Stopping Bacterial Adhesion: A Novel Approach to Treating Infections

Elimination of detached Listeria monocytogenes from the biofilm on stainless steel surfaces during milk and cheese processing using natural plant extracts

Bacterial cells can form biofilm on food contact surfaces, becoming a source of food contamination with profound health implications. The current study aimed to determine some Egyptian medicinal plants antibacterial and antibiofilm effects against foodborne bacterial strains in milk plants. Results indicated that four ethanolic plant extracts, Cinnamon (Cinnamomum verum), Chamomile (Matricaria chamomilla), Marigold (Calendula officinalis), and Sage (Salvia officinalis), had antibacterial (12.0-26.5 mm of inhibition zone diameter) and antibiofilm (10-99%) activities against Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes and Salmonella Typhimurium. The tested extracts had minimum inhibitory concentration values between 0.14 and 2.50 mg/ml and minimum bactericidal concentration values between 0.14 and 12.50 mg/ml. L. monocytogenes was more sensitive for all tested ethanolic extracts; Sage and Cinnamon showed a bacteriocidal effect, while Chamomile and Marigold were bacteriostatic. The ethanolic extracts mixture from Chamomile, Sage, and Cinnamon was chosen for its antibiofilm activity against L. monocytogenes using L-optimal mixture design. Gas chromatography and mass spectrometry analysis showed that this mixture contained 12 chemical compounds, where 2-Propenal,3-phenyl- had the maximum area % (34.82%). At concentrations up to 500 µg/ml, it had no cytotoxicity in the normal Vero cell line, and the IC50 value was 671.76 ± 9.03 µg/ml. Also, this mixture showed the most significant antibacterial effect against detached L. monocytogenes cells from formed biofilm in stainless steel milk tanks. At the same time, white soft cheese fortified with this mixture was significantly accepted overall for the panelist (92.2 ± 2.7) than other cheese samples, including the control group.

Actinobacillus pleuropneumoniae, surface proteins and virulence: a review

Actinobacillus pleuropneumoniae (App) is a globally distributed Gram-negative bacterium that produces porcine pleuropneumonia. This highly contagious disease produces high morbidity and mortality in the swine industry. However, no effective vaccine exists to prevent it. The infection caused by App provokes characteristic lesions, such as edema, inflammation, hemorrhage, and necrosis, that involve different virulence factors. The colonization and invasion of host surfaces involved structures and proteins such as outer membrane vesicles (OMVs), pili, flagella, adhesins, outer membrane proteins (OMPs), also participates proteases, autotransporters, and lipoproteins. The recent findings on surface structures and proteins described in this review highlight them as potential immunogens for vaccine development.

Microbiological and Clinical Effects of a Proanthocyanidin-enriched Extract from Rumex acetosa in Periodontally Healthy Carriers of Porphyromonas gingivalis: a Randomized Controlled Pilot Study

Rumex acetosa significantly inhibits the adhesion of Porphyromonas gingivalis (P. g.) to eukaryotic host cells in vitro. The objective of this randomized placebo-controlled pilot-trial was to analyze effects of a mouth rinse containing 0.8% (w/w) of a quantified proanthocyanidin-enriched extract from Rumex acetosa (RA1) on microbiological, clinical, and cytological parameters in systemically healthy individuals without history of periodontitis, harboring P. g. intraorally. 35 subjects received a supragingival debridement (SD) followed by mouth rinsing (3 times daily) with either RA1 mouth rinse solution (test) or placebo (control) for 7 days as adjunct to routine oral hygiene. Supragingival biofilm samples were taken at screening visit, baseline (BL), 2, 4, 7 and 14 days after SD. P. g. and 11 other oral microorganisms were detected and quantified by rtPCR. Changes in the oral microbiota composition of one test and one control subject were assessed via high throughput 16S rRNS gene amplicon sequencing. Approximal Plaque Index (API) and the modified Sulcular Bleeding Index (SBI) were assessed at BL, 7- and 14-days following SD. Brush biopsies were taken at BL and 14 d following SD. Intergroup comparisons revealed no significant microbiological, cytological, and clinical differences at any timepoint. However, a significant reduction in SBI at day 14 (p = 0.003) and API at day 7 (p = 0.02) and day 14 (p = 0.009) was found in the test group by intragroup comparison. No severe adverse events were observed. The results indicate that RA1 mouth rinse is safe but does not seem to inhibit colonization of P. g. or improve periodontal health following SD.

Natural Product Co-Metabolism and the Microbiota-Gut-Brain Axis in Age-Related Diseases

Complementary alternative medicine approaches are growing treatments of diseases to standard medicine practice. Many of these concepts are being adopted into standard practice and orthomolecular medicine. Age-related diseases, in particular neurodegenerative disorders, are particularly difficult to treat and a cure is likely a distant expectation for many of them. Shifting attention from pharmaceuticals to phytoceuticals and "bugs as drugs" represents a paradigm shift and novel approaches to intervention and management of age-related diseases and downstream effects of aging. Although they have their own unique pathologies, a growing body of evidence suggests Alzheimer's disease (AD) and vascular dementia (VaD) share common pathology and features. Moreover, normal metabolic processes contribute to detrimental aging and age-related diseases such as AD. Recognizing the role that the cerebral and cardiovascular pathways play in AD and age-related diseases represents a common denominator in their pathobiology. Understanding how prosaic foods and medications are co-metabolized with the gut microbiota (GMB) would advance personalized medicine and represents a paradigm shift in our view of human physiology and biochemistry. Extending that advance to include a new physiology for the advanced age-related diseases would provide new treatment targets for mild cognitive impairment, dementia, and neurodegeneration and may speed up medical advancements for these particularly devastating and debilitating diseases. Here, we explore selected foods and their derivatives and suggest new dementia treatment approaches for age-related diseases that focus on reexamining the role of the GMB.

Plasma treatment effects on destruction and recovery of Porphyromonas gingivalis biofilms

The objective of this study was to investigate the treatment effects of non-thermal atmospheric gas plasmas (NTAP) on destruction and the recovery (or re-colonization) of Porphyromonas gingivalis (P. gingivalis) in biofilms. P. gingivalis is a well-known keystone periodontal pathogen strongly associated with periodontal diseases, especially periodontitis. P. gingivalis biofilms were formed on stainless steel coupons and treated for 1, 2, and 5 minutes by NTAP of pure argon gas and argon+oxygen gas mixture. MTT assay, colony forming unit (CFU) counting assay and confocal laser scanning microscopy (CLSM) were used to assess the destruction efficiency. In addition, the plasma treated biofilms were re-cultured in the medium supplemented with antibiotics and oxidative stress sources to determine the synergy of the NTAP with other antimicrobial agents. The results showed the plasma treatment could result in 2.7 log unit reduction in bacterial load. The recovered biofilm CFU with NTAP treatment combined with sub minimal inhibition concentration of amoxicillin was 0.33 log units less than the biofilm treated with amoxicillin alone. The recovered biofilm CFU in NTAP groups was about 2.0 log units less than that in the untreated controls under H₂O₂ treatment. There was approximately 1.0 log unit reduction of biofilm CFU in plasma treated biofilm compared with untreated control under paraquat treatment. The plasma treated biofilms exhibited less resistance to amoxicillin and greater susceptibility to hydrogen peroxide (H₂O₂) and paraquat, suggesting that NTAP may enhance biofilm susceptibility to host defense. These in vitro findings suggested that NTAP could be a novel and effective treatment method of oral biofilms that cause periodontal diseases.

Antimicrobial Activities of Salacia oblonga Wall Leaf and Root Extracts Against Different Bacterial Strains and Fungal Isolates

Antibiotic resistance and the hazardous nature of synthetic drugs is threatening issue in the health sector. The alternative for this problem is to focus on plants that attribute to various compounds that exhibit therapeutic properties. Therefore, the study aims to evaluate the antimicrobial efficacy of Salacia oblonga leaf and root extracts against tested human pathogens. The S. oblonga extracts showed a significant zone of inhibition against bacteria and fungi. The leaf and root extracts of S. oblonga are prepared using low polar to high polar solvents in the Soxhlet apparatus and tested on the selected bacterial and fungal strains. Agar well diffusion and broth dilution methods evaluate antibacterial activity, antifungal activity, and Minimum Inhibitory Concentration (MIC) of extracts. Among the extracts tested, the ethyl acetate extract of root showed more antimicrobial activity against the tested bacterial and fungal strains. The most susceptible bacterial and fungal species against ethyl acetate extract are Micrococcus luteus, Mycobacterium tuberculosis, Microsporum canis, Trichophyton interdigitale, and Microsporum gypseum. The MIC for bacteria ranged from 13.0 to > 200 µg/ml, whereas for fungi, the MIC ranged from 25.9 to > 200 µg/ml. Ethyl acetate extract of root with 100 µg/ml concentration showed 29.1 mm and 28.7 mm zone of inhibition against bacterial strains M. luteus and M. tuberculosis, respectively. The ethyl acetate extract of root with a 100 µg/ml concentration showed 15.8, 15.2, and 15.6 mm zone of inhibition against fungal isolates M. canis, T. interdigitale, and M. gypseum, respectively. The activity of root and leaf extracts increased in a concentration-dependent manner, and further, the compounds isolated from the crude extracts of leaf and root showed antimicrobial activity. Structural elucidation of isolated compounds Lambertic acid and Ferruginol was done using NMR spectroscopy. Reports indicate that Lambertic acid was isolated previously, but the isolation of hydroxy Ferruginol from S. oblonga leaf extract was reported unprecedented.

Detection of biofilm formation of (Serratia and E.coli) and determination of the inhibitory effect of Quercus plant extract against these infectious pathogens

Biofilm is a complex microbial regional, especially resisting antimicrobials Quorum sensing function ate flow into an essential role in the composition concerning completely advanced superior biofilms on numerous microorganism, Biofilms change autonomous cells into particular cell groups. They are obtainable about comprehensions keen on biofilm materialization determined through the best-characterized strain, Escherichia col. The hastened biofilm obstacle of accord containing regular remedying decorates the requirement between significance with toughening modern rule approaches. By resources of the use of Congo process then PCR method since detection around biofilms arrangement, By way of the sunscreens of Quorum detecting were noticed over molecular finding using the PCR of the gene accountable for the structure of Biofilm in Serratia bacteria. The study showed that during the induction period, after 48 hours, the effects of bacterial inhabitation, the methanolic extract was more effective against (Serratia, Ecoli) regarding superb consciousness (10, 20, 30 mg/I).

Quality Related Safety Evaluation of a South African Traditional Formulation (PHELA®) as Novel Anti-Biofilm Candidate

A South African traditional formulation, PHELA^®, is consumed by the traditional people for severe chest problems with coughing, diarrhea, oral ulcers etc. The present study focused on establishing the anti-infective properties of a safe and standardized poly-herbal formulation through a series of criteria and specifications.

Probiotic Bacillus Alleviates Oxidative Stress-Induced Liver Injury by Modulating Gut-Liver Axis in a Rat Model

Emerging evidence suggests a key role of gut microbiota in maintaining liver functions through modulating the gut–liver axis. In this study, we investigated whether microbiota alteration mediated by probiotic Bacillus was involved in alleviating oxidative stress- induced liver injury. Sprague–Dawley rats were orally administered Bacillus SC06 or SC08 for a 24-day period and thereafter intraperitoneally injected diquat (DQ) to induce oxidative stress. Results showed that Bacillus, particularly SC06 significantly inhibited hepatic injuries, as evidenced by the alleviated damaged liver structure, the decreased levels of ALT, AST, ALP and LDH, and the suppressed mitochondrial dysfunction. SC06 pretreatment markedly enhanced the liver antioxidant capacity by decreasing MDA and p47, and increasing T-AOC, SOD and HO-1.16S rRNA sequencing analysis revealed that DQ significantly changed the diversities and composition of gut microbiota, whereas Bacillus pretreatments could attenuate gut dysbiosis. Pearson’s correlation analysis showed that AST and MDA exerted a positive correlation with the opportunistic pathogenic genera and species (Escherichia and Shigella), and negatively correlated with the potential probiotics (Lactobacillus), while SOD exerted a reverse trend. The microbial metagenomic analysis demonstrated that Bacillus, particularly SC06 markedly suppress the metabolic pathways such as carbohydrate metabolism, lipid metabolism, amino acid metabolism and metabolism of cofactors and vitamins. Furthermore, SC06 decreased the gene abundance of the pathways mediating bacterial replication, secretion and pathogenicity. Taken together, Bacillus SC06 alleviates oxidative stress-induced liver injuries via optimizing the composition, metabolic pathways and pathogenic replication and secretion of gut microbiota. These findings elucidate the mechanisms of probiotics in alleviating oxidative stress and provide a promising strategy for preventing liver diseases by targeting gut microbiota.

Nonpharmacological Treatment Strategies for the Management of Canine Chronic Inflammatory Enteropathy—A Narrative Review

Chronic inflammatory enteropathy (CIE) refers to a heterogeneous group of idiopathic diseases of the dog characterised by persistent gastrointestinal (GI) clinical signs. If conventional dietary treatment alone would be unsuccessful, management of CIE is traditionally attained by the use of pharmaceuticals, such as antibiotics and immunosuppressive drugs. While being rather effective, however, these drugs are endowed with side effects, which may impact negatively on the animal’s quality of life. Therefore, novel, safe and effective therapies for CIE are highly sought after. As gut microbiota imbalances are often associated with GI disorders, a compelling rationale exists for the use of nonpharmacological methods of microbial manipulation in CIE, such as faecal microbiota transplantation and administration of pre-, pro-, syn- and postbiotics. In addition to providing direct health benefits to the host via a gentle modulation of the intestinal microbiota composition and function, these treatments may also possess immunomodulatory and epithelial barrier-enhancing actions. Likewise, intestinal barrier integrity, along with mucosal inflammation, are deemed to be two chief therapeutic targets of mesenchymal stem cells and selected vegetable-derived bioactive compounds. Although pioneering studies have revealed encouraging findings regarding the use of novel treatment agents in CIE, a larger body of research is needed to address fully their mode of action, efficacy and safety.

S-layer protein 2 of vaginal Lactobacillus crispatus 2029 enhances growth, differentiation, VEGF production and barrier functions in intestinal epithelial cell line Caco-2

We have previously demonstrated the ability of the human vaginal strain Lactobacillus crispatus 2029 (LC2029) for strong adhesion to cervicovaginal epithelial cells, expression of the surface layer protein 2 (Slp2), and antagonistic activity against urogenital pathogens. Slp2 forms regular two-dimensional structure around the LC2029 cells,which is secreted into the medium and inhibits intestinal pathogen-induced activation of caspase-9 and caspase-3 in the human intestinal Caco-2 cells. Here, we elucidated the effects of soluble Slp2 on adhesion of proteobacteria pathogens inducing necrotizing enterocolitis (NEC), such as Escherichia coli ATCC E 2348/69, E. coli ATCC 31705, Salmonella Enteritidis ATCC 13076, Campylobacter jejuni ATCC 29428, and Pseudomonas aeruginosa ATCC 27853 to Caco-2 cells, as well as on growth promotion, differentiation, vascular endothelial growth factor (VEGF) production, and intestinal barrier function of Caco-2 cell monolayers. Slp2 acts as anti-adhesion agent for NEC-inducing proteobacteria, promotes growth of immature Caco-2 cells and their differentiation, and enhances expression and functional activity of sucrase, lactase, and alkaline phosphatase. Slp2 stimulates VEGF production, decreases paracellular permeability, and increases transepithelial electrical resistance, strengthening barrier function of Caco-2 cell monolayers. These data support the important role of Slp2 in the early postnatal development of the human small intestine enterocytes.

The effect of carbohydrates on the adherence of Pasteurella multocida to the nasal respiratory epithelium

Pasteurella multocida subsp. multocida is responsible for different diseases that generate great economic losses in farm animal. The effectiveness of immunization against those bacteria are variable and the use of antibiotics is questioned; for that reason, we investigated the potential inhibitory effect of different carbohydrates on the adherence in vivo of P. multocida to the rabbit respiratory epithelium as an alternative for the prevention of respiratory infections. Rabbits were intranasally and intratracheally inoculated with a solution containing 200 µl of 1x107 CFU of P. multocida that was previously mixed with 250 µg /200 µl of N-acetylglucosamine, alphamethylglucoside, alphamethylmannoside, N-acetylgalactosamine or sialic acid. The animals that received N-acetylglucosamine, alphamethylglucoside or alphamethylmannoside individually or a mixture of these three carbohydrates plus the bacterium, showed a significant decrease (P <0.05) of the clinical symptoms, microscopic and macroscopic lesions in the nasal septa and in the lungs; also, the number of adhered bacteria to the nasal epithelium were also significantly reduced. This research demonstrates for the first time that such an approach could convert into a method for prevention of P. multocida infection in rabbits that is ecologically and economically safe and effective.

Temperature-Controlled Adhesion to Carbohydrate Functionalized Microgel Films: An E. coli and Lectin Binding Study

The preparation of thermoresponsive mannose functionalized monolayers of poly(N-isopropylacrylamide) microgels and the analysis of the specific binding of concanavalin A (ConA) and E. coli above and below the lower critical solution temperature (LCST) are shown. Via inhibition and direct binding assays it is found that ConA binding is time-dependent, where at short incubation times binding is stronger above the LCST. Given larger incubation times, the interaction of ConA to the microgel network is increased below the LCST when compared to temperatures above the LCST, possibly due to increased ConA diffusion and multivalent binding in the more open microgel network below the LCST. For E. coli, which presents only monovalent lectins and is too large to diffuse into the network, binding is always enhanced above the LCST. This is due to the larger mannose density of the microgel layer above the LCST increasing the interaction to E. coli. Once bound to the microgel layer above the LCST, E. coli cannot be released by cooling down below the LCST. Overall, this suggests that the carbohydrate presenting microgel layers enable specific binding where the temperature-induced transition between swollen and collapsed microgels may increase or decrease binding depending on the receptor size.

The Microbiota-Gut-Brain Axis Heart Shunt Part I: The French Paradox, Heart Disease and the Microbiota

It has been well established that a vegetarian and polyphenol-rich diet, including fruits, vegetables, teas, juices, wine, indigestible fiber and whole grains, provide health-promoting phytochemicals and phytonutrients that are beneficial for the heart and brain. What is not well-characterized is the affect these foods have when co-metabolized within our dynamic gut and its colonizing flora. The concept of a heart shunt within the microbiota-gut-brain axis underscores the close association between brain and heart health and the so-called “French paradox” offers clues for understanding neurodegenerative and cerebrovascular diseases. Moreover, oxidation-redox reactions and redox properties of so-called brain and heart-protective foods are underappreciated as to their enhanced or deleterious mechanisms of action. Focusing on prodromal stages, and common mechanisms underlying heart, cerebrovascular and neurodegenerative diseases, we may unmask and understanding the means to better treat these related diseases.

Screening of BHK-21 cellular proteins that interact with outer membrane protein 43K OMP of Fusobacterium necrophorum

Fusobacterium necrophorum is a Gram negative, spore-free, anaerobic bacterium that can cause pyogenic and necrotic infections in animals and humans. It is a major bovine pathogen and causes hepatic abscesses, foot rot, and necrotic laryngitis. The 43K OMP of F. necrophorum is an outer membrane protein with molecular weight of 43 kDa, exhibiting similarity to pore-forming proteins of other Fusobacterium species that plays an important role in bacterial infections. However, the role of 43K OMP in F. necrophorum adhesion remains unknown. In this study, we evaluated whether the 43K OMP of F. necrophorum mediates adhesion to BHK-21 cells and performed a preliminary screen of the proteins that interact with 43K OMP of F. necrophorum by immunoprecipitation-mass spectrometry. The results showed that the natural 43K OMP and recombinant 43K OMP could bind to BHK-21 cells, and preincubation of F. necrophorum with an antibody against the recombinant 43K OMP of F. necrophorum decreased binding to BHK-21 cells. Seventy differential interacting proteins were successfully screened by immunoprecipitation-mass spectrometry. Among these seventy differential interacting proteins, seven cell membrane proteins and four extracellular matrix proteins shown to be relevant to bacteria adhesion through subcellular localization and single-molecule function analysis. These data increase our understanding of the pathogenesis of F. necrophorum and provide a new theoretical basis for the design of antimicrobial drugs against F. necrophorum.

Influence of N-acylhomoserine lactonase silver nanoparticles on the quorum sensing system of Helicobacter pylori: A potential strategy to combat biofilm formation

The treatment of Helicobacter pylori usually fails due to their ability to form biofilms and resistance to antibiotics. This might potentially lead to gastric carcinoma and mucosa-associated lymphoid tissue lymphoma. In the present study, we elucidate the potential role of N-acylhomoserine lactonase stabilized silver nanoparticles (AiiA-AgNPs) in treating biofilms produced by H. pylori. AiiA-AgNPs inhibited quorum sensing (QS) by degradation of QS molecules, thereby reducing biofilm formation, urease production, and altering cell surface hydrophobicity of H. pylori. AiiA-AgNPs showed no cytotoxic effects on RAW 264.7 macrophages at the effective concentration (1-5 µM) of antibiofilm activity. In addition, AiiA-AgNP in high concentration (80-100 µM) exhibited cytotoxicity against HCT-15 carcinoma cells, depicting its therapeutic role in treating cancer.

Biological Properties and Bioactive Components of Mentha spicata L. Essential Oil: Focus on Potential Benefits in the Treatment of Obesity, Alzheimer's Disease, Dermatophytosis, and Drug-Resistant Infections

In the present study, the medicinal aromatic plant Mentha spicata has been investigated as a source of essential oil (EO) and pharmaceuticals. The quantity and composition of EO from M. spicata cultivated in Palestine were analyzed seasonally over a three-year period. A significantly higher EO content was produced in summer and fall months (2.54–2.79%). Chemical analysis of EO revealed 31 compounds with oxygenated monoterpenes (90%) as the most abundant components followed by sesquiterpene and monoterpene hydrocarbons (6 and 3%, respectively). M spicata can be characterized as a carvone chemotype (65%). EO and carvone have shown strong inhibitory activities against the principal enzymes associated with Alzheimer's disease (AD) and overweight diseases (cholinesterase and porcine pancreatic lipase) and also shown strong antidermatophytic activity against Microsporum canis, Trichophyton rubrum, T. mentagrophytes, and Epidermophyton floccosum. The pancreatic lipase inhibition and the synergism showed the potential activity of M. spicata EO and carvone and that their combinations with standard drugs can be useful for the treatment of obesity and overweight. The results also demonstrated that, in addition to their significant inhibitory activity against biofilm formation of methicillin-resistant Staphylococcus aureus (MRSA), M. spicata EO and carvone had a strong inhibitory effect on metabolic activity and biomass of the preformed biofilm. The current study supports the utilization of M. spicata EO as a traditional medicine and opens perceptions to find more potent substances in the EO for the management of obesity, AD, and dermatophytosis and for combating drug-resistant bacterial infections.

Antibacterial and Antibiofilm Activity of Flavonoid and Saponin Derivatives from Atriplex tatarica against Pseudomonas aeruginosa

A new flavonoid glucoside derivative, patuletin 3 -O-(2- O-feruloyl)-β-d-glucuronopyranosyl-(1→2)-β-d-glucopyranoside, named atriplexin IV (1), and three new triterpenoid saponin derivatives, two sulfonylated, β-d-glucopyranosyl-3 -O-(2- O-sulfo-β-d-galactopyranosyl)-(1→2)-α-l-arabinopyranoside-30-alolean-12-en-28-oate (2), named atriplexogenin I, β-d-glucopyranosyl-3- O-(2- O-sulfo-β-d-galactopyranosyl)-(1→2)-α-l-arabinopyranoside)-30-hydroxyolean-12-en-28-oate (3), named atriplexogenin II, and β-d-glucopyranosyl-3 -O-(β-d-glucopyranosyl-(1→2)-β-d-galactopyranosyl-(1→2)-α-l-arabinopyranoside)-30-alolean-12-en-28-oate (4), named atriplexogenin III, were isolated by silica gel column and semipreparative HPLC chromatography from the n-butanol extract of the salt marsh plant Atriplex tatarica. In addition, two known secondary metabolites, patuletin3 -O-β-d-apiofuranosyl-(1‴→2″)-β-d-glucopyranoside (5) and patuletin 3 -O-5‴- O-feruloyl-β-d-apiofuranosyl-(1‴→2″)-β-d-glucopyranoside (6), were isolated for the first time from A. tatarica. The structures of the isolated compounds were elucidated by 1D and 2D NMR, HRESIMS, IR, and UV data. Antibacterial activity by the microdilution method and antibiofilm activity against P. aeruginosa were assessed. Compound 5 possesses significant antibacterial activity, while the most potent antibiofilm agent is compound 2.

Antibacterial and antibiofilm activity of acetone leaf extracts of nine under-investigated south African Eugenia and Syzygium (Myrtaceae) species and their selectivity indices

BACKGROUND

Antimicrobial resistance (AMR) remains an important global health issue but the gap between AMR and development of new antimicrobials is increasing. Plant extracts may have good activity per se or may be sources of effective antimicrobial compounds which can act against planktonic and/or biofilms of pathogens. We determined the antimicrobial efficacy and cytotoxicity of some under-investigated plants from the Myrtaceae family endemic to South Africa. The ability of the plant extracts to inhibit or destroy pre-formed bacterial biofilms was also determined.

METHODS

Based on previous preliminary in vitro screening and on chemotaxonomy, nine species from the Myrtaceae family were selected. The antimicrobial activity of the crude acetone leaf extracts was determined against six common nosocomial pathogens, namely: Gram-positive bacteria (Bacillus cereus, Enterococcus faecalis, Staphylococcus aureus), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella Typhimurium) using a two-fold serial microdilution assay with p-iodonitrotetrazolium violet as growth indicator. The number of antimicrobial compounds present in extracts was determined by bioautography. Cytotoxicity of extracts was determined against Vero kidney cells using a colorimetric tetrazolium-based assay. The total antibacterial activity (TAA) in ml/g and selectivity index (LC₅₀/MIC) of the plant extracts were calculated. A modified crystal violet assay was used to determine the antibiofilm activity of the extracts.

RESULTS

Syzygium legatii, Syzygium masukuense, and Syzygium species A had the best activities against Gram-negative and Gram-positive bacteria (MIC) values ranging from 0.04-0.08 mg/ml. Eugenia erythrophylla had the best MIC (0.02 mg/ml) against Bacillus cereus. Many extracts had relatively low cytotoxicity (LC₅₀ > 20 μg/ml) leading to reasonable selectivity indices. Three leaf extracts (Syzygium masukuense, Syzygium species A, and Eugenia natalitia) were moderately cytotoxic (20 μg/ml < LC₅₀ < 100 μg/ml). The plant extracts had a good capacity to reduce biofilm formation and good to poor potential to destroy pre-formed biofilms.

CONCLUSIONS

The plant species examined in this study had varying degrees of antibacterial activity against bacterial planktonic and biofilm forms with some having good activity against both forms. Several of these selected species may be potential candidates for further investigation to isolate antimicrobial compounds and to determine the mechanism of activity.

Sequence-Defined Introduction of Hydrophobic Motifs and Effects in Lectin Binding of Precision Glycomacromolecules

This study investigates the influence of an increasingly hydrophobic backbone of multivalent glycomimetics based on sequence-defined oligo(amidoamines) on their resulting affinity toward bacterial lectins. Glycomacromolecules are obtained by stepwise assembly of tailor-made building blocks on solid support, using both hydrophobic aliphatic and aromatic building blocks to enable a gradual change in hydrophobicity of the backbone. Their binding behavior toward model lectin Concanavalin A (ConA) is evaluated using isothermal titration calorimetry (ITC) and surface plasmon resonance (SPR) showing higher affinities for glycomacromolecules with higher content of hydrophobic and aromatic moieties in the backbone. Finally, glycomacromolecules are tested in a bacterial adhesion inhibition study against Escherichia coli where more hydrophobic backbones yield higher inhibitory potentials most likely due to additional secondary interactions with hydrophobic regions of the protein receptor as well as a change in conformation exposing carbohydrate ligands for increased binding. Overall, the results highlight the influence and thereby importance of the polymer backbone itself on the resulting properties of polymeric biomimetics.

Rosmarinus officinalis L. (rosemary) as therapeutic and prophylactic agent

Rosmarinus officinalis L. (rosemary) is a medicinal plant native to the Mediterranean region and cultivated around the world. Besides the therapeutic purpose, it is commonly used as a condiment and food preservative. R. officinalis L. is constituted by bioactive molecules, the phytocompounds, responsible for implement several pharmacological activities, such as anti-inflammatory, antioxidant, antimicrobial, antiproliferative, antitumor and protective, inhibitory and attenuating activities. Thus, in vivo and in vitro studies were presented in this Review, approaching the therapeutic and prophylactic effects of R. officinalis L. on some physiological disorders caused by biochemical, chemical or biological agents. In this way, methodology, mechanisms, results, and conclusions were described. The main objective of this study was showing that plant products could be equivalent to the available medicines.

Fish pathogen bacteria: Adhesion, parameters influencing virulence and interaction with host cells

Wild fisheries are declining due to over-fishing, climate change, pollution and marine habitat destructions among other factors, and, concomitantly, aquaculture is increasing significantly around the world. Fish infections caused by pathogenic bacteria are quite common in aquaculture, although their seriousness depends on the season. Drug-supplemented feeds are often used to keep farmed fish free from the diseases caused by such bacteria. However, given that bacteria can survive well in aquatic environments independently of their hosts, bacterial diseases have become major impediments to aquaculture development. On the other hand, the indiscriminate uses of antimicrobial agents has led to resistant strains and the need to switch to other antibiotics, although it seems that an integrated approach that considers not only the pathogen but also the host and the environment will be the most effective method in the long-term to improve aquatic animal health. This review covers the mechanisms of bacterial pathogenicity and details the foundations underlying the interactions occurring between pathogenic bacteria and the fish host in the aquatic environment, as well as the factors that influence virulence. Understanding and linking the different phenomena that occur from adhesion to colonization of the host will offer novel and useful means to help design suitable therapeutic strategies for disease prevention and treatment.

Dietary yeast-derived mannan oligosaccharides have immune-modulatory properties but do not improve high fat diet-induced obesity and glucose intolerance

The indigestible mannan oligosaccharides (MOS) derived from the outer cell wall of yeast Saccharomyces cerevisiae have shown potential to reduce inflammation. Since inflammation is one of the underlying mechanisms involved in the development of obesity-associated metabolic dysfunctions, we aimed to determine the effect of dietary supplementation with MOS on inflammation and metabolic homeostasis in lean and diet-induced obese mice. Male C57BL/6 mice were fed either a low fat diet (LFD) or a high fat diet (HFD) with, respectively, 10% or 45% energy derived from lard fat, with or without 1% MOS for 17 weeks. Body weight and composition were measured throughout the study. After 12 weeks of intervention, whole-body glucose tolerance was assessed and in week 17 immune cell composition was determined in mesenteric white adipose tissue (mWAT) and liver by flow cytometry and RT-qPCR. In LFD-fed mice, MOS supplementation induced a significant increase in the abundance of macrophages and eosinophils in mWAT. A similar trend was observed in hepatic macrophages. Although HFD feeding induced a classical shift from the anti-inflammatory M2-like macrophages towards the pro-inflammatory M1-like macrophages in both mWAT and liver from control mice, MOS supplementation had no effect on this obesity-driven immune response. Finally, MOS supplementation did not improve whole-body glucose homeostasis in both lean and obese mice.Altogether, our data showed that MOS had extra-intestinal immune modulatory properties in mWAT and liver. However these effects were not substantial enough to significantly ameliorate HFD-induced glucose intolerance or inflammation.

Characterization of Fusobacterium necrophorum subsp. necrophorum outer membrane proteins

Liver abscesses are of major economic importance to the cattle industry. These are mainly associated with the presence of Fusobacterium necrophorum, a non-spore forming and Gram-negative anaerobe. There are two main subspecies, F. necrophorum subspecies necrophorum and subsp. funduliforme, and they differ molecularly, morphologically, biochemically and in virulence. Previous studies have shown that the outer membrane proteins (OMP) of F. necrophorum subsp. necrophorum are important for its successful binding to immobilized bovine adrenal gland capillary endothelial (EJG) cells. In this study, a 42.4 kDa OMP of F. necrophorum subsp. necrophorum with the highest binding capacity to EJG cells was characterized. The gene was cloned into pFLAG-CTS vector and the proteins were subsequently expressed on the surface of E. coli BL21 DE3 cells. When E. coli carrying the recombinant plasmid (SM 2013) was induced using IPTG, there was significant enhancement in the binding to immobilized EJG cells compared to both uninduced SM 2013 and the E. coli carrying control vector only. When fixed EJG cells were incubated with purified native OMP, SM 2013 showed lowered levels of binding, compared to the uninduced SM 2013 and the E. coli carrying control vector only. Pre-incubation of induced SM 2013 with polyclonal antibodies made against the OMP reduced the binding to immobilized EJG cells to uninduced SM 2013 levels. This gain of function by recombinant E. coli confirms the ability of this protein to act as an adhesion to help binding of F. necrophorum subsp. necrophorum to host cells.

Molecular Simulations of Carbohydrates with a Fucose-Binding Burkholderia ambifaria Lectin Suggest Modulation by Surface Residues Outside the Fucose-Binding Pocket

Burkholderia ambifaria is an opportunistic respiratory pathogen belonging to the Burkholderia cepacia complex, a collection of species responsible for the rapidly fatal cepacia syndrome in cystic fibrosis patients. A fucose-binding lectin identified in the B. ambifaria genome, BambL, is able to adhere to lung tissue, and may play a role in respiratory infection. X-ray crystallography has revealed the bound complex structures for four fucosylated human blood group epitopes (blood group B, H type 1, H type 2, and Le^x determinants). The present study employed computational approaches, including docking and molecular dynamics (MD), to extend the structural analysis of BambL-oligosaccharide complexes to include four additional blood group saccharides (A, Le^a, Le^b, and Le^y) and a library of blood-group-related carbohydrates. Carbohydrate recognition is dominated by interactions with fucose via a hydrogen-bonding network involving Arg15, Glu26, Ala38, and Trp79 and a stacking interaction with Trp74. Additional hydrogen bonds to non-fucose residues are formed with Asp30, Tyr35, Thr36, and Trp74. BambL recognition is dominated by interactions with fucose, but also features interactions with other parts of the ligands that may modulate specificity or affinity. The detailed computational characterization of the BambL carbohydrate-binding site provides guidelines for the future design of lectin inhibitors.

Topical application of probiotics in skin: adhesion, antimicrobial and antibiofilm in vitro assays

AIMS

When skin dysbiosis occurs as a result of skin disorders, probiotics can act as modulators, restoring microbial balance. Several properties of selected probiotics were evaluated so that their topical application could be considered.

METHODS AND RESULTS

Adhesion, antimicrobial, quorum sensing and antibiofilm assays were carried out with several probiotic strains and tested against selected skin pathogens. All tested strains displayed significant adhesion to keratin. All lactobacilli with the exception of Lactobacillus delbrueckii, showed antimicrobial activity against skin pathogens, mainly due to organic acid production. Most of them also prevented biofilm formation, but only Propioniferax innocua was able to break down mature biofilms.

CONCLUSIONS

This study demonstrates that although all tested probiotics adhered to human keratin, they showed limited ability to prevent adhesion of some potential skin pathogens. Most of the tested probiotics successfully prevented biofilm formation, suggesting that they may be successfully used in the future as a complement to conventional therapies in the treatment of a range of skin disorders.

SIGNIFICANCE AND IMPACT OF STUDY

The topically used probiotics may be a natural, targeted treatment approach to several skin disorders and a complement to conventional therapies which present many undesirable side effects.

Increased fucosyl glycoconjugate by Mycoplasma hyopneumoniae enhances adherences of Pasteurella multocida type A in the ciliated epithelial cells of the respiratory tract

BACKGROUND

The objective of this study was to elucidate the pathogenic mechanisms of how Mycoplasma hyopneumoniae enhances secondary Pasteurella multocida type A infection which leads to porcine enzootic pneumonia in infected pigs. Sixteen pigs were experimentally infected with M. hyopneumoniae and then euthanized at 7, 14, 21 and 28 days post inoculation. In situ hybridization for M. hyopneumoniae DNA and Ulex europaeus agglutinin-I (UEA-I) lectin histochemistry for fucosyl glycoconjugate, was performed in serial lung sections to determine alteration of fucosyl glycoconjugate in M. hyopneumoniae-infected bronchial and bronchiolar epithelium. Bacterial overlay assay was performed to determine the affinity of P. multocida type A with L-fucose.

RESULTS

The luminal surface of bronchial and bronchiolar epithelial cells that were stained with UEA-I always showed hybridization signals for M. hyopneumoniae but it was negative in the unaffected parts of the lung from M. hyopneumoniae-infected pigs and in lung from negative control pigs. Colocalization of M. hyopneumoniae and UEA-I was especially prominent in the luminal surface of bronchial and bronchiolar epithelial cells in serial section of lung. The mean number of M. hyopneumoniae-positive cells correlated with the mean number of UEA-I-positive cells in lungs from infected pigs throughout the experiment. All eight P. multocida type A isolates from naturally occurring enzootic pneumonia, bound strongly at levels of 2 μg and 5 μg of L-fucose.

CONCLUSIONS

The results of the present study demonstrate that M. hyopneumoniae increases the L-fucose composition to enhance adherence of P. multocida type A to the bronchial and bronchiolar epithelial cells.

Receptors and Binding Structures for Clostridium difficile Toxins A and B

Two characteristics of toxins A and B from C. difficile (TcdA, TcdB) are important for the understanding of the pathogenic effect of these homologous toxins. First, these toxins are huge single-chain but multidomain proteins that display their action intracellularly within the cytosol of host cells. And second, albeit various cell types highly differ in their sensitivity toward these toxins, no toxin-resistant cell type has been described yet. Investigation of receptor-mediated uptake of these toxins is very ambitious. It demands discrimination between cell surface binding, interaction with more than one functional receptor responsible for uptake as well as other functional receptors that recognize bacterial pathogens and are not necessarily related with endocytosis. The current understanding of a complex uptake process is that TcdB interacts with at least two facultative receptors that mediate entry into host cells by redundant endocytotic pathways. Although both homologous toxins do obviously not share the same receptors, this principle of redundant binding domains found for TcdB does also account for TcdA.

Tuning of glyconanomaterial shape and size for selective bacterial cell agglutination

Acting as veritable glue, 1D-coated mannose carbon nanotubes efficiently and selectively regulate the agglutination and proliferation of the enterobacteriaEscherichia colitype 1 fimbriae, much better than the mannose coated 3D-micelles.

Impact of feed additives on surface mucosal health and columnaris susceptibility in channel catfish fingerlings, Ictalurus punctatus

One of the highest priority areas for improvement in aquaculture is the development of dietary additives and formulations which provide for complete mucosal health and protection of fish raised in intensive systems. Far greater attention has been paid to dietary impact on gut health than to protective effects at other mucosal surfaces such as skin and gill. These exterior surfaces, however, are important primary targets for pathogen attachment and invasion. Flavobacterium columnare, the causative agent of columnaris disease, is among the most prevalent of all freshwater disease-causing bacteria, impacting global aquaculture of catfish, salmonids, baitfish and aquaria-trade species among others. This study evaluated whether the feeding of a standard catfish diet supplemented with Alltech dietary additives Actigen(®), a concentrated source of yeast cell wall-derived material and/or Allzyme(®) SSF, a fermented strain of Aspergillus niger, could offer protection against F. columnare mortality. A nine-week feeding trial of channel catfish fingerlings with basal diet (B), B + Allzyme(®) SSF, B + Actigen(®) and B + Actigen(®)+Allzyme(®) SSF revealed good growth in all conditions (FCR < 1.0), but no statistical differences in growth between the treatments were found. At nine weeks, based on pre-challenge trial results, basal, B + Actigen(®), and B + Allzyme(®) SSF groups of fish were selected for further challenges with F. columnare. Replicated challenge with a virulent F. columnare strain, revealed significantly longer median days to death in B + Allzyme(®) SSF and B + Actigen(®) when compared with the basal diet (P < 0.05) and significantly higher survival following the eight day challenge period in B + Actigen(®) when compared with the other two diets (P < 0.05). Given the superior protection provided by the B + Actigen(®) diet, we carried out transcriptomic comparison of gene expression of fish fed that diet and the basal diet before and after columnaris challenge using high-throughput RNA-seq. Pathway and enrichment analyses revealed changes in mannose receptor DEC205 and IL4 signaling at 0 h (prior to challenge) which likely explain a dramatic divergence in expression profiles between the two diets soon after pathogen challenge (8 h). Dietary mannose priming resulted in reduced expression of inflammatory cytokines, shifting response patterns instead to favor resolution and repair. Our results indicate that prebiotic dietary additives may provide protection extending beyond the gut to surface mucosa.

Inhibition of adhesion of intestinal pathogens (Escherichia coli, Vibrio cholerae, Campylobacter jejuni, and Salmonella Typhimurium) by common oligosaccharides

Inhibition of the binding of pathogenic adhesins to host glycans by suitable oligosaccharides forms the basis of antiadhesion therapies. Experiments were carried out to study the inhibition capability of oligosaccharides on the adhesion of four microorganisms (Escherichia coli, Vibrio cholerae, Campylobacter jejuni, and Salmonella Typhimurium) to HT-29 cells. Results showed that, in the absence of oligosaccharides, all of the four pathogens efficiently adhered to the cells. Cell adhesion with different bacteria was inhibited by distinct oligosaccharides (e.g., the adhesion number relative to control of V. cholerae could be significantly decreased by pectin oligosaccharide and chitooligosaccharide to about 16.1% and 18.9%, respectively). Saturation studies showed that the extent of antiadhesive effect for most of the suitable carbohydrates was dependent on their concentration. The observations from the study suggest that various carbohydrates may have antiadhesive activity and may be useful in future therapeutic study.

Antiadherent activity of Schinus terebinthifolius and Croton urucurana extracts on in vitro biofilm formation of Candida albicans and Streptococcus mutans

OBJECTIVE

To evaluate the antiadherent property of crude, methanol and acetate methanol extract fractions from Schinus terebinthifolius and Croton urucurana in hydroalcoholic (HA) and dimethylsulfoxide (DMSO) solvents on in vitro biofilms formed by Streptococcus mutans and Candida albicans strains.

DESIGN

The minimal concentration of adherence (MICA) was determined to evaluate the antiadherent potential of extracts on the in vitro biofilm formation. The extracts of plants were subjected to thin layer chromatography (TLC) in order to detect what class of compounds was responsible for the antiadherent activity. Data were estimated by analysis of variance (ANOVA) complemented by Tukey test level of significance set at 5%.

RESULTS

Both plants demonstrated inhibition of S. mutans and C. albicans on in vitro biofilm formation. The biofilms of C. albicans were more efficiently inhibited by the S. terebinthifolius fraction of acetate-methanol and methanol in hydroalcoholic solvents (p<0.05). The S. mutans biofilms adherence was best inhibited by the S. terebinthifolius crude extract and its methanolic fraction, both in hydroalcoholic solvent (p<0.05). TLC of crude extracts and fractions of S. terebinthifolius detected the presence of several active compounds, including phenolic compounds, anthraquinones, terpenoids, and alkaloids. C. urucurana extracts confirmed activity for both microorganisms (p<0.05). However, higher concentrations were needed to achieve antiadherent activity, mainly to inhibit in vitro biofilm formation of C. albicans.

CONCLUSION

The antiadherent potential of both plants on in vitro biofilms formed by C. albicans and S. mutans were confirmed, suggesting the importance of studies about these extracts for therapeutic prevention of oral diseases associated with oral biofilms.

Improved health and growth of fish fed mannan oligosaccharides: potential mode of action

Nowadays, aquaculture industry still confronts several disease-related problems mainly caused by viruses, bacteria and parasites. In the last decade, the use of mannan oligosaccharides (MOS) in fish production has received increased attention due to its beneficial effects on fish performance and disease resistance. This review shows the MOS use in aquaculture with a specific emphasis on the effectiveness of the several MOS forms available in the market related to disease resistance, fish nutrition and the possible mechanisms involved. Among the main beneficial effects attributed to MOS dietary supplementation, enhanced fish performance, feed efficiency and pathogen protection by potentiation of the systemic and local immune system and the reinforcement of the epithelial barrier structure and functionality are some of the most commonly demonstrated benefits. These combined effects suggest that the reinforcement of the intestinal integrity and functionality, together with the stimulation of the innate immune system, are the primary mode of action of MOS in fish. However, the supplementation strategy related to the structure of the MOS added, the correct dose and duration, as well as fish species, size and culture conditions are determinant factors to achieve improvements in health status and growth performance.

Tannins possessing bacteriostatic effect impair Pseudomonas aeruginosa adhesion and biofilm formation

Plants produce many compounds that are biologically active, either as part of their normal program of growth and development or in response to pathogen attack or stress. Traditionally, Anadenanthera colubrina, Commiphora leptophloeos and Myracrodruon urundeuva have been used by communities in the Brazilian Caatinga to treat several infectious diseases. The ability to impair bacterial adhesion represents an ideal strategy to combat bacterial pathogenesis, because of its importance in the early stages of the infectious process; thus, the search for anti-adherent compounds in plants is a very promising alternative. This study investigated the ability of stem-bark extracts from these three species to control the growth and prevent biofilm formation of Pseudomonas aeruginosa, an important opportunistic pathogen that adheres to surfaces and forms protective biofilms. A kinetic study (0–72 h) demonstrated that the growth of extract-treated bacteria was inhibited up to 9 h after incubation, suggesting a bacteriostatic activity. Transmission electron microscopy and fluorescence microscopy showed both viable and nonviable cells, indicating bacterial membrane damage; crystal violet assay and scanning electron microscopy demonstrated that treatment strongly inhibited biofilm formation during 6 and 24 h and that matrix production remained impaired even after growth was restored, at 24 and 48 h of incubation. Herein, we propose that the identified (condensed and hydrolyzable) tannins are able to inhibit biofilm formation via bacteriostatic properties, damaging the bacterial membrane and hindering matrix production. Our findings demonstrate the importance of this abundant class of Natural Products in higher plants against one of the most challenging issues in the hospital setting: biofilm resilience.

Pilot study: miscellaneous therapy is highly successful for Helicobacter pylori eradication

BACKGROUND

Success in H. pylori eradication with conventional therapies has decreased to unacceptable levels (≤80%). New schemes of combined treatment are currently needed.

AIM

To test a miscellaneous therapy for H. pylori eradication.

METHODS/PATIENTS

Open-label, pilot, single-centre and prospective study. Patients received a 15-day treatment scheme that consisted of 5 initial days of lansoprazole 30 mg b.d., amoxicillin 1 g b.d., and metronidazole 500 mg t.d.s.; days 6 to 10: lansoprazole 30 mg q.d.s. and metronidazole 500 mg t.d.s.; days 11 to 15: lansoprazole 30 mg b.d., clarithromycin 500 mg b.d. and metronidazole 500 mg t.d.s. Each patient underwent an upper endoscopy before treatment and a second follow-up endoscopy at least 4 weeks after therapy. Success was defined on the basis of an eradication rate following a per-protocol analysis ≥95%. Biopsies before and after therapy were obtained for histological evaluation and rapid urease test.

RESULTS

One hundred and twenty-two patients were enrolled and 118 patients completed the study. The eradication rate for H. pylori with miscellaneous therapy was 94% (confidence Interval (CI) 95%, 90-98.3%) in the per-protocol analysis (PP) and 91% (95% CI, 86-96%) in the intention-to-treat (ITT) analysis. Adherence to treatment was 96% (113 patients). Among patients who completed treatment, 55% presented adverse events, mainly nausea and abdominal pain.

CONCLUSION

A miscellaneous therapy, based on the combination of multiple medications in high doses for 2 weeks, and with gastric pH elevation, is a highly effective treatment as a first-line therapy for the eradication of H. pylori.

Adherence inhibition of enteropathogenic Escherichia coli by chitooligosaccharides with specific degrees of acetylation and polymerization

Some oligosaccharides are known to act as molecular decoys by inhibiting pathogen adherence to epithelial cells. The present study was aimed at analyzing whether chitooligosaccharides (CHOS), that is, oligomers of D-glucosamine and N-acetyl-D-glucosamine, have such antiadherence activity. CHOS of varied degree of polymerization (DP) and fraction of acetylation (F(A)) were produced. Adherence of enteropathogenic Escherichia coli (EPEC) to the surface of a human HEp-2 cell line was determined in the absence or presence of the various CHOS fractions. Adherence was assessed by microscopic counting and image analysis of bacterial clusters and cells. The results showed that all CHOS fractions inhibited adherence of EPEC to HEp-2 cells. Hydrolysates with lower F(A) were more effective at reducing adherence. This effect is greater than that obtained with other oligosaccharides, such as galactooligosaccharides, applied at the same concentrations.

Pre-treatment with EDTA-gallium prevents the formation of biofilms on surfaces

Pseudomonas aeruginosa and Streptococcus pyogenes are leading causes of medical device-associated infections. The capacity to establish and maintain these infections is thought to be associated with the ability to form surface-attached biofilms. In the present study, gallium nitrate was used to coat PVC plates and biofilm formation on the plates by Pseudomonas aeruginosa and Streptococcus pyogenes was evaluated. The results demonstrated that coating the PVC surface with gallium reduced bacteria cell aggregation on the PVC surface and inhibited biofilm formation. These results suggest that surface pre-treatment with a gallium nitrate coating is a potential strategy for the prevention of infections associated with Pseudomonas aeruginosa or Streptococcus pyogenes on medical devices.