Bacterial Biofilm and its Role in the Pathogenesis of Disease

Bacterial extracellular vesicles in the initiation, progression and treatment of atherosclerosis

Atherosclerosis is the primary cause of cardiovascular and cerebrovascular diseases. However, current anti-atherosclerosis drugs have shown conflicting therapeutic outcomes, thereby spurring the search for novel and effective treatments. Recent research indicates the crucial involvement of oral and gastrointestinal microbiota in atherosclerosis. While gut microbiota metabolites, such as choline derivatives, have been extensively studied and reviewed, emerging evidence suggests that bacterial extracellular vesicles (BEVs), which are membrane-derived lipid bilayers secreted by bacteria, also play a significant role in this process. However, the role of BEVs in host-microbiota interactions remains insufficiently explored. This review aims to elucidate the complex communication mediated by BEVs along the gut-heart axis. In this review, we summarize current knowledge on BEVs, with a specific focus on how pathogen-derived BEVs contribute to the promotion of atherosclerosis, as well as how BEVs from gut symbionts and probiotics may mitigate its progression. We also explore the potential and challenges associated with engineered BEVs in the prevention and treatment of atherosclerosis. Finally, we discuss the benefits and challenges of using BEVs in atherosclerosis diagnosis and treatment, and propose future research directions to address these issues.

Microbial diversity and interactions: Synergistic effects and potential applications of Pseudomonas and Bacillus consortia

Microbial diversity and interactions in the rhizosphere play a crucial role in plant health and ecosystem functioning. Among the myriads of rhizosphere microbes, Pseudomonas and Bacillus are prominent players known for their multifaceted functionalities and beneficial effects on plant growth. The molecular mechanism of interspecies interactions between natural isolates of Bacillus and Pseudomonas in medium conditions is well understood, but the interaction between the two in vivo remains unclear. This paper focuses on the possible synergies between Pseudomonas and Bacillus associated in practical applications (such as recruiting beneficial microbes, cross-feeding and niche complementarity), and looks forward to the application prospects of the consortium in agriculture, human health and bioremediation. Through in-depth understanding of the interactions between Pseudomonas and Bacillus as well as their application prospects in various fields, this study is expected to provide a new theoretical basis and practical guidance for promoting the research and application of rhizosphere microbes.

Formulation and evaluation of therapeutic antimicrobial citrus and Manuka honey creams with aloe vera, mint essential oil, and Indian costus

Honey has long been recognized for its antimicrobial properties, attributed to components such as polyphenols and biodefense proteins. Among honey types, Manuka honey, rich in methylglyoxal, and citrus honey, abundant in flavonoids and bioactive enzymes, exhibit potent antimicrobial activity. This study aims to enhance the antimicrobial and antibiofilm efficacy of Manuka and citrus honey by incorporating natural additives-aloe vera, Indian costus, and mint essential oil-into cream formulations. Two emulsion types, aerosil fumed silica-based and arabic gum-based, were prepared and optimized using sonication. The antimicrobial activity of these formulations was assessed against pathogenic bacteria, including Bacillus cereus, Pseudomonas aeruginosa, Salmonella enterica subsp. enterica serovar Typhimurium, Methicillin-resistant Staphylococcus aureus, Listeria monocytogenes, Micrococcus luteus, Escherichia coli O157:H7, and Klebsiella pneumoniae, as well as fungi such as Candida albicans and Aspergillus niger. The most effective formulations demonstrated inhibition zones of up to 28 mm against B. cereus and 24 mm against S. Typhimurium. Additionally, antibiofilm activity was evaluated using a 3D biofilm model, with formulations containing citrus honey and Indian costus or Manuka honey and aloe vera achieving biofilm reductions of 44.39% and 21.33%, respectively, against P. aeruginosa and MRSA. Furthermore, the composition of the citrus honey was analyzed using gas chromatography-mass spectrometry to identify the volatile and non-volatile compounds contributing to their antimicrobial properties. These findings suggest that honey-based formulations enhanced with natural additives hold significant potential for combating biofilm-associated infections.

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.

Synthesis of antibiofilm (1R,4S)-(-)-fenchone derivatives to control Pseudomonas syringae pv. tomato

BACKGROUND

Biofilm plays a crucial role in Pseudomonas syringae pv. tomato (Pst) infection. We identified (1R,4S)-(-)-fenchone (FCH) as the most potent antibiofilm agent against Pst among 39 essential oil compounds. Subsequently, we synthesized a series of FCH oxime ester and acylhydrazine derivatives to explore more potent derivatives.

RESULTS

II3 was screened out as the most potent derivative, exhibiting a minimal biofilm inhibitory concentration of 60 μg mL-1 and a lowest concentration with maximal biofilm inhibition (LCMBI) of 200 μg mL-1, lower than those of FCH (80 and 500 μg mL-1, respectively). II3 and FCH showed minimum inhibitory concentration values >1000 μg mL-1 and similar maximal biofilm inhibition extents of 48.7% and 49.5% at their respective LCMBIs, respectively. Meanwhile, neither of them influenced cell viability or the activity of metabolic enzymes at their respective LCMBIs. II3 at its LCMBI significantly reduced biofilm thickness, extracellular polysaccharide content, and pectinase and cellulase production indices. In vivo assay results indicated that II3 could preventatively reduce the bacterial contents in tomato leaves at its LCMBI, and when combined with kasugamycin (KSG) (10 μg mL-1), II3 achieved the same level of bacterial reduction as the sole application of KSG (70 μg mL-1), thereby reducing the required dosage of KSG. Mechanistic studies demonstrated that II3 can down-regulate biofilm-related genes and inhibit PsyR/PsyI quorum sensing system, which differs from the bactericidal mechanisms.

CONCLUSION

These results underscore the potential of II3 as an antibiofilm agent for the control of Pst or FCH as a promising natural candidate for future in-depth optimization. © 2024 Society of Chemical Industry.

Osteomyelitis: Considerations for nursing practice

ABSTRACT

Osteomyelitis is characterized by inflammation of the bone tissue, typically caused by microorganisms such as bacteria. It can be challenging to treat and may lead to unnecessary antibiotic therapies. Prompt identification of osteomyelitis and implementation of effective treatments are necessary to eradicate this infection. This article discusses the pathophysiology, clinical presentation, diagnosis, and nursing management of osteomyelitis, focusing on native bone infection.

Harnessing exogenous membrane vesicles for studying Fusarium circinatum and its biofilm communities

Extracellular vesicles (EVs) are tiny messengers that convey bioactive molecules from donor to recipient cells, leading to changes in their physiology and function. We investigated the role of EVs in shaping growth and the biofilm biology of the tree pathogen Fusarium circinatum and its interaction with the susceptible host, Pinus patula. Vesicles were collected from fungal planktonic and biofilm cultures and from pine seedling needles and roots. The physical properties of these vesicles were analysed using nanoparticle tracking analysis and transmission electron microscopy, which revealed a diverse range of sizes and shapes, respectively. Furthermore, uptake of vesicles by conidia was conducted. The results demonstrated that F. circinatum EVs significantly but variably affected spore viability during the early phase (2-4 h) although they enhanced fungal biofilm integrity. In contrast, P. patula EVs greatly inhibited hyphal formation and biofilm biomass, but failed to inhibit matrix production in the fungal biofilm. Our results therefore show that conidial germination is essential for late fungal development including hyphal and biofilm formation while matrix production is a counter measure against harsh environmental conditions including the effects of plant-derived EVs.

A biocompatible β-cyclodextrin inclusion complex containing natural extracts: a promising antibiofilm agent

Biofilms formed by several bacterial strains still pose a significant challenge to healthcare due to their resistance to conventional treatment approaches, including antibiotics. This study explores the potential of loading natural extracts with antimicrobial activities into β-cyclodextrin (βCD) nanoparticles, which are FDA-approved and have superior biocompatibility owing to their cyclic sugar structures, for biofilm eradication. An inclusion complex of βCD carrying Boswellia sacra essential oils (BOS) was prepared and characterized with regard to its physicochemical properties, antimicrobial efficacy, and antibiofilm activities. Encapsulation of BOS into βCD significantly enhanced the antimicrobial activity of BOS by 4-fold against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and by 8-fold against Gram-negative (Escherichia coli and Pseudomonas putida) bacteria, with minimum inhibitory concentrations ranging from 2.5 to 5 mg mL-1. Furthermore, the BOS-βCD complex demonstrated a dual-action against bacterial biofilms where it prevented biofilm formation and disrupted established biofilms. This resulted in a significant reduction in biofilm biomass, with prevention and disruption rates reaching up to 93.78% and 82.17%, respectively. Additionally, the formula revealed an excellent biocompatibility profile with no induction of oxidative stress in human skin fibroblast cells. Our findings suggest that βCD nanoparticles loaded with BOS essential oils hold promise as an effective formula for preventing the formation of bacterial biofilms and combating preformed ones for use in relevant medical applications.

hmuSTUV operon positively regulates the alginate gene cluster to mediate the pathogenicity of Pseudomonas donghuensis HYS

Pseudomonas donghuensis HYS is highly virulent to Caenorhabditis elegans, but with mechanistic details that are not fully understood. The hmuSTUV operon was reported to participate in the synthesis of heme in Pseudomonas. However, the exact role of the hmuSTUV operon in Pseudomonas virulence has not been elucidated. In this study, we report for the first time that the hmuSTUV operon in P. donghuensis HYS causes host virulence, and that hmuS was a key gene for the toxicity of this operon. Furthermore, RNA-seq data showed that hmuS deletion inhibited alginate gene expression, thereby inhibiting biofilm formation. The hmuSTUV operon and alginate gene cluster are conserved in Pseudomonas. By constructing mutant strains carrying GFP, we found that the hmuS deletion reduced colonisation of HYS to the host gut. Moreover, the expression of the alginate gene cluster was controlled by the construction of a L-arabinose-inducible promoter. hmuS positively regulated alginate gene cluster expression, mediating bacterial virulence against C. elegans. In addition, HYS originating from the East Lake of Wuhan City was more pathogenic to zebrafish than any other pathogenic Pseudomonas, through impairment of zebrafish neurodevelopment and locomotor ability, by colonizing to the zebrafish brain. In conclusion, the hmuSTUV operon positively regulated the alg gene cluster, thereby disabling bacterial biofilm formation and colonisation to mediate bacterial pathogenicity to the host. These novel findings revealed the critical interaction between the hmuSTUV operon and the alg gene cluster in the bacterial virulence of Pseudomonas, providing new insights into Pseudomonas pathogenicity.

Morphogenesis of confined biofilms: how mechanical interactions determine cellular patterning and global geometry

Biofilms are surface-attached bacterial communities encased within extracellular matrices that play significant roles in health and society and serve as prototypical examples of proliferating active nematics. Recent advances in fluorescence microscopy have facilitated an unprecedented view of biofilm development at the single-cell level, thus providing the opportunity to develop a mechanistic understanding of how biofilm development is influenced by mechanical interactions with the environment. Here, we review recent studies that examined the morphogenesis of Vibrio cholerae biofilms under confinement at both single-cell and continuum levels. We describe how biofilms under different confinement modes-embedded and interstitial-can acquire various global geometries and forms of cell orientational ordering different from those in unconfined biofilms, and we demonstrate how these properties arise from the mechanical interplay between the biofilm and its confining medium. We also discuss how this interplay is fundamentally governed by the extracellular matrix, which facilitates the transmission of mechanical stress from the medium into the biofilm via adhesion and friction, and serves as the key feature that distinguishes biofilms from classical bacterial colonies. These studies lay the groundwork for many potential future directions, all of which will contribute to the establishment of a new "developmental biology" of biofilms.

Re-Emergence of Bacteriophages and Their Products as Antibacterial Agents: An Overview

Microbes possess diverse genetic and metabolic traits that help them withstand adverse conditions. Microbial pathogens cause significant economic losses and around 7.7 million human deaths annually. While antibiotics have historically been a lifesaving treatment, their effectiveness is declining due to antibiotic-resistant strains, prompting the exploration of bacterial predation as an alternative. Bacteriophages (BPhs) have reemerged as antibacterial agents, offering advantages over antibiotics, such as (i) high specificity, (ii) self-replication, and (iii) strong killing capacity. This review explores BPh- and enzyme-based antibacterial strategies for infectious disease treatment, discussing phage-antibiotic synergy, the risks of BPh resistance, and the role of quorum sensing in BPh therapy.

Cuminaldehyde synergistically enhances the antimicrobial and antibiofilm potential of gentamicin: A direction towards an effective combination for the control of biofilm-linked threats of Staphylococcus aureus

Staphylococcus aureus, a Gram-positive, coccus-shaped bacterium often causes several infections on human hosts by exploiting biofilm. This current work investigates a potential strategy to manage the threats of biofilm-linked infections by embracing a combinatorial approach involving cuminaldehyde (phytochemical) and gentamicin (antibiotic). Despite showing antimicrobial properties individually, cuminaldehyde and gentamicin could exhibit enhanced antimicrobial potential when used together against S. aureus. The fractional inhibitory concentration index (FICI = 0.36) suggested that the selected compounds (cuminaldehyde and gentamicin) offered synergistic interaction while showing antimicrobial potential against the same organism. A series of experiments indicated that the selected compounds (cuminaldehyde and gentamicin) showed substantial antibiofilm potential against S. aureus when combined. The increased antibiofilm potential was linked to the accumulation of reactive oxygen species (ROS) and increased cell membrane permeability. Additionally, the combination of the selected compounds (cuminaldehyde and gentamicin) also impeded the cell surface hydrophobicity of S. aureus, aiding in the prevention of biofilm formation. The present study also showed that combining the mentioned compounds (cuminaldehyde and gentamicin) notably reduced the secretion of several virulence factors from S. aureus. Furthermore, the current research showed that these compounds (cuminaldehyde and gentamicin) could also exhibit antibiofilm potential against the clinical strains of Methicillin-Resistant S. aureus (MRSA). Taken together, this innovative approach not only enhances the potential of existing standard antibiotics but also opens up new therapeutic possibilities for combating biofilm-related infections.

Durable Antimicrobial Microstructure Surface (DAMS) Enabled by 3D-Printing and ZnO Nanoflowers

Numerous studies have been trying to create nanomaterial-based antimicrobial surfaces to prevent infections due to bacterial growth. One major challenge in real-world applications of these surfaces is their mechanical durability. In this study, we introduce durable antimicrobial microstructure surface (DAMS), which integrates DLP 3D-printed microstructures with zinc oxide (ZnO) nanoflowers. The microstructures function as protection armor for the nanoflowers during abrasion. The antimicrobial ability was evaluated by immersing in 2E8 CFU/mL Escherichia coli (E. coli) suspension and then evaluated using electron microscopy. Our results indicated that DAMS reduced bacterial coverage by more than 90% after 12 h of incubation and approximately 50% after 48 h of incubation before abrasion. More importantly, bacterial coverage was reduced by approximately 50% after 2 min of abrasion with a tribometer, and DAMS remains effective even after 6 min of abrasion. These findings highlight the potential of DAMS as an affordable, scalable, and durable antimicrobial surface for various biomedical applications.

Exploring combination treatment options for persistent methicillin-susceptible Staphylococcus aureus bacteremia

PURPOSE

This review explores the management of persistent methicillin-susceptible Staphylococcus aureus bacteremia (SAB), emphasizing the importance of timely intervention due to SAB's association with metastatic dissemination, relapse, and mortality.

SUMMARY

The literature analysis first delves into risk factors for persistent SAB, highlighting the need for effective treatment strategies. The subsequent focus is on combination strategies for persistent SAB. Daptomycin, ertapenem, ceftaroline, fosfomycin, rifampin, and gentamicin are explored as adjuncts to cefazolin or antistaphylococcal penicillins. Daptomycin combination therapy is assessed through in vivo and clinical studies, indicating potential benefits, especially with higher-risk sources of infection. Ertapenem combination therapy has been demonstrated to have a synergistic effect with cefazolin, presenting a viable salvage option. Rifampin's ability to penetrate biofilm is examined, with discussion of inconclusive evidence on mortality benefits. The review also considers stewardship implications, discussing concerns such as resistance emergence, adverse events, and increased costs associated with combination therapy. Mathematical models suggest combination therapy as an effective approach to prevent resistance. Adverse events vary with each combination, and duration of therapy remains diverse across studies in the absence of well-established dosing guidelines.

CONCLUSION

The review provides a thorough exploration of the literature on treatment of persistent SAB, underscoring the need for evidence-based guidelines, further studies, and clinical judgment in tailoring treatment strategies. The multifaceted analysis contributes valuable insights for clinicians managing this challenging condition.

Antimicrobial, antibiofilm, and antiurease activities of green-synthesized Zn, Se, and ZnSe nanoparticles against Streptococcus salivarius and Proteus mirabilis

This study assesses the antimicrobial, antibiofilm, and antiurease properties of selenium (Se), zinc (Zn), and zinc selenide (ZnSe) nanoparticles (NPs) against clinically pathogenic strains of Streptococcus salivarius and Proteus mirabilis. The Se, Zn, and ZnSe NPs, synthesized by Pseudomonas aeruginosa OG1, were characterized using transmission electron microscopy (TEM) revealing average sizes of approximately 30 ± 10 nm, 30 ± 15 nm, and 40 ± 10 nm, respectively. Atomic force microscopy (AFM) was used to examine the morphological and topological characteristics of the NPs. The structural and crystal characteristics were investigated using X-ray diffraction (XRD). Among the evaluated NPs, Zn NPs at a concentration of 200 mg/mL exhibited the most substantial growth inhibition zone against S. salivarius. Conversely, the highest antibiofilm activity was observed against P. mirabilis, notably with 200 µg/mL Zn NPs. In the context of antiurease activity, both 100 μg Zn and ZnSe NPs caused complete urease inhibition (100%) in P. mirabilis within the initial 5 h, with notable inhibition rates of 94% and 80%, respectively, observed against S. salivarius. Significantly, in the current landscape of NP research primarily focused on antimicrobial and antibiofilm properties, our study stands out due to its pioneering exploration of antiurease activities with these NPs. This distinctive emphasis on antiurease effects contributes original and unique value to our study, offering novel insights into the broader spectrum of NP applications, and paving the way for potential therapeutic advancements.

Anti-biofilm effect of ferulic acid against Enterobacter hormaechei and Klebsiella pneumoniae: in vitro and in silico investigation

Enterobacter hormaechei and Klebsiella pneumoniae, key members of the ESKAPE group of hospital-acquired pathogens, are driving forces behind numerous infections due to their potent biofilm formation and the growing threat of antimicrobial resistance. Ferulic acid (FA) is known for its strong antioxidant properties and is recognized for its numerous physiological benefits, including anti-inflammatory, antimicrobial, anticancer, and antidiabetic effects. The current investigation delves into the antimicrobial and antibiofilm ability of FA against E. hormaechei and K. pneumoniae. Using different assays, we confirmed that FA inhibits the biofilm formation of these pathogens. Through computational studies involving molecular docking and molecular dynamics simulations, it was found that FA exhibits a strong affinity for binding with MrkB in E. hormaechei and MrkH in K. pneumoniae, crucial proteins involved in biofilm formation. We hypothesise that FA might interfere with adhesion-associated molecules and inhibit biofilms through the c-di-GMP pathway and proves as an effective antibiofilm compound.

Evaluation of Antibacterial, Antibiofilm, Antioxidant, and Anti-Inflammatory Activities of Kratom Leaves (Mitragyna speciosa) Fermentation Supernatant Containing Lactobacillus rhamnosus GG

Kratom (Mitragyna speciosa) leaves are commonly used to enhance endurance and treat various diseases. This study evaluated the effect of kratom leaf fermentation with Lactobacillus rhamnosus. Antibacterial activity was investigated against Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Escherichia coli, and E. coli O157:H7. Biofilm inhibition and eradication assays were also performed. Antioxidant properties were determined by measuring the total phenolic and flavonoid content and DPPH and ABTS scavenging activities. Nitric oxide and TNF-α, IL-1β, and IL-6 expressions in LPS-stimulated RAW 264.7 macrophage cells were also measured. Aqueous kratom extract exhibited promising effects against free radicals and pro-inflammatory cytokines. Notably, all fermented kratoms showed significant antibacterial activity against the tested pathogens and antibiofilm formation by S. aureus and MRSA. Furthermore, the eradication of established biofilms of fermented kratoms was observed in S. aureus (day 2, 50 mg/mL) and E. coli (day 2, 100 mg/mL and day 4, 50 mg/mL). To the best of our knowledge, this study is the first to report that fermented and non-fermented kratoms could be nutraceutical sources of antibacterial, antibiofilm, antioxidant, and anti-inflammatory substances against related diseases and can be applied further in dietary or cosmetic products with health-promoting effects.

Transcriptome analysis reveals the molecular mechanism of γ-linolenic acid eradicating the biofilm of vancomycin-resistant Enterococcus faecium

Introduction

Vancomycin-resistant Enterococcus faecium (VRE-fm) biofilms pose a significant clinical challenge due to the limited effectiveness of traditional antibiotics. This study investigates the potential of γ-linolenic acid (GLA) as a novel antibiofilm agent.

Methods

Transcriptome analysis was performed on the V27 isolate, comparing cells in mature biofilms treated with and without GLA. The findings were further validated using qRT-PCR on six VRE-fm isolates and two E. faecalis isolates.

Results

Transcriptome analysis revealed a significant downregulation in the expression levels of genes associated with biofilm formation, including fruA, fruB, sgrA, lpxtg-cwa, tfpp, lafA, lafB, malP, fsrA, and fsrC', while a significant upregulation was observed in the expression of fsrBD. Validation by qRT-PCR in six VRE-fm isolates confirmed the significant changes in the expression levels of all genes except for lpxtg-cwa, with statistical significance. The expression of bgsB and bgsA genes, which are the homologs of lafA and lafB genes, along with the Fsr-regulated genes gelE and sprE in E. faecalis, were also found to be downregulated by GLA. In addition, KEGG analysis identified specific metabolic pathways that were significantly downregulated by GLA.

Conclusion

GLA effectively targets multiple aspects of biofilm formation in VRE-fm, including the downregulation of key biofilm-related genes, the inhibition of quorum sensing systems, and the modulation of metabolic pathways. GLA emerges as a promising candidate for eradicating Enterococcus biofilms.

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.

Graphene Quantum Dots in Bacterial Cellulose Hydrogels for Visible Light-Activated Antibiofilm and Angiogenesis in Infection Management

A novel bacterial cellulose (BC)-based composite hydrogel with graphene quantum dots (BC-GQDs) was developed for photodynamic therapy using blue and green light (BC-GQD_blue and BC-GQD_green) to target pathogenic bacterial biofilms. This approach aims to address complications in treating nosocomial infections and combating multi-drug-resistant organisms. Short-term illumination (30 min) of both BC-GQD samples led to singlet oxygen production and a reduction in pathogenic biofilms. Significant antibiofilm activity (>50% reduction) was achieved against Staphylococcus aureus and Escherichia coli with BC-GQD_green, and against Pseudomonas aeruginosa with BC-GQD_blue. Atomic force microscopy images revealed a substantial decrease in biofilm mass, accompanied by changes in surface roughness and area, further confirming the antibiofilm efficacy of BC-GQDs under blue and green light, without any observed chemical alterations. Additionally, the biocompatibility of BC-GQDs was demonstrated with human gingival fibroblasts (HGFs). For the first time, in vitro studies explored the visible light-induced potential of BC-GQD composites to promote wound healing processes, showing increased migratory potential and the upregulation of eNOS and MMP9 gene expressions in HGFs. Chemical characterization revealed a 70 nm upshift in the photoluminescence emission spectra compared to the excitation wavelength. These novel photoactive BC-GQD hydrogel composites show great promise as effective agents for wound healing regeneration and infection management.

Synthesis, Structural Analysis and Antibacterial Properties of a Novel β-Aminoenone

(Z)-3-butylamino-4,4,4-trifluoro-1-(2-hydroxyphenyl)but-2-en-1-one (1), a new β-aminoenone, has been investigated in terms of its intra- and intermolecular interactions. Vibrational, electronic and nuclear magnetic resonance spectroscopies were used for the characterization, while X-ray diffraction methods afforded the determination of the crystal structure. The compound is arranged in the crystal lattice as centre-symmetric H-bonded dimeric aggregates (C2/c monoclinic space group). Both experimental (infrared, Raman, ultraviolet-visible transitions and X-ray diffraction data) and theoretical (Quantum Theory of Atoms in Molecules and Natural Bond Orbital approaches, calculated spectra and conformational analysis) methods were used to obtain a deep insight into the intra- and intermolecular contacts. The interactions were quali- and quantitatively analysed and the data compared with closely related compounds. In vitro experiments were carried out in this work to evaluate the antibacterial activity of 1 against Gram-positive and Gram-negative bacteria, particularly Pseudomonas aeruginosa (ATCC 27853) and Staphylococcus aureus (6538). Compound 1 demonstrated a discernible suppression of biofilm formation and quorum sensing of both bacterial strains, indicating that it may be developed as an antibacterial candidate to reduce bacterial resistance and persistence on surfaces across a range of industries.

Self-Assembled Nanoflowers from Natural Building Blocks with Antioxidant, Antibacterial, and Antibiofilm Properties

Polyphenols, natural compounds abundant in phenolic structures, have received widespread attention due to their antioxidant, anti-inflammatory, antibacterial, and anticancer properties, making them valuable for biomedical applications. However, the green synthesis of polyphenol-based materials with economical and environmentally friendly strategies is of great significance. In this study, a multifunctional wound dressing was achieved by introducing polyphenol-based materials of copper phosphate-tannic acid with a flower-like structure (Cu-TA NFs), which show the reactive oxygen species scavenging performance. This strategy endowed the electrospun wound dressing, composed of poly(caprolactone)-coated gum arabic-poly(vinyl alcohol) nanofibers (GPP), with the antibacterial and antibiofilm properties. Our research demonstrates that GPP/Cu-TA NFs are effective against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Furthermore, the developed GPP/Cu-TA NFs showed excellent hemocompatibility and biocompatibility. These results suggest that the synergistic properties of this multifunctional polyphenol platform (GPP/Cu-TA NFs) make it a promising candidate for the further development of wound dressing materials.

Deep generative modeling of annotated bacterial biofilm images

Biofilms are critical for understanding environmental processes, developing biotechnology applications, and progressing in medical treatments of various infections. Nowadays, a key limiting factor for biofilm analysis is the difficulty in obtaining large datasets with fully annotated images. This study introduces a versatile approach for creating synthetic datasets of annotated biofilm images with employing deep generative modeling techniques, including VAEs, GANs, diffusion models, and CycleGAN. Synthetic datasets can significantly improve the training of computer vision models for automated biofilm analysis, as demonstrated with the application of Mask R-CNN detection model. The approach represents a key advance in the field of biofilm research, offering a scalable solution for generating high-quality training data and working with different strains of microorganisms at different stages of formation. Terabyte-scale datasets can be easily generated on personal computers. A web application is provided for the on-demand generation of biofilm images.

Eradication of single- and mixed-species biofilms of P. aeruginosa and S. aureus by pulsed streamer corona discharge cold atmospheric plasma

Cold atmospheric plasma has recently gained much attention due to its antimicrobial effects. Among others, plasma has proven its potential to combat microbial biofilms. Yet, knowledge of complex network interactions between individual microbial species in natural infection environments of the biofilm as well as plasma-biofilm inactivation pathways is limited. This study reports the effects of a cold plasma generated by a pulsed streamer corona discharge in air on single- and mixed-species biofilms of P. aeruginosa and S. aureus. The plasma causes significant biofilm biomass reduction, bacteria inactivation, and alteration in intracellular metabolism. For single-species biofilms S. aureus is found more tolerant to plasma than P. aeruginosa, and mixed-species biofilms display higher tolerance of both bacteria to plasma than in single-species biofilms. A comparison between wet and dehydrated biofilms reveals reduced plasma efficacy in wet environments. Consequently, biofilm dehydration prior to the plasma treatment facilitates penetration of plasma reactive species leading to higher bacteria inactivation. The evaluation of plasma-generated gaseous reactive species reveals O3 and NO2 being dominant species contributing to the etching mechanism of the overall plasma anti-biofilm effect. Despite the strong anti-biofilm effect is obtained, the biofilm regrowth on the next day after plasma treatment implies on the inability of pulsed streamer corona discharge to permanently eradicate biofilms on a surface. The search for adequate plasma treatment conditions of biofilms remains crucial to avoid the appearance of more adaptive biofilms.

Myxobacteria from soil can substantially reduce the bacterial load in a wound infection model

AIMS

Myxobacteria are non-pathogenic, saprophytic, soil-dwelling predatory bacteria known for their antimicrobial potential. Many pathogenic bacteria form biofilms to protect themselves from antimicrobial agents and the immune system. This study has investigated the predatory activities of myxobacteria against pathogenic bacteria in biofilms.

METHODS AND RESULTS

A total of 50 soil samples were collected in and around Cardiff, South Wales (UK). Using a baiting method with 6 prey organisms, 32 myxobacteria were isolated and identified by 16S rRNA sequencing, of which 18 were Myxococcus spp. and 14 were Corallococcus spp. Predation assays, biofilm inhibition and disruption assays, and a dynamic, polymicrobial wound biofilm model were used with live myxobacteria to assess efficacy of predation. Good activity in predation assays was observed against Escherichia coli, while Enterococcus faecalis was more recalcitrant to myxobacteria. Staphylococcus aureus and Citrobacter freundii were significantly (P < 0.05) reduced in both biofilm inhibition and disruption assays compared to other pathogens. Considerable reductions (>3 log10 CFU) in the wound infection model were seen after 96 h of incubation, particularly for C. freundii and E. coli.

CONCLUSION

Using live predatory bacteria as an alternative therapeutic agent has received attention in the recent past to combat the problem of antimicrobial resistance. Myxobacteria isolated from soil using multiple prey organisms yielded diverse isolates, including strains which exhibited therapeutically promising activities in a variety of infection/biofilm assays.

Biochemistry of Bacterial Biofilm: Insights into Antibiotic Resistance Mechanisms and Therapeutic Intervention

Biofilms, composed of structured communities of bacteria embedded in a self-produced extracellular matrix, pose a significant challenge due to their heightened resistance to antibiotics and immune responses. This review highlights the mechanisms underpinning antibiotic resistance within bacterial biofilms, elucidating the adaptive strategies employed by microorganisms to withstand conventional antimicrobial agents. This encompasses the role of the extracellular matrix, altered gene expression, and the formation of persister cells, contributing to the recalcitrance of biofilms to eradication. A comprehensive understanding of these resistance mechanisms provides a for exploring innovative therapeutic interventions. This study explores promising avenues for future research, emphasizing the necessity of uncovering the specific genetic and phenotypic adaptations occurring within biofilms. The identification of vulnerabilities in biofilm architecture and the elucidation of key biofilm-specific targets emerge as crucial focal points for the development of targeted therapeutic strategies. In addressing the limitations of traditional antibiotics, this review discusses innovative therapeutic approaches. Nanomaterials with inherent antimicrobial properties, quorum-sensing inhibitors disrupting bacterial communication, and bacteriophages as biofilm-specific viral agents are highlighted as potential alternatives. The exploration of combination therapies, involving antimicrobial agents, biofilm-disrupting enzymes, and immunomodulators, is emphasized to enhance the efficacy of existing treatments and overcome biofilm resilience.

Flash chromatographic isolation of garcinol and isogarcinol from Garcinia indica Choisy (kokum) fruit and evaluation of their potential antibiofilm activity

The present study describes the isolation and separation of isogarcinol and garcinol from kokum fruit by flash chromatography using water (containing 0.1 % formic acid) and methanol mixed with acetonitrile (1:1) with UV detection at 254 nm and was characterised by HR-MS and NMR studies. These were further subjected to antimicrobial studies on Staphylococcus aureus FR1722 and Listeria monocytogenes Scott A by agar diffusion assay and broth microdilution method wherein the MIC (Minimum Inhibitory Concentration) of garcinol and isogarcinol were, 20 μg/mL and 50 μg/mL for S. aureus FR1722 and 50 μg/mL and 100 μg/mL for L. monocytogenes Scott A respectively. Further, studies on the control of biofilm growth were tested using MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide) assay followed by Crystal Violet (CV) assay, which showed up to 80 % inhibition. In addition, the biofilm eradication as evaluated by bright field microscopy and the metabolic activity were also carried out against these bacterial strains and the experimental details are presented.

Can polymeric nanofibers effectively preserve and deliver live therapeutic bacteria?

Probiotics and live therapeutic bacteria (LTB), their strictly regulated therapeutic counterpart, are increasingly important in treating and preventing biofilm-related diseases. This necessitates new approaches to (i) preserve bacterial viability during manufacturing and storage and (ii) incorporate LTB into delivery systems for enhanced therapeutic efficacy. This review explores advances in probiotic and LTB product development, focusing on preservation, protection, and improved delivery. Preservation of bacteria can be achieved by drying methods that decelerate metabolism. These methods introduce stresses affecting viability which can be mitigated with suitable excipients like polymeric or low molecular weight stabilizers. The review emphasizes the incorporation of LTB into polymer-based nanofibers via electrospinning, enabling simultaneous drying, encapsulation, and delivery system production. Optimization of bacterial survival during electrospinning and storage is discussed, as well as controlled LTB release achievable through formulation design using gel-forming, gastroprotective, mucoadhesive, and pH-responsive polymers. Evaluation of the presence of the actual therapeutic strains, bacterial viability and activity by CFU enumeration or alternative analytical techniques is presented as a key aspect of developing effective and safe formulations with LTB. This review offers insights into designing delivery systems, especially polymeric nanofibers, for preservation and delivery of LTB, guiding readers in developing innovative biotherapeutic delivery systems.

Microbial cell-type-based grouping model as a potential indicator of cervicovaginal flora prone to biofilm formation

Cervicovaginal (CV) microbiota is critical for the well-being of host. We investigated the relationship between the ratio of Lactobacilli (LB) and cocci/coccobacilli (C/CB)-type microbial cells with biofilm formation of CV mixed cultures of women with no inflammation/infection or any epithelial abnormalities in Pap-stained smears Group 1 (G1) corresponds to the flora with LB-type cells alone, whereas G2 corresponds to the LB-dominated flora. G3 contains balanced LB and C/CB cells and G4 is dominated with C/CB. G5 corresponds to a flora with C/CB-type cells alone. Biofilm formation of CV mixed cultures was assessed by crystal violet binding assay and optical density (OD)≥0.8 were defined as biofilm producers. G1 and G3 exist in higher frequencies compared to the other smear groups. However, although the frequency of G5 dominated with C/CB-type cells were the lowest (4%); biofilm formation in that group was observed in the highest frequency (42.9%). The least biofilm formation frequency was observed in G3 smears with balanced flora (1%). Biofilm formation in healthy CV flora increases when there becomes an imbalance between LB and C/CB-type cells and an increase in C/CB-type cells. Our approach may enable early detection of vaginal dysbiosis in healthy flora prone to biofilm-associated CV infections such as bacterial vaginosis (BV).

Antimicrobial Peptides: A Promising Alternative to Conventional Antimicrobials for Combating Polymicrobial Biofilms

Polymicrobial biofilms adhere to surfaces and enhance pathogen resistance to conventional treatments, significantly contributing to chronic infections in the respiratory tract, oral cavity, chronic wounds, and on medical devices. This review examines antimicrobial peptides (AMPs) as a promising alternative to traditional antibiotics for treating biofilm-associated infections. AMPs, which can be produced as part of the innate immune response or synthesized therapeutically, have broad-spectrum antimicrobial activity, often disrupting microbial cell membranes and causing cell death. Many specifically target negatively charged bacterial membranes, unlike host cell membranes. Research shows AMPs effectively inhibit and disrupt polymicrobial biofilms and can enhance conventional antibiotics' efficacy. Preclinical and clinical research is advancing, with animal studies and clinical trials showing promise against multidrug-resistant bacteria and fungi. Numerous patents indicate increasing interest in AMPs. However, challenges such as peptide stability, potential cytotoxicity, and high production costs must be addressed. Ongoing research focuses on optimizing AMP structures, enhancing stability, and developing cost-effective production methods. In summary, AMPs offer a novel approach to combating biofilm-associated infections, with their unique mechanisms and synergistic potential with existing antibiotics positioning them as promising candidates for future treatments.

Innovative approaches to controlling Salmonella in the meat industry

Salmonella, a Gram-negative, rod-shaped bacterium from the Enterobacteriaceae family, is a significant cause of illnesses in humans and animals. It resides in the digestive tracts of livestock, poultry, and other warm-blooded animals and can contaminate various environments and foods through fecal matter. Salmonella enterica, the main species that affects humans, is widespread in cattle, pigs, and poultry. Despite efforts to control pathogens in meat systems, over 1.4 million human salmonellosis cases occur annually in the U.S., with serotypes S. enteritidis and S. typhimurium being predominant. Advances in meat processing have targeted pathogen reduction at multiple stages, but more innovative approaches are needed for substantial public health impact. This paper discusses current and future strategies to minimize Salmonella in the food supply. It emphasizes pre- and post-harvest Salmonella prevalence by biomapping it through the whole processing chain, focusing on beef and pork interventions such as probiotics. These interventions have shown promise in reducing pathogen loads in cattle manure and lymph nodes. Techniques such as microbiome, whole genome sequencing (WGS), and electron microscopy (EM) provide detailed insights into Salmonella's genetic and bacterial structural-morphological characteristics, aiding in the development of targeted interventions. Integrating rapid detection, biomapping, and enviromapping enhances pathogen tracking in meat production, reducing Salmonella prevalence and improving risk assessment and food safety. The advanced, current, and innovative techniques allow for timely identification, detailed spatial and quantitative data, and more effective interventions. This leads to safer food products and reduces foodborne illnesses.

Innovative Bacterial Therapies and Genetic Engineering Approaches in Colorectal Cancer: A Review of Emerging Strategies and Clinical Implications

Colorectal cancer (CRC) is considered a widespread cancer, ranking second in mortality and incidence among cancer patients worldwide. CRC develops from adenoma to carcinoma through the dynamic interplay of genetic and environmental factors. The conventional modes of treatment, including operation, chemotherapy, and irradiation, are associated with significant challenges, such as drug resistance and toxicity, necessitating the exploration of new treatment modalities. These difficulties reveal the necessity of the emergence of new therapeutic approaches. This review mainly emphasizes the bacterial-based therapies that have recently developed like the engineered bacteriophage therapy and bacterial immunotherapy that pale the existing chemotherapy in terms of toxicity but are effective in killing tumor cells. Also, it also investigates various molecular genetic engineering strategies such as CRISPR-Cas9, CRISPR prime editing and gene silencing to achieve better targeting of CRC. Implementing these new approaches into the forefront of CRC treatment may bring better, more effective therapy with fewer side effects on patients' quality of life.

Chemical Composition and Antibacterial Effect of Clove and Thyme Essential Oils on Growth Inhibition and Biofilm Formation of Arcobacter spp. and Other Bacteria

Background: In recent years, significant resistance of microorganisms to antibiotics has been observed. A biofilm is a structure that significantly aids the survival of the microbial population and also significantly affects its resistance. Methods: Thyme and clove essential oils (EOs) were subjected to chemical analysis using gas chromatography coupled to mass spectrometry (GC-MS) and gas chromatography with a flame ionization detector (GC-FID). Furthermore, the antimicrobial effect of these EOs was tested in both the liquid and vapor phases using the volatilization method. The effect of the EOs on growth parameters was monitored using an RTS-8 bioreactor. However, the effect of the EOs on the biofilm formation of commonly occurring bacteria with pathogenic potential was also monitored, but for less described and yet clinically important strains of Arcobacter spp. Results: In total, 37 and 28 compounds were identified in the thyme and clove EO samples, respectively. The most common were terpenes and also derivatives of phenolic substances. Both EOs exhibited antimicrobial activity in the liquid and/or vapor phase against at least some strains. The determined antimicrobial activity of thyme and clove oil was in the range of 32-1024 µg/mL in the liquid phase and 512-1024 µg/mL in the vapor phase, respectively. The results of the antimicrobial effect are also supported by similar conclusions from monitoring growth curves using the RTS bioreactor. The effect of EOs on biofilm formation differed between strains. Biofilm formation of Pseudomonas aeruginosa was completely suppressed in an environment with a thyme EO concentration of 1024 µg/mL. On the other hand, increased biofilm formation was found, e.g., in an environment of low concentration (1-32 µg/mL). Conclusions: The potential of using natural matrices as antimicrobials or preservatives is evident. The effect of these EOs on biofilm formation, especially Arcobacter strains, is described for the first time.

Enhancing plant resilience: Nanotech solutions for sustainable agriculture

The global population growth is driving up the demand for agricultural products, while traditional farming methods like those from the Green Revolution are becoming unsustainable due to climate change. To address these challenges and ensure agricultural sustainability, innovative techniques, such as nanotechnology, are essential to meet rising food demands and enhance agricultural sustainability. Nanotechnology, which promotes a more sustainable and resilient agricultural system while enhancing food security, is a key catalyst for the Agri-tech revolution. This review offers a progressive analysis of nanotechnology's role in managing plant stress. It explores how precision agriculture, particularly via nanosensors, is enhancing our comprehension of plant stress conditions. The integration of nanotechnology with genetic engineering methods, notably CRISPR-Cas technology, is also examined. Furthermore, the review considers the potential toxicological effects of nanoparticles (NPs) on both the environment and plants. Our review has the potential to make a significant impact on human food security by enhancing food production and availability while promoting sustainable agricultural practices. By tackling these challenges, we can contribute to a more reliable and sustainable food supply for the global population.

Metabolic interplay between Proteus mirabilis and Enterococcus faecalis facilitates polymicrobial biofilm formation and invasive disease

Biofilms play an important role in the development and pathogenesis of catheter-associated urinary tract infection (CAUTI). Proteus mirabilis and Enterococcus faecalis are common CAUTI pathogens that persistently co-colonize the catheterized urinary tract and form biofilms with increased biomass and antibiotic resistance. In this study, we uncover the metabolic interplay that drives biofilm enhancement and examine the contribution to CAUTI severity. Through compositional and proteomic biofilm analyses, we determined that the increase in biofilm biomass stems from an increase in the protein fraction of the polymicrobial biofilm. We further observed an enrichment in proteins associated with ornithine and arginine metabolism in polymicrobial biofilms compared with single-species biofilms. We show that arginine/ornithine antiport by E. faecalis promotes arginine biosynthesis and metabolism in P. mirabilis, ultimately driving the increase in polymicrobial biofilm protein content without affecting viability of either species. We further show that disrupting E. faecalis ornithine antiport alters the metabolic profile of polymicrobial biofilms and prevents enhancement, and this defect was complemented by supplementation with exogenous ornithine. In a murine model of CAUTI, ornithine antiport did not contribute to E. faecalis colonization but was required for the increased incidence of urinary stone formation and bacteremia that occurs during polymicrobial CAUTI with P. mirabilis. Thus, disrupting metabolic interplay between common co-colonizing species may represent a viable strategy for reducing risk of bacteremia.IMPORTANCEChronic infections often involve the formation of antibiotic-resistant biofilm communities that include multiple different microbes, which pose a challenge for effective treatment. In the catheterized urinary tract, potential pathogens persistently co-colonize for long periods of time and the interactions between them can lead to more severe disease outcomes. In this study, we identified the metabolite L-ornithine as a key mediator of disease-enhancing interactions between two common and challenging pathogens, Enterococcus faecalis and Proteus mirabilis. Disrupting ornithine-mediated interactions may therefore represent a strategy to prevent polymicrobial biofilm formation and decrease risk of severe disease.

Serum amikacin concentrations in dogs with naturally occurring open wounds treated with topical amikacin in carboxymethylcellulose hydrogel

OBJECTIVE

To quantify serum amikacin concentrations in dogs undergoing wound management with topical amikacin (45 mg/mL) 3% carboxymethylcellulose hydrogel.

STUDY DESIGN

Prospective clinical study.

SAMPLE POPULATION

Eleven client-owned dogs.

METHODS

Dogs with naturally occurring wounds, undergoing treatment with topical amikacin gel, were enrolled. A whole blood sample was collected prior to initial application of the gel. Up to a maximum dose of 30 mg/kg of gel, was applied directly on the wound and the wound was bandaged. Serial blood sampling was performed at approximately 2, 4, 8, 12, 18, 24, 32, 40, 48, 56, 64, and 72 h after application of amikacin gel. The sampling schedule was reset following each bandage change and new application of the gel. Up to 20 samples per dog were collected. The Siemens Syva EMIT Amikacin Assay was used to quantify the concentration of amikacin in each blood serum sample. The lower limit of quantification (LLOQ) of the test was 2.5 μg/mL.

RESULTS

Amikacin gel was applied a total of 31 times (dose range, 0.1-24.9 mg/kg). A total of 153 samples were analyzed. Five samples in three different dogs were above the LLOQ at approximately 2 h after gel application (range 2.75-3.82 μg/mL). All other samples were below the LLOQ.

CONCLUSION

Routine use of amikacin gel for open wound management did not result in serum amikacin levels above 5 μg/mL.

CLINICAL SIGNIFICANCE

Topical amikacin gel may be a safe treatment option for wounds in dogs with resistant infections or biofilms.

Potential Antimicrobial and Cytotoxic Activity of Caralluma indica Seed Extract

Background: Plant-derived phytochemicals are crucial in fighting bacterial infections and in cancer therapy. Objective: This study investigates the phytochemical composition of the ethanolic extract obtained from Caralluma indica (C. indica) seeds and assesses its antimicrobial, anticancer, and antioxidant activities. Results: GC-MS analysis found 30 phytochemicals in C. indica seeds, including 5 bioactive compounds that have been shown to have antioxidant, antimicrobial, and cytotoxicity properties, through in silico evaluation. Phytochemical screening of C. indica identified and measured the phenolic compounds, providing insight into its bioactive potential and therapeutic properties. C. indica exhibited robust antioxidant capacity (DPPH, ABTS, nitric oxide, and H2O2 radical scavenging) alongside potent antimicrobial activity against oral pathogen and cytotoxicity activity on a human oral squamous carcinoma cell line (OECM-1) (EC50 of 169.35 µg/mL) and yeast cell Saccharomyces cerevisiae (215.82 µg/mL), with a selective index of 1.27. The subminimum % MBC/MFC of C. indica significantly reduced biofilm formation against oral pathogens (p < 0.05). Molecular docking studies showed a strong correlation (r = 0.862) between antifungal and anticancer targets, suggesting that the antimicrobial agents in C. indica contribute to cancer prevention mechanisms. Conclusions: These findings propose C. indica seeds as promising candidates for combating oral pathogens, inhibiting biofilm formation, and reducing the risk of oral cancer progression.

BDSF Analogues Inhibit Quorum Sensing-Regulated Biofilm Production in Xylella fastidiosa

Xylella fastidiosa is an aerobic, Gram-negative bacterium that is responsible for many plant diseases. The bacterium is the causal agent of Pierce's disease in grapes and is also responsible for citrus variegated chlorosis, peach phony disease, olive quick decline syndrome and leaf scorches of various species. The production of biofilm is intrinsically linked with persistence and transmission in X. fastidiosa. Biofilm formation is regulated by members of the Diffusible Signal Factor (DSF) quorum sensing signalling family which are comprised of a series of long chain cis-unsaturated fatty acids. This article describes the evaluation of a library of N-acyl sulfonamide bioisosteric analogues of BDSF, XfDSF1 and XfDSF2 for their ability to control biofilm production in X. fastidiosa. The compounds were screened against both the wild-type strain Temecula and an rpfF* mutant which can perceive but not produce XfDSF. Planktonic cell abundance was measured via OD600 while standard crystal violet assays were used to determine biofilm biomass. Several compounds were found to be effective biofilm inhibitors depending on the nature of the sulfonamide substituent. The findings reported here may provide future opportunities for biocontrol of this important plant pathogen.

RBProkCNN: Deep learning on appropriate contextual evolutionary information for RNA binding protein discovery in prokaryotes

RNA-binding proteins (RBPs) are central to key functions such as post-transcriptional regulation, mRNA stability, and adaptation to varied environmental conditions in prokaryotes. While the majority of research has concentrated on eukaryotic RBPs, recent developments underscore the crucial involvement of prokaryotic RBPs. Although computational methods have emerged in recent years to identify RBPs, they have fallen short in accurately identifying prokaryotic RBPs due to their generic nature. To bridge this gap, we introduce RBProkCNN, a novel machine learning-driven computational model meticulously designed for the accurate prediction of prokaryotic RBPs. The prediction process involves the utilization of eight shallow learning algorithms and four deep learning models, incorporating PSSM-based evolutionary features. By leveraging a convolutional neural network (CNN) and evolutionarily significant features selected through extreme gradient boosting variable importance measure, RBProkCNN achieved the highest accuracy in five-fold cross-validation, yielding 98.04% auROC and 98.19% auPRC. Furthermore, RBProkCNN demonstrated robust performance with an independent dataset, showcasing a commendable 95.77% auROC and 95.78% auPRC. Noteworthy is its superior predictive accuracy when compared to several state-of-the-art existing models. RBProkCNN is available as an online prediction tool (https://iasri-sg.icar.gov.in/rbprokcnn/), offering free access to interested users. This tool represents a substantial contribution, enriching the array of resources available for the accurate and efficient prediction of prokaryotic RBPs.

Managing drug therapy-related problems and assessment of chronic diabetic wounds

Type 2 diabetes mellitus (T2DM), responsible for most diabetes cases recorded worldwide, increases the risk of chronic wounds and amputation. Patients with T2DM appear to be more susceptible to delayed wound healing due to their treatment adherence. This review explores the specifics of polypharmacy, side effects, possible drug interactions and the importance of medication adherence for therapeutic efficacy. We discuss the effects of anti-diabetes medications on wound healing as well as the role that biofilms and microbial infections play in diabetic wounds. Inconsistent use of medications can lead to poor glycaemic control, which negatively affects the healing process of diabetic foot ulcers. Managing chronic wounds represents a substantial portion of healthcare expenditures. Biofilm-associated infections are difficult for the immune system to treat and respond inconsistently to antibiotics as these infections are slow growing and persistent. Additionally, we emphasize the critical role pharmacists play in enhancing patient adherence and optimizing diabetes treatment by offering comprehensive coverage of drugs associated with problems related to pharmacological therapy in type 2 diabetes.

Essential oils of Eugenia spp. (myrtaceae) show in vitro antibacterial activity against Staphylococcus aureus isolates from bovine mastitis

Bovine mastitis, an inflammation of the mammary glands, is mainly caused by bacteria such as Staphylococcus aureus. While antibiotics are the primary treatment for this disease, their effectiveness is often diminished due to resistant strains and biofilm formation, creating the need for safer and more efficient therapies. Plant-based oil therapies, particularly those derived from the genus Eugenia, are gaining popularity due to their pharmacological potential and historical use. In this study, we evaluated the antibacterial, antibiofilm, and synergistic potential of essential oils (EOs) from four species of the genus Eugenia (E. brejoensis, E. gracillima, E. pohliana, and E. stictopetala) against S. aureus isolates from bovine mastitis. The EO of E. stictopetala was obtained by hydrodistillation, and its composition was analyzed using gas chromatography coupled with mass spectrometry. The experiment employed seven clinical isolates from mastitis and two control strains: ATCC 33591 (methicillin-resistant S. aureus - MRSA) and ATCC 25923 (methicillin-susceptible and biofilm producer). A broth microdilution assay was used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the EOs and oxacillin. The EO of E. stictopetala contained (E)-caryophyllene (18.01%), β-pinene (8.84%), (E)-nerolidol (8.24%), and α-humulene (6.14%) as major compounds. In the MIC assay, all essential oils showed bactericidal and bacteriostatic effects, especially the species E. brejoensis and E. pohliana, which had MICs ranging from 64 to 256 µg/mL. Regarding the antibiofilm effect, all essential oils were capable of interfering with biofilm formation at subinhibitory concentrations of ½ and ¼ of the MIC. However, they did not significantly affect pre-established biofilms. Additionally, a synergistic interaction was detected between the EOs and oxacillin, with a reduction of 75-93.75% in the antimicrobial MIC. Molecular docking studies indicated that the phytochemicals β-(E)-caryophyllene, (E)-nerolidol, Δ-elemene, and α-cadinol present in the EOs formed more stable complexes with penicillin-binding proteins, indicating a possible mechanism of antibacterial action. Therefore, these results show that the essential oils of Eugenia spp. are promising sources for the development of new therapeutic methods, opening new perspectives for a more effective treatment of bovine mastitis.

Biliary stents for active materials and surface modification: Recent advances and future perspectives

Demand for biliary stents has expanded with the increasing incidence of biliary disease. The implantation of plastic or self-expandable metal stents can be an effective treatment for biliary strictures. However, these stents are nondegradable and prone to restenosis. Surgical removal or replacement of the nondegradable stents is necessary in cases of disease resolution or restenosis. To overcome these shortcomings, improvements were made to the materials and surfaces used for the stents. First, this paper reviews the advantages and limitations of nondegradable stents. Second, emphasis is placed on biodegradable polymer and biodegradable metal stents, along with functional coatings. This also encompasses tissue engineering & 3D-printed stents were highlighted. Finally, the future perspectives of biliary stents, including pro-epithelialization coatings, multifunctional coated stents, biodegradable shape memory stents, and 4D bioprinting, were discussed.

Understanding Quorum-Sensing and Biofilm Forming in Anaerobic Bacterial Communities

Biofilms are complex, highly organized structures formed by microorganisms, with functional cell arrangements that allow for intricate communication. Severe clinical challenges occur when anaerobic bacterial species establish long-lasting infections, especially those involving biofilms. These infections can occur in device-related settings (e.g., implants) as well as in non-device-related conditions (e.g., inflammatory bowel disease). Within biofilms, bacterial cells communicate by producing and detecting extracellular signals, particularly through specific small signaling molecules known as autoinducers. These quorum-sensing signals are crucial in all steps of biofilm formation: initial adhesion, maturation, and dispersion, triggering gene expression that coordinates bacterial virulence factors, stimulates immune responses in host tissues, and contributes to antibiotic resistance development. Within anaerobic biofilms, bacteria communicate via quorum-sensing molecules such as N-Acyl homoserine lactones (AHLs), autoinducer-2 (AI-2), and antimicrobial molecules (autoinducing peptides, AIPs). To effectively combat pathogenic biofilms, understanding biofilm formation mechanisms and bacterial interactions is essential. The strategy to disrupt quorum sensing, termed quorum quenching, involves methods like inactivating or enzymatically degrading signaling molecules, competing with signaling molecules for binding sites, or noncompetitively binding to receptors, and blocking signal transduction pathways. In this review, we comprehensively analyzed the fundamental molecular mechanisms of quorum sensing in biofilms formed by anaerobic bacteria. We also highlight quorum quenching as a promising strategy to manage bacterial infections associated with anaerobic bacterial biofilms.

Biofilm-Forming Antibiotic-Resistant Bacteria in Water From Distribution Systems: Occurrence and Public Health Implications

Biofilm is a structurally-connected microbial community, covered by a self-produced polymeric matrix and adhered to biotic or abiotic surfaces. This study aimed to evaluate the occurrence of biofilm-producing antibiotic-resistant bacteria in water from distribution systems. Water samples were taken from 32 tanks across Ondo City and Akure metropolis, Nigeria. Information regarding the sanitation status of the tanks was gathered by observation and oral interviews. The physicochemical properties were determined using standard methods. Using the pour plate technique. Agars included serially diluted water samples were inoculated onto plate count agar, mannitol salt agar, Salmonella-Shigella agar, MacConkey agar, and cetrimide nutrient agar to assess total viable bacteria, Staphylococcus aureus, Salmonella and Shigella, coliforms, and Pseudomonas aeruginosa, respectively. Eosin-methylene blue agar was used to cultivate Escherichia coli and Enterobacter aerogenes. Pure isolates were characterised using API kits and assessed for antibiotic resistance and biofilm production employing the Kirby-Bauer and tissue culture plate techniques, respectively. The ages of the water tanks ranged from 1 to 25 years old; all tanks had cover-lids; 13 (40.63%) had water guards while 12 (37.5%) underwent water treatment. The physicochemical properties chiefly fell within WHO standards for drinking water. One hundred and eighty-seven isolates were obtained. S. aureus (15.51%) had the highest frequency while Salmonella enterica (3.2%) had the lowest frequency. Thirty-six percent of the isolates were strong biofilm producers, while 20.67% Gram-negative and 18.69% Gram-positive bacterial isolates were antibiotic-resistant. This study revealed a high occurrence of biofilm-forming bacteria and prevalence of antibiotic-resistant bacteria in water distribution systems, emphasizing the urgency of improving water quality for public health protection.

Infective Endocarditis by Biofilm-Producing Methicillin-Resistant Staphylococcus aureus-Pathogenesis, Diagnosis, and Management

Infective endocarditis (IE) is a life-threatening condition with increasing global incidence, primarily caused by Staphylococcus aureus, especially methicillin-resistant strains (MRSA). Biofilm formation by S. aureus is a critical factor in pathogenesis, contributing to antimicrobial resistance and complicating the treatment of infections involving prosthetic valves and cardiovascular devices. Biofilms provide a protective matrix for MRSA, shielding it from antibiotics and host immune defenses, leading to persistent infections and increased complications, particularly in cases involving prosthetic materials. Clinical manifestations range from acute to chronic presentations, with complications such as heart failure, embolic events, and neurological deficits. Diagnosis relies on the Modified Duke Criteria, which have been updated to incorporate modern cardiovascular interventions and advanced imaging techniques, such as PET/CT (positron emission tomography, computed tomography), to improve the detection of biofilm-associated infections. Management of MRSA-associated IE requires prolonged antimicrobial therapy, often with vancomycin or daptomycin, needing a combination of antimicrobials in the setting of prosthetic materials and frequently necessitates surgical intervention to remove infected prosthetic material or repair damaged heart valves. Anticoagulation remains controversial, with novel therapies like dabigatran showing potential benefits in reducing thrombus formation. Despite progress in treatment, biofilm-associated resistance poses ongoing challenges. Emerging therapeutic strategies, including combination antimicrobial regimens, bacteriophage therapy, antimicrobial peptides (AMPs), quorum sensing inhibitors (QSIs), hyperbaric oxygen therapy, and nanoparticle-based drug delivery systems, offer promising approaches to overcoming biofilm-related resistance and improving patient outcomes. This review provides an overview of the pathogenesis, current management guidelines, and future directions for treating biofilm-related MRSA IE.

A novel dual-staining method for cost-effective visualization and differentiation of microbial biofilms

Microbial biofilms are intricate communities that pose significant challenges in clinical and microbiological settings due to their resistance to antibiotics and immune responses. Advanced microscopy techniques, such as scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and fluorescence microscopy, are often employed to visualize and differentiate between these biofilms. However, these methods are not feasible in all laboratories because of their high cost and complexity. In contrast, simpler techniques like crystal violet and Congo red staining fail to differentiate bacterial cells from the biofilm matrix. This study introduces a novel dual-staining method using Maneval's stain for microbial biofilm detection and differentiation. This simple, cost-effective method requires only basic equipment and minimal reagents, making it suitable for routine use across various settings. We applied the dual-staining method to various microbial species, including Staphylococcus aureus, Enterococcus faecalis, Candida albicans, Escherichia coli, and Pseudomonas aeruginosa. When compared with the microtiter plate assay, results showed strong agreement, with the dual-staining method effectively differentiating between bacterial cells and the surrounding biofilm matrix, displaying a distinctive blue polysaccharide layer surrounding the magenta‒red bacterial cells. This technique offers a viable alternative to more expensive and complex biofilm detection methods, with potential applications in clinical diagnostics and biofilm research.

Bacterial single-cell RNA sequencing captures biofilm transcriptional heterogeneity and differential responses to immune pressure

Biofilm formation is an important mechanism of survival and persistence for many bacterial pathogens. These multicellular communities contain subpopulations of cells that display metabolic and transcriptional diversity along with recalcitrance to antibiotics and host immune defenses. Here, we present an optimized bacterial single-cell RNA sequencing method, BaSSSh-seq, to study Staphylococcus aureus diversity during biofilm growth and transcriptional adaptations following immune cell exposure. BaSSSh-seq captures extensive transcriptional heterogeneity during biofilm compared to planktonic growth. We quantify and visualize transcriptional regulatory networks across heterogeneous biofilm subpopulations and identify gene sets that are associated with a trajectory from planktonic to biofilm growth. BaSSSh-seq also detects alterations in biofilm metabolism, stress response, and virulence induced by distinct immune cell populations. This work facilitates the exploration of biofilm dynamics at single-cell resolution, unlocking the potential for identifying biofilm adaptations to environmental signals and immune pressure.

Development of Naphthalene-Derivative Bis-QACs as Potent Antimicrobials: Unraveling Structure-Activity Relationship and Microbiological Properties

While the pandemic is behind us, the world community faces a global threat of bacterial resistance outbreak. One of the key ways to combat the spread of multi-resistant bacteria is infection prevention and control tactics using modern antiseptic and disinfectant compositions. Herein, we continue the path to unravel the structure-activity relationship (SAR) of potent pyridine-derived biocide class bis-quaternary ammonium compounds (QACs). In this study, twenty dihydroxynaphthalene-derivative bis-QACs were subjected to extensive microbiological analysis on planktonic cells and biofilms of the ESKAPE microorganisms. Among them, hit compounds were superior in their bacteriostatic and bactericidal action to commercial mono-QACs and were comparable to the best bis-QAC antiseptic on the market. SAR analysis indicated that the linker conformation does not significantly affect the activity, though structure symmetry and especially lipophilicity had an influence on antibacterial performance. Furthermore, we delve deeper in investigation of the antimicrobial potential of bis-QACs and conducted a variety of assays, including time-kill kinetics, bacterial resistance formation, cell morphology, and cytotoxicity. Studies showed promising results for compounds 5d and 6d, indicating 2 to 3-fold less cytotoxicity and hemotoxicity compared to commercial QACs. Moreover, SEM imaging revealed that bis-QACs can cause severe membrane damage to S. aureus and P. aeruginosa strains, confirming great potential of novel compounds as antiseptic and disinfectant.

Molecular Exploration of Mycoplasma fermentans and Mycoplasma genitalium in Mexican Women with Cervicitis

Genital Mycoplasmas are implicated in adverse pregnancy outcomes and the development of infertility. However, the role of Mycoplasma fermentans in these outcomes has not been adequately studied; therefore, its participation in these sufferings requires further investigation. This study aimed to evaluate the prevalence of M. fermentans in pregnant and non-pregnant women. End-point PCR was used to analyze two hundred and twenty-eight endocervical samples for M. hominis, M. genitalium, M. fermentans, M. pirum, Ureaplasma urealyticum, and U. parvum diagnoses. The prevalence of Mycoplasma spp. was as follows: U. parvum was found in 83 samples (36.4%), U. urealyticum in 39 instances (17.1%), M. hominis in 36 (15.7%), M. fermentans in 32 (14%), M. genitalium in 15 (6.6%), and M. pirum in 0 samples. No association was found between the Mycoplasma spp. and some infertility conditions or adverse pregnancy. However, M. fermentans and M. hominis were found to be associated with bacterial vaginosis (RR = 3.4 CI 95% 1.85-6.3, p < 0.005). In conclusion, M. fermentans and M. hominis were isolated more often in women with bacterial vaginosis, which suggests that these bacteria could contribute to the development of this pathology.

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.