Economic significance of biofilms: a multidisciplinary and cross-sectoral challenge

Transcriptional signatures associated with the survival of Escherichia coli biofilm during treatment with plasma-activated water

Biofilm formation on surfaces, tools and equipment can damage their quality and lead to high repair or replacement costs. Plasma-activated water (PAW), a new technology, has shown promise in killing biofilm and non-biofilm bacteria due to reactive oxygen and nitrogen species (RONS), particularly superoxide. However, the exact genetic mechanisms behind PAW's effectiveness against biofilms remain unclear. Here, we examined the stress responses of Escherichia coli biofilms exposed to sub-lethal PAW treatment using bulk RNA sequencing and transcriptomics. We compared gene expression in PAW-treated E. coli biofilms with and without superoxide removal, achieved by adding the scavenger Tiron. Biofilms treated with PAW exhibited a 40 % variation in gene expression compared to those treated with PAW-Tiron and controls. Specifically, PAW treatment resulted in 478 upregulated genes (>1.5 log2FC) and 186 downregulated genes (<-1.5 log2FC) compared to the control. Pathway and biological process enrichment analysis revealed significant upregulation of genes involved in sulfur metabolism, ATP-binding transporter, amino acid metabolism, hypochlorite response systems and oxidative phosphorylation in PAW-treated biofilms compared to control. Biofilm viability and intracellular RONS accumulation were tested for E. coli mutants lacking key genes from these pathways. Knockout mutants of thioredoxin (trxC), thiosulfate-binding proteins (cysP), and NADH dehydrogenase subunit (nuoM) showed significantly reduced biofilm viability after PAW treatment. Notably, ΔtrxC biofilms had the highest intracellular ROS accumulation, as revealed by 2',7'-dichlorofluorescin diacetate staining after PAW treatment. This confirms the importance of these genes in managing oxidative stress caused by PAW and highlights the significance of superoxide in PAW's bactericidal effects. Overall, our findings shed light on the specific genes and pathways that help E. coli biofilms survive and respond to PAW treatment, offering a new understanding of plasma technology and its anti-biofilm mechanisms.

Advancing Light-Driven Reactions with Surface-Modified Optical Fibers

ConspectusThe challenge of optimizing decentralized water, wastewater, and reuse treatment systems calls for innovative, efficient technologies. One advancement involves surface-modified side-emitting optical fibers (SEOFs), which enhance biochemical and chemical light-driven reactions. SEOFs are thin glass or polymeric optical fibers with functionalized surfaces that can be used individually or bundled together. They can be attached to various light sources, such as light-emitting diodes (LEDs) or lasers, which launch ultraviolet (UV) or visible light into the fibers. This light is then emitted along the fiber's surface, creating irradiance similar to a glow stick. The resulting SEOFs uniquely deliver light energy to complex environments while maximizing photon utilization and minimizing energy loss, addressing long-standing inefficiencies in photolysis and photocatalysis systems. SEOFs generate and leverage refracted light and evanescent waves to achieve continuous irradiation of their cladding, wherein photocatalysts are embedded. This method contrasts with traditional slurry-based systems, where light energy is often scattered or absorbed before reaching the reaction sites. Such scattering typically reduces quantum yields and reaction kinetics. In contrast, SEOFs create a controlled light delivery system that enhances reaction efficiency and adaptability to diverse applications.Important chemical and physical concepts are explored when scaling up SEOFs for three potential engineered applications. The selection of polymer materials and nanoparticle compositions is crucial for optimizing SEOFs as waveguides for visible to UV-C wavelengths and for embedding surface-accessible photocatalysts within porous polymer coatings on SEOF surfaces. Additionally, understanding how light propagates within SEOFs and emits along their exterior surface and length is essential for influencing the quantum yields of chemical products and enhancing biochemical sensitivity to low UV-C exposure. UV-C SEOFs are employed for germicidal disinfection, inactivating biofilms and pathogens in water systems. By overcoming UV light attenuation issues in traditional methods, SEOFs facilitate uniform distribution of UV-C energy, disrupting biofilm formation at early stages. SEOFs enhance UV-A and visible-light photocatalytic degradation of pollutants. Embedding photocatalysts in porous polymer cladding enables simultaneous improvements in reaction kinetics and quantum yields. SEOFs enable decentralized light-driven production of clean energy resources such as hydrogen, hydrogen peroxide, and formic acid, offering sustainable alternatives for off-grid systems.The design principles of SEOFs emphasize scalability, flexibility, and efficiency. Recent innovations in polymer chemistry, nanoparticle coatings, and surface roughness engineering have further optimized light delivery and side-emission. Tailoring the refractive index and nanoparticle distribution on fiber surfaces ensures precise evanescent wave propagation, enhancing photocatalytic performance. These advancements, coupled with scalable fabrication techniques, have positioned SEOFs as promising platforms for broad photochemical applications.By summarizing recent advances and identifying future needs, this Account positions SEOFs as a transformative approach to light-driven reactions, merging cutting-edge materials science with sustainable water treatment and energy production goals. This emerging technology offers immense potential to reshape photochemical processes for decentralized applications. Despite significant progress, challenges remain. Future research should focus on optimizing catalyst loading, improving uniformity in side emissions, and enhancing polymer durability for long-term operational stability. Additionally, scaling SEOF configurations to multifiber bundles and integrating them into decentralized water systems will be critical for broader adoption.

Zinc Oxide@Tetracycline Spiky Microparticles Design for Persistent Antibacterial Therapy

Antibiotics have revolutionized medical treatment by effectively combating bacterial infections, particularly those associated with chronic wounds and implant complications. Nevertheless, the persistent use of these drugs has resulted in an increase in antibiotic-resistant bacteria and biofilm infections, highlighting the urgent need for alternative therapies. This study presents an approach for combating persistent bacterial and biofilm infections through the integration of biomimetic design and advanced nanotechnology. Inspired by the natural defense mechanisms of pollen grains and lotus leaves, we engineered zinc oxide spiky microparticles combined with tetracycline-loaded beads mimicking the structure of lotus leaf papillae. This biomimetic design exhibits a multifaceted antimicrobial strategy, leveraging hierarchical micro/nanostructures and the inherent antibacterial properties of their natural counterparts. ZnO microparticles, which mimic the morphology of pollen grains, provide topological cues to rupture adhered bacteria, whereas tetracycline beads, inspired by lotus leaf papillae, deliver a controlled release of antibiotics to target persistent bacteria. Using a synergistic multimodal approach, our biomimetic materials demonstrated exceptional efficacy in eradicating persistent methicillin-resistant Staphylococcus aureus and Escherichia coli infections, offering promising prospects for the development of advanced antibacterial therapies. This study not only underscores the importance of biomimicry in material design but also highlights the potential of integrating nature-inspired strategies with nanotechnology for biomedical applications.

High diversity of nitrifying bacteria and archaea in biofilms from a subsea tunnel

Microbial biofilm formation can contribute to the accelerated deterioration of steel-reinforced concrete structures and significantly impact their service life, making it critical to understand the diversity of the biofilm community and prevailing processes in these habitats. Here, we analyzed 16S rRNA gene amplicon and metagenomics sequencing data to study the abundance and diversity of nitrifiers within biofilms on the concrete surface of the Oslofjord subsea road tunnel in Norway. We showed that the abundance of nitrifiers varied greatly in time and space, with a mean abundance of 24.7 ± 15% but a wide range between 1.2% and 61.4%. We hypothesize that niche differentiation allows the coexistence of several nitrifier groups and that their high diversity increases the resilience to fluctuating environmental conditions. Strong correlations were observed between the nitrifying families Nitrosomonadaceae and Nitrospinaceae, and the iron-oxidizing family Mariprofundaceae. Metagenome-assembled genome analyses suggested that early Mariprofundaceae colonizers may provide a protected environment for nitrifiers in exchange for nitrogen compounds and vitamin B12, but further studies are needed to elucidate the spatial organization of the biofilms and the cooperative and competitive interactions in this environment. Together, this research provides novel insights into the diverse communities of nitrifiers living within biofilms on concrete surfaces and establishes a foundation for future experimental studies of concrete biofilms.

Antimicrobial applications of inorganic radiosensitizers and their potential in biofilm control

Biofilms are structured microbial communities embedded in a self-produced extracellular matrix. This lifestyle provides significant protection against environmental stressors such as desiccation, chemical treatments and even ionizing radiation. Radiation, while a well-established antibacterial strategy, can be less effective in biofilms. Biofilm superior resilience is due to several advantages such as the shielding provided by the matrix, the metabolic heterogeneity and adaptive stress responses of biofilm-associated cells. To address this challenge, researchers are increasingly employing combination strategies in antibiofilm treatment. Radiosensitizers, compounds originally developed to enhance the efficacy of radiation therapy in cancer treatment, have also garnered attention for their potential in antimicrobial applications. These compounds act by amplifying the effects of radiation, often through mechanisms such as increased oxidative stress or inhibition of DNA repair pathways. However, research on radiosensitizers in bacterial systems has focused on planktonic cultures, with limited studies exploring their effects on biofilms. Given the complexity and unique characteristics of biofilms, their response to radiosensitization remains poorly understood and requires further investigation. The use of radiosensitizers in conjunction with radiation presents a promising approach to overcome the inherent resilience of biofilms. By enhancing the susceptibility of biofilm-associated bacteria to radiation and simultaneously disrupting their protective structures, such approaches could lead to more effective and comprehensive solutions. Understanding the nuanced responses of biofilms to these combined treatments is essential for advancing both medical and environmental applications and addressing the challenge of biofilm persistence.

Exploring Broad-Spectrum Antimicrobial Nanotopographies: Implications for Bactericidal, Antifungal, and Virucidal Surface Design

Inspired by the natural defense strategies of insect wings and plant leaves, nanostructured surfaces have emerged as a promising tool in various fields, including engineering, biomedical sciences, and materials science, to combat bacterial contamination and disrupt biofilm formation. However, the development of effective antimicrobial surfaces against fungal and viral pathogens presents distinct challenges, necessitating tailored approaches. Here, we aimed to review the recent advancements of the use of nanostructured surfaces to combat microbial contamination, particularly focusing on their mechano-bactericidal and antifungal properties, as well as their potential in mitigating viral transmission. We comparatively analyzed the diverse geometries and nanoarchitectures of these surfaces and discussed their application in various biomedical contexts, such as dental and orthopedic implants, drug delivery systems, and tissue engineering. Our review highlights the importance of preventing microbial attachment and biofilm formation, especially in the context of rising antimicrobial resistance and the economic impact of biofilms. We also discussed the latest progress in materials science, particularly nanostructured surface engineering, as a promising strategy for reducing viral transmission through surfaces. Overall, our findings underscore the significance of innovative strategies to mitigate microbial attachment and surface-mediated transmission, while also emphasizing the need for further interdisciplinary research in this area to optimize antimicrobial efficacy and address emerging challenges.

Saccharin disrupts bacterial cell envelope stability and interferes with DNA replication dynamics

Saccharin has been part of the human diet for over 100 years, and there is a comprehensive body of evidence demonstrating that it can influence the gut microbiome, ultimately impacting human health. However, the precise mechanisms through which saccharin can impact bacteria have remained elusive. In this work, we demonstrate that saccharin inhibits cell division, leading to cell filamentation with altered DNA synthesis dynamics. We show that these effects on the cell are superseded by the formation of bulges emerging from the cell envelope, which ultimately trigger cell lysis. We demonstrate that saccharin can inhibit the growth of both Gram-negative and Gram-positive bacteria as well as disrupt key phenotypes linked to host colonisation, such as motility and biofilm formation. In addition, we test its potential to disrupt established biofilms (single-species as well as polymicrobial) and its capacity to re-sensitise multidrug-resistant pathogens to last-resort antibiotics. Finally, we present in vitro and ex vivo evidence of the versatility of saccharin as a potential antimicrobial by integrating it into an effective hydrogel wound dressing.

Modifying the antibacterial performance of Cu surfaces by topographic patterning in the micro- and nanometer scale

Antimicrobial surfaces are a promising approach to reduce the spread of pathogenic microorganisms in various critical environments. To achieve high antimicrobial functionality, it is essential to consider the material-specific bactericidal mode of action in conjunction with bacterial surface interactions. This study investigates the effect of altered contact conditions on the antimicrobial efficiency of Cu surfaces against Escherichia coli and Staphylococcus aureus. The fabrication of line-like periodic surface patterns in the scale range of single bacterial cells was achieved utilizing ultrashort pulsed direct laser interference patterning. These patterns create both favorable and unfavorable topographies for bacterial adhesion. The variation in bacteria/surface interaction is monitored in terms of strain-specific bactericidal efficiency and the role of corrosive forces driving quantitative Cu ion release. The investigation revealed that bacterial deactivation on Cu surfaces can be either enhanced or decreased by intentional topography modifications, independent of Cu ion emission, with strain-specific deviations in effective pattern scales observed. The results of this study indicate the potential of targeted topographic surface functionalization to optimize antimicrobial surface designs, enabling strain-specific decontamination strategies.

Impact of citric acid and conventional denture cleansers on surface properties and antimicrobial performance of conventionally heat-processed acrylic resin: An in vitro study

STATEMENT OF PROBLEM

Effective decontamination of denture base acrylic resin is essential for biofilm removal but can compromise the integrity of the material. Citric acid has shown promise as a potent antimicrobial agent, though its effectiveness as a denture cleanser is unknown.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of citric acid on the surface properties and efficacy of biofilm removal on denture base acrylic resin compared with commonly used denture cleansers.

MATERIAL AND METHODS

A total of 130 conventional, heat-processed denture base acrylic resin disks were randomly allocated into 1 of 5 groups based on the decontamination solution applied: control 0.9% sodium chloride (NaCl), 0.1% sodium hypochlorite (SH), Periogard (chlorhexidine digluconate), effervescent denture cleansing tablets (Corega Tabs), and 10% citric acid (CA). Surface properties (roughness, hydrophilicity, microhardness, and color stability) were assessed at 3 time points: baseline (T0), after 5 minutes of exposure (T1), and after 1 week of exposure (T2) to the respective solution. A microcosm biofilm was formed on specimen surfaces to evaluate antimicrobial efficacy of the decontamination solution groups, through assessment of microbial viability, metabolic activity, biofilm dry weight, and morphology. A 2-way repeated measures ANOVA was performed for surface properties evaluations and for microbiological analysis, 1-way ANOVA was used (α=.05).

RESULTS

No significant differences in average surface roughness (Ra) were observed between T0, T1, and T2 across all groups (P>.05). CA significantly increased surface hydrophilicity at T2 (P<.001) compared with the other groups. No significant differences in ΔE00 were seen among the groups: all values near the 50% perceptibility threshold. Compared with the control group, all denture cleansers significantly reduced the viability of total microorganisms and Candida species, with no viable colonies detected after treatment (P<.001). However, CA demonstrated a robust antimicrobial effect, with a significant reduction in biofilm dry weight and metabolic activity (P<.001), suggesting superior biofilm disruption compared with the other groups.

CONCLUSIONS

Citric acid effectively increased hydrophilicity of conventional, heat-processed acrylic resin without negatively impacting surface roughness, microhardness, or color stability.

Evaluation of inhibition and eradication of bacterial biofilm by solasodin

Biofilms are complex microbial structures that have a significant impact on human health, industry and the environment. These complex structures represent one of the main mechanisms of microbial resistance, and their development constitutes a serious health problem. Therefore, the aim of this study was to verify the potential for inhibition and eradication of bacterial biofilm by salosodine, which is a steroidal alkaloid sapogenin found in plants of the Solanum genus. The antibiotics gentamicin, norfloxacin, ampicillin and the antiseptic agent chlorhexidine gluconate were used as positive controls to compare the results. Solasodin showed significant results in inhibiting the formation of Enterococcus faecalis and Staphylococcus aureus biofilms at the two concentrations tested. And when comparing the effect of solasodine for the two concentrations and the effect of the antibiotic gentamicin, it was found that sapogenin showed a better percentage in inhibiting E. faecalis biofilm formation. And against Pseudomonas aeruginosa, solasodine only inhibited biofilm formation at the highest concentration compared to the control. In the biofilm eradication results, solasodine showed a significant reduction in the biomass of the S. aureus biofilm, and when compared with the percentage reduction of the antibiotics, solasodine showed a relevant result for both concentrations. Only at the lowest concentration did solasodine show a reduction in P. aeruginosa biofilm biomass, a reduction close to that of chlorhexidine gluconate. In terms of activity, solasodine has been shown to have the potential to inhibit biofilm formation. However, further tests are needed to investigate the mechanisms of action of this sapogenin on the bacterial biofilms tested.

Considerations for testing anti-fouling coatings designed for implementation into Earth-based and spacecraft water systems

Biofilms are common in water systems and can lead to mechanical failure or illness of water system users. Methods for evaluating anti-fouling coatings have largely been informed by the medical industry and have not been tailored to industrial or spacecraft water systems. The goal of the paper is to help guide researchers in designing experiments to evaluate coatings that accurately represent the system under investigation. This review identified eight experimental design considerations when evaluating coatings in water systems: biofilm reactor operation, microorganism selection, reinoculation, coating surface area, liquid medium, experiment duration, coating performance evaluation, and the use of microgravity. The impact of each decision made within each of these considerations is presented. Further, the methods featured in eight studies investigating coatings for Earth-based or spacecraft water systems are discussed. This review serves to guide researchers toward improved experimental design to enable successful technology transfer from the lab bench to Earth and beyond.

Anthropogenic impacts on the terrestrial subsurface biosphere

The terrestrial subsurface is estimated to be the largest reservoir of microbial life on Earth. However, the subsurface also harbours economic, industrial and environmental resources, on which humans heavily rely, including diverse energy sources and formations for the storage of industrial waste and carbon dioxide for climate change mitigation. As a result of this anthropogenic activity, the subsurface landscape is transformed, including the subsurface biosphere. Through the creation of new environments and the introduction of substrates that fuel microbial life, the structure and function of subsurface microbiomes shift markedly. These microbial changes often have unintended effects on overall ecosystem function and are frequently challenging to manage from the surface of the Earth. In this Review, we highlight emerging research that investigates the impacts of anthropogenic activity on the terrestrial subsurface biosphere. We explore how humans alter the constraints on microbial life in the subsurface through drilling, mining, contamination and resource extraction, along with the resulting impacts of microorganisms on resource recovery and subsurface infrastructure.

Payload Design and Evaluation of Staphylococcus epidermidis Adhesion to Nonfouling Polyampholyte Coatings Onboard the International Space Station

The accumulation of biofilms can potentially be very costly in terms of damage to mechanical systems and health impact on the human body. Space travel, especially long-term space travel, compounds the complications that arise from the accumulation of biofilms because of the lack of access to resources. This study investigates the ability of polyampholyte copolymer thin films to reduce bacteria adhesion in microgravity. Copolymer systems of [2-(acryloyloxy)ethyl] trimethylammonium chloride (TMA) and 2-carboxyethyl acrylate (CAA) and TMA and 3-sulfopropyl methacrylate potassium salt (SA) have previously shown resistance to bacteria adhesion under gravity-impacted conditions. However, their performance under microgravity conditions has never been evaluated. A self-contained payload was designed around multiple constraints to evaluate the ability of the TMA/CAA and TMA/SA thin film coatings to reduce the adhesion and biofilm formation of Staphylococcus epidermidis on aluminum test coupons in microgravity in an experiment conducted onboard the International Space Station (ISS). An Earth-based, gravity-impacted study was completed in parallel with the ISS experiment. The samples were then analyzed on the macroscale using photography and the microscale using confocal microscopy imaging to determine biofilm formation and bacteria attachment, respectively. The percentage of each sample covered by bacteria and/or biofilm was characterized and compared amongst the coating types and gravity exposure conditions. The TMA/SA coatings showed the lowest levels of bacteria adhesion and biofilm formation overall. The TMA/CAA coatings showed the largest reduction in bacteria adhesion and biofilm formation when comparing adhesion between the microgravity- and gravity-impacted samples. Therefore, both the copolymers demonstrate promise for bacteria-resistant coatings in microgravity.

Co-zorbs: Motile, multispecies biofilms aid transport of diverse bacterial species

Biofilms are three-dimensional structures containing one or more bacterial species embedded in extracellular polymeric substances. Although most biofilms are stationary, Flavobacterium johnsoniae forms a motile spherical biofilm called a zorb, which is propelled by its base cells and contains a polysaccharide core. Here, we report the formation of spatially organized, motile, multispecies biofilms, designated "co-zorbs," that are distinguished by a core-shell structure. F. johnsoniae forms zorbs whose cells collect other bacterial species and transport them to the zorb core, forming a co-zorb. Live imaging revealed that co-zorbs also form in zebrafish, thereby demonstrating a different type of bacterial movement in vivo. This finding opens different avenues for understanding community behaviors, the role of biofilms in bulk bacterial transport, and collective strategies for microbial success in various environments.

Biofilm Resilience: Molecular Mechanisms Driving Antibiotic Resistance in Clinical Contexts

Healthcare-associated infections pose a significant global health challenge, negatively impacting patient outcomes and burdening healthcare systems. A major contributing factor to healthcare-associated infections is the formation of biofilms, structured microbial communities encased in a self-produced extracellular polymeric substance matrix. Biofilms are critical in disease etiology and antibiotic resistance, complicating treatment and infection control efforts. Their inherent resistance mechanisms enable them to withstand antibiotic therapies, leading to recurrent infections and increased morbidity. This review explores the development of biofilms and their dual roles in health and disease. It highlights the structural and protective functions of the EPS matrix, which shields microbial populations from immune responses and antimicrobial agents. Key molecular mechanisms of biofilm resistance, including restricted antibiotic penetration, persister cell dormancy, and genetic adaptations, are identified as significant barriers to effective management. Biofilms are implicated in various clinical contexts, including chronic wounds, medical device-associated infections, oral health complications, and surgical site infections. Their prevalence in hospital environments exacerbates infection control challenges and underscores the urgent need for innovative preventive and therapeutic strategies. This review evaluates cutting-edge approaches such as DNase-mediated biofilm disruption, RNAIII-inhibiting peptides, DNABII proteins, bacteriophage therapies, antimicrobial peptides, nanoparticle-based solutions, antimicrobial coatings, and antimicrobial lock therapies. It also examines critical challenges associated with biofilm-related healthcare-associated infections, including diagnostic difficulties, disinfectant resistance, and economic implications. This review emphasizes the need for a multidisciplinary approach and underscores the importance of understanding biofilm dynamics, their role in disease pathogenesis, and the advancements in therapeutic strategies to combat biofilm-associated infections effectively in clinical settings. These insights aim to enhance treatment outcomes and reduce the burden of biofilm-related diseases.

Fungal biofilms in human health and disease

Increased use of implanted medical devices, use of immunosuppressants and an ageing population have driven the rising frequency of fungal biofilm-related diseases. Fungi are now recognized by the World Health Organization (WHO) as an emergent threat to human health, with most medically important species defined as critical or high-priority organisms capable of forming biofilms. Although we strive for a better understanding of diagnostic and therapeutic approaches to detect and treat these fungal diseases more generally, the issue of hard-to-treat biofilms is an ever-increasing problem. These are communities of interspersed cells that are attached to one another on a surface, such as a catheter, or trapped into a cavity such as a paranasal sinus. Biofilms are difficult to detect, difficult to remove and intrinsically tolerant to most antifungal agents. These factors can lead to devastating consequences for the patient, including unnecessary morbidity and mortality, need for reoperations and prolonged hospital stay. This Review describes the breadth and growing impact fungal biofilms have on patient management and explains the mechanisms promoting biofilm formation, focusing on how targeting these can improve therapeutic options.

Microbial extracellular polymeric substances in the environment, technology and medicine

Microbial biofilms exhibit a self-produced matrix of extracellular polymeric substances (EPS), including polysaccharides, proteins, extracellular DNA and lipids. EPS promote interactions of the biofilm with other cells and sorption of organics, metals and chemical pollutants, and they facilitate cell adhesion at interfaces and ensure matrix cohesion. EPS have roles in various natural environments, such as soils, sediments and marine habitats. In addition, EPS are relevant in technical environments, such as wastewater and drinking water treatment facilities, and water distribution systems, and they contribute to biofouling and microbially influenced corrosion. In medicine, EPS protect pathogens within the biofilm against the host immune system and antimicrobials, and emerging evidence suggests that EPS can represent potential virulence factors. By contrast, EPS yield a wide range of valuable products that include their role in self-repairing concrete. In this Review, we aim to explore EPS as a functional unit of biofilms in the environment, in technology and in medicine.

A novel strategy for eradication of staphylococcal biofilms using blood clots

Introduction

Infections with coagulase negative staphylococcal species (CoNS) are a major cause of mortality and morbidity in joint and heart valve replacement procedures, largely due to biofilm formation. Cells within biofilms have higher rates of antibiotic resistance than their planktonic counterparts; consequently, novel mechanisms are needed to combat these infections.

Methods

To enhance antibiotic delivery and penetration, this innovative study involved treating CoNS biofilms with murine blood clots impregnated with antibiotics. We then investigated the impact of this treatment on biofilm density, metabolism, and architecture.

Results

Our pilot study demonstrates that this method of antibiotic delivery results in improved biofilm clearance, relative to conventional exposure methods.

Discussion

Our results demonstrate that blood clot exposure has an intrinsic impact on biofilm density and potentially reduces colonization, warrenting further investigation into the mechanism.

Diagnostic and therapeutic strategies in combating implanted medical device-associated bacterial biofilm infections

Bacterial biofilms exhibit remarkable resistance against conventional antibiotics and are capable of evading the humoral immune response. They account for nearly 80% of chronic infections in humans. Development of bacterial biofilms on medical implants results in their malfunctioning and subsequently leads to high mortality rates worldwide. Therefore, early and precise diagnosis of bacterial biofilms on implanted medical devices is essential to prevent their failure and associated complications. Culture-based methods are time consuming, more prone to contamination and often exhibit low sensitivity. Different molecular, imaging, and physical methods can aid in more accurate and faster detection of implant-associated bacterial biofilms. Biofilm growth on implant surface can be prevented either through modification of the implant material or by application of different antibacterial coatings on implant surface. Experimental studies have shown that pre-existing biofilms from medical implants can be removed by breaking down biofilm matrix, utilizing physical methods, nanomaterials and antimicrobial peptides. The current review delves into mechanism of biofilm formation on implanted medical devices and the subsequent host immune response. Much emphasis has been laid on different ongoing diagnostic and therapeutic strategies to achieve improved patient outcomes and reduced socio-economic burden.

Rice husk- and lemongrass-derived eco-enzymes as potential food contact surface disinfectants against biofilm-forming foodborne pathogens

This study aims to evaluate the rice husk (EE-R)- and lemongrass (EE-L)-derived eco-enzymes (EE) as alternatives to chemical-based disinfectants. The EE-R's and EE-L's antimicrobial activity were tested against Pseudomonas aeruginosa, Salmonella Typhimurium, and Staphylococcus aureus using a broth microdilution method. The antibiofilm activities of EE were determined using crystal violet staining. Lastly, the minimal contact time of EE for effectively reducing biofilm-forming pathogens (<25 CFU/ml) was assessed on various food contact surfaces (wood, glass, plastic, stainless steel, and marble). The results show that EE-R at 25%-50% concentration significantly inhibited P. aeruginosa and S. aureus while reducing the initial biofilm formation by 61% and 58%, respectively. In contrast, EE-L inhibited S. Typhimurium at a concentration of 12.5%-50% and P. aeruginosa at 25%-50%, with a strong preformed biofilm inhibition noticed for S. Typhimurium (70%). For the minimal contact time, EE-R superiorly inhibited P. aeruginosa (60 s) and S. aureus (120 s) on all contact surfaces, while EE-L needed 120 s to reduce P. aeruginosa and S. Typhimurium. These outcomes were comparable to sodium hypochlorite (NaOCl, 2.5%). The study's outcomes implicate the potential application of EE-R and EE-L as surface disinfectants against biofilm-forming bacteria, thus promoting safer food processing practices while minimizing environmental impacts.

Clinical management of chronic wound infections: The battle against biofilm

Bacteria constitute the most abundant life form on earth, of which the majority exist in a protective biofilm state. Since the 1980s, we have learned much about the role of biofilm in human chronic infections, with associated global healthcare costs recently estimated at ~$386 billion. Chronic wound infection is a prominent biofilm-induced condition that is characterised by persistent inflammation and associated host tissue destruction, and clinical signs that are distinct from signs of acute wound infection. Biofilm also enables greater tolerance to antimicrobial agents in chronic wound infections compared with acute wound infections. Given the difficulty in eliminating wound biofilm, a multi-targeted strategy (namely biofilm-based wound care) involving debridement and antimicrobial therapies were introduced and have been practiced since the early 2000s. More recently, acknowledgement of the speed at which biofilm can develop and hence quickly interfere with wound healing has highlighted the need for an early anti-biofilm strategy to combat biofilm before it takes control and prevents wound healing. This strategy, referred to as wound hygiene, involves multiple tools in combination (debridement, cleansing, and antimicrobial dressings) to maximise success in biofilm removal and encourage wound healing. This review is intended to highlight the issues and challenges associated with biofilm-induced chronic infections, and specifically address the challenges in chronic wound management, and tools required to combat biofilm and encourage wound healing.

Biofilm battleground: Unveiling the hidden challenges, current approaches and future perspectives in combating biofilm associated bacterial infections

A biofilm is a complex aggregation of microorganisms, either of the same or different species, that adhere to a surface and are encased in an extracellular polymeric substances (EPS) matrix. Quorum sensing (QS) and biofilm formation are closely linked, as QS genes regulate the development, maturation, and breakdown of biofilms. Inhibiting QS can be utilized as an effective approach to combat the impacts of biofilm infection. The impact of biofilms includes chronic infections, industrial biofouling, infrastructure corrosion, and environmental contamination as well. Therefore, a deep understanding of biofilms is crucial for enhancing public health, advancing industrial processes, safeguarding the environment, and deepening our knowledge of microbial life as well. This review aims to offer a comprehensive examination of challenges posed by bacterial biofilms, contemporary approaches and strategies for effectively eliminating biofilms, including the inhibition of quorum sensing pathways, while also focusing on emerging technologies and techniques for biofilm treatment. In addition, future research is projected to target the challenges associated with the bacterial biofilms, striving to develop new approaches and improve existing strategies for their effective control and eradication.

The maturation of native uropathogenic Escherichia coli biofilms seen through a non-interventional lens

Urinary tract infections (UTI) caused by uropathogenic Escherichia coli (UPEC) are a significant global health challenge. The UPEC biofilm lifestyle is believed to play an important role in infection recurrency and treatment resistance, but our understanding of how the extracellular matrix (ECM) components curli and cellulose contribute to biofilm formation and pathogenicity is limited. Here, we study the spatial and temporal development of native UPEC biofilm using agar-based detection methods where the non-toxic, optically active fluorescent tracer EbbaBiolight 680 reports the expression and structural location of curli in real-time. An in vitro screen of the biofilm capacity of common UPEC strains reveals significant strain variability and identifies UPEC No. 12 (UPEC12) as a strong biofilm former at 28 °C and 37 °C. Non-interventional microscopy, including time-lapse and 2-photon, reveal significant horizontal and vertical heterogeneity in the UPEC12 biofilm structure. We identify region-specific expression of curli, with a shift in localization from the bottom of the flat central regions of the biofilm to the upper surface in the topographically dramatic intermediate region. When investigating if the rdar morphotype affects wettability of the biofilm surface, we found that the nano-architecture of curli guided by cellulose, rather than the rdar macrostructures, leads to increased hydrophobicity of the biofilm. By providing new insights at exceptional temporal and spatial resolution, we demonstrate how non-interventional analysis of native biofilms will facilitate the next generation of understanding into the roles of ECM components during growth of UPEC biofilms and their contribution to the pathogenesis of UTI.

Global challenges and microbial biofilms: Identification of priority questions in biofilm research, innovation and policy

Priority question exercises are increasingly used to frame and set future research, innovation and development agendas. They can provide an important bridge between the discoveries, data and outputs generated by researchers, and the information required by policy makers and funders. Microbial biofilms present huge scientific, societal and economic opportunities and challenges. In order to identify key priorities that will help to advance the field, here we review questions from a pool submitted by the international biofilm research community and from practitioners working across industry, the environment and medicine. To avoid bias we used computational approaches to group questions and manage a voting and selection process. The outcome of the exercise is a set of 78 unique questions, categorized in six themes: (i) Biofilm control, disruption, prevention, management, treatment (13 questions); (ii) Resistance, persistence, tolerance, role of aggregation, immune interaction, relevance to infection (10 questions); (iii) Model systems, standards, regulatory, policy education, interdisciplinary approaches (15 questions); (iv) Polymicrobial, interactions, ecology, microbiome, phage (13 questions); (v) Clinical focus, chronic infection, detection, diagnostics (13 questions); and (vi) Matrix, lipids, capsule, metabolism, development, physiology, ecology, evolution environment, microbiome, community engineering (14 questions). The questions presented are intended to highlight opportunities, stimulate discussion and provide focus for researchers, funders and policy makers, informing future research, innovation and development strategy for biofilms and microbial communities.

Bacterial extracellular vesicle: A non-negligible component in biofilm life cycle and challenges in biofilm treatments

Bacterial biofilms, especially those formed by pathogens, have been increasingly impacting human health. Bacterial extracellular vesicle (bEV), a kind of spherical membranous structure released by bacteria, has not only been reported to be a component of the biofilm matrix but also plays a non-negligible role in the biofilm life cycle. Nevertheless, a comprehensive overview of the bEVs functions in biofilms remains elusive. In this review, we summarize the biogenesis and distinctive features characterizing bEVs, and consolidate the current literature on their functions and proposed mechanisms in the biofilm life cycle. Furthermore, we emphasize the formidable challenges associated with vesicle interference in biofilm treatments. The primary objective of this review is to raise awareness regarding the functions of bEVs in the biofilm life cycle and lay the groundwork for the development of novel therapeutic strategies to control or even eliminate bacterial biofilms.

Insights into the biocorrosion of Q235A steel influenced by the electron transfer process between iron and methanogenic microbiota

Anaerobic microbiologically influenced corrosion (MIC) of Fe (0) metals causes great harm to the environment and economy, which depends on the key electron transfer process between anaerobic microorganisms and Fe (0) metals. However, the key electron transfer process in microbiota dominating MIC remains unclear, especially for methanogenic microbiota wildly distributed in the environment. Herein, three different methanogenic microbiota (Methanothrix, Methanospirillum, and Methanobacterium) were acclimated to systematically investigate electron transfer pathways on corroding Q235A steel coupons. Results indicated that microbiota dominated by Methanothrix, Methanospirillum, or Methanobacterium accelerated the steel corrosion mainly through direct electron transfer (DET) pathway, H2 mediated electron transfer (HMET) pathway, and combined DET and HMET pathways, respectively. Compared with Methanospirillum dominant microbiota, Methanothrix or Methanobacterium dominant microbiota caused more methane production, higher weight loss, corrosion pits with larger areas, higher corrosion depth, and smaller corrosion pits density. Such results reflected that the DET process between microbiota and Fe (0) metals decided the biocorrosion degree and behavior of Fe (0) metals. This study insightfully elucidates the mechanisms of methanogenic microbiota on corroding steels, in turn providing new insights for anti-corrosion motives.

Biofilm Inhibition Activity of Fennel Honey, Fennel Essential Oil and Their Combination

The eradication of bacterial biofilms remains a persistent challenge in medicine, particularly because an increasing number of biofilms exhibit resistance to conventional antibiotics. This underscores the importance of searching for novel compounds that present antibacterial and biofilm inhibition activity. Various types of honey and essential oil were proven to be effective against a number of biofilm-forming bacterial strains. The current study demonstrated the effectiveness of the relatively unexplored fennel honey (FH), fennel essential oil (FEO), and their combination against biofilm-forming bacterial strains Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and Escherichia coli, with a series of in vitro experiments. The authenticity of FH and FEO was checked with light microscopy and gas chromatography-mass spectrometry, respectively. Minimum inhibitory concentrations were determined using the microdilution method, and antibiofilm activity was assessed with crystal violet assay. Structural changes in bacterial cells and biofilms, induced by the treatments, were monitored with scanning electron microscopy. FEO and FH inhibited the biofilm formation of each bacterial strain, with FEO being more effective compared to FH. Their combination was the most effective, with inhibitory rates ranging between 87 and 92%, depending on the bacterial strain. The most sensitive bacterium was E. coli, while P. aeruginosa was the most resistant. These results provide justification for the combined use of honey and essential oil to suppress bacterial biofilms and can serve as a starting point to develop an effective surface disinfectant with natural ingredients.

Bacterial biofilm-mediated environmental remediation: Navigating strategies to attain Sustainable Development Goals

Bacterial biofilm is a structured bacterial community enclosed within a three-dimensional polymeric matrix, governed by complex signaling pathways, including two-component systems, quorum sensing, and c-di-GMP, which regulate its development and resistance in challenging environments. The genetic configurations within biofilm empower bacteria to exhibit significant pollutant remediation abilities, offering a promising strategy to tackle diverse ecological challenges and expedite progress toward Sustainable Development Goals (SDGs). Biofilm-based technologies offer advantages such as high treatment efficiency, cost-effectiveness, and sustainability compared to conventional methods. They significantly contribute to agricultural improvement, soil fertility, nutrient cycling, and carbon sequestration, thereby supporting SDG 1 (No poverty), SDG 2 (Zero hunger), SDG 13 (Climate action), and SDG 15 (Life on land). In addition, biofilm facilitates the degradation of organic-inorganic pollutants from contaminated environments, aligning with SDG 6 (Clean water and sanitation) and SDG 14 (Life below water). Bacterial biofilm also has potential applications in industrial innovation, aligning SDG 7 (Affordable and clean energy), SDG 8 (Decent work and economic growth), and SDG 9 (Industry, innovation, and infrastructure). Besides, bacterial biofilm prevents several diseases, aligning with SDG 3 (Good health and well-being). Thus, bacterial biofilm-mediated remediation provides advanced opportunities for addressing environmental issues and progressing toward achieving the SDGs. This review explores the potential of bacterial biofilms in addressing soil pollution, wastewater, air quality improvement, and biodiversity conservation, emphasizing their critical role in promoting sustainable development.

Curcuma longa rhizome extract: a potential antibiofilm agent against antibiotic-resistant foodborne pathogens

The traditional medicinal value of Curcuma longa (turmeric) and its potential relevance in modern healthcare suggests that traditional remedies and natural products can provide valuable solutions to contemporary challenges, such as combating biofilms and antibiotic-resistant pathogens, potentially offering new strategies for addressing health and safety issues in the fields of food and medicine. This study assessed the antibiofilm and antibacterial characterization of Curcuma longa rhizome extract against antibiotic-resistant foodborne pathogens. Gas Chromatography-Mass Spectrometry (GC-MS) and Fourier-transform infrared (FTIR) analysis were determined to check for the compounds, functional groups, and constituents of the plant extract. In-vitro antibiofilm and antibacterial bioassay of the extract were determined using standard bacteriological procedures. Potential mechanisms of the plant extract were also studied using standard biological methods. The important chemical constituents from the GC-MS extract of C. longa are arturmerone, cinnamyl angelate, tumerone, γ-atlantone, atlantone, α-atlantone, γ-atlantone and curlone. The FTIR analysis of the extract comprises alkyl halides, bromoalkanes, alkanes, ethylene molecules, arenes, amines, alcohols, sulfones, carboxylic acids and their derivatives, aromatic compounds, and phenols. The MIC of C. longa crude extract ranges from ethanol extract (0.03125 - 0.5 mg/mL) and acetone extract (0.0625 - 0.5 mg/mL). The MBC range is as follows: ethanol extract (0.125 - 1 mg/mL), acetone extract (0.125 - 1 mg/mL). The time-kill kinetics showed significant cell reduction with time. The bacterial isolates' nucleic acids and protein leakage were consistent with increased extract concentration and time. There was a reduction in the biofilm cell on the shrimp surface and EPS with increased concentration and time. C. longa exerted significant anti-biofilm activity by removing existing biofilms, disrupting cell connections, and decreasing cells in biofilms. These findings can aid food protection from microbial contamination and prevent biofilms-related infections.

Time-dependent corrosion behavior of EH36 steel caused by Pseudomonas aeruginosa based on big data monitoring technology

Marine microbial corrosion poses a significant threat to the safe service of marine engineering equipment. Previous studies have often failed to thoroughly analyze the continuous and prolonged microbial corrosion process, resulting in an incomplete understanding of microbial corrosion mechanisms involved at various stages and the development of ineffective control strategies. This study employed a corrosion big data online real-time monitoring technique to investigate the time-dependent corrosion behavior of EH36 steel caused by Pseudomonas aeruginosa in aerobic environments over a 30-d incubation period. It was found that P. aeruginosa accelerated the corrosion of EH36 steel in the early stages by enhancing the cathodic oxygen reduction process. As oxygen levels declined, P. aeruginosa transitioned from aerobic to anaerobic respiration, promoting corrosion through biocatalytic nitrate reduction. In the later stages, the reduction in sessile cell counts, extreme low oxygen concentration, and dense surface film increased the charge transfer and film resistances, ultimately leading to corrosion inhibition. The weight loss and electrochemical data confirmed the effectiveness of the big data monitoring technique in investigating microbial corrosion, which provides new approaches for diagnosing and preventing microbial corrosion.

Chemical signaling in biofilm-mediated biofouling

Biofouling is the undesirable accumulation of living organisms and their metabolites on submerged surfaces. Biofouling begins with adhesion of biomacromolecules and/or microorganisms and can lead to the subsequent formation of biofilms that are predominantly regulated by chemical signals, such as cyclic dinucleotides and quorum-sensing molecules. Biofilms typically release chemical cues that recruit or repel other invertebrate larvae and algal spores. As such, harnessing the biochemical mechanisms involved is a promising avenue for controlling biofouling. Here, we discuss how chemical signaling affects biofilm formation and dispersion in model species. We also examine how this translates to marine biofouling. Both inductive and inhibitory effects of chemical cues from biofilms on macrofouling are also discussed. Finally, we outline promising mitigation strategies by targeting chemical signaling to foster biofilm dispersion or inhibit biofouling.

Molecular imaging of bacterial biofilms-a systematic review

The formation of bacterial biofilms in the human body and on medical devices is a serious human health concern. Infections related to bacterial biofilms are often chronic and difficult to treat. Detailed information on biofilm formation and composition over time is essential for a fundamental understanding of the underlying mechanisms of biofilm formation and its response to anti-biofilm therapy. However, information on the chemical composition, structural components of biofilms, and molecular interactions regarding metabolism- and communication pathways within the biofilm, such as uptake of administered drugs or inter-bacteria communication, remains elusive. Imaging these molecules and their distribution in the biofilm increases insight into biofilm development, growth, and response to environmental factors or drugs. This systematic review provides an overview of molecular imaging techniques used for bacterial biofilm imaging. The techniques included mass spectrometry-based techniques, fluorescence-labelling techniques, spectroscopic techniques, nuclear magnetic resonance spectroscopy (NMR), micro-computed tomography (µCT), and several multimodal approaches. Many molecules were imaged, such as proteins, lipids, metabolites, and quorum-sensing (QS) molecules, which are crucial in intercellular communication pathways. Advantages and disadvantages of each technique, including multimodal approaches, to study molecular processes in bacterial biofilms are discussed, and recommendations on which technique best suits specific research aims are provided.

Inhibition of Streptococcus pyogenes biofilm by Lactiplantibacillus plantarum and Lacticaseibacillus rhamnosus

The human pathobiont Streptococcus pyogenes forms biofilms and causes infections, such as pharyngotonsillitis and necrotizing fasciitis. Bacterial biofilms are more resilient to antibiotic treatment, and new therapeutic strategies are needed to control biofilm-associated infections, such as recurrent pharyngotonsillitis. Lactiplantibacillus plantarum and Lacticaseibacillus rhamnosus are two bacterial commensals used for their probiotic properties. This study aimed to elucidate the anti-biofilm properties of L. plantarum and L. rhamnosus cell-free supernatants (LPSN and LRSN, respectively) on S. pyogenes biofilms grown in vitro in supplemented minimal medium. When planktonic or biofilm S. pyogenes were exposed to LPSN or LRSN, S. pyogenes survival was reduced significantly in a concentration-dependent manner, and the effect was more pronounced on preformed biofilms. Enzymatic digestion of LPSN and LRSN suggested that glycolipid compounds might cause the antimicrobial effect. In conclusion, this study indicates that L. plantarum and L. rhamnosus produce glycolipid bioactive compounds that reduce the viability of S. pyogenes in planktonic and biofilm cultures.IMPORTANCEStreptococcus pyogenes infections are a significant concern for populations at risk, such as children and the elderly, as non-invasive conditions such as impetigo and strep throat can lead to severe invasive diseases such as necrotizing fasciitis. Despite its susceptibility to current antibiotics, the formation of biofilm by this pathogen decreases the efficacy of antibiotic treatment alone. The ability of commensal lactobacillus to kill S. pyogenes has been documented by previous studies using in vitro settings. The relevance of our study is in using a physiological setup and a more detailed understanding of the nature of the lactobacillus molecule affecting the viability of S. pyogenes. This additional knowledge will help for a better comprehension of the molecules' characteristics and kinetics, which in turn will facilitate new avenues of research for its translation to new therapies.

Synthesis of novel N-substituted tetrabromophthalic as corrosion inhibitor and its inhibition of microbial influenced corrosion in cooling water system

This study investigates the efficacy of newly synthesized inhibitor with a dual function of corrosion inhibition and biocide for control of microbial influenced corrosion (MIC) in carbon steel API 5LX in the cooling tower water (CTW) environment. Four types of N-substituted tetrabromophthalic inhibitor (N-TBI) were synthesized, and the structural characterization was performed via proton nuclear magnetic resonance spectroscopy, thermogravimetric analysis and high-resolution mass spectrometry. These studies revealed the distinctive optical, thermal, and dielectric properties of the synthesized inhibitors. The corrosion inhibition efficiency has been evaluated by the weight loss (WL) analysis and electrochemical measurements (ECM) and biofilm assay. Biofilm assays and WL showed that inhibitor II exhibited the highest inhibition efficiency 74% and 79% respectively than others. Further ECM showed that the higher charge transfer resistance and the lower corrosion current, suggesting a protective film formed on the metal surface which was due to the adsorption of the N-TBI. Fourier transform infrared spectroscopy confirmed the adsorption of the N-TBI as C-O stretching and C-H bending with the Fe complex. X-ray diffractometer revealed that the presence of inhibitors in the corrosion product (Fe3O4, Fe2O3, FeH2O2, FeS) were highly reduced than the control system. Overall, this study highlighted the potential application of N-TBI with dual function of corrosion inhibition and biocide to control the MIC for carbon steel API 5LX used in the CTW environment.

Smart self-defensive coatings with bacteria-triggered antimicrobial response for medical devices

Bacterial colonization and biofilm formation on medical devices represent one of the most urgent and critical challenges in modern healthcare. These issues not only pose serious threats to patient health by increasing the risk of infections but also exert a considerable economic burden on national healthcare systems due to prolonged hospital stays and additional treatments. To address this challenge, there is a need for smart, customized biomaterials for medical device fabrication, particularly through the development of surface modification strategies that prevent bacterial adhesion and the growth of mature biofilms. This review explores three bioinspired approaches through which antibacterial and antiadhesive coatings can be engineered to exhibit smart, stimuli-responsive features. This responsiveness is greatly valuable as it provides the coatings with a controlled, on-demand antibacterial response that is activated only in the presence of bacteria, functioning as self-defensive coatings. Such coatings can be designed to release antibacterial agents or change their surface properties/conformation in response to specific stimuli, like changes in pH, temperature, or the presence of bacterial enzymes. This targeted approach minimizes the risk of developing antibiotic resistance and reduces the need for continuous, high-dose antibacterial treatments, thereby preserving the natural microbiome and further reducing healthcare costs. The final part of the review reports a critical analysis highlighting the potential improvements and future evolutions regarding antimicrobial self-defensive coatings and their validation.

Quorum sensing and antibiotic resistance in polymicrobial infections

Quorum sensing (QS) is a critical bacterial communication system regulating behaviors like biofilm formation, virulence, and antibiotic resistance. This review highlights QS's role in polymicrobial infections, where bacterial species interactions enhance antibiotic resistance. We examine QS mechanisms, such as acyl-homoserine lactones (AHLs) in Gram-negative bacteria and autoinducing peptides (AIPs) in Gram-positive bacteria, and their impact on biofilm-associated antibiotic resistance. The challenges uniquely associated with polymicrobial infections, such as those found in cystic fibrosis lung infections, chronic wound infections, and medical device infections, are also summarized. Furthermore, we explore various laboratory models, including flow cells and dual-species culture models, used to study QS interactions in polymicrobial environments. The review also discusses promising quorum sensing inhibitors (QSIs), such as furanones and AHL analogs, which have demonstrated efficacy in reducing biofilm formation and virulence in laboratory and clinical studies. By addressing the interplay between QS and antibiotic resistance, this paper aims to advance therapeutic strategies that disrupt bacterial communication and improve antibiotic efficacy, ultimately mitigating the global challenge of antibiotic resistance in polymicrobial infections.

Mechanisms of antimicrobial resistance in biofilms

Most bacteria in nature exist in aggregated communities known as biofilms, and cells within a biofilm demonstrate major physiological changes compared to their planktonic counterparts. Biofilms are associated with many different types of infections which can have severe impacts on patients. Infections involving a biofilm component are often chronic and highly recalcitrant to antibiotic therapy as a result of intrinsic physical factors including extracellular matrix production, low growth rates, altered antibiotic target production and efficient exchange of resistance genes. This review describes the biofilm lifecycle, phenotypic characteristics of a biofilm, and contribution of matrix and persister cells to biofilms intrinsic tolerance to antimicrobials. We also describe how biofilms can evolve antibiotic resistance and transfer resistance genes within biofilms. Multispecies biofilms and the impacts of various interactions, including cooperation and competition, between species on tolerance to antimicrobials in polymicrobial biofilm communities are also discussed.

Study of the Structure of Hyperbranched Polyglycerol Coatings and Their Antibiofouling and Antithrombotic Applications

While blood-contacting materials are widely deployed in medicine in vascular stents, catheters, and cannulas, devices fail in situ because of thrombosis and restenosis. Furthermore, microbial attachment and biofilm formation is not an uncommon problem for medical devices. Even incremental improvements in hemocompatible materials can provide significant benefits for patients in terms of safety and patency as well as substantial cost savings. Herein, a novel but simple strategy is described for coating a range of medical materials, that can be applied to objects of complex geometry, involving plasma-grafting of an ultrathin hyperbranched polyglycerol coating (HPG). Plasma activation creates highly reactive surface oxygen moieties that readily react with glycidol. Irrespective of the substrate, coatings are uniform and pinhole free, comprising O─C─O repeats, with HPG chains packing in a fashion that holds reversibly binding proteins at the coating surface. In vitro assays with planar test samples show that HPG prevents platelet adhesion and activation, as well as reducing (>3 log) bacterial attachment and preventing biofilm formation. Ex vivo and preclinical studies show that HPG-coated nitinol stents do not elicit thrombosis or restenosis, nor complement or neutrophil activation. Subcutaneous implantation of HPG coated disks under the skin of mice shows no evidence of toxicity nor inflammation.

Marine-derived bioactive materials as antibiofilm and antivirulence agents

Microbial infections are major human health issues, and, recently, the mortality rate owing to bacterial and fungal infections has been increasing. In addition to intrinsic and extrinsic antimicrobial resistance mechanisms, biofilm formation is a key adaptive resistance mechanism. Several bioactive compounds from marine organisms have been identified for use in biofilm therapy owing to their structural complexity, biocompatibility, and economic viability. In this review, we discuss recent trends in the application of marine natural compounds, marine-bioinspired nanomaterials, and marine polymer conjugates as possible therapeutic agents for controlling biofilms and virulence factors. We also comprehensively discuss the mechanisms underlying biofilm formation and inhibition of virulence factors by marine-derived materials and propose possible applications of novel and effective antibiofilm and antivirulence agents.

Microbial acidification by N, S, Fe and Mn oxidation as a key mechanism for deterioration of subsea tunnel sprayed concrete

The deterioration of fibre-reinforced sprayed concrete was studied in the Oslofjord subsea tunnel (Norway). At sites with intrusion of saline groundwater resulting in biofilm growth, the concrete exhibited significant concrete deterioration and steel fibre corrosion. Using amplicon sequencing and shotgun metagenomics, the microbial taxa and surveyed potential microbial mechanisms of concrete degradation at two sites over five years were identified. The concrete beneath the biofilm was investigated with polarised light microscopy, scanning electron microscopy and X-ray diffraction. The oxic environment in the tunnel favoured aerobic oxidation processes in nitrogen, sulfur and metal biogeochemical cycling as evidenced by large abundances of metagenome-assembled genomes (MAGs) with potential for oxidation of nitrogen, sulfur, manganese and iron, observed mild acidification of the concrete, and the presence of manganese- and iron oxides. These results suggest that autotrophic microbial populations involved in the cycling of several elements contributed to the corrosion of steel fibres and acidification causing concrete deterioration.

Coacervate Dense Phase Displaces Surface-Established Pseudomonas aeruginosa Biofilms

For millions of years, barnacles and mussels have successfully adhered to wet rocks near tide-swept seashores. While the chemistry and mechanics of their underwater adhesives are being thoroughly investigated, an overlooked aspect of marine organismal adhesion is their ability to remove underlying biofilms from rocks and prepare clean surfaces before the deposition of adhesive anchors. Herein, we demonstrate that nonionic, coacervating synthetic polymers that mimic the physicochemical features of marine underwater adhesives remove ∼99% of Pseudomonas aeruginosa (P. aeruginosa) biofilm biomass from underwater surfaces. The efficiency of biofilm removal appears to align with the compositional differences between various bacterial biofilms. In addition, the surface energy influences the ability of the polymer to displace the biofilm, with biofilm removal efficiency decreasing for surfaces with lower surface energies. These synthetic polymers weaken the biofilm-surface interactions and exert shear stress to fracture the biofilms grown on surfaces with diverse surface energies. Since bacterial biofilms are 1000-fold more tolerant to common antimicrobial agents and pose immense health and economic risks, we anticipate that our unconventional approach inspired by marine underwater adhesion will open a new paradigm in creating antibiofilm agents that target the interfacial and viscoelastic properties of established bacterial biofilms.

Assessing Biofilm at the Bedside: Exploring Reliable Accessible Biofilm Detection Methods

INTRODUCTION

Biofilm is linked through a variety of mechanisms to the pathogenesis of chronic wounds. However, accurate biofilm detection is challenging, demanding highly specialized and technically complex methods rendering it unapplicable for most clinical settings. This study evaluated promising methods of bedside biofilm localization, fluorescence imaging of wound bacterial loads, and biofilm blotting by comparing their performance against validation scanning electron microscopy (SEM).

METHODS

In this clinical trial, 40 chronic hard-to-heal wounds underwent the following assessments: (1) clinical signs of biofilm (CSB), (2) biofilm blotting, (3) fluorescence imaging for localizing bacterial loads, wound scraping taken for (4) SEM to confirm matrix encased bacteria (biofilm), and (5) PCR (Polymerase Chain Reaction) and NGS (Next Generation Sequencing) to determine absolute bacterial load and species present. We used a combination of SEM and PCR microbiology to calculate the diagnostic accuracy measures of the CSB, biofilm blotting assay, and fluorescence imaging.

RESULTS

Study data demonstrate that 62.5% of wounds were identified as biofilm-positive based on SEM and microbiological assessment. By employing this method to determine the gold truth, and thus calculate accuracy measures for all methods, fluorescence imaging demonstrated superior sensitivity (84%) and accuracy (63%) compared to CSB (sensitivity 44% and accuracy 43%) and biofilm blotting (sensitivity 24% and accuracy 40%). Biofilm blotting exhibited the highest specificity (64%), albeit with lower sensitivity and accuracy. Using SEM alone as the validation method slightly altered the results, but all trends held constant.

DISCUSSION

This trial provides the first comparative assessment of bedside methods for wound biofilm detection. We report the diagnostic accuracy measures of these more feasibly implementable methods versus laboratory-based SEM. Fluorescence imaging showed the greatest number of true positives (highest sensitivity), which is clinically relevant and provides assurance that no pathogenic bacteria will be missed. It effectively alerted regions of biofilm at the point-of-care with greater accuracy than standard clinical assessment (CSB) or biofilm blotting paper, providing actionable information that will likely translate into enhanced therapeutic approaches and better patient outcomes.

Commercial Silver-Based Dressings: In Vitro and Clinical Studies in Treatment of Chronic and Burn Wounds

Chronic wounds are a major health problem because of delayed healing, causing hardships for the patient. The infection present in these wounds plays a role in delayed wound healing. Silver wound dressings have been used for decades, beginning in the 1960s with silver sulfadiazine for infection prevention for burn wounds. Since that time, there has been a large number of commercial silver dressings that have obtained FDA clearance. In this review, we examine the literature involving in vitro and in vivo (both animal and human clinical) studies with commercial silver dressings and attempt to glean the important characteristics of these dressings in treating infected wounds. The primary presentation of the literature is in the form of detailed tables. The narrative part of the review focuses on the different types of silver dressings, including the supporting matrix, the release characteristics of the silver into the surroundings, and their toxicity. Though there are many clinical studies of chronic and burn wounds using silver dressings that we discuss, it is difficult to compare the performances of the dressings directly because of the differences in the study protocols. We conclude that silver dressings can assist in wound healing, although it is difficult to provide general treatment guidelines. From a wound dressing point of view, future studies will need to focus on new delivery systems for silver, as well as the type of matrix in which the silver is deposited. Clearly, adding other actives to enhance the antimicrobial activity, including the disruption of mature biofilms is of interest. From a clinical point of view, the focus needs to be on the wound healing characteristics, and thus randomized control trials will provide more confidence in the results. The application of different wound dressings for specific wounds needs to be clarified, along with the application protocols. It is most likely that no single silver-based dressing can be used for all wounds.

Surface-anchored carbon nanomaterials for antimicrobial surfaces

Carbon nanomaterials (CNMs) are known for their antimicrobial (antibacterial and antiviral) activity when dispersed in a liquid, but whether this can be transferred to the surface of common materials has rarely been investigated. We have compared two typical CNMs (double-walled carbon nanotubes and few-layer graphene) in their non-oxidised and oxidised forms in terms of their antibacterial (Pseudomonas aeruginosa and Staphylococcus aureus) and antiviral (SARS-CoV2) activities after anchoring them onto the surface of silicone. We propose a very simple and effective protocol using the air-brush spray deposition method to entrap CNMs on the surfaces of two different silicone materials and demonstrate that the nanomaterials are anchored within the polymer while still being in contact with bacteria. We also investigated their antiviral activity against SARS-COV2 after deposition on standard surgical respiratory masks. Our results show that while suspensions of double-walled carbon nanotubes had a moderate effect on P. aeruginosa, this was not transferred after anchoring them to the surface of silicone. In contrast, graphene oxide showed a very strong antibacterial effect on P. aeruginosa and oxidised double-walled carbon nanotubes on S. aureus only when anchored to the surface. No significant antiviral activity was observed. This work paves the way for new antibacterial surfaces based on CNMs.

Biofilm Disruption from within: Light-Activated Molecular Drill-Functionalized Polymersomes Bridge the Gap between Membrane Damage and Quorum Sensing-Mediated Cell Death

Bacterial biofilms represent an escalating global health concern with the proliferation of drug resistance and hospital-acquired infections annually. Numerous strategies are under exploration to combat biofilms and preempt the development of antibacterial resistance. Among these, mechanical disruption of biofilms and enclosed bacteria presents a promising avenue, aiming to induce membrane permeabilization and consequent lethal damage. Herein, we introduce a hemithioindigo (HTI) motor activated by visible light, capable of disrupting sessile bacteria when integrated into a polymeric vesicle carrier. Under visible light, bacteria exhibited a notable outer membrane permeability, reduced membrane fluidity, and diminished viability following mechanical drilling. Moreover, various genetic responses pertaining to the cell envelope were examined via qRT-PCR, alongside the activation of a self-lysis mechanism associated with phage stress, which was coupled with increases in quorum sensing, demonstrating a potential self-lysis cascade from within. The multifaceted mechanisms of action, coupled with the energy efficiency of mechanical damage, underscore the potential of this system in addressing the challenges posed by pathogenic biofilms.

Clinical Evaluation of Microbial Communities and Associated Biofilms with Breast Augmentation Failure

The incidence of breast implant illness (BII) and BII-related explant procedures has not decreased with current surgical and treatment techniques. It is speculated the main underlying cause of BII complications is the result of chronic, sub-clinical infections residing on and around the implant. The infection, and subsequent biofilm, produce antagonistic compounds that drive chronic inflammation and immune responses. In this study, the microbial communities in over 600 consecutive samples of infected explant capsules and tissues were identified via next-generation sequencing to identify any commonality between samples. The majority of the bacteria identified were Gram-positive, with Cutibacterium acnes and Staphylococcus epidermidis being the dominant organisms. No correlation between sample richness and implant filling was found. However, there was a significant correlation between sample richness and patient age. Due to the complex nature, breast augmentation failures may be better addressed from a holistic approach than one of limited scope.

Co-zorbs: Motile, multispecies biofilms aid transport of diverse bacterial species

Biofilms are three-dimensional structures containing one or more bacterial species embedded in extracellular polymeric substances. Although most biofilms are stationary, Flavobacterium johnsoniae forms a motile spherical biofilm called a zorb, which is propelled by its base cells and contains a polysaccharide core. Here, we report formation of spatially organized, motile, multispecies biofilms, designated "co-zorbs," that are distinguished by a core-shell structure. F. johnsoniae forms zorbs whose cells collect other bacterial species and transport them to the zorb core, forming a co-zorb. Live imaging revealed that co-zorbs also form in zebrafish, thereby demonstrating a new type of bacterial movement in vivo. This discovery opens new avenues for understanding community behaviors, the role of biofilms in bulk bacterial transport, and collective strategies for microbial success in various environments.

Artificial Intelligence-Driven Analysis of Antimicrobial-Resistant and Biofilm-Forming Pathogens on Biotic and Abiotic Surfaces

The growing threat of antimicrobial-resistant (AMR) pathogens to human health worldwide emphasizes the need for more effective infection control strategies. Bacterial and fungal biofilms pose a major challenge in treating AMR pathogen infections. Biofilms are formed by pathogenic microbes encased in extracellular polymeric substances to confer protection from antimicrobials and the host immune system. Biofilms also promote the growth of antibiotic-resistant mutants and latent persister cells and thus complicate therapeutic approaches. Biofilms are ubiquitous and cause serious health risks due to their ability to colonize various surfaces, including human tissues, medical devices, and food-processing equipment. Detection and characterization of biofilms are crucial for prompt intervention and infection control. To this end, traditional approaches are often effective, yet they fail to identify the microbial species inside biofilms. Recent advances in artificial intelligence (AI) have provided new avenues to improve biofilm identification. Machine-learning algorithms and image-processing techniques have shown promise for the accurate and efficient detection of biofilm-forming microorganisms on biotic and abiotic surfaces. These advancements have the potential to transform biofilm research and clinical practice by allowing faster diagnosis and more tailored therapy. This comprehensive review focuses on the application of AI techniques for the identification of biofilm-forming pathogens in various industries, including healthcare, food safety, and agriculture. The review discusses the existing approaches, challenges, and potential applications of AI in biofilm research, with a particular focus on the role of AI in improving diagnostic capacities and guiding preventative actions. The synthesis of the current knowledge and future directions, as described in this review, will guide future research and development efforts in combating biofilm-associated infections.

Acceleration mechanism of riboflavin on Fe0-to-microbe electron transfer in corrosion of EH36 steel by Pseudomonas aeruginosa

Riboflavin (RF), as a common electron mediator that can accelerate extracellular electron transfer (EET), is usually used as a probe to confirm EET-microbiologically influenced corrosion (MIC). However, the acceleration mechanism of RF on EET-MIC is still unclear, especially the effect on gene expression in bacteria. In this study, a 13-mer antimicrobial peptide E6 and tetrakis hydroxymethyl phosphonium sulfate (THPS) were used as new tools to investigate the acceleration mechanism of RF on Fe0-to-microbe EET in corrosion of EH36 steel caused by Pseudomonas aeruginosa. 60 min after 20 ppm (v/v) THPS and 20 ppm THPS & 100 nM E6 were injected into P. aeruginosa 1 and P. aeruginosa 2 (two glass bottles containing P. aeruginosa with different treatments) at the 3-d incubation, respectively, P. aeruginosa 1 and P. aeruginosa 2 had a similar planktonic cell count, whereas the sessile cell count in P. aeruginosa 1 was 1.3 log higher than that in P. aeruginosa 2. After the 3-d pre-growth and subsequent 7-d incubation, the addition of 20 ppm (w/w) RF increased the weight loss and maximum pit depth of EH36 steel in P. aeruginosa 1 by 0.7 mg cm-2 and 4.1 μm, respectively, while only increasing those in P. aeruginosa 2 by 0.4 mg cm-2 and 1.7 μm, respectively. This suggests that RF can be utilized by P. aeruginosa biofilms since the corrosion rate should be elevated by the same value if it only acts on the planktonic cells. Furthermore, the EET capacity of P. aeruginosa biofilm was enhanced by RF because the protein expression of cytochrome c (Cyt c) gene in sessile cells was significantly increased in the presence of RF, which accelerated EET-MIC by P. aeruginosa against EH36 steel.

Antimicrobial and Antibiofilm Activity of Monolaurin against Methicillin-Resistant Staphylococcus aureus Isolated from Wound Infections

Background

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the major pathogens associated with life-threatening infections, showing resistance to various antibiotics. This study aimed to assess the influence of monolaurin on biofilm-forming MRSA.

Methods

The agar dilution method determined the minimum inhibitory concentration (MIC) of monolaurin against MRSA isolates and explored its impact on the resistance profile of selected antibiotics. The assessment of combined therapy involving monolaurin and antibiotics was conducted using fractional inhibitory concentration (FIC). The tissue culture plate strategy appraised monolaurin's antibiofilm activity and its inhibitory concentration (IC50), with assessment via scanning electron microscopy. Reverse transcription polymerase chain reaction (RT-PCR) discerned a monolaurin effect on the expression of the icaD gene.

Results

Monolaurin exhibited MIC values ranging from 500 to 2000 μg/mL. FIC index showed a synergistic effect of monolaurin with β-lactam antibiotics ranging from 0.0039 to 0.25 (p < 0.001). Among the 103 investigated MRSA isolates, 44 (44.7%) displayed moderate biofilm formation, while 59 (55.3%) were strong biofilm producers. Antibiofilm activity demonstrated concentration dependence, confirming monolaurin's capacity to inhibit biofilm formation and exhibited strong eradicating effects against preformed MRSA biofilms with IC50 values of 203.6 μg/mL and 379.3 μg/mL, respectively. Scanning electron microscope analysis revealed reduced cell attachments and diminished biofilm formation compared to the control. The expression levels of the icaD gene were remarkably reduced at monolaurin concentrations of 250 and 500 μg/mL.

Conclusion

Monolaurin had significant inhibitory effects on MRSA pre-existing biofilms as well as biofilm development. So, it can be employed in the treatment of severe infections, particularly those associated with biofilm formation including catheter-associated infections.