Development Of Antimicrobial Drugs Research Articles

Discovery and Characterization of a Novel Bacteriocin That Strongly Inhibits Staphylococcus aureus

Drug resistance in Staphylococcus aureus is a serious problem, and the development of new antimicrobial drugs to circumvent drug resistance has become a trend. In this study, we isolated a strain of Bacillus subtilis with high tolerance to alcohol, pH, NaCl, bile salt, surfactants, temperature, and simulated intestinal fluids. We optimized culture parameters to obtain the best fermentation conditions for the production of inhibitory compounds in cell-free culture media. The crude extract showed excellent stability when exposed to temperature, pH, and ultraviolet radiation, with almost no loss of bacteriostatic activity after treatment. After isolation and purification, the peptide sequences were identified using ultraperformance liquid chromatography–mass spectrometry (UPLC–MS), and the antibacterial sequences were analyzed using bioinformatics. The results of the identification showed that there was one novel bacteriocin (NSGGSYGSGGGGGGGNSHGY) with a molecular weight of 1513.58 Da. The minimum inhibitory concentration (MIC) of the B5 bacteriocin was 31.25 μg/mL against S. aureus, and it is noteworthy that bacteriocin B5 also showed weak antibacterial activity against Vibrio parahaemolyticus. In conclusion, this study developed a novel bacteriocin that has the potential to be used as an alternative to S. aureus antibiotics.

Photodynamic Inactivation as a Promising Method of Combating Resistant Strains of Staphylococci

Relevance. The development of antimicrobial drugs and alternative methods, technologies and means of prevention, diagnosis and treatment of human infectious diseases caused by antibiotic-resistant microorganisms is one of the priorities of ensuring the biological safety of the country. Aims. To evaluate the bactericidal activity of tetrapyrrole macroheterocycles (porphyrins) at different light irradiation durations in relation to staphylococci, in vitro. Materials and methods. Studied strains of microorganisms: museum strains of microorganisms – S. aureus ATCC 29213, S. epidermidis ATCC 14990 and antibiotic-resistant strains of bacteria of the genus Staphylococcus (n=18) isolated from clinical biomaterial and from environmental objects in a medical organization. The studied chemical compounds are three different compounds of water-soluble asymmetrically substituted porphyrins containing heterocyclic fragments on the periphery of the porphyrin cycle (residues of benzoxazole, N-methylbenzimidazole and benzothiazole). Results. The activity of all three porphyrin compounds in relation to museum strains of staphylococcus and 77.8% of clinical antibiotic-resistant strains (n=14; 95% CI 20.1-97.5) turned out to be maximal (complete lysis) after 10 minutes of irradiation. Conclusions. The tested tetrapyrrole macroheterocycles (porphyrins) exhibit bactericidal activity against museum and clinical strains of staphylococcus, with different levels of antibiotic resistance, which determines Keywords: antibiotic resistance, water-soluble porphyrin, photodynamic inactivation, photosensitizer, photochemistry, staphylococci No conflict of interest to declare.

In vitro activity of the novel antimicrobial peptide WR-286 in combination with vancomycin against methicillin-resistant Staphylococcus aureus

Background: Multidrug resistance bacteria are a serious problem for health specialists and all the people in the world. The main reasons for this problem are the misuse of antibiotics and the limited number of antibiotics as compared to different human diseases. The important antibiotic-resistant bacteria include Methicillin-resistant Staphylococcus aureus (MRSA). Antimicrobial peptides (AMPs) are regarded as promising antimicrobial agents because they satisfy the requirements for the creation of innovative antimicrobial drugs. The aim of the study: To design a novel antimicrobial peptide and study its effect against MRSA when we combined it with vancomycin. Materials and methods: To produce the hexapeptide WR-286, 1-(2, 6-difluorobenzyl)-1H-1, 2, 3-triazole-4-carboxylic acid, tryptophan (W), and arginine (R) were rationally combined. Different bacterial strains were used to test WR-286's antibacterial properties. Investigations of WR-286's hemolytic activity toward human erythrocytes were also conducted. Finally, utilizing the checkerboard approach and the fractional inhibitory index, synergistic tests with vancomycin were carried out. Results: With MIC values as low as 35 μM, WR-286 demonstrated strong antibacterial activity against MRSA. The toxicity of WR-286 to human red blood cells was very low. Additionally, the peptide and vancomycin's activity were improved by the synergistic experiments. Conclusion: According to the current investigation, WR-286 has little hemolytic activity and displays promising antibacterial activity against MRSA. Additionally, when coupled with vancomycin, the peptide has synergistic effect. The novel AMPs described in this work are promising potential candidates for antimicrobial drug development.

Rapid and Sensitive Quantification of Bacterial Viability Using Ratiometric Fluorescence Sensing.

Bacterial viability assessment plays an important role in food-borne pathogen detection and antimicrobial drug development. Here, we first used GelRed as a DNA-binding stain for a bacterial viability assessment. It was found that live bacteria were able to exclude GelRed, which however could easily penetrate dead ones and be absorbed nonspecifically on the bacterial periplasm. Cations were used to reduce the nonspecific adsorption and greatly increase the red fluorescence ratio of dead to live bacteria. Combined with SYTO 9 (a membrane-permeable dye) for double-staining, a ratiometric fluorescent method was established. Using Escherichia coli O157:H7 as a bacteria model, the ratiometric fluorescent method can probe dead bacteria as low as 0.1%. A linear correlation between the ratiometric fluorescence and the theoretical ratio of dead bacteria was acquired, with a correlation coefficient R2 of 0.97. Advantages in sensitivity, accuracy, and safety of the GelRed/SYTO9-based ratiometric fluorescent method against traditional methods were demonstrated. The established method was successfully applied to the assessment of germicidal efficacy of different heat treatments. It was found that even 50 °C treatment could lead to the death of minor bacteria. The as-developed method has many potential applications in microbial researches, and we believe it could be expanded to the viability assessment of mammalian cells.

Genomic insights into an endophytic Streptomyces sp. VITGV156 for antimicrobial compounds.

Endophytic Streptomyces sp. are recognized as a potential resource for valuable natural products but are less explored. This study focused on exploring endophytic Streptomyces species residing within tomato plants (Solanum lycopersicum) harboring genes for the production of a novel class of antibiotics. Our research involved the isolation and characterization of Streptomyces sp. VITGV156, a newly identified endophytic Streptomyces species that produces antimicrobial products. VITGV156 harbors a genome of 8.18 mb and codes 6,512 proteins, of which 4,993 are of known function (76.67%) and 1,519 are of unknown function (23.32%). By employing genomic analysis, we elucidate the genome landscape of this microbial strain and shed light on various BGCs responsible for producing polyketide antimicrobial compounds, with particular emphasis on the antibiotic kendomycin. We extended our study by evaluating the antibacterial properties of kendomycin. Overall, this study provides valuable insights into the genome of endophytic Streptomyces species, particularly Streptomyces sp. VITGV156, which are prolific producers of antimicrobial agents. These findings hold promise for further research and exploitation of pharmaceutical compounds, offering opportunities for the development of novel antimicrobial drugs.

Biofilm microenvironment-activated multimodal therapy nanoplatform for effective anti-bacterial treatment and wound healing

Antimicrobial drug development faces challenges from bacterial resistance, biofilms, and excessive inflammation. Here, we design an intelligent nanoplatform utilizing mesoporous silica nanoparticles doped with copper ions for loading copper sulfide (DM/Cu2+-CuS). The mesoporous silica doped with tetrasulfide bonds responds to the biofilm microenvironment (BME), releasing Cu2+ions, CuS along with hydrogen sulfide (H2S) gas. The release of hydrogen sulfide within 72 h reached 793.5 µM, significantly higher than that observed with conventional small molecule donors. H2S induces macrophages polarization towards the M2 phenotype, reducing inflammation and synergistically accelerating endothelial cell proliferation and migration with Cu2+ions. In addition, H2S disrupts extracellular DNA within biofilms, synergistically photothermal enhanced peroxidase-like activity of CuS to effectively eradicate biofilms. Remarkably, DM-mediated consumption of endogenous glutathione enhances the anti-biofilm activity of H2S and improves oxygen species (ROS) destruction efficiency. The combination of photothermal therapy (PTT), chemodynamic therapy (CDT), and gas treatment achieves sterilization rates of 99.3 % and 99.6 % against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), respectively, in vitro under 808 nm laser irradiation. Additionally, in vivo experiments demonstrate a significant biosafety and antibacterial potential. In summary, the H2S donor developed in this study exhibits enhanced biocompatibility and controlled release properties. By integrating BME-responsive gas therapy with antibacterial ions, PTT and CDT, a synergistic multimodal strategy is proposed to offer new therapeutic approaches for wound healing. Statement of significanceThe advanced DMOS/Cu2+-CuS (DMCC) multimodal therapeutic nanoplatform has been developed for the treatment of drug-resistant bacterial wound infections and has exhibited enhanced therapeutic efficacy through the synergistic effects of photothermal therapy, chemodynamic therapy, Cu2+ions, and H2S. The DMCC exhibited exceptional biocompatibility and could release CuS, Cu2+, and H2S in response to elevated concentrations of glutathione within the biofilm microenvironment. H2S effectively disrupted the biofilm structure. Meanwhile, peroxidase activity of CuS combined with GSH-mediated reduction of Cu2+ to Cu+ generated abundant hydroxyl radicals under acidic conditions, leading to efficient eradication of pathogenic bacteria. Furthermore, both H2S and Cu2+ could modulate M2 macrophages polarization and regulate immune microenvironment dynamics. These strategies collectively provided a novel approach for developing antibacterial nanomedical platforms.

Recent Advances in Amphipathic Peptidomimetics as Antimicrobial Agents to Combat Drug Resistance.

The development of antimicrobial drugs with novel structures and clear mechanisms of action that are active against drug-resistant bacteria has become an urgent need of safeguarding human health due to the rise of bacterial drug resistance. The discovery of AMPs and the development of amphipathic peptidomimetics have lay the foundation for novel antimicrobial agents to combat drug resistance due to their overall strong antimicrobial activities and unique membrane-active mechanisms. To break the limitation of AMPs, researchers have invested in great endeavors through various approaches in the past years. This review summarized the recent advances including the development of antibacterial small molecule peptidomimetics and peptide-mimic cationic oligomers/polymers, as well as mechanism-of-action studies. As this exciting interdisciplinary field is continuously expanding and growing, we hope this review will benefit researchers in the rational design of novel antimicrobial peptidomimetics in the future.

PROBLEMS OF DETERMINING THE MEDICINAL HERBAL REMEDIES ANTIMICROBIAL ACTIVITY AND THEIR SOLUTION METHODS

Intriduction. Currently, the antibiotic resistance development in pathogenic microorganisms remains a global problem. To solve this problem, an active search and development of new antimicrobial drugs, including those of plant origin, is underway. In the many years course of experience in this area, methods used to determine antimicrobial activity are being developed and improved, however, not all of them are suitable for determining the activity of biologically active substances of plant origin. The purpose of the study. To summarize information about existing methods for determining antimicrobial activity under in vitro experimental conditions. Material and methods. The article is based on publication materials from the PubMed and E-library databases, search.rsl. The literary search was carried out by keywords: antimicrobial activity, antibacterial effect, antibiotic, herbal preparations. The review includes articles that are relevant to the research topic and have been published over the past 10 years. Results and discussion. The article describes the main methods for determining antimicrobial activity in vitro and determines the possibility of using these methods in relation to herbal remedies. Conclusions. The findings indicated that the choice of the research method should depend primarily on the object under study and the type of microorganism in respect of which the activity is determined. Most of the developed and widely used methods for determining antimicrobial activity do not allow an adequate assessment of the activity of herbal remedies. Thus, when working with herbal remedies, the methods of double serial dilutions in liquid nutrient media with the use of indicators and the developing direction of activity research on biofilms can be considered the most accurate.

Scanning electron microscopic investigation on Chicory tribe (Compositae) botanical sources and their antimicrobial potential.

This study discusses the micro-level structural details of Cichorieae pollen sources elucidated by scanning electron microscopy (SEM) and explains their symmetry and morphometry. The in-depth knowledge from the electron ultrastructure of Asteraceae pollen has provided insights into enhanced pollen morphology, and the antimicrobial significance of species under study presents novel avenues for their natural defense mechanisms in the development of antimicrobial agents. In this research, both quantitative and qualitative features of pollen were examined. The pollen grains are prolate-spheroidal and oblate-spheroidal in shape, characterized by a maximum polar diameter of 55.6-61.0 μm and a maximum equatorial distance of 68.3-74.4 μm. SEM reveals various configurations such as echinate perforate-tectate, psilate, and echino-lophate perforate. The Cichorieae species have significant antimicrobial efficacy and are promising sources for the development of novel antimicrobial drugs with potential implications in pharmaceutical and healthcare industries. SEM analysis of Cichorieae pollens has provided remarkable insights into their unique structures, revealing diverse shapes and surface ornamentations, which can be used for accurate Asteraceae species identification. RESEARCH HIGHLIGHTS: SEM provides unique pollen surface structures and patterns of Chicory pollen grains. Chemical composition of Chicory botanical sources provides valuable information on their potential as antimicrobial agents. SEM imaging reveals specialized fenestrate grain structures of taxonomic importance.

Synthesis, Structure-activity Relationship, and Biological Activity of Benzimidazole-quinoline: A Review to Aid in the Design of a New Drug

Abstract: Heterocyclic compounds are fundamental building blocks for developing novel bioactive compounds. Due to their extensive uses in both industrial and synthetic organic chemistry, quinoline and benzimidazole have recently become important heterocycles. Clinical trials have investigated quinoline and benzimidazole analogues to treat a variety of illnesses, including cancer, bacterial and fungal infection, DNA damage, etc. Medicinal chemists are paying attention to nitrogen-containing hybrid heterocyclic compounds that have a wide range of therapeutical potential with lesser adverse effects. Many efforts have been made to find new and more efficient ways to synthesize these molecules. However, microbial resistance is becoming a major threat to the scientific community; hence, the necessity for the discovery and development of novel antimicrobial drugs with novel modes of action is becoming highly significant. One strategy to overcome this problem is to produce hybrid molecules by combining two or more bioactive heterocyclic moieties in a single molecular platform. Based on established research data on quinoline- bearing benzimidazole derivatives, it can be concluded that both moieties are used for the synthesis of promising therapeutically active agents. This present review comprises the synthetic approaches of biologically active quinolines containing benzimidazole derivatives with their structure-activity relationship studies to provide an overview of the work done on quinoline derivatives to the medicinal chemist for future research.

Application of inhibitors targeting the type III secretion system in phytopathogenic bacteria

Plant bacterial diseases have inflicted substantial economic losses in global crop, fruit, and vegetable production. The conventional methods for managing these diseases typically rely on the application of antibiotics. However, these antibiotics often target the growth factors of the pathogenic bacteria, leading to the accumulation and emergence of drug-resistant strains, which exacerbates antibiotic resistance. Innovative methods are urgently needed to treat and prevent the toxicity caused by these pathogenic bacteria. Targeting virulence mechanisms in pathogens is a globally recognized and effective strategy for mitigating bacterial resistance. Type III secretion system (T3SS) serves as a crucial virulence determinant in Gram-negative pathogens, and its non-essentials for pathogen growth renders it an ideal target. Targeting the T3SS holds significant potential to alleviate selective pressure for resistance mutations in pathogens. Therefore, targeting T3SS in pathogenic bacteria, while preserving their growth, has emerged as a novel avenue for the development of antimicrobial drugs. In recent years, a multitude of small molecular inhibitors targeting T3SS have been identified. This article offers a comprehensive review of T3SS inhibitors in plant pathogens, while also presenting the latest research advancements in this research direction.

Recommendations for topical antimicrobial therapy of inflammatory diseases of the middle ear based on the results of evidence-based clinical study

Introduction. In conditions of widespread resistance of pathogens to traditional antimicrobial drugs, active attention is paid to the development of topical antimicrobial drugs for the effective treatment of inflammatory pathology of the middle ear.Aim. To study the efficacy and safety of a new dosage form of the drug Dioxydin® (2.5 mg/ml ear drops) in the treatment of patients with acute purulent otitis media and exacerbation of chronic purulent otitis media in comparison with ear drops containing 0.3% ciprofloxacin solution.Materials and methods. A multicenter randomized comparative clinical trial included adults with acute purulent otitis media or exacerbation of chronic purulent otitis media and during 6 face-to-face visits (days 1st, 3rd, 6th, 9th, as well as a therapy completion visit and a follow-up visit), the effect of drugs was evaluated according to examination, otoscopy, microbiological and audiometric examinations. Safety was assessed by the frequency of adverse events and the results of blood, urine tests and vital signs.Results. The achievement of the primary criteria was evaluated among 164 participants randomized into 2 groups: the proportion of patients with no indications for systemic antibacterial therapy at Visit 2 and with no ear pain at Visit 4, Dioxydin® ear drops had no less effectiveness than the comparison drug (64.6 and 89.9% versus 68.3 and 87.3%, respectively). In terms of the frequency of elimination of the pathogen and improvement of air conduction, the compared drugs also had no statistically significant differences, and according to some secondary criteria, Dioxydin® significantly exceeded 0.3% ciprofloxacin solution (the proportion of patients with a pronounced decrease in pain and congestion in the ear, as well as hyperemia of the eardrum). According to the safety criteria, the compared drugs had no significant differences.Conclusions. The results of the study confirmed the high efficacy and safety of Dioxydin® ear drops in the treatment of otitis media in adults.

Unlocking the mechanism of action: a cost-effective flow cytometry approach for accelerating antimicrobial drug development.

Antimicrobial resistance is one of the greatest challenges to global health. While the development of new antimicrobials can combat resistance, low profitability reduces the number of new compounds brought to market. Elucidating the mechanism of action is crucial for developing new antimicrobials. This can become expensive as there are no universally applicable pipelines. Phenotypic heterogeneity of microbial populations resulting from antimicrobial treatment can be captured through flow cytometric fingerprinting. Since antimicrobials are classified into limited groups, the mechanism of action of known compounds can be used for predictive modeling. We demonstrate a cost-effective flow cytometry approach for determining the mechanism of action of new compounds. Cultures of Actinomyces viscosus and Fusobacterium nucleatum were treated with different antimicrobials and measured by flow cytometry. A Gaussian mixture mask was applied over the data to construct phenotypic fingerprints. Fingerprints were used to assess statistical differences between mechanism of action groups and to train random forest classifiers. Classifiers were then used to predict the mechanism of action of cephalothin. Statistical differences were found among the different mechanisms of action groups. Pairwise comparison showed statistical differences for 35 out of 45 pairs for A. viscosus and for 32 out of 45 pairs for F. nucleatum after 3.5 h of treatment. The best-performing random forest classifier yielded a Matthews correlation coefficient of 0.92 and the mechanism of action of cephalothin could be successfully predicted. These findings suggest that flow cytometry can be a cheap and fast alternative for determining the mechanism of action of new antimicrobials.IMPORTANCEIn the context of the emerging threat of antimicrobial resistance, the development of novel antimicrobials is a commonly employed strategy to combat resistance. Elucidating the mechanism of action of novel compounds is crucial in this development but can become expensive, as no universally applicable pipelines currently exist. We present a novel flow cytometry-based approach capable of determining the mechanism of action swiftly and cost-effectively. The workflow aims to accelerate drug discovery and could help facilitate a more targeted approach for antimicrobial treatment of patients.

Structural insights into the Clp protein degradation machinery.

The Clp protease system is important for maintaining proteostasis in bacteria. It consists of ClpP serine proteases and an AAA+ Clp-ATPase such as ClpC1. The hexameric ATPase ClpC1 utilizes the energy of ATP binding and hydrolysis to engage, unfold, and translocate substrates into the proteolytic chamber of homo- or hetero-tetradecameric ClpP for degradation. The assembly between the hetero-tetradecameric ClpP1P2 chamber and the Clp-ATPases containing tandem ATPase domains from the same species has not been studied in depth. Here, we present cryo-EM structures of the substrate-bound ClpC1:shClpP1P2 from Streptomyces hawaiiensis, and shClpP1P2 in complex with ADEP1, a natural compound produced by S. hawaiiensis and known to cause over-activation and dysregulation of the ClpP proteolytic core chamber. Our structures provide detailed information on the shClpP1-shClpP2, shClpP2-ClpC1, and ADEP1-shClpP1/P2 interactions, reveal conformational transition of ClpC1 during the substrate translocation, and capture a rotational ATP hydrolysis mechanism likely dominated by the D1 ATPase activity of chaperones.IMPORTANCEThe Clp-dependent proteolysis plays an important role in bacterial homeostasis and pathogenesis. The ClpP protease system is an effective drug target for antibacterial therapy. Streptomyces hawaiiensis can produce a class of potent acyldepsipeptide antibiotics such as ADEP1, which could affect the ClpP protease activity. Although S. hawaiiensis hosts one of the most intricate ClpP systems in nature, very little was known about its Clp protease mechanism and the impact of ADEP molecules on ClpP. The significance of our research is in dissecting the functional mechanism of the assembled Clp degradation machinery, as well as the interaction between ADEP1 and the ClpP proteolytic chamber, by solving high-resolution structures of the substrate-bound Clp system in S. hawaiiensis. The findings shed light on our understanding of the Clp-dependent proteolysis in bacteria, which will enhance the development of antimicrobial drugs targeting the Clp protease system, and help fighting against bacterial multidrug resistance.

Antimicrobial Action Mechanisms of Natural Compounds Isolated from Endophytic Microorganisms.

Infectious diseases are a significant challenge to global healthcare, especially in the face of increasing antibiotic resistance. This urgent issue requires the continuous exploration and development of new antimicrobial drugs. In this regard, the secondary metabolites derived from endophytic microorganisms stand out as promising sources for finding antimicrobials. Endophytic microorganisms, residing within the internal tissues of plants, have demonstrated the capacity to produce diverse bioactive compounds with substantial pharmacological potential. Therefore, numerous new antimicrobial compounds have been isolated from endophytes, particularly from endophytic fungi and actinomycetes. However, only a limited number of these compounds have been subjected to comprehensive studies regarding their mechanisms of action against bacterial cells. Furthermore, the investigation of their effects on antibiotic-resistant bacteria and the identification of biosynthetic gene clusters responsible for synthesizing these secondary metabolites have been conducted for only a subset of these promising compounds. Through a comprehensive analysis of current research findings, this review describes the mechanisms of action of antimicrobial drugs and secondary metabolites isolated from endophytes, antibacterial activities of the natural compounds derived from endophytes against antibiotic-resistant bacteria, and biosynthetic gene clusters of endophytic fungi responsible for the synthesis of bioactive secondary metabolites.

HKFGCN: A novel multiple kernel fusion framework on graph convolutional network to predict microbe-drug associations

Accumulating clinical studies have consistently demonstrated that the microbes in the human body closely interact with the human host, actively participating in the regulation of drug effectiveness. Identifying the associations between microbes and drugs can facilitate the development of drug discovery, and microbes have become a new target in antimicrobial drug development. However, the discovery of microbe-drug associations relies on clinical or biological experiments, which are not only time-consuming but also financially burdensome. Thus, the utilization of computational methods to predict microbe-drug associations holds promise for reducing costs and enhancing the efficiency of biological experiments. Here, we introduce a new computational method, called HKFGCN (Heterogeneous information Kernel Fusion Graph Convolution Network), to predict the microbe-drug associations. Instead of extracting feature from a single network in previous studies, HKFGCN separately extracts topological information features from different networks, and further refines them by generating Gaussian kernel features. HKFGCN consists of three main steps. Firstly, we constructed two similarity networks and a microbe-drug association network based on numerous biological data. Second, we employed two types of encoders to extract features from these networks. Next, Gaussian kernel features were obtained from the drug and microbe features at each layer. Finally, we reconstructed the bipartite microbe-drug graph based on the learned representations. Experimental results demonstrate the excellent performance of the HKFGCN model across different datasets using the cross-validation scheme. Additionally, we conduced case studies on human immunodeficiency virus, and the results were corroborated by existing literatures. The prediction model’s code is available at https://github.com/roll-of-bubble/HKFGCN.

Design, synthesis, and biological evaluation of carbazole derivatives as potent antibacterial agents targeting membrane function via FabH Inhibition

This study synthesized a series of carbazole compounds and tested their antimicrobial activity. Several of the synthesized compounds demonstrated potent inhibitory effects against Gram-negative bacteria. Molecular docking simulations with the fatty acid synthesis enzyme FabH revealed their potential antimicrobial action by interfering with fatty acid synthesis. Additionally, ADMET analysis confirmed favorable pharmacokinetic properties, providing a foundation for drug development and preclinical research. Furthermore, the optimized compound 2-(9HCarbazol-9-yl)-N-(4-(trifluoromethoxy)phenyl)acetamide was evaluated for its inhibitory and disruptive effects on biofilms using live/dead cell staining. The results demonstrated significant inhibition and disruption of biofilms, enhancing their antimicrobial efficacy. These findings offer valuable clues for the development of new antimicrobial drugs and hold promise for addressing the challenge of antimicrobial resistance with novel therapeutic strategies.

Molecular guidelines for promising antimicrobial agents

Antimicrobial resistance presents a pressing challenge to public health, which requires the search for novel antimicrobial agents. Various experimental and theoretical methods are employed to understand drug-target interactions and propose multistep solutions. Nonetheless, efficient screening of drug databases requires rapid and precise numerical analysis to validate antimicrobial efficacy. Diptool addresses this need by predicting free energy barriers and local minima for drug translocation across lipid membranes. In the current study employing Diptool free energy predictions, the thermodynamic commonalities between selected antimicrobial molecules were characterized and investigated. To this end, various clustering methods were used to identify promising groups with antimicrobial activity. Furthermore, the molecular fingerprinting and machine learning approach (ML) revealed common structural elements and physicochemical parameters in these clusters, such as long carbon chains, charged ammonium groups, and low dipole moments. This led to the establishment of guidelines for the selection of effective antimicrobial candidates based on partition coefficients (logP) and molecular mass ranges. These guidelines were implemented within the Reinforcement Learning for Structural Evolution (ReLeaSE) framework, generating new chemicals with desired properties. Interestingly, ReLeaSE produced molecules with structural profiles similar to the antimicrobial agents tested, confirming the importance of the identified features. In conclusion, this study demonstrates the ability of molecular fingerprinting and AI-driven methods to identify promising antimicrobial agents with a broad range of properties. These findings deliver substantial implications for the development of antimicrobial drugs and the ongoing battle against antibiotic-resistant bacteria.

In vitro evaluation of the susceptibility of bacterial biofilms to hecogenin acetate

Biofilms are a bacterial resistance strategy through which microorganisms organize themselves in the form of a colony fixed to a surface that is protected by a polymer matrix. Infectious diseases that result in biofilm formation have been considered a relevant public health problem due to the potential to increase patient morbidity and mortality, in addition to increasing the burden on health services. Such pathologies are treated with the use of antimicrobial drugs, the indiscriminate use of which has contributed to the process of bacterial resistance, demanding the need to invest in new alternatives to combat them. Based on this, the present work aimed to evaluate the anti-biofilm formation and eradication capacity of Hecogenin Acetate, a steroidal sapogenin of natural origin with important antibacterial properties. For this, we used strains of Streptococcus mutans INCQS 00,446 (ATCC 25,175), Enterococcus faecalis INCQS 00,018 (ATCC 14,506), Staphylococcus epidermidis INCQS 00,016 (ATCC 12,228), Staphylococcus aureus ATCC 25,923, Pseudomonas aeruginosa ATCC 9027 and Escherichia coli ATCC 259,223. The formation, formation inhibition and treatment assays were carried out in microdilution plates and revealed using the crystal violet method. Readings were carried out using absorbance at wavelengths of 492 nm. All tests were performed in triplicate and statistical analyzes were performed using Graphpad Prism v.5.0 software. It was observed that the bacterial strains used have a relevant capacity for biofilm formation, with the Gram positive ones identified in the present study as the best former. In the results of the analyzes with bacterial biofilm, it was identified that Hecogenin Acetate had a relevant antibiofilm capacity, and could therefore serve as a basis for further research into the development of new antimicrobial drugs.

THE ANTIBACTERIAL POTENTIAL OF EUKARYOTIC MARINE MICROALGAE AGAINST PATHOGENS FROM CHICKEN, DOG AND AQUACULTURE

Antibiotic resistance is an emerging concern, leading to the search for alternative antibacterial agents. Scientists looking for potential alternatives to antibiotics see promise in the antimicrobial propensity of microalgae. We investigated the antibacterial potentials of Tetraselmis, Chlorella, and Nannochloropsis against pathogenic bacteria from chicken, dogs, and fish. We identified E. coli, Stenotrophomonas sp., Streptococcus sp., Staphylococcus sp., Aeromonas sp. and Lysinibacillus sp. by colony characteristics, Gram staining and VITEK-2 tests. Results demonstrated that Tetraselmis was highly sensitive against Stenotrophomonas sp. (p < 0.0001) and E. coli (p < 0.001) from chicken, and Staphylococcus sp. (p < 0.01) from dogs. Moreover, Chlorella was highly sensitive against E. coli (p < 0.0001) from dogs. All the bacteria isolated from chicken were moderate to highly sensitive to Chlorella. Nannochloropsis was marginally sensitive to all the bacteria isolated from chickens and dogs. The minimum inhibitory concentration values indicate that a minimum of 10 mg/ml of Tetraselmis can suppress the growth of Aeromonas sp. from fish and Chlorella can suppress E. coli and Stenotrophomonas sp. from chicken. Results indicate that native microalgae may have an active somatic or secretory components that prevent bacterial cell division and/or induce lysis. Advanced studies should be performed to identify the active component for the development of newer and sustainable antimicrobial drugs.