Bacterial Biofilm Formation Research Articles

Tailored synthesis of CoFe2O4 nanorods to prevent clogging in the microstructured biochar-supported MFC anode for sustained performance

Biochar with highly porous structures and organic functional moieties can act as an efficient micro-substrate for bacterial interaction. This study explores the potential of biochar combined with a CoFe2O4 catalyst as an anode material in Microbial Fuel Cells (MFCs). To prevent bacterial clogging of the biochar pores, we strategically synthesized rod-shaped CoFe2O4 nano substrates. When decorated on the biochar surface, these nanorods served as pillars for bacterial growth, preventing pore clogging and enhancing the electron transfer mechanism. SEM and TEM images confirmed the presence of nanorods on the biochar surface. S. putrefaciens utilizes Co+2 and Fe+2 ions released from CoFe2O4 as electron acceptors, promoting their growth and colonization on the anode surface. The contact angle measurements of the fabricated anode showed it to be hydrophilic, with a water contact angle (θw) of 37.4°. OSP analyses revealed that the anode has a textured surface, further favoring bacterial adhesion and biofilm formation. The double-chambered MFC exhibited the highest current density of 32.225 A/m3. This study underscores the importance of biochar and the strategic enhancement of electrode performance through the surface tuning of nanocatalysts for application in microbial fuel cells.

Unlocking the therapeutic potential of Nigella sativa extract: phytochemical analysis and revealing antimicrobial and antioxidant marvels

The growing global threat of antimicrobial resistance endangers both human and animal life, necessitating the urgent discovery of novel antimicrobial solutions. Medicinal plants hold promise as sources of potential antimicrobial compounds. In this study, we investigated the phytochemical constituents and microbicidal capabilities of the ethanolic extract from Nigella sativa (black seed). Gas chromatography analysis (GC) identified 11 compounds, among them thymoquinone, and thymol, contributing to antimicrobial and antioxidant properties. Antimicrobial assays demonstrated notable inhibition zones against broad spectra of bacteria, including Pseudomonas aeruginosa, Escherichia coli, Salmonella typhi, Staphylococcus aureus, Enterobacter, and Bacillus subtilis, along with potent antifungal activity against Aspergillus niger, Penicillium, and Candida albicans. Notably, when combined with antibiotics, the extract displayed exceptional synergistic antimicrobial efficacy. The black seed extract demonstrated membrane-damaging activity and disrupted virulence factors that protect microbes from antimicrobial agents, including the formation of bacterial biofilm and protease secretion. Thymoquinone, the primary active constituent of the extract, exhibited similar antimicrobial and ant virulence properties. In silico analysis targeting key regulators of quorum sensing and biofilm formation in P. aeruginosa, such as RhlG, LasR, and PqsR, showed a remarkable affinity of thymol and thymoquinone for these targets. Moreover, the N. sativa extract exhibited dose-dependent cytotoxicity against both the promastigote and amastigote forms of Leishmania tropica parasites, hinting at potential antiparasitic activity. In addition to its antimicrobial properties, the extract displayed potential antioxidant activity at a concentration of 400 μg/mL.

Antifouling Properties of Electrospun Polymeric Coatings Induced by Controlled Surface Morphology

Nosocomial infections affect implanted medical devices and greatly challenge their functional outcomes, becoming sometimes life threatening for the patients. Therefore, aggressive antibiotic therapies are administered, which often require the use of last‐resort drugs, if the infection is caused by multi‐drug‐resistant bacteria. Reducing the risk of bacterial contamination of medical devices in the hospitals has thus become an emerging issue. Promising routes to control these infections are based on materials provided with intrinsic bactericidal properties (i.e., chemical action) and on the design of surface coatings able to limit bacteria adhesion and fouling phenomena (i.e., physical action), thus preventing bacterial biofilm formation. Here, we report the development and validation of coatings made of layer‐by‐layer deposition of electrospun poly(vinylidene fluoride‐co‐trifluoro ethylene) P(VDF‐TrFE) fibers with controlled orientations, which ultimately gave rise to antifouling surfaces. The obtained 10‐layer surface morphology with 90° orientation fibers was able to efficiently prevent the adhesion of bacteria, by establishing a superhydrophobic‐like behavior compatible with the Cassie‐Baxter regimen. Moreover, the results highlighted that surface wettability and bacteria adhesion could be controlled using fibers with diameter comparable to bacteria size (i.e., achievable via electrospinning process), by tuning the intra‐fiber spacing, with relevant implications in the future design of biomedical surface coatings.

Current scenario of indole hybrids with antibacterial potential against Acinetobacter baumannii pathogens: A mini-review.

Acinetobacter baumannii with the capability to "escape" almost all currently available antibacterials is eroding the safety of basic medical interventions and is an increasing cause of mortality globally, prompting a substantial requirement for new classes of antibacterial agents. Indoles participate in the regulation of persistent bacterial formation, biofilm formation, plasmid stability, and drug resistance. In particular, indole hybrids demonstrated promising antibacterial activity against both drug-sensitive and drug-resistant A. baumannii pathogens, representing a fertile source for the discovery of novel therapeutic agents for clinical deployment in controlling A. baumannii infections. This mini-review outlines the current innovations of indole hybrids with antibacterial activity against A. baumannii pathogens, covering articles published from 2020 to the present, to open new avenues for exploring novel anti-A. baumannii candidates.

Preliminary osteogenic and antibacterial investigations of wood derived antibiotic-loaded bone substitute for the treatment of infected bone defects.

Introduction: The development of reliable treatments for infected or potentially infected bone loss resulting from open fractures and non-unions is extremely urgent, especially to reduce the prolonged courses of antimicrobial therapy to which affected patients are subjected. Numerous bone graft substitutes have been used over the years, but there are currently no effective solutions to treat critical bone loss, especially in the presence of infection. The present study evaluated the use of the biomorphic calcium phosphate bone scaffold b. Bone™, based on a next-generation resorbable biomimetic biomaterial, in bone reconstruction surgery in cases of infection. Methods: Using an "in vitro 3D bone fracture model" to predict the behavior of this drug delivery system during critical bone loss at an infected (or potentially infected) site, the effects of scaffolds loaded with gentamicin or vancomycin on the viability and differentiation capacity of human mesenchymal stem cells (hMSCs) were evaluated. Results: This scaffold, when loaded with gentamicin or vancomycin, exhibits a typical drug release curve that determines the inhibitory effects on the growth of Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli, as well as relative biofilm formation. Discussion: The study demonstrates that b.bone scaffolds can effectively address key challenges in orthopedic surgery and patient care by inhibiting bacterial growth and biofilm formation through rapid, potent antibiotic release, reducing the risk of treatment failure due to resistance, and providing a promising solution for bone infections and improved patient outcomes. Future studies could explore the combination of different antibiotics on these scaffolds for more tailored and effective treatments against post-traumatic osteomyelitis pathogens.

Quorum Quenching Approaches against Bacterial-Biofilm-Induced Antibiotic Resistance.

With the widespread phenomenon of antibiotic resistance and the diffusion of multiple drug-resistant bacterial strains, enormous efforts are being conducted to identify suitable alternative agents against pathogenic microorganisms. Since an association between biofilm formation and antibiotic resistance phenotype has been observed, a promising strategy pursued in recent years focuses on controlling and preventing this formation by targeting and inhibiting the Quorum Sensing (QS) system, whose central role in biofilm has been extensively demonstrated. Therefore, the research and development of Quorum Quenching (QQ) compounds, which inhibit QS, has gradually attracted the attention of researchers and has become a new strategy for controlling harmful microorganisms. Among these, a number of both natural and synthetic compounds have been progressively identified as able to interrupt the intercellular communication within a microbial community and the adhesion to a surface, thus disintegrating mature/preformed biofilms. This review describes the role played by QS in the formation of bacterial biofilms and then focuses on the mechanisms of different natural and synthetic QS inhibitors (QSIs) exhibiting promising antibiofilm ability against Gram-positive and Gram-negative bacterial pathogens and on their applications as biocontrol strategies in various fields.

The treatment of bacterial biofilms cultivated on knee arthroplasty implants using the bioelectric effect.

Introduction: The formation of bacterial biofilms on knee arthroplasty implants can have catastrophic consequences. The aim of this study was to analyze the effectiveness of the bioelectric effect in the elimination of bacterial biofilms on cultivated knee arthroplasty implants. Methods: A novel device was designed to deliver a bioelectric effect on the surface of knee arthroplasty implants. 4-femoral prosthetic implants were cultivated with a staphylococcus aureus inoculum for 15days. The components were divided into four different groups: A (not treated), B (normal saline 20-minutes), C (bioelectric effect 10-minutes), D (bioelectric effect 20-minutes). The implants were sonicated, and the detached colonies were quantified as the number of colony-forming unit (CFUs). The implants were sterilised and the process was repeated in a standardized manner four more times, to obtain a total of five samples per group. Results: The number of the CFUs after a 10-minute exposure to the bioelectric effect was of 208.2 ± 240.4, compared with 6,041.6 ± 2010.7 CFUs in group A, representing a decrease of 96.5% ± 4.3 (p = 0.004). And a diminution of 91.8% ± 7.9 compared with 2,051.0 ± 1,364.0 CFUs in group B (p = 0.109). The number of bacterial colonies after a 20-minute exposure to the bioelectric effect was 70 ± 126.7 CFUs, representing a decrease of 98.9% ± 1.9 (p = 0.000) compared with group A. And a decrease of 97.8% ± 3.0 (p = 0.019) compared with group B. Conclusions: The bioelectric effect was effective in the elimination of bacterial biofilm from knee arthroplasty implants. This method could be used in the future as part of conventional surgical procedures.

Pathogenicity of Multidrug-Resistant Salmonella typhimurium Isolated from Ducks.

Salmonella typhimurium (S. typhimurium) is one of the most common Salmonella serotypes in epidemiological surveys of poultry farms in recent years. It causes growth retardation, mortality, and significant economic losses. The extensive use of antibiotics has led to the emergence of multi-drug resistance (MDR) in Salmonella, which has become a significant global problem and long-term challenge. In this study, we investigated the prevalence and features of S. typhimurium strains in duck embryos and cloacal swabs from large-scale duck farms in Shandong, China, including drug resistance and virulence genes and the pathogenicity of an S. typhimurium strain by animal experiment. The results demonstrated that a total of 8 S. typhimurium strains were isolated from 13,621 samples. The drug resistance results showed that three of the eight S. typhimurium strains were MDR with the dominant resistance profile of CTX-DX-CTR-TE-AMX-AMP-CAZ. In particular, the virulence genes invA, hilA, pefA, rck, and sefA showed high positive rates. Based on the analysis of the biological characteristics of bacterial biofilm formation and mobility, a strain of S. typhimurium with the strongest biofilm formation ability, designated 22SD07, was selected for animal infection experiments with broiler ducklings. The results of animal experiments demonstrated that infection with 22SD07 reduced body weight and bursa index but increased heart and liver indexes compared to the control group. Histological examination revealed desquamation of the intestinal villous epithelium, the presence of large aggregates of lymphocytes, and a decrease in goblet cells following infection. Furthermore, the expression of IL-10 was significantly increased in the liver at 3 dpi, while TNF-α was significantly increased in the spleen at 7 dpi. The above results indicate that S. typhimurium may pose a potential threat to human health through the food chain. This helps us to understand the frequency and characteristics of S. typhimurium in duck farms and emphasizes the urgent need to strengthen and implement effective continuous monitoring to control its infection and transmission.

Clinical use and applications of a citrate-based antiseptic lavage for the prevention and treatment of PJI.

Total joint arthroplasties (TJA) are some of the most commonly performed surgeries in the United States with the number of TJA expected to rise significantly over the next decade as the population ages and arthritic burden worsens. However, the rise in TJA volume correlates with a heightened risk of complications, notably prosthetic joint infections (PJI), despite their low occurrence rate of less than 2%. PJI imposes a significant burden on surgery success, patient well-being, and healthcare costs, with an estimated annual expense of 1.85 billion dollars for hip and knee PJI by 2030. This manuscript delves into the pathophysiology of PJI, exploring our current understanding of the role of bacterial biofilm formation on implanted foreign hardware, providing protection against the host immune system and antibiotics. The article reviews current agents and their efficacy in treating PJI, as well as their cytotoxicity toward native cells involved in wound healing, prompting the exploration of a novel citrate-based solution. The paper highlights the superior properties and efficacy of a novel citrate-based irrigation solution on the treatment and prevention of PJI via increased antimicrobial properties, greater biofilm disruption, increased exposure time, and reduced cytotoxicity compared to conventional solutions, positioning it as a promising alternative. It also provides a perspective on its clinical use in the operating theater, with a step-by-step approach in TJA, whether primary or revisionary.

Antibacterial and Antibiofilm Activity of Croton urticifolius Lam. Essential Oil Via Membrane Disruption.

Antimicrobial resistance is a global health issue, in which microorganisms develop resistance to antimicrobial drugs, making infections more difficult to treat. This threatens the effectiveness of standard medical treatments and necessitates the urgent development of new strategies to combat resistant microbes. Studies have increasingly explored natural sources of new antimicrobial agents that harness the rich diversity of compounds found in plant species. This pursuit holds promise for the discovery of novel treatments for combating antimicrobial resistance. In this context, the chemical composition, antibacterial, and antibiofilm activities of the essential oil from Croton urticifolius Lam. leaves (CuEO) were evaluated. CuEO was extracted via hydrodistillation, and its chemical constituents were identified via gas chromatography-mass spectrometry (GC/MS). The antibacterial activity of CuEO was evaluated in a 96-well plate via the microdilution method, and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were determined. The effect of CuEO on biofilm formation was assessed by quantifying the biomass using crystal violet staining and viable cell counting. In addition, alterations in the cellular morphology of biofilms treated with CuEO were examined using scanning electron microscopy (SEM) and laser confocal microscopy. GC/MS analysis identified 26 compounds, with elemicine (39.72%); eucalyptol (19.03%), E-caryophyllene (5.36%), and methyleugenol (4.12%) as the major compounds. In terms of antibacterial activity, CuEO showed bacteriostatic effects against Staphylococcus aureus ATCC 700698, S. aureus ATCC 25923, Staphylococcus epidermidis ATCC 12228, and Escherichia coli ATCC 11303, and bactericidal activity against S. aureus ATCC 700698. In addition, CuEO significantly inhibited bacterial biofilm formation. Microscopic analysis showed that CuEO damaged the bacterial membrane by leaching out the cytoplasmic content. Therefore, the results of this study show that the essential oil of C. urticifolius may be a promising natural alternative for preventing infections caused by bacterial biofilms. This study is the first to report the antibiofilm activity of C. urticifolius essential oil.

1H-Pyrrole-2,5-dicarboxylic acid, a quorum sensing inhibitor from one endophytic fungus in Areca catechu L., acts as antibiotic accelerant against Pseudomonas aeruginosa.

Pseudomonas aeruginosa has already been stipulated as a "critical" pathogen, emphasizing the urgent need for researching and developing novel antibacterial agents due to multidrug resistance. Bacterial biofilm formation facilitates cystic fibrosis development and restricts the antibacterial potential of many current antibiotics. The capacity of P. aeruginosa to form biofilms and resist antibiotics is closely correlated with quorum sensing (QS). Bacterial QS is being contemplated as a promising target for developing novel antibacterial agents. QS inhibitors are a promising strategy for treating chronic infections. This study reported that the active compound PT22 (1H-pyrrole-2,5-dicarboxylic acid) isolated from Perenniporia tephropora FF2, one endophytic fungus from Areca catechu L., presents QS inhibitory activity against P. aeruginosa. Combined with gentamycin or piperacillin, PT22 functions as a novel antibiotic accelerant against P. aeruginosa. PT22 (0.50 mg/mL, 0.75 mg/mL, and 1.00 mg/mL) reduces the production of QS-related virulence factors, such as pyocyanin and rhamnolipid, and inhibits biofilm formation of P. aeruginosa PAO1 instead of affecting its growth. The architectural disruption of the biofilms was confirmed by visualization through scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Real-time quantitative PCR (RT-qPCR) indicated that PT22 significantly attenuated the expression of QS-related genes followed by docking analysis of molecules against QS activator proteins. PT22 dramatically increased the survival rate of Galleria mellonella. PT22 combined with gentamycin or piperacillin presents significant inhibition of biofilm formation and eradication of mature biofilm compared to monotherapy, which was also confirmed by visualization through SEM and CLSM. After being treated with PT22 combined with gentamycin or piperacillin, the survival rates of G. mellonella were significantly increased compared to those of monotherapy. PT22 significantly enhanced the susceptibility of gentamycin and piperacillin against P. aeruginosa PAO1. Our results suggest that PT22 from P. tephropora FF2 as a potent QS inhibitor is a candidate antibiotic accelerant to combat the antibiotic resistance of P. aeruginosa.

Antibiofilm activity of promethazine against ESBL-producing strains of Escherichia coli in urinary catheters

The bacterium Escherichia coli is one of the main causes of urinary tract infections. The formation of bacterial biofilms, especially associated with the use of urinary catheters, contributes to the establishment of recurrent infections and the development of resistance to treatment. Strains of E. coli that produce extended-spectrum beta-lactamases (ESBL) have a greater ability to form biofilms. In addition, there is a lack of drugs available in the market with antibiofilm activity. Promethazine (PMZ) is an antihistamine known to have antimicrobial activity against different pathogens, including in the form of biofilms, but there are still few studies of its activity against ESBL E. coli biofilms. The aim of this study was to evaluate the antimicrobial activity of PMZ against ESBL E. coli biofilms, as well as to assess the application of this drug as a biofilm prevention agent in urinary catheters. To this end, the minimum inhibitory concentration and minimum bactericidal concentration of PMZ in ESBL E. coli strains were determined using the broth microdilution assay and tolerance level measurement. The activity of PMZ against the cell viability of the in vitro biofilm formation of ESBL E. coli was analyzed by the MTT colorimetric assay and its ability to prevent biofilm formation when impregnated in a urinary catheter was investigated by counting colony-forming units (CFU) and confirmed by scanning electron microscopy (SEM). PMZ showed bactericidal activity and significantly reduced (p < 0.05) the viability of the biofilm being formed by ESBL E. coli at concentrations of 256 and 512 μg/ml, as well as preventing the formation of biofilm on urinary catheters at concentrations starting at 512 μg/ml by reducing the number of CFUs, as also observed by SEM. Thus, PMZ is a promising candidate to prevent the formation of ESBL E. coli biofilms on abiotic surfaces.

Physical parametric study of bacterial biofilm disruption and removal by jet impingement: A CFD investigation

Bacterial biofilm formation is one of the most critical challenges in industrial and health systems. It is the leading cause of nearly 80 % of clinical infections. Biofilms are usually evaluated from the physiological point of view as microbial cells enclosed in an extracellular polymer and represent a complex, dynamic bacterial community. Cohesive mechanical forces hold the bacteria within the biofilm together. These forces contribute to the biofilm's mechanical and structural stability, resulting in its viscoelastic properties. Studying the biofilm's mechanical properties as a viscoelastic matter can provide a better understanding of the biofilm's characteristics and the survival strategies of bacteria in the biofilm state of life. In the present study, a 2D-axisymmetric RANS-CFD simulation model using the Volume Of Fluid (VOF) method was developed to track changes in biofilm surface and ripple formation across six biofilm thicknesses ranging from 15 μm to 115 μm, two substrate geometries including flat and curved, and two substrate roughnesses of 0.4 μm and 0.9 μm height. A modified Herschel-Bulkley model was employed to capture the biofilm's non-Newtonian shear-thinning behavior under high-velocity gas jet impingement. The results revealed the importance of biofilm thickness, substrate geometries, and properties like roughness in biofilm's mechanical behavior. Higher thickness of biofilm resulted in smaller jet-impingement region and more significant ripples formation. Biofilm on curved substrates decreased in thickness more rapidly than those on flat substrates. The substrate's geometry impacted biofilm folding patterns, removal, and mechanical behavior. Selected substrate roughnesses did not create any resistance against the mechanical removal of biofilms. Here, we successfully captured biofilms' non-Newtonian and shear-thinning behavior with numerical simulations consistent with previously reported experimental results. This could benefit industrial and health systems by tackling biofilm-related challenges and developing more accurate and detailed models of biofilms to optimize tools for drug testing or screening and enhance the models for in-vitro and in-vivo analysis.

Limosilactobacillus reuteri DSM 17938 Inhibition of Biofilm Formation by Prevotella intermedia and Fusobacterium nucleatum Across Salivary pH: An In Vitro Study

Abstract Objectives This study aims to investigate Limosilactobacillus reuteri DSM 17938's antibiofilm effects on Prevotella intermedia and Fusobacterium nucleatum, common causes of alveolar osteitis. It seeks topical alternatives to prevent this condition posttooth extraction. The secondary objective is to assess these effects under different pH conditions (pH 4.5 and pH 7), mimicking oral cavity saliva pH dynamics. Materials and Methods Ethical approval was secured for the saliva collection process involving five healthy adult participants who had undergone wisdom tooth extraction. Saliva samples were diligently collected on the 7th day post-surgery. The unstimulated saliva underwent a series of treatments, including the addition of phenylmethylsulfonyl fluoride (PMSF), pH adjustments, centrifugation, and filtration. The pH levels were re-measured, and subsequent adjustments were made to achieve pH values of 4.5 or 7. Limosilactobacillus reuteri DSM 17938, with a concentration of 1×108 colony-forming units (CFU) per 5 drops, was utilized in the study. Biofilm testing involved incubating saliva samples with varying pH (4.5 or 7) alongside bacterial suspensions (Prevotella intermedia, Fusobacterium nucleatum, or a mixed species). The Interlac suspension was introduced, and plates were anaerobically incubated for 24 hours. Biofilm results were obtained using a spectrometer. The test is conducted in triplicate. Statistical Analysis To scrutinize the impact of pH on biofilm development, the acquired data underwent a two-way ANOVA test in SPSS as part of the statistical analysis. A significance level of p&lt;0.05 was used to determine statistical significance. Results Limosilactobacillus reuteri DSM 17938 significantly reduced biofilm formation across bacterial strains (p = 0.000). Statistical analysis indicated a significant impact of pH on biofilm development (p = 0.000) compared to no saliva samples, with higher formation observed under acidic conditions (pH 4.5). However, the pH levels of 4.5 and 7 did not result in significantly different bacterial biofilm formation (p = 0.529). Conclusion This research highlights Limosilactobacillus reuteri DSM 17938's potency in inhibiting biofilm formation of Prevotella intermedia and Fusobacterium nucleatum. Salivary pH variations significantly influence biofilm development, emphasizing the need to consider pH when assessing probiotic effectiveness. Despite limitations in saliva sample sterilization, this study provides valuable insights into alternative approaches for preventing alveolar osteitis. Further research should explore clinical applications and refine sterilization methods for more accurate results.

VG111: A novel formulation demonstrating clinical evidence of anti-pathogenic activity and accelerated wound healing in humans and companion animals

Objectives: The increasing incidence of chronic wounds such as diabetic foot ulcers and pressure ulcers, often compounded by bacterial infections and biofilm formation, presents significant challenges in wound management. Despite advancements in wound care products and a better understanding of molecular wound repair mechanisms, the treatment of chronic ulcerating conditions remains incomplete. VG111, a novel natural product formulation, emerges as a promising therapeutic candidate addressing the need for an effective wound healing agent with antimicrobial and tissue regenerative properties. Materials and Methods: A thorough evaluation of VG111 included antimicrobial assays to determine its minimum inhibitory concentration against an array of pathogens, assessment of its biofilm disruption capabilities, investigation into its profibrogenic activity through scratch assays, and analysis of its immunomodulatory effects on macrophage-derived cytokines. Quality consistency was ensured by high-performance liquid chromatography fingerprinting, while clinical applicability was assessed through observations in canine and human wound healing cases. Statistical Analysis: The cytotoxic effects of VG111 were assessed using a Two-way ANOVA, indicating no significant cytotoxicity at the tested concentration (Column factor p&lt;0.0001). Results: VG111 demonstrated potent antimicrobial action with effective concentrations ranging from 2.5% to 5.0% v/v, targeting resistant strains of Methicillin-resistant Staphylococcus aureus, colistin-resistant Escherichia coli, Acinetobacter baumannii, and other priority pathogens. It showed biofilm clearance, enhanced fibroblast migration, and a favorable immunomodulatory profile by reducing inflammatory cytokines in vitro. In vivo applications corroborated these findings, with significant wound healing observed in both veterinary and clinical settings, negating the need for additional antibiotics. Conclusions: The study emphasized on VG111 as a robust wound healing agent with significant antimicrobial and biofilm-disrupting properties. Its broad-spectrum efficacy against critical pathogens and ability to promote tissue regeneration mark it as a promising avenue in the management of complex chronic wounds, meriting further clinical exploration.

Essential Oils from Southern Italian Aromatic Plants Synergize with Antibiotics against Escherichia coli, Pseudomonas aeruginosa and Enterococcus faecalis Cell Growth and Biofilm Formation.

The spread of antibiotic-resistant pathogens has prompted the development of novel approaches to identify molecules that synergize with antibiotics to enhance their efficacy. This study aimed to investigate the effects of ten Essential Oils (EOs) on the activity of nine antibiotics in influencing growth and biofilm formation in Escherichia coli, Pseudomonas aeruginosa, and Enterococcus faecalis. The effects of the EOs alone and in combination with antibiotics on both bacterial growth and biofilm formation were analyzed by measuring the MIC values through the broth microdilution method and the crystal violet assay, respectively. All EOs inhibited the growth of E. coli (1.25 ≤ MIC ≤ 5 mg/mL) while the growth of P. aeruginosa and E. faecalis was only affected by EOs from Origanum vulgare, (MIC = 5 mg/mL) and O. vulgare (MIC = 1.25 mg/mL) and Salvia rosmarinus (MIC = 5 mg/mL), respectively. In E. coli, most EOs induced a four- to sixteen-fold reduction in the MIC values of ampicillin, ciprofloxacin, ceftriaxone, gentamicin, and streptomycin, while in E. faecalis such a reduction is observed in combinations of ciprofloxacin with C. nepeta, C. bergamia, C. limon, C. reticulata, and F. vulgare, of gentamicin with O. vulgare, and of tetracycline with C. limon and O. vulgare. A smaller effect was observed in P. aeruginosa, in which only C. bergamia reduced the concentration of tetracycline four-fold. EO-antibiotic combinations also inhibit the biofilm formation. More precisely, all EOs with ciprofloxacin in E. coli, tetracycline in P. aeruginosa, and gentamicin in E. faecalis showed the highest percentage of inhibition. Combinations induce up- and down-methylation of cytosines and adenines compared to EO or antibiotics alone. The study provides evidence about the role of EOs in enhancing the action of antibiotics by influencing key processes involved in resistance mechanisms such as biofilm formation and epigenetic changes. Synergistic interactions should be effectively considered in dealing with pathogenic microorganisms.

Antimicrobial Peptide Screening for Designing Custom Bactericidal Hydrogels.

Staphylococcus aureus (S. aureus) is an opportunistic pathogen that lives on surfaces and skin and can cause serious infections inside the body. Antimicrobial peptides (AMPs) are part of the innate immune system and can eliminate pathogens, including bacteria and viruses, and are a promising alternative to antibiotics. Although studies have reported that AMP-functionalized hydrogels can prevent bacterial adhesion and biofilm formation, AMP dosing and the combined effects of multiple AMPs are not well understood. Here, three AMPs with different antibacterial properties were synthesized and the soluble minimum inhibitory concentrations (MICs) of each AMP against methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) were determined. Hydrogels with immobilized AMPs at their MIC (DD13-RIP 27.5 µM; indolicidin 43.8 µM; P10 120 µM) were effective in preventing MRSA adhesion and biofilm formation. Checkerboard AMP screens identified synergy between indolicidin (3.1 µM) and P10 (12.5 µM) based on soluble fractional inhibitory concentration indices (FICIs) against MRSA, and hydrogels formed with these AMPs at half of their synergistic concentrations (total peptide concentration, 7.8 µM) were highly efficacious in killing MRSA. Mammalian cells cultured atop these hydrogels were highly viable, demonstrating that these AMP hydrogels are biocompatible and selectively eradicate bacteria, based on soluble checkerboard-screening data.

Quercetin disrupts biofilm formation and attenuates virulence of Aeromonas hydrophila.

Aeromonas hydrophila poses significant health and economic challenges in aquaculture owing to its pathogenicity and prevalence. Overuse of antibiotics has led to multidrug resistance and environmental pollution, necessitating alternative strategies. This study investigated the antibacterial and antibiofilm potentials of quercetin against A. hydrophila. Efficacy was assessed using various assays, including antibacterial activity, biofilm inhibition, specific growth time, hemolysis inhibition, autoaggregation, and microscopic evaluation. Additionally, docking analysis was performed to explore potential interactions between quercetin and virulence proteins of A. hydrophila, including proaerolysin, chaperone needle-subunit complex of the type III secretion system, and alpha-pore forming toxin (PDB ID: 1PRE, 2Q1K, 6GRK). Quercetin exhibited potent antibacterial activity with 21.1 ± 1.1 mm zone of inhibition at 1.5 mg mL-1. It also demonstrated significant antibiofilm activity, reducing biofilm formation by 46.3 ± 1.3% at the MIC and attenuating autoaggregation by 55.9 ± 1.5%. Hemolysis was inhibited by 41 ± 1.8%. Microscopic analysis revealed the disintegration of the A. hydrophila biofilm matrix. Docking studies indicated active hydrogen bond interactions between quercetin and the targeted virulence proteins with the binding energy -3.2, -5.6, and -5.1 kcal mol⁻1, respectively. These results suggest that quercetin is an excellent alternative to antibiotics for combating A. hydrophila infection in aquaculture. The multifaceted efficacy of quercetin in inhibiting bacterial growth, biofilm formation, virulence factors, and autoaggregation highlights the potential for aquaculture health and sustainability. Future research should delve into the precise mechanisms of action and explore synergistic combinations with other compounds for enhanced efficacy and targeted interventions.

Effect of traditional medicinal plants on the pathogenic potential of the versatile pathogen Staphylococcus aureus

This study explores the effects of Neem (Azadirachta indica) and Papaya (Carica papaya) leaf extracts on the pathogenicity of Staphylococcus aureus. Through in vitro assays, we investigated the impact of these medicinal plant extracts on bacterial metabolic activity and pathogenic factors. Results indicate that the growth of Staphylococcus aureus was differentially decreased by the plant extracts, with Neem demonstrating a greater reduction compared to Papaya. Moreover, both Neem and Papaya extracts, either alone or in combination, significantly inhibited bacterial biofilm formation, with reductions of 39%, 48%, and 7%, respectively. Both aqueous and ethanolic extracts exhibited inhibitory effects on bacterial growth, with ethanolic extract showing stronger potency. However, the extracts did not influence the bacteria's haemolytic characteristics. Overall, these findings suggest that traditional medicinal plant extracts possess potential in mitigating S. aureus pathogenicity, however, further mechanistic investigations are warranted to elucidate underlying mechanisms. Jahangirnagar University J. Biol. Sci. 12(1 &amp; 2): 73-86, 2023 (June &amp; December)

Effect of Lattice Structure on Mechanical Properties of Ti-6Al-4V-Ta Alloy for Improved Antibacterial Properties

This study investigates the effect of a tantalum addition and lattice structure design on the mechanical and antibacterial properties of Ti-6Al-4V alloys. TPMS lattice structures, such as Diamond, Gyroid, and Primitive, were generated by MSLattice 1.0 software and manufactured using laser powder bed fusion (LPBF). The results indicate that Gyroid and Primitive structures at a 40% density exhibit superior ultimate compressive strength, which closely emulates bone’s biomechanical properties. To be precise, adding 8% tantalum (Ta) significantly increases the material’s elastic modulus and energy absorption, enhancing the material’s suitability for dynamic load-bearing implants. Nevertheless, the Ta treatment reduces bacterial biofilm formation, especially on Gyroid surfaces, suggesting its potential for infection management. Overall, all findings provide critical insights into the development of advanced implant materials, contributing to the fields of additive manufacturing, materials science, and biomedical engineering and paving the way for improved patient outcomes in orthopedic applications.