Antibiotic resistance in microbes: History, mechanisms, therapeutic strategies and future prospects

Structure-guided identification and characterization of potent inhibitors targeting PhoP and MtrA to combat mycobacteria

Mycobacteria are causative agents of tuberculosis (TB), which is a global health concern. Drug-resistant TB strains are rapidly emerging, thereby necessitating the urgent development of new drugs. Two-component signal transduction systems (TCSs) are signaling pathways involved in the regulation of various bacterial behaviors and responses to environmental stimuli. Applying specific inhibitors of TCSs can disrupt bacterial signaling, growth, and virulence, and can help combat drug-resistant TB. We conducted a comprehensive pharmacophore-based inhibitor screening and biochemical and biophysical examinations to identify, characterize, and validate potential inhibitors targeting the response regulators PhoP and MtrA of mycobacteria. The constructed pharmacophore model Phar-PR-n4 identified effective inhibitors of formation of the PhoP-DNA complex: ST132 (IC50 = 29 ± 1.6 µM) and ST166 (IC50 = 18 ± 1.3 µM). ST166 (KD = 18.4 ± 4.3 μM) and ST132 (KD = 14.5 ± 0.1 μM) strongly targeted PhoP in a slow-on, slow-off manner. The inhibitory potency and binding affinity of ST166 and ST132 for MtrAC were comparable to those of PhoP. Structural analyses and molecular dynamics simulations revealed that ST166 and ST132 mainly interact with the α8-helix and C-terminal β-hairpin of PhoP, with functionally essential residue hotspots for structure-based inhibitor optimization. Moreover, ST166 has in vitro antibacterial activity against Macrobacterium marinum. Thus, ST166, with its characteristic 1,2,5,6-tetrathiocane and terminal sulphonic groups, has excellent potential as a candidate for the development of novel antimicrobial agents to combat pathogenic mycobacteria.

Prevalence, pandemic, preventions and policies to overcome antimicrobial resistance

Antimicrobial resistance (AMR) is a growing concern in Asia, and it is essential to understand the prevalence, pandemic, prevention, and policies to overcome it. According to the World Health Organization (WHO), AMR is one of the main causes of death; in 2019, it was linked to 4.95 million fatalities and caused about 1.27 million deaths. A core package of actions has been provided by WHO to help countries prioritize their needs when creating, carrying out, and overseeing national action plans on antimicrobial resistance. Using a people-cantered approach to AMR, the interventions address the needs and obstacles that individuals and patients encounter when trying to obtain healthcare. The people-cantered core package of AMR treatments seeks to improve public and policymakers; awareness and comprehension of AMR by changing the narrative of AMR to emphasize the needs of people and systemic impairments. Additionally, it backs a more comprehensive and programmatic national response to AMR, which emphasizes the value of fair and inexpensive access to high-quality healthcare services for the avoidance, identification, and management of drug-resistant diseases. The report signals increasing resistance to antibiotics in bacterial infections in humans and the need for better data. In conclusion, the prevalence of AMR in Asia is a significant public health concern, and it is crucial to implement policies and interventions to overcome it.

Systematic alanine and stapling mutational analysis of antimicrobial peptide Chem-KVL

Chem-KVL is a tandem repeating peptide, with 14 amino acids that was modified based on a short peptide from a fragment of the human host defense protein chemerin. Chem-KVL increases cationicity and hydrophobicity and shows broad-spectrum antibacterial activity. To determine the molecular determinants of Chem-KVL and whether staple-modified Chem-KVL would improve antibacterial activity and protease stability or decrease cytotoxicity, we combined alanine and stapling scanning, and designed a series of alanine and staple-derived Chem-KVL peptides, termed Chem-A1 to Chem-A14 and SCL-1 to SCL-7. We next examined their antibacterial activity against several gram-positive and gram-negative bacteria, their proteolytic stability, and their cytotoxicity. Ala scanning of Chem-KVL suggested that both the positively charged residues (Lys and Arg) and the hydrophobic residues (Lue and Val) were critical for the antibacterial activities of Chem-KVL peptide. Of note, Chem-A4 was able to remarkably inhibit the growth of gram-positive and gram-negative bacteria when compared to the original peptide. And the antibacterial activities of stapled SCL-4 and SCL-7 were several times higher than those of the linear peptide against gram-positive and gram-negative bacteria. Stapling modification of peptides resulted in increased helicity and protein stability when compared with the linear peptide. These stapled peptides, especially SCL-4 and SCL-7, may serve as the leading compounds for further optimization and antimicrobial therapy.

A systematic review of antibiotics and antibiotic resistance genes (ARGs) in mariculture wastewater: Antibiotics removal by microalgal-bacterial symbiotic system (MBSS), ARGs characterization on the metagenomic

Antibiotic residues in mariculture wastewater seriously affect the aquatic environment. Antibiotic Resistance Genes (ARGs) produced under antibiotic stress flow through the environment and eventually enter the human body, seriously affecting human health. Microalgal-bacterial symbiotic system (MBSS) can remove antibiotics from mariculture and reduce the flow of ARGs into the environment. This review encapsulates the present scenario of mariculture wastewater, the removal mechanism of MBSS for antibiotics, and the biomolecular information under metagenomic assay. When confronted with antibiotics, there was a notable augmentation in the extracellular polymeric substances (EPS) content within MBSS, along with a concurrent elevation in the proportion of protein (PN) constituents within the EPS, which limits the entry of antibiotics into the cellular interior. Quorum sensing stimulates the microorganisms to produce biological responses (DNA synthesis - for adhesion) through signaling. Oxidative stress promotes gene expression (coupling, conjugation) to enhance horizontal gene transfer (HGT) in MBSS. The microbial community under metagenomic detection is dominated by aerobic bacteria in the bacterial-microalgal system. Compared to aerobic bacteria, anaerobic bacteria had the significant advantage of decreasing the distribution of ARGs. Overall, MBSS exhibits remarkable efficacy in mitigating the challenges posed by antibiotics and resistant genes from mariculture wastewater.

Antibiotic resistance: A key microbial survival mechanism that threatens public health

Antibiotic resistance (AMR) is a global public health threat, challenging the effectiveness of antibiotics in combating bacterial infections. AMR also represents one of the most crucial survival traits evolved by bacteria. Antibiotics emerged hundreds of millions of years ago as advantageous secondary metabolites produced by microbes. Consequently, AMR is equally ancient and hardwired into the genetic fabric of bacteria. Human use of antibiotics for disease treatment has created selection pressure that spurs the evolution of new resistance mechanisms and the mobilization of existing ones through bacterial populations in the environment, animals, and humans. This integrated web of resistance elements is genetically complex and mechanistically diverse. Addressing this mode of bacterial survival requires innovation and investment to ensure continued use of antibiotics in the future. Strategies ranging from developing new therapies to applying artificial intelligence in monitoring AMR and discovering new drugs are being applied to manage the growing AMR crisis.

Characterization and antibacterial evaluation of Eco-friendly silver nanoparticles synthesized by halophilic Streptomyces rochei SSCM102 isolated from mangrove sediment

BACKGROUND

Antimicrobial resistance has surged due to widespread antimicrobial drug use, prompting interest in biosynthesizing nanoparticles from marine-derived actinomycetes extracellular metabolites, valued for their diverse bioactive compounds. This approach holds promise for addressing the urgent need for novel antimicrobial agents. The current study aimed to characterize novel bioactive compounds from unexplored biodiversity hotspots, halophilic Streptomyces sp. isolated from mangrove sediment in the Pichavaram region, India.

METHODS AND RESULTS

Streptomyces rochei SSCM102 was conclusively identified through morphological and molecular characterization. Synthesis of silver nanoparticles (AgNPs) from Streptomyces rochei SSCM102 was characterized using various techniques, including UV-Vis, XRD, SEM, EDX, and FT-IR. The UV-Vis spectrum of the reduced AgNPs exhibited a prominent peak at 380 nm, confirming the AgNPs. The UV-Vis spectrum confirmed the synthesis of AgNP, and SEM analysis revealed a cubic morphology with sizes ranging from 11 to 21 nm. The FTIR spectrum demonstrated a shift in frequency widths between 626 cm-1 and 3432 cm-1. The EDX analysis substantiated the presence of metallic silver, evident from a strong band at 1.44 keV. The synthesized AgNPs exhibited antibacterial efficacy against human pathogens Escherichia coli (64 ± 0.32 µg/ml), Klebsiella pneumoniae (32 ± 0.16 µg/ml), and Pseudomonas aeruginosa (16 ± 0.08 µg/ml) by MIC and MBC values of 128 ± 0.64 (µg/ml), 64 ± 0.32 (µg/ml) and 32 ± 0.16 (µg/ml), respectively. Additionally, at a concentration of 400 µg/ml, the AgNPs displayed a 72% inhibition of DPPH radicals, indicating notable antioxidant capacity. The LC50 value of 130 µg/mL indicates that the green-synthesized AgNPs have lower toxicity by Brine Shrimp Larvae assay.

CONCLUSION

The study's novel approach to synthesizing eco-friendly silver nanoparticles using Halophilic Streptomyces rochei SSCM102 contributes significantly to the field of biomedical research and drug development. By demonstrating potent antibacterial properties and aligning with sustainability goals, these nanoparticles offer promising avenues for novel antibacterial therapies.

Visible-Light-Responsive Novel Ru(II)-Metallo-Antibiotics with Potential Antibiofilm and Antibacterial Activity

Growing challenges with antibiotic resistance pose immense challenges in combating microbial infections and biofilm prevention on medical devices. Lately, antibacterial photodynamic therapy (aPDT) is now emerging as an alternative therapy to overcome this problem. Herein, we synthesized and characterized four Ru(II)-complexes, viz., [Ru(ph-tpy)(bpy)Cl]PF6 (Ru1), [Ru(ph-tpy)(dpq)Cl]PF6 (Ru2), [Ru(ph-tpy)(dppz)Cl]PF6 (Ru3), and [Ru(ph-tpy)(dppn)Cl]PF6 (Ru4) (where 4'-phenyl-2,2':6',2″-terpyridine = ph-tpy; 2,2'-bipyridine = bpy; dipyrido[3,2-f:2',3'-h]quinoxaline = dpq; dipyrido[3,2-a:2',3'-c]phenazine = dppz; and Benzo[I]dipyrido[3,2-a:2',3'-c]phenazine = dppn), among which Ru2-Ru4 are novel. Octahedral geometry of the complexes with a RuN5Cl core was evident from the crystal structure of Ru2. Ru1-Ru4 showed an MLCT absorption band in the 450-600 nm region, useful for aPDT performances. Further, optimum triplet excited state energy and excellent photostability of Ru1-Ru4 made them good photosensitizers for aPDT. Ru1-Ru4 demonstrated enhanced antimicrobial activity on visible-light exposure (400-700 nm, 10 J cm-2), confirmed using different antibacterial assays. Mechanistic studies revealed that inhibition of bacterial growth was due to the generation of oxidative stress (via NADH oxidation and ROS generation) upon treatment with Ru2-Ru4, resulting in destruction of the bacterial wall. Ru2 performed best killing performance against both Gram-negative (Escherichia coli) and Gram-positive (Bacillus subtilis) bacteria when exposed to light. Ru2-Ru4, when coated on a polydimethylsiloxane (PDMS) disk, showed long-term reusability and durable antibiofilm properties. Molecular docking confirmed the efficient interaction of Ru2-Ru4 with FabH (regulates fatty acid biosynthesis of E. coli) and PgaB (gives structural stability and helps biofilm formation of E. coli), resulting in probable downregulation. In vivo studies with healthy Wistar rats confirmed the biocompatibility of Ru2. This study shows that these lead complexes (Ru2-Ru4) can be used as potent alternative antimicrobial agents in low concentrations toward bacterial eradication with photodynamic therapy (PDT).

Therapeutic potential activity of quercetin complexes against Streptococcus pneumoniae

This study investigates quercetin complexes as potential synergistic agents against the important respiratory pathogen Streptococcus pneumoniae. Six quercetin complexes (QCX1-6) were synthesized by reacting quercetin with various metal salts and boronic acids and characterized using FTIR spectroscopy. Their antibacterial activity alone and in synergism with antibiotics was evaluated against S. pneumoniae ATCC 49619 using disc diffusion screening, broth microdilution MIC determination, and checkerboard assays. Complexes QCX-3 and QCX-4 demonstrated synergy when combined with levofloxacin via fractional inhibitory concentration indices ≤ 0.5 as confirmed by time-kill kinetics. Molecular docking elucidated interactions of these combinations with virulence enzymes sortase A and sialidase. A biofilm inhibition assay found the synergistic combinations more potently reduced biofilm formation versus monotherapy. Additionally, gene-gene interaction networks, biological activity predictions and in-silico toxicity profiling provided insights into potential mechanisms of action and safety.

Cascade encapsulation of antimicrobial peptides, exosomes and antibiotics in fibrin-gel for first-aid hemostasis and infected wound healing

Wounding is one of the most common healthcare problems. Bioactive hydrogels have attracted much attention in first-aid hemostasis and wound healing due to their excellent biocompatibility, antibacterial properties, and pro-healing bioactivity. However, their applications are limited by inadequate mechanical properties. In this study, we first prepared edible rose-derived exosome-like nanoparticles (ELNs) and used them to encapsulate antimicrobial peptides (AMP), abbreviated as ELNs(AMP). ELNs(AMP) showed superior intracellular antibacterial activity, 2.5 times greater than AMP, in in vitro cell infection assays. We then prepared and tested an FDA-approved fibrin-gel of fibrinogen and thrombin encapsulating ELNs(AMP) and novobiocin sodium salt (NB) (ELNs(AMP)/NB-fibrin-gels). The fibrin gel showed a sustained release of ELNs(AMP) and NB over the eight days of testing. After spraying onto the skin, the formulation underwent in situ gelation and developed a stable patch with excellent hemostatic performance in a mouse liver injury model with hemostasis in 31 s, only 35.6 % of the PBS group. The fibrin gel exhibited pro-wound healing properties in the mouse-infected skin defect model. The thickness of granulation tissue and collagen of the ELNs(AMP)/NB-fibrin-gels group was 4.00, 6.32 times greater than that of the PBS group. In addition, the ELNs(AMP)/NB-fibrin-gels reduced inflammation (decreased mRNA levels of TNF-α, IL-1β, IL6, MCP1, and CXCL1) at the wound sites and demonstrated a biocompatible and biosafe profile. Thus, we have developed a hydrogel system with excellent hemostatic, antibacterial, and pro-wound healing properties, which may be a candidate for next-generation tissue regeneration with a wide clinical application for first-aid hemostasis and infected wound healing.

The role of gaming for information, education and communication of AMR: full review of online education resources

Background

The first objective of the Global Action Plan on antimicrobial resistance (AMR) is to improve awareness and understanding of AMR through effective communication, education and training. Towards this several efforts have been made to create AMR awareness resources. The aim of these resources is to inform the public about responsible antibiotic use and drive positive behavioural change. Digital media and specifically games can serve as unique innovative platforms in public communication programmes.

Objectives

This study focuses on compiling and evaluating game-based AMR resources. Recognizing the engaging and creative potential of games as learning tools, the primary objective of this study was to identify games that can be used, individually or in combination depending on their unique focus and gameplay experience, for AMR awareness. Furthermore, games are evaluated on five objective criteria and recommendations are made towards further development of gaming resources towards AMR awareness.

Methods

Meticulous curation was performed to mine information, education and communication resources, with a primary focus on games for AMR awareness and evaluating them based on game design and gameplay, AMR content and learning, engagement and replay appeal, learning outcomes, and level of difficulty and challenges.

Results

In this study, we selected 12 AMR games. Our evaluations, spanning various gamification elements and interactive parameters, informed recommendations for future AMR resource development, including multilevel game design, varied graphics, simple-to-understand rules, sustained challenge and a sense of reward, among others.

Conclusions

This study generated the first-ever comprehensive catalogue of AMR games that may assist public communication programmes for AMR awareness. Evaluation of these games led to actionable design recommendations for future resources towards effective communication of AMR complexity, enhanced learning and awareness.

Application of machine learning for antibiotic resistance in water and wastewater: A systematic review

Antibiotic resistance (AR) is considered one of the greatest global threats in the current century, which can only be overcome if all interconnected areas of humans, animals and the environment are taken into account as part of the One Health concept proposed by the World Health Organization (WHO). Water and wastewater are among the most important environmental media of AR sources, where the phenomena are generally non-linear. Therefore, the aim of this study was to investigate the application of machine learning-based methods (MLMs) to solve AR-induced problems in water and wastewater. For this purpose, most relevant databases were searched in the period between 1987 and 2023 to systematically analyze and categorize the applications. Accordingly, the results showed that out of 12 applications, 11 (91.6%) were for shallow learning and 1 (8.3%) for deep learning. In shallow learning category, n = 6, 50% of the applications were regression and n = 4, 33.3% were classification, mainly using artificial neural networks, decision trees and Bayesian methods for the following objectives: Predicting the survival of antibiotic-resistant bacteria (ARB), determining the order of influencing parameters on AR-based scores, and identifying the major sources of antibiotic resistance genes (ARGs). In addition, only one study (8.3%) was found for clustering and no study for association. Surprisingly, deep learning had been used in only one study (8.3%) to predict ARGs sequences. Therefore, working on the knowledge gaps of AR, especially using clustering, association and deep learning methods, would be a promising option to analyze more aspects of the related problems. However, there is still a long way to go to consider and apply MLMs as unique approaches to study different aspects of AR in water and wastewater.

Aluminum oxide, cobalt aluminum oxide, and aluminum-doped zinc oxide nanoparticles as an effective antimicrobial agent against pathogens

Since the clock of antimicrobial resistance was set, modern medicine has shed light on a new cornerstone in technology to overcome the worldwide dread of the post-antimicrobial era. Research organizations are exploring the use of nanotechnology to modify metallic crystals from macro to nanoscale size, demonstrating significant interest in the field of antimicrobials. Herein, the antimicrobial activities of aluminum oxide (Al2O3), cobalt aluminum oxide (CoAl2O4), and aluminum doped zinc oxide (Zn0.9Al0.1O) nanoparticles were examined against some nosocomial pathogens. The study confirmed the formation and characterization of Al2O3, CoAl2O4, and Zn0.9Al0.1O nanoparticles using various techniques, revealing the generation of pure nanoscale nanoparticles. With inhibition zones ranging from 9 to 14 mm and minimum inhibitory concentrations varying from 4 mg/mL to 16 mg/mL, the produced nanoparticles showed strong antibacterial activity against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. Meanwhile, the bactericidal concentrations ranged from 8 mg/mL to 40 mg/mL. In culture, Zn0.9Al0.1O NPs demonstrated a unique ability to inhibit the development of nosocomial infections with high bactericidal activity (8 mg/mL). Transmission electron microscope images revealed changes in cell shape, bacterial cell wall morphology, cytoplasmic membrane, and protoplasm due to the introduction of tested nanoparticles. These results pave the way for the use of these easily bacterial wall-piercing nanoparticles in combination with potent antibiotics to overcome the majority of bacterial strains' resistance.

Investigating the effectiveness of liposome-bacteriophage nanocomplex in killing Staphylococcus aureus using epithelial cell coculture models

Host cell invasion with strong antibiotics evading is a major feature of respiratory Staphylococcus aureus infections with severe recurrence. Bacteriophage (phage) therapy and design of liposomal phage to target intracellular pathogens have been described recently. The practicality for pulmonary delivery of liposomal phage, and how formulation compositions affecting the aerosolization and intracellular bacterial killing remain unexplored. In the present study, three commonly used phospholipids (SPC, EPC, and HSPC) were selected to investigate their ability for phage K nebulization and intracellular therapy in the form of liposome-phage nanocomplexes. The three lipid nanocarriers showed protection on phage K upon mesh nebulization and the pulmonary deposition efficiency was influenced by the lipid used. Moreover, the intracellular bacterial killing was strongly depended on the lipid types, where EPC-phage exhibited the best killing performance with no relapsing. Phage K with the aid of EPC liposomes was also observed to manage the tissue infection in a 3D spheroid model more effectively than other groups. Altogether, this novel EPC liposome-phage nanocomplex can be a promising formulation approach that enables inhalable phage to manage respiratory infections caused by bacteria strongly associated with human epithelial cells.

Patterns of antibiotic prescription in implant dentistry and antibiotic resistance awareness among European dentists: A questionnaire-based study

OBJECTIVES

Antimicrobial resistance is an alarming global public health concern, threatening the effective treatment of common infections. This phenomenon is driven by the improper prescription of antibiotics. This study aimed to elucidate the patterns of antibiotic prescription in implant dentistry among European dentists and their awareness of antibiotic resistance.

MATERIALS AND METHODS

An anonymous online validated questionnaire was distributed via e-mail to 6431 recipients through the European Association for Osseointegration. It comprised of 17 structured questions investigating demographic variables, working environment, clinical experience, attitude towards antibiotic prescription in particular in relation to implant dentistry and COVID-19 pandemic, and awareness of antibiotic resistance. Data were collected from April to May 2023.

RESULTS

281 dentists from 33 European countries completed the survey. Almost 80% affirmed to routinely prescribe antibiotics as prophylaxis as well as after dental implant placement, especially in medically compromised patients or in cases of bone grafting. Amoxicillin, alone (61%) or in combination with clavulanic acid (56%), was the most common antibiotic of choice. Awareness of penicillin resistance among respondents was high. For peri-implantitis treatment, more than half reported the use of systemic antibiotics. The large majority (95%) did not prescribe more antibiotics since the beginning of COVID-19 pandemic. Less than 40% declared to follow national guidelines for antibiotic prescription.

CONCLUSION

This survey revealed a high prescription rate of antibiotics in implant dentistry, despite the awareness about antibiotic resistance among the respondents. The development and adherence to European guidelines has been identified as a potential strategy for improving antimicrobial stewardship.

Inhibition of bacterial RNA polymerase function and protein-protein interactions: a promising approach for next-generation antibacterial therapeutics

The increasing prevalence of multidrug-resistant pathogens necessitates the urgent development of new antimicrobial agents with innovative modes of action for the next generation of antimicrobial therapy. Bacterial transcription has been identified and widely studied as a viable target for antimicrobial development. The main focus of these studies has been the discovery of inhibitors that bind directly to the core enzyme of RNA polymerase (RNAP). Over the past two decades, substantial advancements have been made in understanding the properties of protein-protein interactions (PPIs) and gaining structural insights into bacterial RNAP and its associated factors. This has led to the crucial role of computational methods in aiding the identification of new PPI inhibitors to affect the RNAP function. In this context, bacterial transcriptional PPIs present promising, albeit challenging, targets for the creation of new antimicrobials. This review will succinctly outline the structural foundation of bacterial transcription networks and provide a summary of the known small molecules that target transcription PPIs.

Antifungal potential of multi-drug-resistant Pseudomonas aeruginosa: harnessing pyocyanin for candida growth inhibition

Introduction

Pseudomonas aeruginosa is notorious for its multidrug resistance and its involvement in hospital-acquired infections. In this study, 20 bacterial strains isolated from soil samples near the Hindan River in Ghaziabad, India, were investigated for their biochemical and morphological characteristics, with a focus on identifying strains with exceptional drug resistance and pyocyanin production.

Methods

The isolated bacterial strains were subjected to biochemical and morphological analyses to characterize their properties, with a particular emphasis on exopolysaccharide production. Strain GZB16/CEES1, exhibiting remarkable drug resistance and pyocyanin production. Biochemical and molecular analyses, including sequencing of its 16S rRNA gene (accession number LN735036.1), plasmid-curing assays, and estimation of plasmid size, were conducted to elucidate its drug resistance mechanisms and further pyocynin based target the Candida albicans Strain GZB16/CEES1 demonstrated 100% resistance to various antibiotics used in the investigation, with plasmid-curing assays, suggesting plasmid-based resistance gene transmission. The plasmid in GZB16/CEES1 was estimated to be approximately 24 kb in size. The study focused on P. aeruginosa's pyocyanin production, revealing its association with anticandidal activity. The minimum inhibitory concentration (MIC) of the bacterial extract against Candida albicans was 50 μg/ml, with a slightly lower pyocyanin-based MIC of 38.5 μg/ml. Scanning electron microscopy illustrated direct interactions between P. aeruginosa strains and Candida albicans cells, leading to the destruction of the latter.

Discussion

These findings underscore the potential of P. aeruginosa in understanding microbial interactions and developing strategies to combat fungal infections. The study highlights the importance of investigating bacterial-fungal interactions and the role of pyocyanin in antimicrobial activity. Further research in this area could lead to the development of novel therapeutic approaches for combating multidrug-resistant infections.

Exploring the physicochemical traits, antifungal capabilities, and 3D spatial complexity of hydroxyapatite with Ag+Mg2+ substitution in the biocomposite thin films

The silver/magnesium doped hydroxyapatite (AgMgHAp, Ca10-x-yAgxMgy(PO4)6(OH)2, xAg=0.05 and yMg=0.02) nanocomposites coatings were deposited on Si substrate using the dip coating technique. The resulting coatings were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR-ATR) spectroscopy, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The EDS analysis highlighted the presence of the constitutive elements of the silver/magnesium doped hydroxyapatite (AgMgHAp) nanocomposites coatings. The surface microtexture of the AgMgHAp was assessed by atomic force microscopy (AFM) technique. The AFM data suggested the obtaining of a uniform deposited layer comprised of equally distributed nanoconglomerates. FT-IR studies highlighted the presence of vibrational modes associated with the phosphate and hydroxyl groups. No bands associated with silver or magnesium were observed. The XPS analysis highlighted the presence of the constituent elements of hydroxyapatite (Ca 2p, P 2 s, O 1 s), as well as dopants (Ag 3d, Mg 1 s and Mg 2p). The antifungal evaluation of AgMgHAp coatings was carried out using the Candida albicans ATCC 10231 fungal strain. The results of the antifungal assay revealed that the AgMgHAp coatings exhibited a strong inhibitory antifungal activity. Furthermore, the data highlighted that the AgMgHAp inhibited the development of biofilm on their surface. The results revealed that the antifungal activity of the coating varied based on the duration of incubation. On the other hand, the data also showed that AgMgHAp nanocomposites coatings inhibited the fungal cell adhesion and development from the early stages of the incubation. In addition to morphological analysis, we additionally take advantage of AFM images to investigate and explore the domain of fractal and multifractal analysis applied to the films under evaluation. Our studies indicates that nanocomposite coatings made from AgMgHAp demonstrate strong antifungal properties. Our studies indicates that nanocomposite coatings made from AgMgHAp demonstrate strong antifungal properties. These results suggest the potential of AgMgHAp nanocomposite coatings as a promising solution for developing innovative antifungal devices in biomedical applications.

Targeting bacterial biofilm-related genes with nanoparticle-based strategies

Persistent infection caused by biofilm is an urgent in medicine that should be tackled by new alternative strategies. Low efficiency of classical treatments and antibiotic resistance are the main concerns of the persistent infection due to biofilm formation which increases the risk of morbidity and mortality. The gene expression patterns in biofilm cells differed from those in planktonic cells. One of the promising approaches against biofilms is nanoparticle (NP)-based therapy in which NPs with multiple mechanisms hinder the resistance of bacterial cells in planktonic or biofilm forms. For instance, NPs such as silver (Ag), zinc oxide (ZnO), titanium dioxide (TiO2), copper oxide (Cu), and iron oxide (Fe3O4) through the different strategies interfere with gene expression of bacteria associated with biofilm. The NPs can penetrate into the biofilm structure and affect the expression of efflux pump, quorum-sensing, and adhesion-related genes, which lead to inhibit the biofilm formation or development. Therefore, understanding and targeting of the genes and molecular basis of bacterial biofilm by NPs point to therapeutic targets that make possible control of biofilm infections. In parallel, the possible impact of NPs on the environment and their cytotoxicity should be avoided through controlled exposure and safety assessments. This study focuses on the biofilm-related genes that are potential targets for the inhibition of bacterial biofilms with highly effective NPs, especially metal or metal oxide NPs.

Antibiotics alter development and gene expression in the model cnidarian Nematostella vectensis

Background

Antibiotics are commonly used for controlling microbial growth in diseased organisms. However, antibiotic treatments during early developmental stages can have negative impacts on development and physiology that could offset the positive effects of reducing or eliminating pathogens. Similarly, antibiotics can shift the microbial community due to differential effectiveness on resistant and susceptible bacteria. Though antibiotic application does not typically result in mortality of marine invertebrates, little is known about the developmental and transcriptional effects. These sublethal effects could reduce the fitness of the host organism and lead to negative changes after removal of the antibiotics. Here, we quantify the impact of antibiotic treatment on development, gene expression, and the culturable bacterial community of a model cnidarian, Nematostella vectensis.

Methods

Ampicillin, streptomycin, rifampicin, and neomycin were compared individually at two concentrations, 50 and 200 µg mL-1, and in combination at 50 µg mL-1 each, to assess their impact on N. vectensis. First, we determined the impact antibiotics have on larval development. Next Amplicon 16S rDNA gene sequencing was used to compare the culturable bacteria that persist after antibiotic treatment to determine how these treatments may differentially select against the native microbiome. Lastly, we determined how acute (3-day) and chronic (8-day) antibiotic treatments impact gene expression of adult anemones.

Results

Under most exposures, the time of larval settlement extended as the concentration of antibiotics increased and had the longest delay of 3 days in the combination treatment. Culturable bacteria persisted through a majority of exposures where we identified 359 amplicon sequence variants (ASVs). The largest proportion of bacteria belonged to Gammaproteobacteria, and the most common ASVs were identified as Microbacterium and Vibrio. The acute antibiotic exposure resulted in differential expression of genes related to epigenetic mechanisms and neural processes, while constant application resulted in upregulation of chaperones and downregulation of mitochondrial genes when compared to controls. Gene Ontology analyses identified overall depletion of terms related to development and metabolism in both antibiotic treatments.

Discussion

Antibiotics resulted in a significant increase to settlement time of N. vectensis larvae. Culturable bacterial species after antibiotic treatments were taxonomically diverse. Additionally, the transcriptional effects of antibiotics, and after their removal result in significant differences in gene expression that may impact the physiology of the anemone, which may include removal of bacterial signaling on anemone gene expression. Our research suggests that impacts of antibiotics beyond the reduction of bacteria may be important to consider when they are applied to aquatic invertebrates including reef building corals.

Co-delivery of doxycycline and rifampicin using CdTe-labeled poly (lactic-co-glycolic) acid for treatment of Brucella melitensis infection

Brucellosis poses a significant challenge in the medical field as a systemic infection with a propensity for relapse. This study presented a novel approach to brucellosis treatment, enhancing the efficacy of doxycycline and rifampicin through the use of poly (lactic-co-glycolic) acid coupled with cadmium-telluride quantum dots (Dox-Rif-PLGA@CdTe). The double emulsion solvent evaporation method was employed to prepare Dox-Rif-PLGA@CdTe. The study scrutinized the physicochemical attributes of these nanoparticles. The impact of antibiotic-loaded nanoparticles on Brucella melitensis was evaluated through well diffusion, minimum inhibitory concentration (MIC), and cell culture. The chemical analysis results demonstrated a possibility of chemical reactions occurring among the constituents of nanoparticles. Assessments using the well diffusion and MIC methods indicated that the impact of free drugs and nanoparticles on bacteria was equivalent. However, the drug-loaded nanoparticles significantly decreased the colony-forming units (CFUs) within the cell lines compared to free drugs. In conclusion, the synthesis of nanoparticles adhered to environmentally friendly practices and demonstrated safety. The sustained drug release over 100 h facilitated drug accumulation at the bacterial site, resulting in a heightened therapeutic effect on B. melitensis and improved outcomes in brucellosis treatment. The application of these synthesized nanodrugs exhibited promising therapeutic potential.

Friends or foes? Novel antimicrobials tackling MDR/XDR Gram-negative bacteria: a systematic review

Gram-negative bacteria have been one of the most studied classes in the field of microbiology, especially in the context of globally alarming antimicrobial resistance levels to these pathogens over the course of the past decades. With high numbers of these microorganisms being described as multidrug-resistant (MDR), or even extended-drug-resistant (XDR) bacteria, specialists in the field have been struggling to keep up with higher prevalence of difficult-to-treat infections caused by such superbugs. The FDA approval of novel antimicrobials, such as cefiderocol (FDC), ceftolozane/tazobactam (C/T), ceftazidime/avibactam (CZA), imipenem/relebactam (IMR), sulbactam/durlobactam (SUL-DUR) and phase 3 clinical trials' results of aztreonam/avibactam (ATM-AVI) has proven that, while all these substances provide encouraging efficacy rates, antibiotic resistance keeps up with the pace of drug development. Microorganisms have developed more extensive mechanisms of resistance in order to target the threat posed by these novel antimicrobials, thus equiring researchers to be on a constant lookout for other potential drug candidates and molecule development. However, these strategies require a proper understanding of bacterial resistance mechanisms to gain a comprehensive outlook on the issue. The present review aims to highlight these six antibiotic agents, which have brought hope to clinicians during the past decade, discussing general properties of these substances, as well as mechanisms and patterns of resistance, while also providing a short overview on further directions in the field.

Systematic review registration

https://www.crd.york.ac.uk/prospero/#searchadvanced, Identifier CRD42024505832.

A comprehensive study on Geranium robertianum L. antibacterial potential

AIMS

The research aimed to optimize the ultrasound-assisted extraction of secondary metabolites and the antibacterial activity of the plant species Geranium robertianum. The phytochemical profiles of the optimized extracts, as well as their antibacterial and synergistic activity with an antibiotic and their potential mechanisms of action and cytotoxicity, were examined.

METHODS AND RESULTS

Response Surface Methodology was used to optimize extraction conditions. Optimized ethanol and acetone extracts were tested via microdilution, checkerboard, time-kill kinetics, and cell membrane permeability methods. The extracts displayed broad antibacterial activity with minimum inhibitory concentrations ranging from 1.25 to 20 mg ml-1. In addition, the extract synergistically reacted with gentamicin against gentamicin-resistant strains of Escherichia coli and Staphylococcus aureus, enhancing the efficacy of the antibiotic up to 32-fold. The extracts demonstrated strain-dependent bactericidal activity in a 24-h time interval. They increase the permeability of the cell membrane, thus disrupting its normal functioning. The cytotoxic concentration (CC50) on human keratinocytes was 1771.24 ± 5.78 µg ml-1 for ethanol extract, and 958.01 ± 6.14 µg ml-1 for acetone extract. Kaempferol, ellagic acid, quercetin, and rutin were recognized as the main components in both extracts.

CONCLUSIONS

The findings of this study indicate that the extracts of G. robertianum can be considered as potential natural antibacterial agents in the control of microorganisms.

Antimicrobial sensitisers: Gatekeepers to avoid the development of multidrug-resistant bacteria

The resistance of multidrug-resistant bacteria to existing antibiotics forces the continued development of new antibiotics and antibacterial agents, but the high costs and long timeframe involved in the development of new agents renders the hope that existing antibiotics may again play a part. The "antibiotic adjuvant" is an indirect antibacterial strategy, but its vague concept has, in the past, limited the development speed of related drugs. In this review article, we put forward an accurate concept of a "non-self-antimicrobial sensitisers (NSAS)", to distinguish it from an "antibiotic adjuvant", and then discuss several scientific methods to restore bacterial sensitivity to antibiotics, and the sources and action mechanism of existing NSAS, in order to guide the development and further research of NSAS.

Thymol, a Monoterpenoid within Polymeric Iodophor Formulations and Their Antimicrobial Activities

Antimicrobial resistance (AMR) poses an emanating threat to humanity's future. The effectiveness of commonly used antibiotics against microbial infections is declining at an alarming rate. As a result, morbidity and mortality rates are soaring, particularly among immunocompromised populations. Exploring alternative solutions, such as medicinal plants and iodine, shows promise in combating resistant pathogens. Such antimicrobials could effectively inhibit microbial proliferation through synergistic combinations. In our study, we prepared a formulation consisting of Aloe barbadensis Miller (AV), Thymol, iodine (I2), and polyvinylpyrrolidone (PVP). Various analytical methods including SEM/EDS, UV-vis, Raman, FTIR, and XRD were carried out to verify the purity, composition, and morphology of AV-PVP-Thymol-I2. We evaluated the inhibitory effects of this formulation against 10 selected reference strains using impregnated sterile discs, surgical sutures, gauze bandages, surgical face masks, and KN95 masks. The antimicrobial properties of AV-PVP-Thymol-I2 were assessed through disc diffusion methods against 10 reference strains in comparison with two common antibiotics. The 25-month-old formulation exhibited slightly lower inhibitory zones, indicating changes in the sustained-iodine-release reservoir. Our findings confirm AV-PVP-Thymol-I2 as a potent antifungal and antibacterial agent against the reference strains, demonstrating particularly strong inhibitory action on surgical sutures, cotton bandages, and face masks. These results enable the potential use of the formulation AV-PVP-Thymol-I2 as a promising antimicrobial agent against wound infections and as a spray-on contact-killing agent.

NhaA: A promising adjuvant target for colistin against resistant Escherichia coli

The emergence and widespread of multidrug-resistant Gram-negative bacteria have posed a severe threat to human health and environmental safety, escalating into a global medical crisis. Utilization of antibiotic adjuvants is a rapid approach to combat bacterial resistance effectively since the development of new antimicrobial agents is a formidable challenge. NhaA, driven by proton motive force, is a crucial secondary transporter on the cytoplasmic membrane of Escherichia coli. We found that 2-Aminoperimidine (2-AP), which is a specific inhibitor of NhaA, could enhance the activity of colistin against sensitive E. coli and reverse the resistance in mcr-1 positive E. coli. Mechanistic studies indicated that 2-AP induced dysfunction in cytoplasmic membrane through the suppression of NhaA, leading to metabolic inhibition and ultimately enhancing the sensitivity of E. coli to colistin. Moreover, 2-AP restored the efficacy of colistin against resistant E. coli in two animal infection models. Our findings reveal the potential of NhaA as a novel target for colistin adjuvants, providing new possibilities for the clinical application of colistin.

Potentiation of the Antimicrobial Effect of Oxytetracycline Combined with Cinnamon, Clove, Oregano, and Red Thyme Essential Oils against MDR Salmonella enterica Strains

Tetracyclines have a high resistance percentage in Salmonella spp. of both human and animal origin. Essential oils, such as cinnamon (Cinnamomum zeylanicum), clove (Eugenia caryophyllata), oregano (Origanum vulgare), and red thyme (Thymus zygis), have shown bactericidal activity against this bacterium. However, in many cases, the minimum inhibitory concentration (MIC) exceeds the cytotoxicity limits. The objective of this study was to assess the in vitro efficacy of combining oxytetracycline with essential these oils against field multidrug-resistant (MDR) Salmonella enterica strains. The MIC of each product was determined using the broth microdilution method. The interaction was evaluated using the checkerboard method, by means of the fractional inhibitory concentration index (FICindex) determination. The results showed a positive interaction (synergy and additivity) between oxytetracycline and the four oils tested, resulting in a reduction in both products' MICs by 2 to 4 times their initial value, in the case of oils, and by 2 to 1024 times in the case of the antibiotic. The combination of oxytetracycline and cinnamon achieved the best results (FICindex 0.5), with a decrease in the antibiotic effective concentration to below the sensitivity threshold (MIC of the combined oxytetracycline 0.5 µg/mL). There was no antagonistic effect in any case, although differences in response were observed depending on the bacterial strain. The results of this study suggest that combining oxytetracycline with cinnamon oil could be an effective alternative for controlling tetracycline-resistant strains of Salmonella. However, its individual use should be further evaluated through in vitro susceptibility tests.

Fraxetin Targeting to Sortase A Decreases the Pathogenicity of Streptococcus agalactiae to Nile Tilapia

Sortase A (SrtA) is responsible for anchoring surface proteins to the cell wall, and has been identified as a promising target developing anti-infective drugs of Gram-positive bacteria. The aim of the study was to identify inhibitors of Streptococcus agalactiae (S. agalactiae) SrtA from natural compounds to overcome the spread of antibiotic resistance in aquaculture. Here, we found that the MIC of fraxetin against S. agalactiae was higher than 256 μg/mL, indicating that fraxetin had no anti- S. agalactiae activity. But fraxetin could dose-dependently decrease the activity of SrtA in vitro at concentrations ranging between 4-32 μg/mL by a fluorescence resonance energy transfer (FRET) assay. Moreover, the inhibition of SrtA by fraxetin decreased the anchoring of surface proteins with the LPXTG motif to the cell wall by detecting the immunofluorescence change of serine-rich repeat protein 1 (Srr1) on the bacterial cell surface. The results of fibronectin binding and cell adhesion assays indicated that fraxetin could significantly decrease the adhesion ability of S. agalactiae in a dose-dependent manner. The results were further proven by immunofluorescence staining. Animal challenge results showed that treatment with fraxetin could reduce the mortality of tilapia infected with S. agalactiae to 46.67%, indicating that fraxetin could provide a significant amount of protection to tilapia by inactivating SrtA. Taken together, these findings provided a novel inhibitor of S. agalactiae SrtA and a promising candidate for treating S. agalactiae infections in aquaculture.

Emerging challenges in antimicrobial resistance: implications for pathogenic microorganisms, novel antibiotics, and their impact on sustainability

Overuse of antibiotics is accelerating the antimicrobial resistance among pathogenic microbes which is a growing public health challenge at the global level. Higher resistance causes severe infections, high complications, longer stays at hospitals and even increased mortality rates. Antimicrobial resistance (AMR) has a significant impact on national economies and their health systems, as it affects the productivity of patients or caregivers due to prolonged hospital stays with high economic costs. The main factor of AMR includes improper and excessive use of antimicrobials; lack of access to clean water, sanitation, and hygiene for humans and animals; poor infection prevention and control measures in hospitals; poor access to medicines and vaccines; lack of awareness and knowledge; and irregularities with legislation. AMR represents a global public health problem, for which epidemiological surveillance systems have been established, aiming to promote collaborations directed at the well-being of human and animal health and the balance of the ecosystem. MDR bacteria such as E. coli, Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus spp., Acinetobacter spp., and Klebsiella pneumonia can even cause death. These microorganisms use a variety of antibiotic resistance mechanisms, such as the development of drug-deactivating targets, alterations in antibiotic targets, or a decrease in intracellular antibiotic concentration, to render themselves resistant to numerous antibiotics. In context, the United Nations issued the Sustainable Development Goals (SDGs) in 2015 to serve as a worldwide blueprint for a better, more equal, and more sustainable existence on our planet. The SDGs place antimicrobial resistance (AMR) in the context of global public health and socioeconomic issues; also, the continued growth of AMR may hinder the achievement of numerous SDGs. In this review, we discuss the role of environmental pollution in the rise of AMR, different mechanisms underlying the antibiotic resistance, the threats posed by pathogenic microbes, novel antibiotics, strategies such as One Health to combat AMR, and the impact of resistance on sustainability and sustainable development goals.

Green Synthesized Chitosan Nanoparticles for Controlling Multidrug-Resistant mecA- and blaZ-Positive Staphylococcus aureus and aadA1-Positive Escherichia coli

Antimicrobial resistance has recently been considered an emerging catastrophe globally. The public health and environmental threats were aggravated by the injudicious use of antibiotics in animal farming, aquaculture, and croup fields, etc. Consequently, failure of antibiotic therapies is common because of the emergence of multidrug-resistant (MDR) bacteria in the environment. Thus, the reduction in antibiotic spillage in the environment could be an important step for overcoming this situation. Bear in mind, this research was focused on the green synthesis of chitosan nanoparticles (ChiNPs) using Citrus lemon (Assam lemon) extract as a cross-linker and application in controlling MDR bacteria to reduce the antibiotic spillage in that sector. For evaluating antibacterial activity, Staphylococcus aureus and Escherichia coli were isolated from environmental specimens, and their multidrug-resistant pattern were identified both phenotypically by disk diffusion and genotypically by detecting methicillin- (mecA), penicillin- (blaZ), and streptomycin (aadA1)-resistance encoding genes. The inhibitory zone's diameter was employed as a parameter for determining the antibacterial effect against MDR bacteria revealing 30 ± 0.4 mm, 34 ± 0.2 mm, and 36 ± 0.8 mm zones of inhibition against methicillin- (mecA) and penicillin (blaZ)-resistant S. aureus, and streptomycin (aadA1)-resistant E. coli, respectively. The minimum inhibitory concentration at 0.31 mg/mL and minimum bactericidal concentration at 0.62 mg/mL of yielded ChiNPs were used as the broad-spectrum application against MDR bacteria. Finally, the biocompatibility of ChiNPs was confirmed by showing a negligible decrease in BHK-21 cell viability at doses less than 2 MIC, suggesting their potential for future application in antibiotic-free farming practices.

Unleashing the promise of emerging nanomaterials as a sustainable platform to mitigate antimicrobial resistance

The emergence and spread of antibiotic-resistant (AR) bacterial strains and biofilm-associated diseases have heightened concerns about exploring alternative bactericidal methods. The WHO estimates that at least 700 000 deaths yearly are attributable to antimicrobial resistance, and that number could increase to 10 million annual deaths by 2050 if appropriate measures are not taken. Therefore, the increasing threat of AR bacteria and biofilm-related infections has created an urgent demand for scientific research to identify novel antimicrobial therapies. Nanomaterials (NMs) have emerged as a promising alternative due to their unique physicochemical properties, and ongoing research holds great promise for developing effective NMs-based treatments for bacterial and viral infections. This review aims to provide an in-depth analysis of NMs based mechanisms combat bacterial infections, particularly those caused by acquired antibiotic resistance. Furthermore, this review examines NMs design features and attributes that can be optimized to enhance their efficacy as antimicrobial agents. In addition, plant-based NMs have emerged as promising alternatives to traditional antibiotics for treating multidrug-resistant bacterial infections due to their reduced toxicity compared to other NMs. The potential of plant mediated NMs for preventing AR is also discussed. Overall, this review emphasizes the importance of understanding the properties and mechanisms of NMs for the development of effective strategies against antibiotic-resistant bacteria.

Design, Synthesis, and Biological Evaluation of Novel Arylomycins against Multidrug-Resistant Gram-Negative Bacteria

G0775, an arylomycin-type SPase I inhibitor that is being evaluated in a preclinical study, exhibited potent antibacterial activities against some Gram-negative bacteria but meanwhile suffered defects such as a narrow antibacterial spectrum and poor pharmacokinetic properties. Herein, systematic structural modifications were carried out, including optimization of the macrocyclic skeleton, warheads, and lipophilic regions. The optimization culminated in the discovery of 138f, which showed more potent activity and a broader spectrum against clinically isolated carbapenem-resistant Gram-negative bacteria, especially against Acinetobacter baumannii and Pseudomonas aeruginosa. 162, the free amine of 138f, exhibited an excellent pharmacokinetic profile in rats. In a neutropenic mouse thigh model of infection with multidrug-resistant P. aeruginosa, the potent in vivo antibacterial efficacy of 162 was confirmed and superior to that of G0775 (3.5-log decrease vs 1.1-log decrease in colony-forming unit (CFU)). These results support 162 as a potential antimicrobial agent for further research.

A comprehensive synthetic library of poly-N-acetyl glucosamines enabled vaccine against lethal challenges of Staphylococcus aureus

Poly-β-(1-6)-N-acetylglucosamine (PNAG) is an important vaccine target, expressed on many pathogens. A critical hurdle in developing PNAG based vaccine is that the impacts of the number and the position of free amine vs N-acetylation on its antigenicity are not well understood. In this work, a divergent strategy is developed to synthesize a comprehensive library of 32 PNAG pentasaccharides. This library enables the identification of PNAG sequences with specific patterns of free amines as epitopes for vaccines against Staphylococcus aureus (S. aureus), an important human pathogen. Active vaccination with the conjugate of discovered PNAG epitope with mutant bacteriophage Qβ as a vaccine carrier as well as passive vaccination with diluted rabbit antisera provides mice with near complete protection against infections by S. aureus including methicillin-resistant S. aureus (MRSA). Thus, the comprehensive PNAG pentasaccharide library is an exciting tool to empower the design of next generation vaccines.

Powerful Approach for New Drugs as Antibacterial Agents via Molecular Docking and In Vitro Studies of Some New Cyclic Imides and Quinazoline-2,5-diones

We generated novel elven 1,2,3,6-tetrahydrophthalimides and tetrahydroquinazoline derivatives from 1,2,3,6-tetrahydrophthalic anhydride (1) in response to our interest in using the anhydrides to produce heterocyclic nitrogen compounds. The elemental and spectral analyses of the produced compounds validated the recommended configurations and MOE 2014.09 (Molecular Operating Environment) computations were used to perform their in silico analysis. The synthesized compounds have been analyzed and put through various experiments, including in vitro and in silico methods to assess their biological activity against Escherichia coli Penicillin-Binding Protein 3 (PBP3) and Staphylococcus aureus Penicillin-Binding Protein 2 (PBP2), among these compounds showing promising data as antibacterial drugs.

Antioxidant and antibacterial activities of 5-mercapto(substitutedthio)-4-substituted-1,2,4-triazol based on nalidixic acid: A comprehensive study on its synthesis, characterization, and In silico evaluation

This study introduces a series of novel Alkyl thio-1,2,4-triazole (4a-p) and mercapto-1,2,4-triazole (3a-d) compounds derived from nalidixic acid. The synthesis was streamlined, involving interactions between nalidixic acid hydrazide and various isothiocyanates to yield cyclic and alkyl(aryl) sulfide compounds, characterized using 1H NMR, 13C NMR, IR, and elemental analysis. Antioxidant capabilities were quantified through DPPH and ABTS assays, highlighting significant potential, especially for compound 3d, which demonstrated an ABTS IC50 value of 0.397 μM, on par with ascorbic acid (IC50 = 0.87 μM). Antibacterial efficacy was established through MIC assessments against a broad spectrum of Gram-positive and Gram-negative bacteria, including Candida albicans. Compounds 3b, 4e, 4h, 4j, 4i, 4m, and 4o showed broad-spectrum activity, with 4k and 4m exhibiting pronounced potency against E. coli. Molecular docking studies validated the antibacterial potential, with compounds 4f and 4h showing high binding affinities (docking scores of -9.8 and -9.6 kcal/mol, respectively), indicating robust interactions with the bacterial enzyme targets. These scores underscore the compounds' mechanistic basis for their antibacterial action and support their therapeutic promise. Furthermore, compounds 3b, 4i, and 4m, identified through drug-likeness and toxicity predictions, were highlighted for their favorable profiles, suggesting their suitability for oral antibiotic therapies. This comprehensive study, blending synthetic, in vitro, and in silico approaches, emphasizes the triazole derivatives' potential as future candidates for antibiotic and antioxidant applications, particularly spotlighting compounds 3b, 4i, and 4m due to their promising efficacy and safety profiles.

Zinc Oxide-Based Nanomaterials for Microbiostatic Activities: A Review

The world is fighting infectious diseases. Therefore, effective antimicrobials are required to prevent the spread of microbes and protect human health. Zinc oxide (ZnO) nano-materials are known for their antimicrobial activities. Because of their distinctive physical and chemical characteristics, they can be used in medical and environmental applications. ZnO-based composites are among the leading sources of antimicrobial research. They are effective at killing (microbicidal) and inhibiting the growth (microbiostatic) of numerous microorganisms, such as bacteria, viruses, and fungi. Although most studies have focused on the microbicidal features, there is a lack of reviews on their microbiostatic effects. This review provides a detailed overview of available reports on the microbiostatic activities of ZnO-based nano-materials against different microorganisms. Additionally, the factors that affect the efficacy of these materials, their time course, and a comparison of the available antimicrobials are highlighted in this review. The basic properties of ZnO, challenges of working with microorganisms, and working mechanisms of microbiostatic activities are also examined. This review underscores the importance of further research to better understand ZnO-based nano-materials for controlling microbial growth.

Antibacterial, antibiofilm, and antivirulence potential of the main diterpenes from Copaifera spp. oleoresins against multidrug-resistant bacteria

To evaluate the antibacterial, antibiofilm and antivirulence potential of the main diterpenes from Copaifera spp. oleoresins against multidrug-resistant (MDR) bacteria. Antimicrobial assays included determination of the Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), Minimum Inhibitory Concentration of Biofilm (MICB50), as well as synergistic and antivirulence assays for eight diterpenes against MDR. The tests revealed that two diterpenes (named 1 and 5) showed the best results, with MIC and MBC between 12.5 and 50 μg/mL against most MDR bacteria. These diterpenes exhibited promising MICB50 in concentration between 3.12-25 μg/mL but showed no synergistic antimicrobial activity. In the assessment of antivirulence activity, diterpenes 1 and 5 inhibited only one of the virulence factors evaluated (Dnase) produced by some strains of S. aureus at subinhibitory concentration (6.25 μg/mL). Results obtained indicated that diterpenes isolated from Copaifera oleoresin plays an important part in the search of new antibacterial and antibiofilm agents that can act against MDR bacteria.

Effect of wheat crops on the persistence and attenuation of antibiotic resistance genes in soil after swine wastewater application

Swine wastewater (SW) application introduces antibiotic resistance genes (ARGs) into farmland soils. However, ARG attenuation in SW-fertigated soils, especially those influenced by staple crops and soil type, remains unclear. This study investigated twelve soil ARGs and one mobile genetic element (MGE) in sandy loam, loam, and silt loam soils before and after SW application in wheat-planted and unplanted soils. The results revealed an immediate increase in the abundance of ARGs in soil by two orders of magnitude above background levels following SW application. After SW application, the soil total ARG abundance was attenuated, reaching background levels at 54 days; However, more individual ARGs were detected above the detection limit than pre-application. Among the 13 genes, acc(6')-lb, tetM, and tetO tended to persist in the soil during wheat harvest. ARG half-lives were up to four times longer in wheat-planted soils than in bare soils. Wheat planting decreased the persistence of acc(6')-lb, ermB, ermF, and intI2 but increased the persistence of others such as sul1 and sul2. Soil type had no significant impact on ARG and MGE fates. Our findings emphasize the need for strategic SW application and the consideration of crop cultivation effects to mitigate ARG accumulation in farmland soils.

A Study of the Synergistic Effects of Essential Oils from Origanum compactum and Origanum elongatum with Commercial Antibiotics against Highly Prioritized Multidrug-Resistant Bacteria for the World Health Organization

The irrational use of antibiotics has favored the emergence of resistant bacteria, posing a serious threat to global health. To counteract antibiotic resistance, this research seeks to identify novel antimicrobials derived from essential oils that operate through several mechanisms. It aims to evaluate the quality and composition of essential oils from Origanum compactum and Origanum elongatum; test their antimicrobial activity against various strains; explore their synergies with commercial antibiotics; predict the efficacy, toxicity, and stability of compounds; and understand their molecular interactions through docking and dynamic simulations. The essential oils were extracted via hydrodistillation from the flowering tops of oregano in the Middle Atlas Mountains in Morocco. Gas chromatography combined with mass spectrometry (GC-MS) was used to examine their composition. Nine common antibiotics were chosen and tested alone or in combination with essential oils to discover synergistic effects against clinically important and resistant bacterial strains. A comprehensive in silico study was conducted, involving molecular docking and molecular dynamics simulations (MD). O. elongatum oil includes borneol (8.58%), p-cymene (42.56%), thymol (28.43%), and carvacrol (30.89%), whereas O. compactum oil is mostly composed of γ-terpinene (22.89%), p-cymene (15.84%), thymol (10.21%), and (E)-caryophyllene (3.63%). With O. compactum proving to be the most potent, these essential oils showed antibacterial action against both Gram-positive and Gram-negative bacteria. Certain antibiotics, including ciprofloxacin, ceftriaxone, amoxicillin, and ampicillin, have been shown to elicit synergistic effects. To fight resistant bacteria, the essential oils of O. compactum and O. elongatum, particularly those high in thymol and (E)-caryophyllene, seem promising when combined with antibiotics. These synergistic effects could result from their ability to target the same bacterial proteins or facilitate access to target sites, as suggested by molecular docking simulations. Molecular dynamics simulations validated the stability of the examined protein-ligand complexes, emphasizing the propensity of substances like thymol and (E)-caryophyllene for particular target proteins, opening the door to potentially effective new therapeutic approaches against pathogens resistant to multiple drugs.

Murepavadin promotes the killing efficacies of aminoglycoside antibiotics against Pseudomonas aeruginosa by enhancing membrane potential

Murepavadin is a peptidomimetic that specifically targets the lipopolysaccharide transport protein LptD of Pseudomonas aeruginosa. Here, we found that murepavadin enhances the bactericidal efficacies of tobramycin and amikacin. We further demonstrated that murepavadin enhances bacterial respiration activity and subsequent membrane potential, which promotes intracellular uptake of aminoglycoside antibiotics. In addition, the murepavadin-amikacin combination displayed a synergistic bactericidal effect in a murine pneumonia model.

The antimicrobial property of JY-1, a complex mixture of Traditional Chinese Medicine, is linked to it abilities to suppress biofilm formation and disrupt membrane permeability

The substantial increase of infections, caused by novel, sudden, and drug-resistant pathogens, poses a significant threat to human health. While numerous studies have demonstrated the antibacterial and antiviral effects of Traditional Chinese Medicine, the potential of a complex mixture of traditional Chinese Medicine with a broad-spectrum antimicrobial property remains underexplored. This study aimed to develop a complex mixture of Traditional Chinese Medicine (TCM), JY-1, and investigate its antimicrobial properties, along with its potential mechanism of action against pathogenic microorganisms. Antimicrobial activity was assessed using a zone of inhibition assay and the drop plate method. Hyphal induction of Candida albicans was conducted using RPMI1640 medium containing 10% FBS, followed by microscopic visualization. Quantitative real-time PCR (RT-qPCR) was employed to quantify the transcript levels of hyphal-specific genes such as HWP1 and ALS3. The impact of JY-1 on biofilm formation was evaluated using both the XTT reduction assay and scanning electron microscopy (SEM). Furthermore, the cell membrane integrity was assessed by protein and nucleic acid leakage assays. Our results clearly showed that JY-1 significantly inhibits the vegetative growth of Candida spp. and Cryptococcus spp. In addition, this complex mixture is effectively against a wide range of pathogenic bacteria, including Staphylococcus aureus, Vancomycin-resistant enterococci, Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae. More interestingly, JY-1 plays a direct anti-viral role against the mammalian viral pathogen vesicular stomatitis virus (VSV). Further mechanistic studies indicate that JY-1 acts to reduce the expression of hyphal specific genes HWP1 and ALS3, resulting in the suppression of the hyphal formation of C. albicans. The antimicrobial property of JY-1 could be attributed to its ability to reduce biofilm formation and disrupt the cell membrane permeability, a process resulting in microbial cell death and the release of cellular contents. Taken together, our work identified a potent broad-spectrum antimicrobial agent, a complex mixture of TCM which might be developed as a potential antimicrobial drug.

Dandelion-derived vesicles-laden hydrogel dressings capable of neutralizing Staphylococcus aureus exotoxins for the care of invasive wounds

Delayed wound healing caused by bacterial infection remains a major challenge in clinical treatment. Exotoxins incorporated in bacterial extracellular vesicles play a key role as the disease-causing virulence factors. Safe and specific antivirulence agents are expected to be developed as an effective anti-bacterial infection strategy, instead of single antibiotic therapy. Plant-derived extracellular vesicle-like nanoparticles have emerged as promising therapeutic agents for skin diseases, but the elucidations of specific mechanisms of action and clinical transformation still need to be advanced. Here, dandelion-derived extracellular vesicle-like nanoparticles (TH-EVNs) are isolated and exert antivirulence activity through specifically binding to Staphylococcus aureus (S. aureus) exotoxins, thereby protecting the host cell from attack. The neutralization of TH-EVNs against exotoxins has considerable binding force and stability, showing complete detoxification effect in vivo. Then gelatin methacryloyl hydrogel is developed as TH-EVNs-loaded dressing for S. aureus exotoxin-invasive wounds. Hydrogel dressings demonstrate good physical and mechanical properties, thus achieving wound retention and controlled release of TH-EVNs, in addition to promoting cell proliferation and migration. In vivo results show accelerated re-epithelialization, promotion of collagen maturity and reduction of inflammation after treatment. Collectively, the developed TH-EVNs-laden hydrogel dressings provide a potential therapeutic approach for S. aureus exotoxin- associated trauma.

Bacteriophages as a potential substitute for antibiotics: A comprehensive review

Over the years, the administration of antibiotics for the purpose of addressing bacterial infections has become increasingly challenging due to the increased prevalence of antimicrobial resistance exhibited by various strains of bacteria. Multidrug-resistant (MDR) bacterial species are rising due to the unavailability of novel antibiotics, leading to higher mortality rates. With these conditions, there is a need for alternatives in which phage therapy has made promising results. Phage-derived endolysins, phage cocktails, and bioengineered phages are effective and have antimicrobial properties against MDR and extensively drug-resistant strains. Despite these, it has been observed that phages can give antimicrobial activity to more than one bacterial species. Thus, phage cocktail against resistant strains provides broad spectrum treatment and magnitude of effectivity, which is many folds higher than antibiotics. Many commercially available endolysins such as Staphefekt SA.100, Exebacase (CF-301), and N-Rephasin®SAL200 are used in biofilm penetration and treating plant diseases. The role of CMP1 phage endolysin in transgenic tomato plants in preventing Clavibacter michiganensis infection and the effectiveness of phage in protecting Atlantic salmon from vibriosis have been reported. Furthermore, phage-derived endolysin therapy, such as TSPphg phage exogenous treatment, can aid in disrupting cell walls, leading to bacterial cell lysis. As animals in aquaculture and slaughterhouses are highly susceptible to bacterial infections, effective phage therapy instead of antibiotics can help treat poultry animals, preserve them, and facilitate disease-free trade. Using bioengineered phages and phage cocktails enhances the effectiveness by providing a broad spectrum of phages and target specificity. Research is currently being conducted on clinical trials to confirm the efficacy of engineered phages and phage cocktails in humans. Although obtaining commercial approval may be time-consuming, it will be beneficial in the postantibiotic era. This review provides an overview of the significance of phage therapy as a potential alternative to antibiotics in combating resistant bacterial strains and its application to various fields and emphasizes the importance of safeguarding and ensuring treatment efficacy.

The importance, benefits, and future of nanobiosensors for infectious diseases

Infectious diseases, caused by pathogenic microorganisms such as bacteria, viruses, parasites, or fungi, are crucial for efficient disease management, reducing morbidity and mortality rates and controlling disease spread. Traditional laboratory-based diagnostic methods face challenges such as high costs, time consumption, and a lack of trained personnel in resource-poor settings. Diagnostic biosensors have gained momentum as a potential solution, offering advantages such as low cost, high sensitivity, ease of use, and portability. Nanobiosensors are a promising tool for detecting and diagnosing infectious diseases such as coronavirus disease, human immunodeficiency virus, and hepatitis. These sensors use nanostructured carbon nanotubes, graphene, and nanoparticles to detect specific biomarkers or pathogens. They operate through mechanisms like the lateral flow test platform, where a sample containing the biomarker or pathogen is applied to a test strip. If present, the sample binds to specific recognition probes on the strip, indicating a positive result. This binding event is visualized through a colored line. This review discusses the importance, benefits, and potential of nanobiosensors in detecting infectious diseases.

Insights into the response of nitrogen metabolism to sulfamethoxazole contamination in constructed wetlands with varied substrates

This study conducted an analysis of the variations in nitrogen metabolism pathways within constructed wetlands (CWs) using zeolite (CW-Z), ceramsite (CW-C), and lava (CW-L) under high concentration sulfamethoxazole (SMX) stress. The introduction of SMX hindered the formation of hydrogen bonds on the substrate surfaces; however, these surfaces still maintained a dense and thick biofilm. CW-Z exhibited superior removal efficiencies for ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3--N) compared to CW-C and CW-L, with removal rates of 92.54 ± 2.88 % and 89.39 ± 6.74 %, respectively. Interestingly, the proportion of genes involved in nitrification, denitrification and nitrate reduction genes in CW-C (36.05 %) were higher than that in CW-C (29.81 %) and CW-L (29.70 %) but the interactions among nitrogen functional bacteria in CW-Z were much more complex. Further analysis of the nitrogen metabolism pathway indicated that under CW-Z enhanced dissimilatory nitrate reduction SMX stress, while CW-L enhanced assimilatory nitrate reduction process compared to CW-C.

Exploration of the Antibacterial and Anti-Inflammatory Activity of a Novel Antimicrobial Peptide Brevinin-1BW

Antibiotic resistance has emerged as a grave threat to global public health, leading to an increasing number of treatment failures. Antimicrobial peptides (AMPs) are widely regarded as potential substitutes for traditional antibiotics since they are less likely to induce resistance when used. A novel AMP named Brevinin-1BW (FLPLLAGLAASFLPTIFCKISRKC) was obtained by the Research Center of Molecular Medicine of Yunnan Province from the skin of the Pelophylax nigromaculatus. Brevinia-1BW had effective inhibitory effects on Gram-positive bacteria, with a minimum inhibitory concentration (MIC) of 3.125 μg/mL against Enterococcus faecalis (ATCC 29212) and 6.25 μg/mL against both Staphylococcus aureus (ATCC 25923) and multidrug-resistant Staphylococcus aureus (ATCC 29213) but had weaker inhibitory effects on Gram-negative bacteria, with a MIC of ≥100 μg/mL. Studies using scanning electron microscopy (SEM) and flow cytometry have revealed that it exerts its antibacterial activity by disrupting bacterial membranes. Additionally, it possesses strong biofilm inhibitory and eradication activities as well as significant lipopolysaccharide (LPS)-binding activity. Furthermore, Brevinin-1BW has shown a significant anti-inflammatory effect in LPS-treated RAW264.7 cells. In conclusion, Brevinin-1BW is anticipated to be a promising clinical agent with potent anti-Gram-positive bacterial and anti-inflammatory properties.

Frequency of drug-resistant bacterial isolates among pregnant women with UTI in maternity and children's hospital, Bisha, Saudi Arabia

Urinary tract infections (UTIs) are one of the most prevalent bacterial infections affecting humans, with a higher incidence among women. Pregnant women are at an increased risk of developing UTIs, which can have detrimental consequences for both the mother and fetus. UTIs can be caused by various bacteria, and the prevalence of drug-resistant UTIs in maternity and children's hospitals is a cause for concern due to the potential for severe complications if left untreated. The primary objective of the current study was to determine the distribution of UTI-causing bacteria and investigate the antibiotic sensitivity patterns of isolated cultures obtained from pregnant women with UTIs at the Maternity and Children's Hospital, Bisha, Saudi Arabia. This cross-sectional study was conducted from October 2021 to October 2023, involving the analysis of urine samples collected from 321 participants who acquired UTIs during pregnancy. Using biochemical tests and standard cultures, the urine samples were examined for pathogenic bacteria and their anti-microbial sensitivity patterns. The study analyzed susceptibility results according to the Clinical Laboratory Standards Institute guidelines (M100, 28th Edition, 2018). Bacterial strains demonstrating resistance to three or more antibiotics were classified as multidrug-resistant (MDR). This study revealed the distribution of UTI-causing bacteria to be as follows: Escherichia coli, 57.01%; Klebsiella pneumoniae, 24.61%; Pseudomonas aeruginosa, 4.36%; Proteus mirabilis and Enterobacter cloacae, 3.74%; Streptococcus agalactiae, 3.11%; Enterococcus faecalis, 2.18%; and Staphylococcus aureus, 1.24%. Antimicrobial susceptibility testing varied among gram-positive and gram-negative bacteria. Gentamicin demonstrated the highest sensitivity among both gram-positive and gram-negative bacteria; piperacillin-tazobactam was the second most effective drug against gram-negative bacteria. The bacterial isolates showed varying susceptibility to different antibiotics, with Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa being mainly sensitive to gentamicin, piperacillin-tazobactam, and ciprofloxacin, respectively. The strategies for reducing the risk of UTIs need to be improved to limit the spread of MDR bacteria. These strategies may include promoting hygienic practices and administering appropriate antibiotics to prevent the emergence and spread of drug-resistant bacteria. Further research is required to monitor the trends in antibiotic resistance among UTI-causing bacteria and develop effective strategies for managing this public health menace.

Synergistic inhibition mechanism of quinazolinone and piperacillin on penicillin-binding protein 2a: a promising approach for combating methicillin-resistant Staphylococcus aureus

The production of penicillin-binding protein 2a (PBP2a), a cell wall synthesis protein, is primarily responsible for the high-level resistance observed in methicillin-resistant Staphylococcus aureus (MRSA). PBP2a exhibits a significantly reduced affinity for most β-lactam antibiotics owing to its tightly closed active site. Quinazolinones (QNE), a novel class of non-β-lactam antibiotics, could initiate the allosteric regulation of PBP2a, resulting in the opening of the initially closed active pocket. Based on our previous study, we have a basic understanding of the dual-site inhibitor ceftaroline (CFT) induced allosteric regulation of PBP2a. However, there are still limitations in the knowledge of how combining medicines, QNE and piperacillin (PIP), induce the allosteric response of PBP2a and inhibit its function. Herein, molecular dynamics (MD) simulations were performed to elucidate the intricate mechanisms underlying the combination mode of QNE and PIP. Our study successfully captured the opening process of the active pocket upon the binding of the QNE at the allosteric site, which alters the signaling pathways with a favorable transmission to the active site. Subsequent docking experiments with different conformational states of the active pocket indicated that all three inhibitors, PIP, QNE, and CFT, exhibited higher docking scores and more favorable docking poses to the open active pocket. These findings reveal the implied mechanism of QNE-mediated allostery underlying combination therapy and provide novel insights into developing innovative therapeutic modalities against MRSA.Communicated by Ramaswamy H. Sarma.

Antimicrobials: An update on new strategies to diversify treatment for bacterial infections

Ninety-five years after Fleming's discovery of penicillin, a bounty of antibiotic compounds have been discovered, modified, or synthesised. Diversification of target sites, improved stability and altered activity spectra have enabled continued antibiotic efficacy, but overwhelming reliance and misuse has fuelled the global spread of antimicrobial resistance (AMR). An estimated 1.27 million deaths were attributable to antibiotic resistant bacteria in 2019, representing a major threat to modern medicine. Although antibiotics remain at the heart of strategies for treatment and control of bacterial diseases, the threat of AMR has reached catastrophic proportions urgently calling for fresh innovation. The last decade has been peppered with ground-breaking developments in genome sequencing, high throughput screening technologies and machine learning. These advances have opened new doors for bioprospecting for novel antimicrobials. They have also enabled more thorough exploration of complex and polymicrobial infections and interactions with the healthy microbiome. Using models of infection that more closely resemble the infection state in vivo, we are now beginning to measure the impacts of antimicrobial therapy on host/microbiota/pathogen interactions. However new approaches are needed for developing and standardising appropriate methods to measure efficacy of novel antimicrobial combinations in these contexts. A battery of promising new antimicrobials is now in various stages of development including co-administered inhibitors, phages, nanoparticles, immunotherapy, anti-biofilm and anti-virulence agents. These novel therapeutics need multidisciplinary collaboration and new ways of thinking to bring them into large scale clinical use.

Relation of poverty with treatment-seeking behavior and antibiotic misuse among UTI patients in Pakistan

Objective

The current study aimed to assess the relation between multi-dimension poverty, treatment-seeking behavior, and antibiotic misuse among urinary tract infection (UTI) patients.

Method

A cross-sectional approach was utilized to recruit patients who had a history of UTI in the previous month from two provinces of Pakistan. The treatment-seeking behavior and antibiotic misuse data were collected on a self-developed questionnaire, whereas the poverty data were collected on a modified multi-dimension poverty index (MPI). Descriptive statistics were applied to summarize the data. The logistic regression analysis was carried out to assess the association of multi-dimension poverty with patient treatment-seeking behavior and antibiotic misuse.

Results

A total of 461 participants who had UTI symptoms in the previous month were recruited. Most of the participants in the severely deprived stage treated the UTI (p < 0.001); however, there was a high proportion of the participants who consulted with friends and family for UTI treatment (p < 0.001). The patients with deprivation status (deprived and severely deprived) were less associated with formal consultation. The poorer subgroups were less likely to practice antibiotic course completion.

Conclusion

The current study highlighted that poverty plays an important role in antibiotic misuse. Poorer subgroups were associated with informal consultations and the incompletion of the antibiotic course. Further studies are needed to explore the potential role of poverty in treatment-seeking behavior and antibiotic misuse.

The influence of the phylum Planctomycetota in the environmental resistome

Antimicrobial resistance is one of the leading causes of death worldwide and research on this topic has been on the spotlight for a long time. More recently and in agreement with the One Health Approach, the focus has moved towards the environmental resistome. Members of the phylum Planctomycetota are ubiquitously present in the environment including in hotspots for antimicrobial resistance selection and dissemination. Furthermore, phenotypic broad-range resistance has been observed in diverse members of this phylum. Here we review the evidence available on antimicrobial resistance in the underexploited Planctomycetota and highlight key aspects for future studies.