Successful treatment of endodontic and periapical diseases requires the elimination of bacteria and microbial biofilms from root canals. Currently, the most preferred irrigation method involves the ...delivery of sodium hypochlorite via the combination of a syringe and ultrasonic activation. Calcium hydroxide is the main choice for intracanal medicament between endodontic appointments and treatment. However, conventional chemical disinfection of root canals is controversial due to drug permeability and drug resistance. New small biomolecule formulations with high penetrability and bioremediatory capacity, including antimicrobial peptides such as M33D and LL-37, antisense RNA ASwalR/ASvicR and nanoparticles such as silver nanoparticles, mesoporous calcium-silicate nanoparticles and chitosan nanoparticles, have effective antibacterial and antibiofilm properties for use in root canal systems and dentinal tubules, thereby promoting the healing of apical lesions. However, the in vivo drug stability, biosafety, and cl
Staphylococcus aureus (S. aureus) is an important cause of infections associated with implanted medical devices due to the formation of bacterial biofilm, which can prevent the penetration of drugs, ...thus posing a serious multi-drug resistance. Methicillin-resistant Staphylococcus aureus (MRSA) is one of them. In order to enhance the biofilm elimination effect of Baicalein (BA), a BA-loaded Tyr/HA/CD-CS nano-delivery system was successfully prepared using β-cyclodextrin grafted with chitosan (CD-CS), Hyaluronic Acid (HA), and D-Tyrosine (D-Tyr). The Tyr/HA/CD-CS-BA-NPs have a uniform particle size distribution with a particle size of 238.1 ± 3.06 nm and a PDI of 0.130 ± 0.02. The NPs showed an obvious inhibitory effect on planktonic bacteria with a MIC of 12.5 μg/mL. In vivo and in vitro tests showed that the NPs could enhance the elimination effect of BA on the MRSA biofilm. The results of Confocal Laser Scanning Microscopy (CLSM), Live & Dead Kit, and colony count experiments illustrated that Tyr/HA/CD-CS-BA-NPs could enhance the permeability of drugs to the biofilm and improve the ability to kill the biofilm bacteria, which may be an important mechanism to enhance the elimination of the MRSA biofilm. These findings will help develop new, effective medicaments for treating bacterial biofilm infections.
Polymicrobial biofilms with fungi and bacteria are the leading cause for the failure of medical devices and related infections. In this study, antibiofilm activities of carboxymethyl chitosan ...(CM-chitosan) on monomicrobial and polymicrobial biofilms of Staphylococcus epidermidis and Candida tropicalis in vitro were evaluated. CM-chitosan was effective as a sole agent, inhibiting both monomicrobial and polymicrobial biofilms in microplates and also on the silicone surface in short- and long-term periods. Biofilm architecture was investigated by scanning electron microscopy and confocal laser scanning microscopy was used to examine living/dead organisms within biofilm. CM-chitosan inhibited planktonic growth as well as adhesion. Further biofilm formation was inhibited by CM-chitosan added at 90min or 12h after biofilm initiation. CM-chitosan may serve as a possible antibiofilm agent to limit monomicrobial and polymicrobial biofilm.
Functional bacterial amyloids play a crucial role in the formation of biofilms, which mediate chronic infections and contribute to antimicrobial resistance. This study focuses on the FapC amyloid ...fibrillar protein from Pseudomonas, a major contributor to biofilm formation. We investigate the initial steps of FapC amyloid formation and the impact of the chaperone‐like protein FapA on this process. Using solution nuclear magnetic resonance (NMR), we recently showed that both FapC and FapA are intrinsically disordered proteins (IDPs). Here, the secondary structure propensities (SSPs) are compared to alphafold (DeepMind, protein structure prediction tool/algorithm: https://alphafold.ebi.ac.uk/) models. We further demonstrate that the FapA chaperone interacts with FapC and significantly slows down the formation of FapC fibrils. Our NMR titrations reveal ~ 18% of the resonances show FapA‐induced chemical shift perturbations (CSPs), which has not been previously observed, the largest being for A82, N201, C237, C240, A241, and G245. These sites may suggest a specific interaction site and/or hotspots of fibrillation inhibition/control interface at the repeat‐1 (R1)/loop‐2 (L2) and L2/R3 transition areas and at the C‐terminus of FapC. Remarkably, ~ 90% of FapA NMR signals exhibit substantial CSPs upon titration with FapC, the largest being for S63, A69, A80, and I92. A temperature‐dependent effect of FapA was observed on FapC by thioflavin T (ThT) and NMR experiments. This study provides a detailed understanding of the interaction between the FapA and FapC, shedding light on the regulation and slowing down of amyloid formation, and has important implications for the development of therapeutic strategies targeting biofilms and associated infections.
This study shows that the Pseudomonas FapA chaperone interacts with functional amyloid FapC and significantly slows down FapC fibrillation. Despite both proteins being intrinsically disordered, by using solution NMR spectroscopy, we demonstrate that FapA chaperone and FapC interaction. This study provides a detailed understanding of the interaction between these two proteins and sheds light on the regulation and slowing down of amyloid formation.
The ongoing escalation of drug-resistant bacteria creates the leading challenges for human health. Current predictions show that deaths due to bacterial illness will be more in comparison to cancer ...in 2050. Irrational use of antibiotics, prolonged regimen and using as a prophylactic treatment for various infections are leading cause of microbial resistance. It is an emerging approach to introduce evolving nanomaterials (NMs) as a base of antibacterial therapy to overcome the bacterial resistance pattern. NMs can implement several bactericidal ways and turn into a challenge for bacteria to survive and develop resistance against NMs. All the pathways depend on the surface chemistry, shape, core material and size of NMs. Because of these reasons, NMs based stuff shows a critical role in advancing the treatment efficiency by interacting with the cellular system of bacteria and functioned as an antibiotic substitute. We divided this review into two sections. The first part highlights the development of microbial resistance to antibiotics and their mechanisms. The second section details the NMs mechanisms to combat antibiotic resistance. In short, we try to summarize the advances in NMs role to deal with microbial resistance and giving solution as antibiotics substitute.
Bacterial biofilms, highly resistant to the conventional antimicrobial therapy, remain an unresolved challenge pressing the medical community to investigate new and alternative strategies to fight ...chronic implant-associated infections. Recently, strictly lytic bacteriophages have been revalued as powerful agents to kill antibiotic-resistant bacteria even in biofilm. Here, the interaction of T3 bacteriophage and planktonic and biofilm Escherichia coli TG1, respectively, was evaluated using isothermal microcalorimetry. Microcalorimetry is a non-invasive and highly sensitive technique measuring growth-related heat production of microorganisms in real-time. Planktonic and biofilm E. coli TG1 were exposed to different titers of T3 bacteriophage, ranging from 102 to 107 PFU/ml. The incubation of T3 with E. coli TG1 showed a strong inhibition of heat production both in planktonic and biofilm already at lower bacteriophage titers (103 PFU/ml). This method could be used to screen and evaluate the antimicrobial potential of different bacteriophages, alone and in combination with antibiotics in order to improve the treatment success of biofilm-associated infections.
Remarkable resistance of bacterial biofilms to high doses of antimicrobials and antibiotics is one of their main challenges. Encapsulation of proteolytic enzymes is one of the suggested strategies to ...tackle this problem. In this regard, the antibacterial and anti-biofilm activity of biocompatible hyaluronic acid- Lysine nanogels containing serratiopeptidase (SRP-loaded HA-Lys nanogel) was assessed against P. aeruginosa and S. aureus strains. SRP-loaded HA-Lys nanogel was prepared using dropping method and optimized by Box-Behnken experimental design. These formulations were studied for physical characterization, release profile, stability, bioactivity, and anti-biofilm effects. The particle size, polydispersity index (PDI), and surface charge were measured by Zetasizer Nano ZS. The average particle size and zeta potential of the optimum sample were 156 nm and -14.1 mV, respectively. SRP release showed an initial burst followed by sustained release and the highest release was around 77%. Enzyme biological activity data revealed the higher efficiency of free SRP compared to SRP-loaded HA-Lys nanogel. The time-kill assay showed that both forms of SRP-loaded HA-Lys nanogel and blank HA-Lys nanogel showed significant antimicrobial activity against examined bacteria in comparison to the free enzyme. The obtained results demonstrated improved anti-biofilm efficacy and down regulation of tested biofilm genes for both SRP-loaded HA-Lys nanogel 100% and blank HA-Lys nanogel 100% compared to SRP 100%.
Bacterial behaviors such as virulence factor secretion and biofilm formation are critical for survival, and are effectively regulated through quorum sensing, a mechanism of intra- and interspecies ...communication in response to changes in cell density and species complexity. Many bacterial species colonize host tissues and form a defensive structure called a biofilm, which can be the basis of inflammatory diseases. Periodontitis, a chronic inflammatory disease affecting the periodontium, is caused by subgingival biofilms related to periodontopathogens. In particular, Fusobacterium nucleatum is a major co-aggregation bridge organism in the formation and growth of subgingival biofilms, linking the early and late colonizers in periodontal biofilms. According to our previous study, the intergeneric quorum-sensing signal molecule autoinducer-2 (AI-2) of F. nucleatum plays a key role in intra- and interspecies interactions of periodontopathogens, and may be a good target for periodontal biofilm inhibition. Recently, brominated furanones produced by the macroalga Delisea pulchra were shown to inhibit biofilm formation via AI-2, and have been investigated toward the goal of increasing the inhibition effect. In this study, we describe the synthesis of new bromofuranone analogs, i.e., 3-(dibromomethylene)isobenzofuran-1(3H)-one derivatives, and demonstrate their inhibitory activities against biofilm formation by periodontopathogens, including F. nucleatum, Porphyromonas gingivalis, and Tannerella forsythia.
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•New bicyclic brominated furanones were synthesized as potent QS inhibitors.•Inhibitors showed high inhibitory effects on the periodontopathogen biofilm formation.•Active compounds significantly inhibited the F. nucleatum AI-2 activity.•The inhibitors showed neither cytotoxicity nor induction of inflammatory response.
Abstract
Background
Previous studies found differences in the utilization of different carbon sources during biofilm formation by Bacillus cereus. Illumina HiSeq high-throughput sequencing technology ...was used to investigate the changes in gene transcript levels in Bacillus cereus biofilm bacteria under different carbon source conditions.
Results
Compared with the control group, the number of differentially expressed genes in the glucose, maltose, lactose, and skim milk-supplemented groups was 351, 1136, 133, and 487, respectively. The results showed that the pathways involved in the differentially expressed genes were mainly distributed in glycolysis and pentose phosphate pathway, tricarboxylic acid cycle, amino acid metabolism, and fatty acid metabolism. The gene expression of enzymes related to acetoin synthesis from pyruvate was mostly upregulated in the glucose-supplemented group. The gene expression of enzymes related to pyruvate synthesis of branched-chain amino acids in the maltose-supplemented group was mostly upregulated. In the lactose-supplemented group, the gene expression of acetoin biosynthesis from pyruvate was upregulated. Pyruvate production through glycolysis pathway increased in the skim milk-supplemented group, but the metabolic capacity of the tricarboxylic acid cycle did not change significantly.
Conclusion
The content of pyruvate stored by Bacillus cereus biofilm bacteria through glycolysis or pentose phosphate pathway increased, but the carbon flux into the tricarboxylic acid cycle did not increase, which suggested that carbon fluxes in the extracellular polysaccharide synthesis pathway of the biofilm may be increased, resulting in increased biofilm biomass formation.
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