Antibiofilm Properties Research Articles

A Critical Review of Postbiotics as Promising Novel Therapeutic Agents for Clostridial Infections.

Clostridial infections, known for their severity and rapid progression, present significant challenges in both clinical and veterinary fields. These bacteria, which can survive without oxygen and produce protective spores, cause many diseases, ranging from simple gastrointestinal disorders to severe and potentially fatal infections including botulism, tetanus, and gas gangrene. The rising occurrence of antibiotic-resistant strains and the repetitive character of some Clostridial illnesses, including Clostridioides difficile infections (CDI), highlight the immediate need for alternate treatment approaches. Postbiotics, which are metabolites derived from probiotics, are showing great potential as effective agents against these diseases. The current study offers a comprehensive investigation of the potential of postbiotics as therapeutic agents for treating Clostridial infections, including C. difficile, Clostridium perfringens, Clostridium botulinum, and Clostridium tetani. It also examines the processes by which postbiotics exert their effects. Preliminary investigations have shown that postbiotics have promising antibacterial and antibiofilm properties, indicating their potential as adjunct agents in methods for controlling microbial growth. Nevertheless, more study is required to thoroughly demonstrate their medicinal uses.

Nitric oxide-releasing self-healing hydrogel for antibacterial and antibiofilm efficacy against polymicrobial infection.

Aim: Bacterial infections and the formation of biofilms are currently key factors in the delay of wound healing. S-Nitroso glutathione (GSNO) is recognized as a nitric oxide (NO) donor that exhibits potent antibacterial and antibiofilm activities. However, some of the stability limitations of NO require it to be prepared pharmaceutically.Materials & methods: Here, we developed a self-healing hydrogel dressing consisting of GSNO, polyvinyl alcohol/borax (PVA/B)and carboxymethyl chitosan (cmCHI). This research aimed to determine the antibacterial and antibiofilm activities of a self-healing hydrogel (PVA-B-cmCHI/GSNO) against multiple bacteria and polymicrobial biofilms.Results: Forty mg/ml PVA-B-cmCHI/GSNO significantly increased the antibacterial activity against Pseudomonas aeruginosa, S. aureus, Methicillin resistant Staphylococcus aureus (MRSA), as indicated by a >5log reduction in bacterial viability (∼99.999% killing). PVA-B-cmCHI/GSNO showed antibiofilm activity three-times greater than that of the blank self-healing hydrogel (PVA-B-cmCHI) by inhibiting 80% of the biofilm formation.Conclusion: The results suggest that the NO-releasing self-healing hydrogels exhibit notable antibacterial and antibiofilm properties and thus could be a promising approach for the treatment of bacterial or biofilm-infected wounds.

Enhancing Antibacterial Efficacy: Combining Novel Bacterial Topoisomerase Inhibitors with Efflux Pump Inhibitors and Other Agents Against Gram-Negative Bacteria

Background: The novel bacterial topoisomerase inhibitors (NBTIs) developed in our laboratory show potent on-target enzyme inhibition but suffer from low activity against Gram-negative bacteria. Methods: With the aim of improving the antibacterial activity of our compounds against Gram-negative bacteria, we tested them in combination with different efflux pump inhibitors (EPIs), a strategy that showed promise in several other classes of antimicrobials. We also investigated the combined effect of NBTIs with ATP-competitive inhibitors of bacterial type II topoisomerases (ACIs), as well as the antibiofilm properties of our compounds and the combination with EPIs against early and mature Acietobacter baumannii biofilm. Results: Our results demonstrate that combinations of NBTIs with EPI Phenylalanine-arginyl-β-naphthylamide significantly reduce the corresponding NBTIs’ minimal inhibitory concentration values and show potentiation of A. baumannii biofilm inhibition as compared to NBTIs alone. Although combinations of NBITs and ACIs did not show synergistic effects, the FIC index value calculations revealed additive effects for all the combinations of a selected NBTI in combination with three ACIs in all the assayed Gram-negative bacteria from the ESKAPE group. Conclusions: These results show for the first time that combinations of NBTIs with either EPIs or a different class of the topoisomerase inhibitors may be a beneficial strategy to combat difficult-to-treat bacterial infections.

Characterization of phage HZY2308 against Acinetobacter baumannii and identification of phage-resistant bacteria

Background Acinetobacter baumannii (AB) is a notable cause of hospital-acquired infections, with carbapenem-resistant Acinetobacter baumannii (CRAB) classified as a high-priority critical pathogen. Bacteriophage therapy is emerging as a promising alternative to combat drug-resistant bacterial infections. In this study, a lytic phage, HZY2308, was isolated from hospital sewage, and the biological properties, biosafety and anti-biofilm properties of phage HZY2308 were characterized and identified. Moreover, the antibacterial effect of phage HZY2308 in combination with antibiotics was investigated, and the apparent characteristics of phage-resistant strain AB48-R were demonstrated, which provided data support for further studies to elucidate the mechanism of generating phage resistance.MethodsPhage HZY2308 was isolated by double agar plate method using clinical strain AB48 as the host bacterium. The morphology of phage HZY2308 was identified by transmission electron microscopy (TEM), and biological characteristics of phage HZY2308 were identified by host range, the efficiency of plating (EOP), sensitivity to temperature, pH, and chloroform, one-step growth curve, the optimal multiplicity of infection (MOI), and detection of endotoxin and cytotoxicity. Besides, the complete genome map of HZY2308 was constructed using CGview, and the phylogenetic tree of HZY2308 was constructed with MEGA. Additionally, the full genomic sequence of phage HZY2308 and the selected phage were compared using Easyfig. Checkerboard test of phage HZY2308 in combination with tigecycline (TGC) was performed to investigate their synergistic effect and bactericidal kinetics. The effect of HZY2308 on biofilm was investigated by semi-quantitative staining of biofilm with crystal violet, determination of bacterial activity in biofilm by 2,3-Bis (2-methoxy-4-nitro-5-sulfophenyl) -2 H-tetrazolium-5-carboxanilide (XTT) assay and observation of biofilm structure by fluorescence microscopy. Finally, Phage-resistant bacteria AB48-R were characterized by colony-forming capacity, morphology, growth curves, adsorption efficiency, and antibiotic susceptibility assays.ResultsA lytic phage, HZY2308, was isolated from hospital sewage, which exhibited advantageous traits such as a brief incubation period, large burst size, and robust stability. Safety assessments conducted at both genetic and cellular levels also have yielded positive outcomes. Besides, phage HZY2308 effectively inhibited AB biofilm formation and disrupted established biofilm structures. Furthermore, a synergistic antibacterial effect was noted when phage HZY2308 was combined with tigecycline. Interestingly, the phage-resistant strain, AB48-R was screened through natural selection. Compared to the wild strain AB48, the adsorption efficiency of the phage to AB48-R diminished. However, AB48-R’s sensitivity to antibiotics such as cefepime, gentamicin, amikacin, and tobramycin increased, indicating an evolutionary trade-off.ConclusionsPhage HZY2308 shows strong antimicrobial potential, especially in combination with tigecycline, and the phage-resistant strain exhibits increased antibiotic sensitivity.

Comprehensive evaluation of the antibacterial and antibiofilm activities of NiTi orthodontic wires coated with silver nanoparticles and nanocomposites: an in vitro study.

Fixed orthodontic appliances act as a niche for microbial growth and colonization. Coating orthodontic wires with antimicrobial silver nanoparticles (AgNPs) and nanocomposite was adopted in this study to augment the biological activity of these wires by increasing their antibacterial and antibiofilm properties and inhibiting bacterial infections that cause white spot lesions and lead to periodontal disease. Three concentrations of biologically synthesized AgNPs were used for coating NiTi wires. The shape, size, and charge of the AgNPs were determined. Six groups of 0.016 × 0.022-inch NiTi orthodontic wires, each with six wires, were used; and coated with AgNPs and nanocomposites. The antimicrobial and antibiofilm activities of these coated wires were tested against normal flora and multidrug-resistant bacteria (Gram-positive and Gram-negative bacterial isolates). The surface topography, roughness, elemental percentile, and ion release were characterized. AgNPs and nanocomposite coated NiTi wires showed significant antimicrobial and antibiofilm activities. The chitosan-silver nanocomposite (CS-Ag) coated wires had the greatest bacterial growth inhibition against both Gram-positive and Gram-negative bacteria. The surface roughness of the coated wires was significantly reduced, impacting the surface topography and with recorded low Ni and Ag ion release rates. NiTi orthodontic wires coated with AgNPs, and nanocomposites have shown increased antimicrobial and antibiofilm activities, with decreased surface roughness, friction resistance and limited- metal ion release.

Preparation and optimization of hydrophilic modified pullulan encapsulated tetracycline for significant antibacterial and anti-biofilm activity against Stenotrophomonas maltophilia isolates.

The study aimed to assess the effectiveness of these formulations against S. maltophilia in terms of their antimicrobial and anti-biofilm properties. The physicochemical characteristics of HM-PULL-Tetracycline were analyzed using a field scanning electron microscope, X-ray dispersion, Zeta potential, and dynamic light scattering analysis. The antibacterial and anti-biofilm activity was assessed using minimal biofilm inhibitory concentration and broth micro-dilution. In addition, the biocompatibility of HM-PULL-Tetracycline was assessed by investigating its cytotoxicity on the human diploid fibroblasts (HDF) normal cell line using the MTT test. The HM-PULL-Tetracycline formulation successfully prevented biofilm formation, measuring 179.7± 2.66 nm in size and with an encapsulation efficiency of 84.86± 3.14%. It exhibited a biofilm growth inhibition rating of 69% and significantly down-regulated the expression of the smf-1, rpfF, rmlA, and spgM biofilm genes in S. maltophilia strains (p<0.05). Furthermore, the HM-PULL-Tetracycline formulation exhibited a 4 to 6-fold increase in antibacterial efficacy compared to unbound tetracycline. The HM-PULL-Tetracycline formulation demonstrated cell viability of over 90% at all doses tested against HDF normal cells. The findings of the current investigation demonstrate that HM-PULL-Tetracycline enhances the bactericidal and anti-biofilm properties without causing harm to healthy human cells. This suggests that Could be a promising approach for medication administration.

Characterization of Exopolysaccharides from Lactiplantibacillus plantarum PC715 and Their Antibiofilm Activity Against Hafnia alvei

Exopolysaccharides (EPSs) secreted by lactic acid bacteria have the potential to enhance human health by showing various biological functions. This study investigated the biological role and antibiofilm properties of EPS715, a new neutral EPS produced by pickled vegetables originating from Lactobacillus plantarum PC715. The results indicate that EPS715 is primarily composed of rhamnose, glucose, and mannose. Its molecular weight (Mw) is 47.87 kDa, containing an α-glucoside linkage and an α-pyranose ring. It showed an amorphous morphology without a triple helix structure. Furthermore, EPS715 showed improved antioxidant activity. Specifically, its scavenging capacity of ABTS+ radicals, DPPH radicals, and the hydroxyl (·OH) reduction capacity at 5 mg/mL was 98.64 ± 2.70%, 97.37 ± 0.79%, and 1.64 ± 0.05%, respectively. Its maximal scavenging capacity was &gt;40%, and the hydroxyl (·OH) radical scavenging ability was dose-dependent. Moreover, the biofilm of various pathogens including S. aureus, B. cereus, S. saprophyticus, Acinetobacter spp., and H. alvei was substantially dispersed and affected by EPS715, with a maximum inhibition rate of 78.17% for H. alvei. The possible mechanism by which EPS715 shows antibiofilm properties against the H. alvei may be attributed to its effects on the auto-aggregation, hydrophilic characteristics, and motility of Hafnia spp. Thus, EPS715 has significant antioxidant and antibiofilm characteristics that may hold substantial potential for applications in food and medicinal products.

Determination of Biological Activity and Biochemical Content of Ethanol Extract from Fruiting Body of Tricholoma bufonium (Pers.) Gillet

The current study investigates the biochemical composition and biological activities of ethanol extract from the fruit body of Tricholoma bufonium, marking the first detailed examination of this species. The primary goal was to assess the antimicrobial, anti-biofilm, and antioxidant properties of ethanol extract from the fruit body of T. bufonium against a range of bacterial strains. Conventional microbiological and biochemical techniques were employed to assess the antimicrobial efficacy of the extract and to determine its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values. Furthermore, a GC-MS analysis identified bioactive compounds, such as palmitic acid and oleic acid, which are likely contributors to the observed antimicrobial activity. The anti-biofilm activity was tested using glucose monohydrate-modified environments for biofilm formation, while the antioxidant potential was measured using the DPPH radical scavenging assay, CUPRAC (cupric ion reducing antioxidant capacity) assay, and FRAP (ferric ion reducing antioxidant power) assay. The ethanol extract exhibited potent antimicrobial activity, particularly against Enterococcus faecium, Bacillus subtilis, and Staphylococcus aureus MRSA, with MIC values as low as 0.0338 mg/mL for several pathogens. Additionally, the extract exhibited significant anti-biofilm activity against Bacillus cereus and antioxidant activity with an EC50 value of 11.745 mg/mL. These results suggest that ethanol extract from the fruit body of T. bufonium may be a potent candidate for developing novel antimicrobial agents, particularly against resistant strains such as MRSA, while also providing antioxidant benefits.

Ajoene: a natural compound with enhanced antimycobacterial and antibiofilm properties mediated by efflux pump modulation and ROS generation against M. Smegmatis.

Tuberculosis (TB) continues to be a primary worldwide health concern due to relatively ineffective treatments. The prolonged duration of conventional antibiotic therapy warrants innovative approaches to shorten treatment courses. In response to challenges, the study explores potential of Ajoene, a naturally occurring garlic extract-derived compound, for potential TB treatment. Mycobacterium smegmatis as a model organism for M. tuberculosis (M. tb) to investigate Ajoene's efficiency. In vitro techniques like antimicrobial susceptibility, antibiofilm, EtBr accumulation assay, and ROS assay evaluate the potency of Ajoene and conventional TB drugs against Mycobacterium smegmatis. An in-silico study also investigated the interaction between Ajoene and quorum-sensing proteins, specifically regX3, MSMEG_5244, and MSMEG_3944, which are involved in biofilm formation and sliding activity. In vitro findings revealed that Ajoene exhibited significant antibacterial activity by inhibiting growth and showing bactericidal effects. It also demonstrated additive interactions with common antibiotics such as Isoniazid and Rifampicin. Furthermore, Ajoene demonstrated a comparative interaction with commonly used antibiotics, such as Isoniazid and Rifampicin, and reduced M. smegmatis motility, both alone and in combination with these antibiotics. In silico analysis shows that Ajoene exhibited a higher binding affinity with regX3, a protein orthologous to the regX3 gene in M.tb. Ajoene also demonstrated consistent antibiofilm effects, particularly when combined synergistically with Isoniazid and Rifampicin. Mechanistic investigations demonstrated Ajoene's potential to inhibit efflux pumps and promote ROS generation in bacteria, suggesting a potential direct killing mechanism. Collectively, the findings emphasize Ajoene's effectiveness as a novel antimycobacterial and antibiofilm molecule for TB treatment.

Toxicity, Antibacterial, Antioxidant, Antidiabetic, and DNA Cleavage Effects of Dextran-Graft-Polyacrylamide/Zinc Oxide Nanosystems.

Synthesis of metal oxide nanoparticles-polymer nanocomposites is an emerging strategy in nanotechnology to improve targeted delivery and reduce the toxicity of nanoparticles. In this study, we report biological effects of previously described hybrid nanocomposites containing dextran-graft-polyacrylamide/zinc oxide nanoparticles (D-PAA/ZnO NPs) prepared from zinc sulfate (D-PAA/ZnONPs(SO42-)) and zinc acetate (D-PAA/ZnONPs(-OAc)) focusing primarily on their antimicrobial activity. D-PAA/ZnONPs(SO42-) and D-PAA/ZnONPs(-OAc) nanosystems were tested in a complex way to assess their antioxidant activity (DPPH assay), antidiabetic potential (α-amylase inhibition), DNA cleavage activity, antimicrobial, and antibiofilm activity. In addition, the toxicity of D-PAA/ZnONPs(SO42-) and D-PAA/ZnONPs(-OAc) nanosystems against primary murine splenocytes was tested using MTT assay. The studied nanosystems inhibited E.coli growth. For all the investigated strains, minimum inhibitory concentrations (MICs) of D-PAA/ZnONPs(SO42-) and D-PAA/ZnONPs(-OAc) were in the range of 8mg/L-128mg/L and 16mg/L-128mg/L, respectively. The nanocomposites demonstrated effective antibiofilm properties as 94.27% and 86.43%. The compounds showed good antioxidant, anti-α-amylase, and DNA cleavage activities. D-PAA/ZnONPs(SO42-) and D-PAA/ZnONPs(-OAc) nanosystems reduced cell viability and promoted cell death of primary murine spleen cells at concentrations higher than those that proved to be antibacterial indicating the presence of therapeutic window. D-PAA/ZnONPs(SO42-) and D-PAA/ZnONPs(-OAc) nanosystems show antioxidant, antidiabetic, DNA cleavage, antimicrobial, and antibiofilm activity against the background of good biocompatibility suggesting the presence of therapeutic potential, which should be further investigated in vivo.

Nanostructured silver vanadate gel: Evaluation of physicochemical, mechanical, and antibiofilm properties against a five-species oral model

The aim of this study was to develop a gel with nanostructured silver vanadate decorated with silver nanoparticles (β-AgVO3) and to evaluate its physicochemical, mechanical, and antibiofilm properties against a five-species oral model composed of Candida albicans, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, and Pseudomonas aeruginosa. The formulations were prepared with 0 % w/v (G0), 0.02 % w/v (G1), 0.05 % w/v (G2), and 0.12 % w/v (G3) β-AgVO3. The physicochemical properties of pH (n = 5), viscosity (n = 5), spreadability (n = 10) and syringability (n = 10) were evaluated, as well as the mechanical properties of hardness, cohesiveness, compressibility, elasticity, and adhesiveness using the texture profile assay (TPA) (n = 5) and ex vivo mucoadhesion (n = 5). The antibiofilm effect was assessed by counting colony-forming units (CFU/mL) (n = 8), metabolic activity (XTT) (n = 8), and scanning electron microscopy (SEM) (n = 1), using 0.12 % chlorhexidine gel (CG) as a positive control and G0 as a negative control. All groups demonstrated a neutral pH. G2 and G3 exhibited reduced viscosity and syringeability, along with increased spreadability. The incorporation of β-AgVO3 did not impact the gel's elasticity or cohesiveness but led to a decrease in hardness, compressibility, and adhesiveness. Ex vivo mucoadhesion was not altered by the addition of the nanomaterial. G3 showed a higher microbial reduction compared to GC and G0. It was concluded that the formulations with β-AgVO3 showed compatible physicochemical and mechanical properties for application and maintenance in the oral cavity. G3 showed superior antimicrobial effect against all microorganisms compared to GC and G0.

Antibacterial and antibiofilm features of mutSMAP-18 against Vibrio cholerae

Cholera continues to be a pointed global health issue, prominently in developing nations, where the disease's severe diarrheal symptoms pose substantial public health risks. With the escalating spread of antibiotic resistance among V. cholerae strains, alternative therapeutic approaches are imperative. Antimicrobial peptides are increasingly recognized for their potential, with research focusing on finding the most effective options. We explored the antibacterial and antibiofilm properties of analogues of sheep myeloid antimicrobial peptide-18 (SMAP-18) against V. cholerae in this investigation. Our prior research demonstrated that substituting glycine with alanine at different positions within SMAP-18 altered its structure and antimicrobial activity. Among these altered analogues, our focus was on a mutant variant (mutSMAP-18), characterized by glycine-to-alanine substitutions at positions 2, 7, and 13. Our results indicated that mutSMAP-18 exhibited heightened antimicrobial and antibiofilm activities against V. cholerae compared to SMAP-18. We conducted several mechanistic investigations to check the membrane integrity using DNA-binding dye, SYTOX Green or measuring calcein dye leakage and analyzing flow cytometry by fluorescence-activated cell sorting (FACScan). From these tests, we elucidated that SMAP-18 primarily functions intracellularly, while mutSMAP-18 targets the bacterial membrane. Additionally, scanning electron microscopy (SEM) images illustrated membrane disruption at lower concentrations for mutSMAP-18. Notably, mutSMAP-18 demonstrated significant antibiofilm properties against V. cholerae. Overall, these findings offer valuable perspectives for developing novel antibacterial therapies targeting the pathogenic V. cholerae.

Small cyclic dipeptide produced by Lactobacillus rhamnosus with anti-biofilm properties against Streptococcus mutans biofilm

The human oral cavity harbors many bacterial species collectively termed the oral microbiome and is integral for maintaining oral health. Dysbiosis of oral microbiota leads to common oral diseases, including dental caries, gingivitis, and periodontitis. Streptococcus mutans is the primary causative agent of dental caries. Studies have explored the use of probiotic Lactobacillus spp. to mitigate S. mutans biofilms. In the present study, we have tested the use of Lactobacillus rhamnosus extracts/metabolites for anti-biofilm properties. A small organic compound/metabolite was isolated from the cell-free supernatant of L. rhamnosus, and this metabolite resulted in a dose-dependent inhibition of S. mutans biofilms. Confocal microscopy revealed that the thickness of S. mutans biofilms was severely reduced upon metabolite treatment. With the help of FTIR spectra and mass spectrometry analysis, the molecular formula (C11H19O2N2) was deduced. The inhibitor compound was further identified as a small cyclic peptide, cyclo (-L-Leu-L-Pro). Our data also revealed that isolated metabolite impedes S. mutans biofilms by modulating gene expression of several essential genes involved in biofilm establishment.

Facile fabrication and characterization of carboxymethyl cellulose loaded with TiO2NPs hydrogel as a promising disinfectant for eliminating the dissemination of waterborne pathogens through wastewater decontamination

The purpose of this work was to develop and characterize an intriguing hydrogel called TiO₂NPs@CMC hydrogel, which is composed of carboxymethyl cellulose (CMC) and loaded with titanium oxide nanoparticles (TiO₂NPs) for effective waterborne pathogen disinfection in wastewater. The TiO₂NPs were synthesized through hydrolysis and peptization, incorporated into a CMC matrix, and subsequently cross-linked with calcium chloride (CaCl₂). Characterization through TEM, FTIR, and SEM validated the development of a porous structure, efficient incorporation of TiO₂NP, and successful crosslinking. In this study, TiO2NPs were prepared and affirmed the significant particle distribution with a small size using TEM. The TiO₂NPs@CMC hydrogel exhibited significant antimicrobial and antibiofilm properties against various pathogens, such as Salmonella typhi, E. coli O157, Shigella dysenteriae, Enterococcus faecalis, Bacillus cereus, and Candida albicans, with highest inhibition zone diameters of up to 29 mm for S. typhi. The inhibitory effect demonstrated that the hydrogel significantly decreased bacterial populations at 100 μg/mL concentrations. The hydrogel demonstrated a 2.7-log reduction in microbial counts in sewage water within 120 min, achieving complete inactivation of pathogens at a concentration of 2xMIC within 180 min. The biofilm inhibition rate reached 87.6 % against B. cereus. Toxicity assessments demonstrated significant biocompatibility, with no negative effects noted in environmental applications. The findings indicate that TiO₂NPs@CMC hydrogel is a viable option for sustainable wastewater treatment, providing an efficient, safe, and environmentally friendly method for the removal of waterborne pathogens and the prevention of biofilm formation.

A Novel pH-Responsive Nano-Sized Lanthanum-Doped Polyvinyl Alcohol-Carbon Quantum Dot Composite for Root Canal Irrigation.

The primary goals of endodontic therapy are to eliminate microbes and prevent reinfection. Persistent root canal infections and failure of root canal therapy are primarily attributed to the presence of bacteria, particularly E. faecalis. Chemical irrigants play a crucial role in complementing mechanical instrumentation in ensuring adequate disinfection. However, current techniques and available irrigants are limited in their ability to achieve optimal sterilization of the root canal system. In this study, we developed a novel material called La@PCDs by combining CQD-PVA and lanthanum for root canal irrigation. A one-pot hydrothermal method was used to prepare composites of lanthanum and CQD-PVA (La@PCDs). Scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and the particle size were employed to characterize La@PCDs. ROS generation was evaluated by measuring the fluorescence intensity emitted at 525 nm from 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA). In vitro experiments were conducted to assess the effectiveness of the nanoparticles in combating Enterococcus faecalis and eradicating in situ biofilm eradication in root canal. Furthermore, cytotoxicity assessments were carried out to demonstrate the safety of La@PCDs. SEM and FTIR results showed that La@PCDs were successfully prepared and exhibiting a homogeneous size distribution and irregular morphology. ROS assessment demonstrated that La@PCDs have a synergistic effect, promoting the production of a large number of ROS. This effect only occurred under acidic PH conditions. The inherent acidity in the biofilm microenvironment can act as internal stimulus. In vitro experiments revealed superior antibacterial efficiency under acidic conditions without causing significant cytotoxicity compared to the commonly used NaClO irrigant. The biosafety of La@PCDs was confirmed. Compared to existing materials, these nanoparticles exhibit favorable antibacterial and anti-biofilm properties, along with improved biocompatibility. These findings emphasize the potential of the integrated La@PCDs as a promising option for enhancing root canal irrigation and disinfection.

Antibiofilm and antivirulence efficacy of Pleurotus platypus methanolic extract against Staphylococcus aureus through ROS generation and cell membrane disruption

Multi-drug resistance is recognized as a significant worldwide public health concern in the current century. Biofilm formation further exacerbates bacterial resistance to antibacterial medications, host immunological responses, and phagocytosis, resulting in long-lasting chronic illnesses. Investigating natural resources is a very potent approach for developing alternative anti-infective medications to effectively control multi-drug resistant bacterial infections. In this study, a unique mushroom species namely Pleurotus platypus had been discovered from the Terai-Duars region of West Bengal, India. The myco-chemical profiling and preliminary chemical analysis of Pleurotus platypus methanolic extract determined the significant presence of metabolites belonging to several major chemical classes such as flavonoid, alkaloid, triterpenoid, polyphenol, benzoic acids, coumarin, flavone etc. Most intriguingly, the extract possessed effective antibacterial, antibiofilm and antivirulence properties against Staphylococcus aureus and Methicillin resistant Staphylococcus aureus, one of the most notable drug-resistant opportunistic and nosocomial pathogens. Mechanistically, the mushroom extract enhanced the production of Reactive Oxygen Species (ROS) inside the targeted bacteria, causing alterations in membrane potential, damage to the cellular membrane and further release of intracellular DNA, destined to cell death. Moreover, the methanolic extract reported the eradication of pre-existing biofilms from the urinary catheter surface, hinting towards its future application in the related field. To summarize, Pleurotus platypus methanolic extract could be an excellent alternative antibacterial and antibiofilm therapeutic candidate for the effective management of Staphylococcus infections with improved outcome.

Limonene encapsulated alginate/collagen as antibiofilm drug against Acinetobacter baumannii

This work examined the antibacterial and antibiofilm properties of alginate/collagen nanoparticles containing limonene. The multi-drug resistant (MDR) strains were screened, and the morphological features of the produced nanoparticles were determined utilizing SEM, DLS, and FTIR. Additionally, the encapsulation effectiveness, stability, and drug release were assessed. The levels of OmpA and Bap biofilm genes were assessed using qRT-PCR. At the same time, the antibacterial and cytotoxic activities of the nanoparticles were evaluated using well diffusion and MTT techniques, respectively. LAC nanoparticles measuring 300 ± 9.6 nm in size, 83.64 ± 0.19% encapsulation efficiency, and 60-day stability at 4 °C were synthesized. The biological investigation demonstrated that LAC nanoparticles had potent antibacterial capabilities. This was shown by their ability to significantly decrease the transcription of OmpA and Bap biofilm genes at a statistically significant level of p ≤ 0.05. The nanoparticles exhibited reduced antibiotic resistance compared to free limonene and alginate/collagen. Compared to limonene, LAC nanoparticles exhibited negligible cytotoxicity against HEK-293 at doses ranging from 1.56 to 100 µg/mL (p ≤ 0.01). The findings underscore the potential of LAC nanoparticles as a breakthrough in the fight against highly resistant pathogens. The potent antibacterial effects of LAC nanoparticles versus Acinetobacter baumannii (A. baumannii) MDR strains, considered highly resistant pathogens of significant concern, could inspire new strategies in antibacterial research.

In-vitro antibacterial and antibiofilm activities and in-silico analysis of a potent cyclic peptide from a novel Streptomyces sp. strain RG-5 against antibiotic-resistant and biofilm-forming pathogenic bacteria.

The proliferation of multidrug-resistant and biofilm-forming pathogenic bacteria poses a serious threat to public health. The limited effectiveness of current antibiotics motivates the search for new antibacterial compounds. In this study, a novel strain, RG-5, was isolated from desert soil. This strain exhibited potent antibacterial and antibiofilm properties against multidrug-resistant and biofilm-forming pathogenic bacteria. Through phenotypical characterizations, 16S rRNA gene sequence and phylogenetic analysis, the strain was identified as Streptomyces pratensis with 99.8% similarity. The active compound, RG5-1, was extracted, purified by reverse phase silica column HPLC, identified by ESI-MS spectrometry, and confirmed by 1H and 13C NMR analysis as 2,5-Piperazinedione, 3,6-bis(2-methylpropyl), belonging to cyclic peptides. This compound showed interesting minimum inhibitory concentrations (MICs) of 04 to 15µg/mL and minimum biofilm inhibitory concentrations (MBICs 50%) of ½ MIC against the tested bacteria. Its molecular mechanism of action was elucidated through a molecular docking study against five drug-protein targets. The results demonstrated that the compound RG5-1 has a strong affinity and interaction patterns with glucosamine-6-phosphate synthase at - 6.0kcal/mol compared to reference inhibitor (- 5.4kcal/mol), medium with penicillin-binding protein 1a (- 6.1kcal/mol), and LasR regulator protein of quorum sensing (- 5.4kcal/mol), confirming its antibacterial and antibiofilm activities. The compound exhibited minimal toxicity and favorable physicochemical and pharmacological properties. This is the first report that describes its production from Streptomyces, its activities against biofilm-forming and multidrug-resistant bacteria, and its mechanism of action. These findings indicate that 2,5-piperazinedione, 3,6-bis(2-methylpropyl) has the potential to be a promising lead compound in the treatment of antibiotic-resistant and biofilm-forming pathogens.

Synthesis, Antibacterial, Anti-Biofilm Properties, and Docking Study of Indeno[1,2-b]Pyridin-5-One Derivatives

In this context, we designed and synthesized a series of hydrazonal and their related indeno[1,2-b]pyridin-5-one derivatives to investigate their antibacterial and anti-biofilm properties. Several of the synthesized compounds exhibited significant efficacy against all microorganism species tested. Most of the compounds demonstrated favorable results when tested against Gram-positive bacteria. The derivatives 4a, 4f, 6c, and 6f exhibit the highest antimicrobial efficacy, as indicated by their minimum inhibitory concentration (MIC) values ranging from 4 to 512 μg/mL. We conducted additional investigations on 4a, 6c, and 6f for the purpose of examining their synergy using Checkerboard assay. Compound 6c demonstrated a synergistic impact against methicillin-sensitive Staphylococcus aureus (MSSA) and Pseudomonas aeruginosa, while exhibiting moderate synergistic activity against methicillin-resistant Staphylococcus aureus (MRSA). In addition, the simultaneous use of gentamycin with compounds 4a and 6f demonstrates a synergistic impact in fighting against methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa, respectively. Three chosen compounds were evaluated for their antibiofilm efficacy. Application of 4a, 6c, and 6f effectively reduced the production of biofilms in MRSA, MSSA, and Pseudomonas aeruginosa, resulting in a significant decrease compared to the untreated samples. In addition, ADME and pharmacokinetic analyses were conducted for the three most potent derivatives, namely 4a, 6c, and 6f. Compounds 4a and 6c were subjected to docking in the LasR Quorum-Sensing Receptor, whereas compounds 6c and 6f were docked in the sortase enzyme.

Inhibition of Pseudomonas aeruginosa Carbonic Anhydrases, Exploring Ciprofloxacin Functionalization Toward New Antibacterial Agents: An In-Depth Multidisciplinary Study.

Ciprofloxacin (CPX) is one of the most employed antibiotics in clinics to date. However, the rise of drug-resistant bacteria is dramatically impairing its efficacy, especially against life-threatening pathogens, such as Pseudomonas aeruginosa. This Gram-negative bacterium is an opportunistic pathogen, often infecting immuno-compromised patients with severe or fatal outcomes. The evidence of the possibility of exploiting Carbonic Anhydrase (CA, EC: 4.2.1.1) enzymes as pharmacological targets along with their role in P. aeruginosa virulence inspired the derivatization of CPX with peculiar CA-inhibiting chemotypes. Thus, a large library of CPX derivatives was synthesized and tested on a panel of bacterial CAs and human isoenzymes I and II. Selected derivatives were evaluated for antibacterial activity, revealing bactericidal and antibiofilm properties for some compounds. Importantly, promising preliminary absorption, distribution, metabolism, and excretion (ADME) properties in vitro were found and no cytotoxicity was detected for some representative compounds when tested in Galleria mellonella larvae.