showing an aggregating effect on all the species, with additional anti-adherent activity in the case of Pseudomonas aeruginosa. The viability also changes, with a significant decrease (p < 0.05) in the CoCrMo alloy. In the case of S. epidermidis, the viability in the supernatant from the samples was different, too, with a decrease in the colony-forming units in the Ti6Al4V, which could be related to cation release from the surface. Beyond adhesion is a multifactorial and complex process, and considering that topography and wettability were similar, the chemical composition could play a main role in the different properties observed.

Exploring the Potential of a Herbal Nanoemulsion as an Antimicrobial Mouthwash.

The study aimed to formulate a nanoemulsion, combine it with aqueous extracts of herbal powders, and test its efficiency as caries-preventing mouthwash. Formulation of nanoemulsion using microfluidizer, characterization of nanoemulsion, minimum inhibitory concentration, adherence test, biofilm assay, and artificial mouth assay was carried out. The biofilms of Streptococcus mutans, Lactobacillus casei, Actinomyces viscosus, and a combination of the three cultures were developed and treated with formulations to study the inhibitory effect of the samples. In artificial mouth assay, human tooth samples were used as surfaces to grow the biofilm of S. mutans, and daily, the teeth were treated with the formulations to test their real-time efficiency. The nanoemulsion was characterized using dynamic light scattering and the size of the particles was within the 100-300nm range. Above 50°C, the nanoemulsion combined with plant extract lost its emulsified state within 2h of incubation, while the nanoemulsion was stable. Nanoemulsion with plant extract inhibited the adherence of L. casei (73%) and biofilm of L. casei (66%). In artificial mouth assay, after 10days of nanoemulsion, nanoemulsion with plant extract showed DIAGNOdent pen values 3.5 and 2 respectively whereas the negative control value was 14.4 indicating caries initiation. The nanoemulsion with plant extract showed anti-adherence and anti-biofilm activity and hence can be used as a potent anticariogenic mouthwash.