Search Results (940)

Dental caries is a major global health issue associated with biofilm formation by Streptococcus mutans (S. mutans). Conventional antimicrobials often fail to eliminate biofilms due to their structural resistance, highlighting the need for new strategies. This study investigated the antibacterial and antibiofilm effects of protamine peptides (PPs), which are cell-penetrating antimicrobial peptides derived from salmon protamine, alone and in combination with antimicrobial agents. Antimicrobial susceptibility was evaluated using alamarBlue^® and colony count assays, while biofilm formation was analyzed using crystal violet staining, confocal microscopy, and extracellular polysaccharide (EPS) quantification. PP exhibited moderate antibacterial activity but strongly suppressed EPS accumulation and biofilm development, leading to a flattened biofilm structure. Cotreatment with ε-poly-L-lysine (PL) significantly enhanced antibacterial and antibiofilm effects compared with either agent alone, whereas this effect was not observed with other cationic polymers. Fluorescence imaging revealed that PL promoted the intracellular localization of PP without increasing membrane damage, indicating a cooperative mechanism by which PL enhances membrane permeability and PP targets intracellular sites. These findings demonstrate that combining a cell-penetrating peptide with a membrane-active agent is a novel approach to overcome bacterial tolerance. The PP–PL combination effectively suppressed S. mutans growth and biofilm formation through dual action on membranes and EPS metabolism, offering a promising basis for the development of peptide-based preventive agents and biofilm-resistant dental materials. Full article

Bacterial infections remain a major challenge to human health, especially in wound healing, where they can cause prolonged inflammation, delayed recovery, and severe complications. Current research is increasingly focused on developing innovative antimicrobial materials capable of overcoming the limitations of conventional antibiotics, whose effectiveness has declined due to the rise in bacterial resistance. Among the various alternatives, silver nanoparticles have gained particular attention for their broad-spectrum antibacterial properties and have already been successfully applied in the functionalization of commercial wound dressings. The aim of this study was to optimize the functionalization of commercial cotton gauzes based on in situ UV-assisted reduction of silver nanoparticles, reducing methanol usage and identifying the minimal silver nitrate precursor concentration to achieve antimicrobial efficacy while maintaining biocompatibility. Different precursor concentrations were then evaluated through cytocompatibility assays (MTT, Live/Dead, and scratch tests on fibroblasts) and antimicrobial analyses against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus (including an antibiotic-resistant strain), and Candida albicans. The results demonstrated that a 0.5% w/w silver nitrate concentration provided strong antimicrobial and antibiofilm activity without compromising textile properties or cytocompatibility. Furthermore, this optimized process reduced material waste, highlighting its potential for scalable production of antimicrobial wound dressings. Full article

The intensification of aquaculture practices has been accompanied by an increased incidence of bacterial diseases, leading to a greater reliance on antibiotics for disease control. Consequently, the widespread and often indiscriminate use of these compounds has contributed to the emergence and dissemination of antibiotic-resistant bacteria within aquaculture systems, posing a serious threat to animal health, environmental sustainability, and public health. In this regard, research efforts have focused on developing alternative strategies to reduce antibiotic use. Natural compounds have gained particular attention due to their well-documented antimicrobial and antibiofilm activities. In this context, the combined application of antibiotics and natural compounds has emerged as a promising approach to enhance antimicrobial efficacy while potentially mitigating the development of resistance. This review synthesizes the current knowledge on antibiotic resistance in aquaculture, highlights the role of biofilm formation as a key resistance mechanism, and critically examines the potential of antibiotic–natural compound combinations against major aquaculture pathogens, with particular emphasis on bacterial growth inhibition, biofilm disruption, and virulence attenuation. Collectively, the evidence discussed underscores the potential of synergistic strategies as a sustainable tool for improving disease management in aquaculture while supporting efforts to limit antibiotic resistance. Full article

Dental caries is a multifactorial chronic infectious disease that impacts healthcare costs globally, caused by alterations of the plaque microbiome and proliferation of cariogenic Streptococcus mutans. Treatments targeting S. mutans, such as alternative strategies using probiotics, might be effective in preventing the development of dental caries. In this study, the probiotic formulation of Lactobacillus reuteri SGL01, vitamin C, and acerola was tested against S. mutans DSM20523. Antimicrobial activity was assessed by deferred antagonism and spot-on-lawn assays for L. reuteri SGL01. MIC and MBC of L. reuteri SGL01 cell-free supernatant (CFS), vitamin C, and acerola were determined with the microdilution method. Time–kill assays determined the bactericidal kinetics for each compound. The checkerboard method was used to evaluate the potential synergistic activity of CFS–vitamin C or CFS–acerola at scalar dilutions from 1 to 8X MIC. Lastly, antibiofilm activity was tested for each compound. Antimicrobial activity of L. reuteri SGL01 was first assessed by classic methods. MIC and MBC values differed for one dilution for all compounds, with values of 25% and 50% for CFS, 9.3 mg/mL and 18.7 mg/mL for vitamin C, and 18.7 mg/mL and 37.5 mg/mL for acerola, respectively. Moreover, time–kill assays confirmed the bactericidal activity at different timepoints: 4 h for CFS, 6 h for vitamin C, and 24 h for acerola. The fractional inhibitory concentration index (FICI) showed indifference for all combinations, and for associations tested at 2, 4, and 8XMIC. S. mutans biofilm production was impaired for all components, with stronger activity by vitamin C and acerola at lower concentrations. The probiotic formulation containing L. reuteri SGl01, vitamin C, and acerola extract exerts a bactericidal effect, especially strong for the CFS, as well as antibiofilm activity. Thus, the combination of these three components could be advantageous for their complementary effects, with use as a novel treatment against the development of dental caries by S. mutans. Full article

Polyphenols with antimicrobial and antibiofilm properties are gaining popularity due to their natural origins and relatively safe nature, and they have met the interest of the food industry because of their possible applicability as food preservatives. We have investigated the effect of different analogs of dimeric A-type proanthocyanidins (PACs) on four food matrix models, including unprocessed meat, fish, vegetables and dairy products previously contaminated with susceptible food pathogens. The best effects were achieved when cherry tomato was used as the food matrix for all the target bacteria (Staphylococcus aureus CECT 828, Listeria innocua CECT 910 and Bacillus cereus UJA27q) and for both temperatures tested (6 and 25 °C). Moreover, several combinations of these analogs also showed synergistic effects, mainly on S. aureus CECT 828, which may allow these antimicrobials to be used at lower levels in food matrices, which would promote their sensory acceptability. However, further studies should be conducted next to understand the mechanisms of these synergistic activities between the phenolic compounds against foodborne pathogens, as well as to ensure the absence of toxic effects when used as food preservatives. Full article

Background/Objectives: Bacterial biofilms formed by Escherichia coli pose a significant challenge in veterinary medicine due to their intrinsic resistance to antibiotics. Antimicrobial peptides (AMPs) represent a promising alternative. AMPs exert their bactericidal activity by binding to negatively charged phospholipids in bacterial membranes via electrostatic interactions, leading to membrane disruption and rapid cell lysis. Methods: In vitro assays including MIC determination, biofilm eradication testing (crystal violet, colony counts, and CLSM), swimming motility, and EPS quantification were performed. CRISPR/Cas9 was used to construct and complement a kduD mutant. A transposon mutagenesis library was screened for biofilm-defective mutants. In an in vivo murine excisional wound infection model treated with the mouse cathelicidin-related antimicrobial peptide (CRAMP-34), wound closure and bacterial burden were monitored. Gene expression changes were analyzed via RT-qPCR. Results: CRAMP-34 effectively eradicated pre-formed biofilms of a clinically relevant, porcine-origin E. coli strain and promoted wound healing in the murine infection model. We conducted a genome-wide transposon mutagenesis screen, which identified kduD as a critical gene for robust biofilm formation. Functional characterization revealed that kduD deletion drastically impairs flagellar motility and alters exopolysaccharide production, leading to defective biofilm architecture without affecting growth. Notably, the anti-biofilm activity of CRAMP-34 phenocopied aspects of the kduD deletion, including motility inhibition and transcriptional repression of a common set of biofilm-related genes. Conclusions: This research highlights CRAMP-34 as a potent anti-biofilm agent and unveils kduD as a previously unrecognized regulator of E. coli biofilm development, which is also targeted by CRAMP-34. Full article

Athamanta L. is a small genus of the Apiaceae family, comprising only sixteen species and subspecies, which are distributed in the Canary Islands, Central Europe, and the Mediterranean basin. Background/Objectives: Since the time of Dioscurides, the species of this genus have been reported to have had several ethnopharmacological activities, and some of them are also used currently. Athamanta sicula L., growing in Italy, Tunisia, Algeria, and Morocco, is the only species of this genus present in Sicily. To further explore the phytochemical profile and biological properties of this species, the present study focused on the essential oil (EO) extracted from the aerial parts of wild A. sicula populations collected in central Sicily. Methods: The chemical composition of the EO, obtained by hydrodistillation, was determined by GC–MS analysis. The presence of myristicin was confirmed by isolation and by ¹H-NMR spectroscopic characterization. Results: The EO and its main constituents have been tested for possible antimicrobial properties against several bacterial strains, showing MIC values in the of 15–30 mg/mL range, and the mechanism of action was further investigated, revealing membrane-targeting effects consistent with outer membrane permeabilization. In addition, antibiofilm activity (with up to ~80% inhibition of biofilm formation at sub-MICs), antioxidant potential (demonstrating dose-dependent radical scavenging activity), and biocompatibility with eukaryotic cells were assessed to provide a comprehensive pharmacological profile of A. sicula EO. Specifically, the most abundant constituent was myristicin (62.2%), the principal representative of the phenylpropanoid class (64.4%). Hydrocarbon monoterpenes represented the second class of the EO (27.4%), with β-phellandrene (12.2%) as the main compound. Conclusions: Myristicin emerged as the key contributor to the antimicrobial and antibiofilm activity of the EO. The obtained results highlight the relevance of A. sicula EO as a myristicin-rich essential oil with notable in vitro biological activity. Full article

Staphylococcus aureus biofilms represent a critical healthcare challenge, driving chronic infections and antimicrobial resistance. This study investigates the anti-staphylococcal efficacy of two Lactiplantibacillus strains isolated from traditional Bulgarian pickled vegetables (turshiya): L. plantarum IZITR_24 and L. paraplantarum IZITR_13. Combining whole genome sequencing (WGS) with functional assays, we established a robust genotype-to-phenotype framework to characterize their antimicrobial arsenal. Based on WGS, we identified conserved plantaricin (plnJK, plnEF) clusters in both isolates, with IZITR_13 additionally carrying genes for pediocin and enterolysin A—alongside the confirmed absence of virulence factors. Reconstituted lyophilized cell-free supernatants (LCFSs) were evaluated in dose–response microtiter assays to determine the minimum biofilm inhibitory concentration (MBIC) and minimum inhibitory concentration (MIC). Both strains demonstrated clear, dose-dependent inhibitory activity against the S. aureus growth and biofilm formation. Microscopy (SEM/CLSM) confirmed significant biofilm disruption and cell membrane permeabilization. The observed consistency between genome-inferred capacity and phenotypes highlights the strong predictive value of a genome-first screening approach for selecting bacteriocin-producing lactic acid bacteria (LAB). These findings position IZITR_24 and IZITR_13 as promising postbiotic producers with potent antibiofilm activity against S. aureus. By utilizing their stable postbiotic products rather than relying on live colonization, this study proposes a targeted, antibiotic-sparing strategy to combat persistent staphylococcal biofilms. Full article

The growing global threat of antimicrobial resistance (AMR), particularly in cutaneous wound infections, represents a significant clinical and economic challenge. Biofilm formation by multidrug-resistant pathogens, such as Acinetobacter baumannii, often complicates healing and leads to therapeutic failure. Antimicrobial peptides (AMPs) are a promising alternative to conventional antibiotics due to their potent membrane-disrupting mechanism of action and lower propensity to induce resistance. Background/Objectives: This study aimed to evaluate the antibacterial, antibiofilm, and in vivo efficacy of four snake venom-derived cathelicidin-like peptides—Btn (15-34) and BotrAMP14 from Bothrops atrox, and Ctn (15-34) and CrotAMP14 from Crotalus durissus—against multidrug-resistant A. baumannii, Escherichia coli, and Pseudomonas aeruginosa clinical isolates from skin infections, with emphasis on A. baumannii, a WHO priority pathogen. Methods: Minimal Inhibitory Concentration (MIC), Minimal Bactericidal Concentration (MBC), and Minimal Biofilm Inhibitory Concentration (MBIC) were determined against A. baumannii, Escherichia coli, and Pseudomonas aeruginosa. Time-kill kinetics, hemolytic activity, and cytotoxicity assays were performed. A murine skin wound infection model was established to evaluate in vivo antibacterial efficacy and safety. Results: MIC/MBC values ranged from 0.78 to 25 µM against planktonic cells. In comparison, MBIC ranged from 1.56 to 12.5 µM against biofilms. BotrAMP14 eradicated A. baumannii within 4 min, while CrotAMP14 achieved bactericidal action in 20 min at 1.56 µM. Both peptides exhibited no hemolytic activity up to 128 µM and low cytotoxicity (IC₅₀ > 128 µM). In vivo, BotrAMP14 and CrotAMP14 demonstrated significant antibacterial activity at 24 h and 48 h post-infection, respectively, surpassing that of meropenem. Conclusions: These findings suggest that BotrAMP14 and CrotAMP14 are promising topical antimicrobial agents for managing multidrug-resistant skin infections and may help address the urgent need for alternative therapies against antibiotic-resistant pathogens. Full article

Microbial contamination of food is a crucial cause of food spoilage and foodborne diseases, posing a severe threat to global public health. Although chemical preservatives are effective, their potential hazards to human health and the environment, coupled with the growing demand for “clean label” products, have driven the search for natural alternatives. Lactic acid bacteria (LAB), recognized as the Generally Recognized as Safe (GRAS) microorganisms, have emerged as the promising bio-preservatives due to their safety, effectiveness, and multifunctionality. This review systematically summarized the core antimicrobial properties of LAB, including their inhibitory spectrum against foodborne pathogens, spoilage microorganisms, viruses, parasites, and their ability to degrade toxic substances such as mycotoxins, pesticides, and heavy metals. Key inhibitory mechanisms of LAB are highlighted, encompassing the production of antimicrobial metabolites, leading to metabolism disruption and cell membrane damage, nutrition and niche competition, quorum-sensing interference, and anti-biofilm formation. Furthermore, recent advances in LAB applications in preserving various food matrices (meat, dairy products, fruits and vegetables, cereals) are integrated, including their roles in enhancing food sensory quality, extending shelf life, and retaining nutritional value. The review also discusses critical factors influencing LAB’s inhibitory activity (medium composition, culture conditions, ionic components, pathway regulator, etc.) and the challenges associated with the application of LAB. Finally, future research directions are outlined, including the novel LAB and metabolites exploration, AI-driven cultural condition optimization, genetic engineering application, nano-encapsulation and active packaging development, and building up the LAB-based cellular factories. In conclusion, LAB and their antimicrobial metabolites hold great promise as green and safe food preservatives. This review is to provide comprehensive theoretical support for the rational improvement and efficient application of LAB-based natural food preservatives, contributing to the development of a safer and more sustainable food processing and preservation systems. Full article

Foodborne diseases remain a major global challenge because pathogenic microorganisms persist in food systems, often protected by biofilms and increasing resistance to conventional chemical preservatives and sanitizers. Control strategies that were effective in the past are becoming less reliable in complex processing environments, creating a need for more precise and adaptable food-safety approaches. This review examines emerging technologies that shift food safety from broad, reactive control toward targeted, data-driven intervention. Biological tools, including bacteriophages, phage-derived enzymes, bacteriocins, quorum-sensing inhibitors, and gene-guided antimicrobial systems, are discussed for their capacity to selectively control specific pathogens while limiting unintended effects on beneficial microbiota. The review also addresses nano-enabled strategies that improve antimicrobial stability, delivery, and performance, along with plant-derived and microbial bioactive compounds that support clean-label and sustainable preservation. In parallel, advances in anti-biofilm surface engineering, such as nano-textured, contact-active, and responsive materials, are examined as preventive measures to reduce microbial attachment and persistence on food-contact surfaces. Beyond individual interventions, this review emphasizes integration within coordinated multi-hurdle systems supported by real-time monitoring and predictive analytics. Emerging digital frameworks, including digital twins of food-processing lines, are highlighted as tools to link detection, risk prediction, and targeted control. Finally, remaining knowledge gaps, regulatory challenges, and research priorities are identified, highlighting the need for realistic testing, long-term safety evaluation, standardized validation, and collaborative efforts to translate precision food-safety technologies into dependable real-world applications. Full article

Background: Staphylococcus aureus is a clinically relevant pathogen with a strong ability to form biofilms on a wide range of surfaces, which markedly reduces the effectiveness of antimicrobial treatments and contributes to therapeutic failure. Although essential oils (EOs) represent effective and economical antimicrobial alternatives, their clinical application is limited by rapid oxidation, volatility, and potential cytotoxicity. In this context, nanoencapsulation emerges as a promising strategy to improve EO stability, control release, and reduce toxicity. In this study, Tetradenia riparia essential oil was encapsulated into poly(lactide) (PLA) nanoparticles (NP) using the nanoprecipitation method. Methods: The physicochemical properties of the nanoparticles were characterized, and their antibacterial, antibiofilm, and cytotoxic activities were evaluated. Antibiofilm and antibacterial effects against S. aureus were assessed by the broth microdilution method, while cytotoxicity was determined using a VERO cell line. Results: The nanoparticles exhibited nanometric size, spherical morphology, and homogeneous structure. Both free EO and EO-loaded nanoparticles demonstrated antibacterial and antibiofilm activity against S. aureus. Importantly, EO-loaded nanoparticles were significantly less cytotoxic than free EO. Nanoencapsulation effectively prevented rapid EO evaporation and degradation, thereby enhancing stability. The nanoparticles exhibited a zeta potential of approximately −23.1 mV, indicating adequate colloidal stability. Differential scanning calorimetry revealed a reduction in melting enthalpy from 429.63 J/g (blank nanoparticles) to 115.83 J/g for EO-loaded nanoparticles, indicating decreased polymer crystallinity and a system favorable for controlled EO release. Conclusions: Overall, these findings demonstrate that nanoencapsulation of T. riparia essential oil into PLA nanoparticles preserves antimicrobial efficacy, reduces cytotoxicity, and improves physicochemical stability, supporting the potential of this nanostructured system as a promising strategy for the treatment of S. aureus biofilm-associated infections. Full article

Background: Tracheostomy procedures are associated with increased risk of nosocomial infections due to microbial colonization and biofilm formation on tube surfaces. These biofilms contribute to persistent infections and hinder clinical recovery. Plant-derived products have gained interest as alternative strategies for preventing device-associated infections. Methods: This study evaluated the phytochemical composition and the antimicrobial, anti-adherent, antibiofilm, anti-inflammatory, antioxidant, and toxicity properties of Tapirira obtusa bark extract (TOBE). Antimicrobial activity was determined by minimum inhibitory concentrations (MICs). Biofilm formation and microbial viability were assessed in mono- and mixed-species biofilms. Anti-inflammatory effects were evaluated by NF-κB inhibition and TNF-α quantification. Antioxidant activity was measured using the DPPH assay. Phytochemical analysis identified major bioactive groups, and toxicity was tested in the Galleria mellonella model. Results: TOBE exhibited notable antimicrobial activity, with MIC values between 3.9 and 31.25 µg/mL. At 78 µg/mL, the extract significantly reduced biofilm biomass and microbial viability (p < 0.05). TOBE also downregulated NF-κB activation and decreased TNF-α levels. Antioxidant assays confirmed radical-scavenging capacity. Phytochemical screening revealed phenolics, flavonoids, and tannins, and toxicity results indicated a safe profile. Conclusion: TOBE effectively inhibits microbial growth and biofilm development on orotracheal tube surfaces while exhibiting anti-inflammatory and antioxidant properties without detectable toxicity. These findings support its potential as a plant-based adjunct for preventing tracheostomy-related infections and improving patient outcomes. Full article

Pseudomonas aeruginosa (P. aeruginosa) forms biofilms that are difficult to eliminate. The matrix protects the cells, efflux pumps reduce intracellular drug levels, and dormant subpopulations survive treatment. Routine minimum inhibitory concentration (MIC) testing does not account for these features, which helps explain why infections often continue even when therapy appears appropriate. This review describes how quorum-sensing (QS) and cyclic di-guanosine monophosphate (c-di-GMP) regulate matrix production, efflux activity, and dormancy within P. aeruginosa biofilms. Important matrix components, including Psl, Pel, alginate, and extracellular DNA, slow the movement of antimicrobial agents. Regulatory proteins such as sagS and brlR increase the activity of the MexAB-OprM and MexEF-OprN efflux systems, further reducing intracellular drug concentrations. Oxygen and nutrient limitation promote persister cells and viable but nonculturable cells, with both having the ability to survive antibiotic levels that would normally be lethal. These defenses explain the gap between MIC values and biofilm-specific measurements, such as the minimum biofilm inhibitory concentration and the minimum biofilm eradication concentration. This review also summarizes emerging antibiofilm strategies. These include QS inhibitors, compounds that lower c-di-GMP, such as nitric oxide donors, nanoparticles, depolymerases, bacteriophages, and therapies that are directed at host targets. Modern diagnostic tools, such as confocal laser scanning microscopy, optical coherence tomography, and Raman spectroscopy, improve detection and guide treatment planning. A staged therapeutic approach is presented that begins with the dispersal or loosening of the matrix, continues with targeted antibiotics, and concludes with support for immune clearance. Viewing these strategies within a One Health framework highlights the role of biofilms in clinical disease and in environmental reservoirs and supports more effective surveillance and prevention. Full article

Topical antibiotics have long been used for the prevention and treatment of superficial skin and soft tissue infections; however, increasing evidence indicates that their clinical value is undermined by rising antimicrobial resistance, high rates of allergic sensitization, inadequate activity against biofilms, and a lack of wound-healing properties. Agents such as bacitracin, neomycin, polymyxin B, mupirocin, and fusidic acid act through narrow, target-specific mechanisms that facilitate resistance selection and provide limited benefit in chronic or polymicrobial wound environments. Contemporary antimicrobial stewardship frameworks therefore discourage routine use of topical antibiotics and increasingly favor non-antibiotic antiseptics with broad-spectrum activity and low resistance risk, including silver, iodine, polyhexamethylene biguanide, octenidine, and medical-grade honey. These modalities, however, primarily serve to reduce microbial burden and do not directly address the underlying biological impairments that prevent healing. Nitric oxide-releasing gels (NORGs) represent a novel class of topical antimicrobials that combine multi-target bactericidal activity with physiologic pro-healing effects. Nitric oxide exerts potent antimicrobial and antibiofilm effects via oxidative and nitrosative stress, disruption of metabolic pathways, inhibition of DNA replication, and interference with quorum sensing. Simultaneously, nitric oxide enhances angiogenesis, modulates inflammation, improves microvascular perfusion, and promotes fibroblast and keratinocyte function. Preclinical models and early-phase clinical studies demonstrate broad-spectrum efficacy—including activity against multidrug-resistant organisms—with favorable tolerability and minimal risk of resistance development. Although the current evidence base remains preliminary, NORGs offer a promising antimicrobial platform with the potential to reduce reliance on topical antibiotics while simultaneously addressing key barriers to wound healing. Larger randomized controlled trials, direct comparisons with established advanced dressings, and robust pharmacoeconomic evaluations are needed to define their optimal role within stewardship-aligned wound-care practice. Full article