Disrupt Biofilm Formation Research Articles

Microbial Dynamics in Periodontal Regeneration: Understanding Microbiome Shifts and the Role of Antifouling and Bactericidal Materials: A Narrative Review

Periodontal regeneration is a multifaceted therapeutic approach to restore the tooth-supporting structures lost due to periodontal diseases. This manuscript explores the intricate interactions between regenerative therapies and the oral microbiome, emphasizing the critical role of microbial balance in achieving long-term success. While guided tissue regeneration (GTR), bone grafting, and soft tissue grafting offer promising outcomes in terms of tissue regeneration, these procedures can inadvertently alter the oral microbial ecosystem, potentially leading to dysbiosis or pathogenic recolonization. Different grafting materials, including autografts, allografts, xenografts, and alloplasts, influence microbial shifts, with variations in the healing timeline and microbial stabilization. Biologics and antimicrobials, such as enamel matrix derivatives (EMD) and sub-antimicrobial dose doxycycline (SDD), play a key role in promoting microbial homeostasis by supporting tissue repair and reducing pathogenic bacteria. Emerging strategies, such as enzyme-based therapies and antifouling materials, aim to disrupt biofilm formation and enhance the effectiveness of periodontal treatments. Understanding these microbial dynamics is essential for optimizing regenerative therapies and improving patient outcomes. The future of periodontal therapy lies in the development of advanced materials and strategies that not only restore lost tissues but also stabilize the oral microbiome, ultimately leading to long-term periodontal health.

MMV 1804559 is a potential antistaphylococcal and antibiofilm agent targeting the clfA gene of Staphylococcus aureus.

Staphylococcus aureus, a high-priority pathogen proclaimed to cause infections ranging from mild to life-threatening, presents significant challenges in treatment. New therapies can be developed quicker using open drug discovery platforms offering a distinct approach to expedite the development of innovative antibacterial and anti-biofilm therapeutics. This study set out to address these issues by finding new uses for current medications to find compounds that are effective against S. aureus. In this study, we screened the global priority health box, launched by Medicines for Malaria Ventures containing 240 compounds, for their effectiveness against S. aureus. MMV1795508, MMV1542799, MMV027331, MMV1593278, and MMV1804559 showed potential antibacterial activity at 10µM concentration. These compounds underwent further evaluation for their ability to clear intracellular bacteria, disrupt biofilm formation and eradicate existing biofilms. MMV1804559 demonstrated strong efficacy across all tested parameters, achieving 94% inhibition of intracellular bacteria, 79.19% disruption of biofilm cells, and 66.18% inhibition of biofilm formation. Scanning electron microscopy revealed notable membrane perforations and blebbing in MMV1804559-treated cells, indicating its impact on bacterial membranes. Gene expression analysis of cells treated with MMV1804559 showed downregulation of clfA and clfB genes, critical for biofilm formation. Additionally, docking studies confirmed the binding affinity of MMV1804559 with clfA, supported by favorable docking scores, MM/GBSA binding energy, and increased hydrogen bond interactions in the binding pocket, suggesting clfA as a target for MMV1804559. MMV1804559 could serve as a potential therapy for S. aureus by targeting biofilm development and cell adhesion processes.

Antifungal properties of abnormal cannabinoid derivatives: Disruption of biofilm formation and gene expression in Candida species

Abnormal cannabinoids (including comp 3) are a class of synthetic lipid compounds with non-psychoactive properties and regioisomer configurations, but distinct from traditional cannabinoids since they do not interact with the established CB1 and CB2 receptors. Previous research showed the cardioprotective and anti-inflammatory potentials of comp 3 and more recently its antimicrobial effect on methicillin-resistant Staphylococcus aureus (MRSA). Given the escalating challenges posed by Candida infections and the rise of antifungal drug resistance, the exploration of novel therapeutic avenues is crucial. This study aimed to assess the anti-Candida properties of newly synthesized AbnCBD derivatives. AbnCBD derivatives were synthesized by acid catalysis-induced coupling and further derivatized. We evaluated the potential of the AbnCBD derivatives to inhibit the growth stages of various Candida species. By in vitro colorimetric assays and in vivo mice experiments, we have shown that AbnCBD derivatives induce differential inhibition of Candida growth. The AbnCBD derivatives, especially comp 3, comp 10, and comp 9 significantly reduced the growth of C. albicans, including FLC-resistant strains, and of C. tropicalis and C. parapsilosis but not of C auris compared to their controls (FLC and 0.5 % DMSO). Comp 3 also disrupted C. albicans biofilm formation and eradicated mature biofilms. Notably, other derivatives of AbnCBD disrupted the biofilm formation and maturation of C. albicans but did not affect yeast growth. In a murine model of VVC, comp 3 demonstrated significant fungal clearance and reduced C. albicans burden compared to vehicle and FLC controls. These findings highlight the potential of AbnCBDs as promising antifungal agents against Candida infections.

Investigating Sortase A inhibitory potential of herbal compounds using integrated computational and biochemical approaches

Multi-drug resistance in bacteria is emerging as a major global health challenge, causing substantial harm in terms of mortality, morbidity, and financial strain on healthcare systems. These bacteria are constantly acquiring new virulence factors and drug-resistance mechanisms, which highlights the critical need for innovative antimicrobial medicines and identification of new therapeutic targets, such as Sortase A (EfSrtAΔN59). EfSrtAΔN59, a transpeptidase significant for the adhesion and virulence of Enterococcus faecalis (E. faecalis), presents an attractive target for disrupting biofilm formation—a key factor in persistent infections. This study investigates the inhibitory effects of two natural flavonoids- Rutin Trihydrate and Quercetin, on EfSrtAΔN59 and biofilm formation in E. faecalis. With in vitro enzymatic assays and biofilm quantification techniques, we demonstrate that both compounds significantly attenuate EfSrtAΔN59 activity, thereby hindering bacterial biofilm formation. Rutin Trihydrate and Quercetin exhibited strong binding affinities to the EfSrtAΔN59 enzyme, as confirmed by molecular docking and MD simulation studies. This was further substantiated by a notable reduction in biofilm biomass in bacterial cultures treated with these compounds. These findings highlight the potential of Rutin Trihydrate and Quercetin as promising candidates for the development of novel anti-virulence therapies aimed at mitigating E. faecalis infections, thereby offering a compelling alternative to traditional antibiotics.

Unravelling Virulence Activities of Hospital Isolated Acinetobacter baumannii: Exploring The Prospective Application of Aspirin as an Antivirulence Agent

Acinetobacter baumannii infections pose a global public health threat due to the increasing resistance to various antimicrobial agents. This study reports the virulence characteristics of A. baumannii strains isolated from patients at Hospital Canselor Tuanku Muhriz UKM (HCTM) and explores the potential of aspirin as an antivirulence agent. Fourteen A. baumannii isolates from various infection sites exhibited resistance to at least two antibiotics. Among them, 43% (n=6) displayed high motility, correlating with the site of isolation. Additionally, 58% (n=7) formed strong biofilms, 36% (n=5) secreted proteases and 36% (n=5) resisted oxidative stress. Notably, isolates Ab_H4 and Ab_H10 displayed the highest virulence, warranting further investigation. Molecular analysis using polymerase chain reaction (PCR) showed that both Ab_H4 and Ab_H10 possessed the bap and katG genes. Although both strains were capable of secreting proteases, only Ab_H4 possessed the cpaA gene, suggesting the involvement of other genes in protease secretion in Ab_H10. Despite high motility, no pilT gene was detected in any isolates. Treatment with sub-inhibitory concentrations of aspirin (3.25 mg/ml) restored susceptibility to previously resistant antibiotics, disrupted biofilm formation and reduced proteases and catalases secretion. However, no significant impact on bacterial motility was observed. Interestingly, sub-inhibitory concentrations of aspirin induced biofilm formation in the environmental strain control (Ab_UKMCC), which was significantly reduced upon exposure to the MIC. These findings highlight the high virulence capabilities of several strains isolated from HCTM and show the potential of aspirin as an antivirulence agent, offering valuable insights for combating A. baumannii infections.

Diverse YqeK Diadenosine Tetraphosphate Hydrolases Control Biofilm Formation in an Iron-Dependent Manner

YqeK is a bacterial HD-domain metalloprotein that hydrolyzes the putative second messenger diadenosine tetraphosphate (Ap4A). Elevated Ap4A levels are primarily observed upon exposure of bacteria to factors such as heat or oxidative stress and cause pleiotropic effects, including antibiotic sensitivity and disrupted biofilm formation. Ap4A thus plays a central role in bacterial physiology and metabolism, and its hydrolysis by YqeK is intimately linked to the ability of these microbes to cope with stress. Although YqeK is reported to hydrolyze Ap4A under aerobic conditions, all four existing crystal structures reveal an active site that consists of a diiron center, portraying a cryptic chemical nature for the active metallocofactor. This study examines two YqeK proteins from two ecologically diverse parent organisms: the obligate anaerobe Clostridium acetobutylicum and the facultative aerobe Bacillus halodurans. Both enzymes utilize Fe-based cofactors for catalysis, while under ambient or oxidative conditions, Bh YqeK hydrolyzes Ap4A more efficiently compared to Ca YqeK. This redox-dependent activity difference stems from the following two molecular mechanisms: the incorporation of mixed-metal, Fe-based bimetallic cofactors, in which the second metal is redox inert (i.e., Fe–Zn) and the upshift of the Fe–Fe cofactor reduction potentials. In addition, three strictly conserved, positively charged residues vicinal to the active site are critical for tuning Ap4A hydrolysis. In conclusion, YqeK is an Fe-dependent phosphohydrolase that appears to have evolved to permit Ap4A hydrolysis under different environmental niches (aerobic vs. anaerobic) by expanding its cofactor configuration and O2 tolerance.

A novel brominated chalcone derivative as a promising multi-target inhibitor against multidrug-resistant Listeria monocytogenes

Foodborne pathogens continue to challenge public health due to their ability to cause severe illness and their increasing resistance to current antimicrobial treatments. Listeria monocytogenes is a resilient foodborne pathogen that poses significant risks to vulnerable populations, leading to severe infections and high hospitalization rates. The emergence of antimicrobial-resistant (AMR) strains of L. monocytogenes underscores the need for novel therapeutic strategies. In this study, we investigated the antimicrobial efficacy of the (2E)-3-(3,5-dibromo-2-hydroxylphenyl)-1-(5-methylfuran-2-yl) prop-2-en-1-one (DK06) against multidrug-resistant L. monocytogenes. DK06 exhibited a significant dose-dependent inhibition of L. monocytogenes growth, achieving a maximum inhibition of 92.9 % at 320 μM. Molecular docking and dynamics simulations revealed high binding affinities for key virulence proteins PlcB and ArgA, with stable protein-ligand interactions. DK06 also disrupted biofilm formation at sub-MIC levels, reducing extracellular polymeric substances (EPS) and biofilm mass, as observed by scanning electron microscopy (SEM) analysis. Furthermore, DK06 downregulated the expression of virulence genes (plcB, argA, and hly) and decreased hemolytic activity. In vivo zebrafish studies confirmed the safety of DK06 up to 80 μM, demonstrating its efficacy in reducing mortality and oxidative stress associated with L. monocytogenes infection. DK06 also attenuated inflammation by downregulating key inflammatory markers (tnfa, il1b, il6, and nfkb). These findings indicate that DK06 is a promising multi-target inhibitor with potential application in treating infections and combating antimicrobial resistance.

Combating bacterial biofilms and related drug resistance: Role of phyto-derived adjuvant and nanomaterials

The emergence of antimicrobial resistance (AMR) in clinical microbes has led to a search for novel antibiotics for combating bacterial infections. The treatment of bacterial infections becomes more challenging with the onset of biofilm formation. AMR is further accelerated by biofilm physiology and differential gene expression in bacteria with an inherent resistance to conventional antibiotics. In the search for innovative strategies to control the spread of AMR in clinical isolates, plant-derived therapeutic metabolites can be repurposed to control biofilm-associated drug resistance. Unlike antibiotics, designed to act on a single cellular process, phytochemicals can simultaneously target multiple cellular components. Furthermore, they can disrupt biofilm formation and inhibit quorum sensing, offering a comprehensive approach to combat bacterial infections. In bacterial biofilms, the first line of AMR is due to biofilms associated with the extracellular matrix, diffusion barriers, quorum sensing, and persister cells. These extracellular barriers can be overcome using phytochemical-based antibiotic adjuvants to increase the efficacy of antibiotic treatment and restrict the spread of AMR. Furthermore, phytochemicals can be used to target bacterial intracellular machinery such as DNA replication, protein synthesis, efflux pumps, and degrading enzymes. In parallel with pristine phytochemicals, phyto-derived nanomaterials have emerged as an effective means of fighting bacterial biofilms. These nanomaterials can be formulated to cross the biofilm barriers and function on cellular targets. This review focuses on the synergistic effects of phytochemicals and phyto-derived nanomaterials in controlling the progression of biofilm-related AMR. IT provides comprehensive insights into recent advancements and the underlying mechanisms of the use of phyto-derived adjuvants and nanomaterials.

Characterization of biofilm-forming ability and antibiotic resistance profiles of clinical Pseudomonas aeruginosa isolates from patients with cystic fibrosis

Background: Pseudomonas aeruginosa is a key pathogen in cystic fibrosis (CF) associated infections, known for its biofilm-forming ability and resistance to multiple antibiotics. Understanding the relationship between biofilm production and antibiotic resistance profiles in clinical isolates can guide treatment strategies. Aims and Objectives: The aims of this study were to investigate the biofilm-forming abilities and antibiotic resistance profiles of clinical P. aeruginosa isolates from patients with CF and to determine the relationship between these two factors and their impact on treatment efficacy. Materials and Methods: A cross-sectional study was conducted on 100 clinical isolates of P. aeruginosa from CF patients. Biofilm-forming capacity was categorized as strong, moderate, or weak based on quantitative assays. Antibiotic resistance was assessed for ciprofloxacin, tobramycin, ceftazidime, meropenem, and piperacillin/tazobactam. Multi-drug resistance was defined as resistance to three or more antibiotic classes. Statistical correlations between biofilm-forming capacity and resistance levels were evaluated using the Chi-square tests. Results: Fifty-six percentages of isolates were strong biofilm producers, while 34% and 10% were moderate and weak producers, respectively. The highest antibiotic resistance was observed against ciprofloxacin (60%), followed by tobramycin (50%) and ceftazidime (45%). Forty percentages of the isolates were classified as multi-drug resistant. Strong biofilm producers demonstrated a significantly high correlation with antibiotic resistance (P<0.05). Two predominant clonal groups were identified among the isolates, suggesting a possible clonal spread of resistance traits. Conclusion: The study confirms a strong association between robust biofilm production and heightened antibiotic resistance in P. aeruginosa isolates from CF patients. These findings highlight the need for targeted therapeutic strategies to disrupt biofilm formation and curb resistance spread.

Biosynthesis of silver nanoparticle using Bacillus licheniformis culture-supernatant for combating pathogenic biofilms

Bacterial biofilms pose a significant threat to healthcare due to their recalcitrance to antibiotics and disinfectants. This study explores the anti-biofilm potential of Bacillus licheniformis cell-free culture supernatant (CFS) and its derived silver nanoparticles (bSNPs) against Staphylococcus aureus and Pseudomonas aeruginosa. The CFS exhibited potent anti-biofilm activity against both bacterial species, even at low concentrations, while devoid of significant bactericidal effects, mitigating resistance risks. Characterization studies revealed the non-proteinaceous nature and thermal stability of the CFS's anti-biofilm agent, suggesting a robust and heat-resistant structure. Green synthesis of bSNPs from CFS resulted in nanoparticles with significant anti-biofilm properties, particularly against P. aeruginosa, indicating differences in susceptibility between the bacterial species. Epifluorescence microscopy confirmed bSNPs' ability to inhibit and partially disrupt biofilm formation without inducing cellular lysis. The study highlights the potential of B. licheniformis CFS and bSNPs as promising biofilm control agents, offering insights into their mechanisms of action and broad-spectrum efficacy. Further research elucidating the underlying molecular mechanisms and identifying specific bioactive compounds is warranted for the translation of these findings into clinically relevant applications for combating biofilm-associated infections.

Effects of Metal and Metal Oxide Nanoparticles against Biofilm-Forming Bacteria: A Systematic Review.

Biofilm formation by bacteria poses a significant challenge across diverse industries, displaying resilience against conventional antimicrobial agents. Nanoparticles emerge as a promising alternative for addressing biofilm-related issues. This review aims to assess the efficacy of metal and metal oxide nanoparticles in inhibiting or disrupting biofilm formation by various bacterial species. It delineates trends, identifies gaps, and outlines avenues for future research, emphasizing best practices and optimal nanoparticles for biofilm prevention and eradication. Additionally, it underscores the potential of nanoparticles as substitutes for traditional antibiotics in healthcare and combating antibiotic resistance. A systematic literature search, encompassing Web of Science, PubMed, and Google Scholar from 2015 to 2023, yielded 48 publications meeting the review criteria. These studies employed diverse methods to explore the antibacterial activity of nanoparticles against biofilm-forming bacteria strains. The implications of this study are profound, offering prospects for novel antimicrobial agents targeting biofilm-forming bacteria, often resistant to conventional antibiotics. In conclusion, nanoparticles present a promising frontier in countering biofilm-forming bacteria. This review delivers a structured analysis of current research, providing insights into the potential and challenges of nanoparticle utilization against biofilm-related challenges. While nanoparticles exhibit inherent antimicrobial properties with applications spanning healthcare, agriculture, and industries, the review acknowledges limitations such as the narrow scope of tested nanoparticles and the imperative need for extensive research on long-term toxicity and environmental impacts.

Phytofabrication of biocompatible zinc oxide nanoparticle using Gymnema sylvestre and its potent in vitro antibacterial, antibiofilm, and cytotoxicity against human breast cancer cells (MDA-MB-231).

The increasing incidence of breast cancer and bacterial biofilm in medical devices significantly heightens global mortality and morbidity, challenging synthetic drugs. Consequently, greener-synthesized nanomaterials have emerged as a versatile alternative for various biomedical applications, offering new therapeutic avenues. This study explores the synthesis of biocompatible zinc oxide (ZnONPs) nanoparticles using Gymnema sylvestre and its antibacterial, antibiofilm, and cytotoxic properties. Characterization of ZnONPs inferred that UV-Vis spectra exhibited a sharp peak at 370nm. Fourier transform infrared spectroscopical analysis revealed the presence of active functional groups such as aldehyde, alkyne, cyclic alkene, sulfate, alkyl aryl ether, and Zn-O bonds. X-ray diffraction analysis results confirmed the crystalline nature of the nanoparticle. Scanning electron microscope analysis evidenced hexagonal morphology, and energy-dispersive X-ray analysis confirmed zinc content. High-resolution transmission electron microscope analysis showed hexagonal and rod-shaped ZnONPs with a size of 5nm. Zeta potential results affirmed the stability of nanoparticles. The ZnONPs effectively inhibited gram-positive (18-20mm) than gram-negative (12-18mm) bacterial pathogens with lower bacteriostatic and higher bactericidal values. Biofilm inhibitory property inferred ZnONPs were more effective against gram-positive (38-94%) than gram-negative bacteria (27-86%). The concentration of ZnONPs to exert 50% biofilm-inhibitory is lower against gram-positive bacteria (179.26-203.95μg/mL) than gram-negative bacteria (201.46-236.19μg/mL). Microscopic visualization inferred that at 250μg/mL, ZnONPs strongly disrupted biofilm formation, as evidenced by decreased biofilm density and altered architecture. The cytotoxicity of ZnONPs against breast cancer cells showed a dose-dependent reduction in cell viability with an IC50 value of 19.4µg/mL. AO/EB staining indicated early and late apoptotic cell death of breast cancer cells under fluorescence microscopy. The results of hemolytic activity validated the biocompatibility of the ZnONPs. Thus, the unique properties of the green-synthesized ZnONPs suggest their potential as effective drug carriers for targeted delivery in cancer therapy and the treatment of biofilm-related infections.

Gallium-based metal–organic frameworks with antibacterial and anti-inflammatory properties for oral health protection

The fascial space of the oral and maxillofacial region contains loose connective tissues, which possess weak anti-infection ability and are often prone to infection, leading to acute suppurative inflammation and sepsis through blood. Although antibiotic use can reduce the probability of bacterial infections, owing to the emergence of antibiotic-resistant bacteria, the search for new antimicrobial drugs is imminent. Herein, we report a metal–organic framework (MOF) antibacterial material designed and synthesized with gallium (Ga) as the central atom, which possesses significant antibacterial, anti-inflammatory, and antioxidant effects. Our data suggested that GA-based MOFs (Ga–MOFs; 1 μg/mL) could sufficiently kill Porphyromonas gingivalis, Streptococcus pyogenes, and Staphylococcus aureus. Ga–MOFs exhibited a bactericidal effect against these three pathogens by disrupting biofilm formation, exopolysaccharide production, and bacterial membrane integrity. In addition, we found that 1 μg/mL of Ga–MOFs was not cytotoxic to human oral epithelial cell (HOEC) lines and it significantly reduced the adhesion of the three pathogens to HOEC. Ga–MOFs protect macrophages from excessive oxidative stress by scavenging excess intracellular reactive oxygen species and upregulating antioxidant gene levels, thereby enhancing cellular antioxidant defense. In addition, Ga–MOFs can promote the transformation of macrophages from the proinflammatory phenotype to the anti-inflammatory phenotype, thereby protecting oral health. Herein, novel Ga–MOF materials were chemically synthesized for therapeutic applications in oral infections, which provides new ideas for the development of novel nonantibiotic drugs to accelerate patient recovery.

Efficacy of Crude Extract from Streptomyces cellulosae Against Biofilm-Related Genes of Candida albicans

Background: Candida albicans (C. albicans) is notably pathogenic due to its ability to form biofilms that are resistant to conventional antifungal treatments. Objectives: This study aims to explore the effectiveness of Streptomyces cellulosae (S. cellulosae) extract in disrupting biofilm formation by targeting specific genes within C. albicans. Methods: The study began by isolating S. cellulosae from soil and C. albicans from clinical specimens. S. cellulosae was then cultured and fermented to produce bioactive compounds. The ability of these extracts to inhibit C. albicans biofilm formation was tested using a crystal violet assay. Additionally, the effects of the S. cellulosae extracts on the expression of biofilm-related genes in C. albicans were evaluated using quantitative real-time PCR (qRT-PCR). The growth rates of C. albicans were also measured to determine the impact of the extracts. Results: The crude extract of S. cellulosae significantly (P < 0.05) inhibited the formation of C. albicans biofilms at concentrations exceeding 0.5 µg/mL, with the inhibition becoming more pronounced at concentrations above 2.0 µg/mL. The qRT-PCR results showed significant changes in the expression of biofilm-related genes ALS1, ALS3, and EFG1 at different extract concentrations (P < 0.05). The extract also significantly affected the expression of the HWPa and BRG1 genes. Conclusions: The crude extract of Streptomyces cellulosae shows potential as a novel antibiofilm agent against C. albicans. This finding opens new avenues for research and potential therapeutic applications in combating biofilm-associated infections.

Discovery of Antibacterial Compounds against Xanthomonas citri subsp. citri from a Marine Fungus Aspergillus terreus SCSIO 41202 and the Mode of Action.

Citrus canker, caused by Xanthomonas citri subsp. citri (Xcc), is a severe citrus disease. Currently, copper-containing pesticides are widely used to manage this disease, posing high risks to the environment and human health. This study reports the discovery of naturally occurring anti-Xcc compounds from a deep-sea fungus, Aspergillus terreus SCSIO 41202, and the possible mode of action. The ethyl acetate extract of A. terreus was subjected to bioassay-guided isolation, resulting in the discovery of eight anti-Xcc compounds (1-8) with minimum inhibitory concentrations (MICs) ranging from 0.078 to 0.625 mg/mL. The chemical structures of these eight metabolites were determined by integrative analysis of various spectroscopic data. Among these compounds, Asperporonin A (1) and Asperporonin B (2) were identified as novel compounds with a very unusual structural skeleton. The electronic circular dichroism was used to determine the absolute configurations of 1 and 2 through quantum chemical calculation. A bioconversion pathway involving pinacol rearrangement was proposed to produce the unusual compounds (1-2). Compound 6 exhibited an excellent anti-Xcc effect with a MIC value of 0.078 mg/mL, which was significantly more potent than the positive control CuSO4 (MIC = 0.3125 mg/mL). Compound 6 inhibited cell growth by disrupting biofilm formation, destroying the cell membrane, and inducing the accumulation of reactive oxygen species. In vivo tests indicated that compound 6 is highly effective in controlling citrus canker disease. These results indicate that compounds 1-8, especially 6, have the potential as lead compounds for the development of new, environmentally friendly, and efficient anti-Xcc pesticides.

Synthesis, in vitro and in silico screening of novel ferrocenyl substituted cyclohexenone and indazole derivatives as effective antimycobacterial agents

In response to the escalating threat of mycobacterial infections, including extensively drug-resistant tuberculosis (XDR) and multidrug-resistant tuberculosis (MDR), we synthesized novel ferrocene incorporating cyclohexenone and indazole derivatives. The compounds were synthesized via multistep reaction approach starting from chalcone precursors and evaluated against Mycobacterium fortuitum. The MIC and MBC values were calculated by following CLSI guidelines, with a focus on their ability to inhibit bacterial growth and disrupt biofilm formation. All the test compounds showed potent in vitro antimycobacterial activity against M. fortuitum. The MIC values range from 3.907 µg/mL to 500 µg/mL, whereas the MBC values range from 15.625 µg/mL to >500 µg/mL. Among the synthesized compounds, compound 3b exhibited potent antimycobacterial activity compared with standard drug Amikacin used to treat multidrug-resistant tuberculosis. 3b demonstrated significant inhibition of bacterial growth and showed the capacity to effectively suppress biofilm formation and disrupt pre-existing biofilms. This molecule also displayed favourable ADMET profile and good oral bioavailability, besides showing potential interactions with the target enzyme as revealed by docking studies and validated by enzyme assay. Collectively, these studies position 3b as a potential lead molecule that could be further optimized to develop ferrocene incorporating indazole based antimycobacterial agents.

Efficacy of a new K3-specific bacteriophage for controlling Klebsiella pneumoniae in milk and its potential to disrupt biofilm formation

Klebsiella pneumoniae (K. pneumoniae) has caused huge economic loss in the dairy industry by inducing mastitis and even endanger public health through contaminated milk products. Suppressing bacterial proliferation in raw milk, particularly in cold settings, is important to preserve milk quality. Owing to increasingly serious antibiotic resistance, bacterial infection has gradually become a difficult matter to settle. Thus, bacteriophages emerge as a potentially effective substitute for antibiotics, garnering renewed interest. Here, we isolated and characterized a new phage, designated P1010, which lyses K3 K. pneumoniae specifically among 23 serotypes. The phage exhibited a latent time of 8 min and produced roughly 101 phages per infected bacteria. Possessing a genome of 44,270 base pairs, the linear double-stranded DNA molecule was devoid of lysogeny, toxin, or tRNA-relevant genes. Of note, P1010 succeeded in significantly suppress bacterial growth in milk both under cold storage condition and room temperature. During the biofilm formation inhibition experiment, OD595 values and viable bacteria counts in the phage treatment groups were significantly reduced. A depolymerase derived from P1010 was identified, possessing a K3 specific enzymatic spectrum. In summary, Klebsiella phage P1010 exhibited bright prospects as biocontrol agents in controlling K. pneumoniae contamination in the dairy industry, offering a viable alternative to antibiotics.

Effect of Matricaria aurea Essential Oils on Biofilm Development, Virulence Factors and Quorum Sensing-Dependent Genes of Pseudomonas aeruginosa.

The emergence of drug-resistant microorganisms presents a substantial global public health threat. The increase in pathogens resistant to commonly prescribed antibiotics underscores the urgent requirement to explore alternative treatment strategies. This study adopts a novel approach by harnessing natural resources, specifically essential oils (EO), to combat bacterial pathogenicity. The primary aim of this research was to analyze the chemical composition of the aerial part of the Matricaria aurea (M. aureas) EO and evaluate its potential for inhibiting quorum sensing (QS) and disrupting biofilm formation in Pseudomonas aeruginosa (P. aeruginosa). The gas chromatography-mass spectrometry (GCMS) analysis unveiled that α-bisabolol oxide A constituted the predominant portion, comprising 64.8% of the total, with β-bisabolene at 6.3% and α-farnesene at 4.8% following closely behind. The antibiofilm efficacy was observed at concentrations of 0.3, 0.15, and 0.08 mg/mL, demonstrating negligible effects on cell viability. Furthermore, the EO from M. aurea effectively inhibited the formation of P. aeruginosa biofilms by diminishing aggregation, hydrophobicity, and swarming motility. Significantly, the EO treatment resulted in a conspicuous decrease in the production of pyocyanin, rhamnolipid, and extracellular polymeric substances (EPS), along with a reduction in the enzymatic activity of protease and chitinase. The EO effectively hindered QS by disrupting QS mechanisms, resulting in a marked decline in the secretion of N-Acyl homoserine lactone (AHL) molecules and the expression of phazA1 and aprA genes. This investigation offers compelling evidence supporting the potential of M. aurea EO as a promising therapeutic candidate for addressing infectious diseases induced by biofilm formation.

Acid adaptation alters Streptococcus mutans drug susceptibility profile

The ability of Streptococcus mutans, the primary causative agent of dental caries, to generate and tolerate an acidic environment is a leading factor in its capacity to outcompete other organisms within the oral cavity. The acid tolerance response (ATR) involves coordination of multiple pathways to upregulate macromolecule repair, maintenance of cytosolic pH, and restructuring the membrane. In this study, we asked if the changes associated with adaptation to a low pH environment would result in detectable changes to drug susceptibility. Accordingly, we screened using the Selleck library of 853 FDA approved drugs for agents that exhibit antimicrobial activity toward planktonic cultures of S. mutans or disrupt biofilm formation in growth medium titrated to pH 5 or in the presence of hydrogen peroxide. Results revealed that a total of 182 compounds displayed antimicrobial properties toward the test strain in at least one screening condition. Our findings provide evidence that the S. mutans ATR is characterized by a concerted shift in drug susceptibility. The presence of an intact ATR, associated with growth in continuous culture at pH 5, leads to increased sensitivity to 22 compounds and decreased sensitivity to a separate set of 20 compounds. Disruption of the ATR in a mutant lacking the fabM gene resulted in a susceptibility profile that was distinct from the result of our results. This suggests that loss of unsaturated fatty acids produces a physiological change that is not only measurable, but perhaps more significant than the process of ATR. Additional tests revealed that S. mutans exhibits a distinct drug susceptibility profile compared to a closely related, non-cariogenic bacterium, S. gordonii. Overall, shifts in S. mutans susceptibility patterns based on pH of growth medium or type of culture (batch vs. continuous culture), indicate that the ATR can be tracked using changes in drug susceptibility profile. Furthermore, our results provide clues that compounds could be useful in treatment of dental caries as well as providing molecular tools to study shifts in physiology of disease-associated bacteria.

Multifunctional nanocomposites integrated green synthesized amphiphilic chitosan/thyme extract/nanosilver for antimicrobial and anti-biofilm applications

BackgroundBacterial biofilms pose a significant challenge in various industries, including healthcare and food production, as they can lead to persistent infections, antibiotic resistance, and contamination. Targeted antimicrobial therapies hold great potential for mitigating the detrimental effects of biofilms. MethodsNew amphiphilic chitosans (ACSs) were prepared and used in combination with thyme extract (TE) as synergistic reducing and stabilizing agents in the preparation of biofunctionalized nanosilver (amphiphilic chitosans-TE-nanosilver, ACSs-TE-Ag) for antibacterial and anti-biofilm applications. ResultsACSs-TE-Ag nanocomposites can synergistically inhibt bacterial proliferation and biofilm formation. ACS2-TE-Ag was the most effective antibacterial agent against E. coli and S. aureus, with MIC values of 0.63 and 1.14 μg/mL, respectively. SEM analysis of the treated bacterial cells showed that ACSs-TE-Ag's greater activity is due to their capacity to rupture the bacterial cell membrane, causing intracellular content leaking and cell death. ACSs-TE-Ag can prevent biofilms by inhibiting bacterial cells from adhering to coated surfaces and killing cells in submerged cultures or biofilms. ConclusionsThe ACSs-TE-Ag nanocomposites exhibit strong bactericidal impacts, disrupt biofilm formation, inhibits bacterial adhesion, and effectively kill bacterial cells within the biofilm matrix. Furthermore, its biocompatibility and low cytotoxicity make it a potential candidate for various biomedical applications.