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Antibacterial coatings are rapidly emerging as a primary component of the global mitigation strategy of bacterial pathogens. Thanks to recent concurrent advances in materials science and biotechnology methodologies, and a growing understanding of environmental microbiology, an extensive variety of options are now available to design surfaces with antibacterial properties. However, progress towards a more widespread use in clinical settings crucially depends on addressing the key outstanding issues. We review release-based antibacterial coatings and focus on the challenges and opportunities presented by the latest generation of these materials. In particular, we highlight recent approaches aimed at controlling the release of antibacterial agents, imparting multi-functionality, and enhancing long-term stability. Coatings releasing antibacterial agents have shown great potential to reduce nosocomial infections. The development of controlled release strategies is necessary to optimize therapeutic effects. Next-generation coatings should be multifunctional and integrate multiple antibacterial effects. Standardized assessment of both stability and antibacterial properties still need to be addressed, especially for long-term applications.

Antibacterial agents are very important in the textile industry, water disinfection, medicine, and food packaging. Organic compounds used for disinfection have some disadvantages, including toxicity to the human body, therefore, the interest in inorganic disinfectants such as metal oxide nanoparticles (NPs) is increasing. This review focuses on the properties and applications of inorganic nanostructured materials and their surface modifications, with good antimicrobial activity. Such improved antibacterial agents locally destroy bacteria, without being toxic to the surrounding tissue. We also provide an overview of opportunities and risks of using NPs as antibacterial agents. In particular, we discuss the role of different NP materials.

The emergence of bacterial resistance has motivated researchers to discover new antibacterial agents. Nowadays, fluoroquinolones keep their status as one of the essential classes of antibacterial agents. The new generations of fluoroquinolones are valuable therapeutic tools with a spectrum of activity, including Gram-positive, Gram-negative, and atypical bacteria. This review article surveys the design of fluoroquinolone hybrids with other antibacterial agents or active compounds and underlines the new hybrids’ antibacterial properties. Antibiotic fluoroquinolone hybrids have several advantages over combined antibiotic therapy. Thus, some challenges related to joining two different molecules are under study. Structurally, the obtained hybrids may contain a cleavable or non-cleavable linker, an essential element for their pharmacokinetic properties and mechanism of action. The design of hybrids seems to provide promising antibacterial agents helpful in the fight against more virulent and resistant strains. These hybrid structures have proven superior antibacterial activity and less susceptibility to bacterial resistance than the component molecules. In addition, fluoroquinolone hybrids have demonstrated other biological effects such as anti-HIV, antifungal, antiplasmodic/antimalarial, and antitumor activity. Many fluoroquinolone hybrids are in various phases of clinical trials, raising hopes that new antibacterial agents will be approved shortly.

Antibiotic resistance is fast spreading globally, leading to treatment failures and adverse clinical outcomes. This review focuses on the resistance mechanisms of the top five threatening pathogens identified by the World Health Organization's global priority pathogens list: carbapenem-resistant , carbapenem-resistant , carbapenem-resistant, extended-spectrum beta-lactamase (ESBL)-producing , vancomycin-resistant and methicillin, vancomycin-resistant . Several novel drug candidates have shown promising results from and studies, as well as clinical trials. The novel drugs against carbapenem-resistant bacteria include LCB10-0200, apramycin, and eravacycline, while for , the drug candidates are LysSAP-26, DDS-04, SPR-206, nitroxoline, cefiderocol, and plazomicin. TNP-209, KBP-7072, and CRS3123 are agents against , while Debio 1450, gepotidacin, delafloxacin, and dalbavancin are drugs against antibiotic-resistant . In addition to these identified drug candidates, continued and studies are required to investigate small molecules with potential antibacterial effects screened by computational receptor docking. As drug discovery progresses, preclinical and clinical studies should also be extensively conducted on the currently available therapeutic agents to unravel their potential antibacterial effect and spectrum of activity, as well as safety and efficacy profiles.

Background The use of bacteria to synthesize nanoparticles as an environment-friendly method has recently been considered by researchers. Bacteria residing in different mines have shown high potential in the synthesis of metal nanoparticles due to their compatibility with the environment. The aim of this study was to evaluate the ability of Zarshouran gold mine bacteria to synthesize silver nanoparticles and their antibacterial activity. Methods After isolation of mine bacteria and several screening steps, silver ion tolerant bacteria that were able to synthesize extracellular silver nanoparticles were isolated and the most suitable isolate was selected and sequenced. The characteristics, stability, and production efficiency of silver nanoparticles were evaluated using UV–vis spectrophotometry, DLS, TEM, FTIR, and X-ray diffraction analysis. Finally, the antibacterial effect of silver nanoparticles against pathogenic bacteria was investigated. Results Among the eight silver-tolerant bacteria, isolate No. 6 had high antibacterial activity and high potential in the synthesis and stabilization of silver nanoparticles. Therefore, this isolate was selected for the next experiments. The results of 16S rDNA sequencing showed that this isolate is related to Bacillus pumilus . We registered in the NCBI Bank called ROM6 with access number MW440543. The DLS and TEM analysis showed that silver nanoparticles produced by this isolate were most spherical with a size of less than 25 nm and were stable for at least 180 days. The efficiency at concentrations less than 0.9 g/l silver nitrate was over 90% and the minimum inhibition concentration of nanoparticles was determined against S. aureus, E. coli, P. aeruginosa, and A. baumannii ranging from 1.4 to 5.6 µg/ml. Conclusion We found that the bacteria residing in the gold mine have a high capacity for the synthesis of spherical and high stable silver nanoparticles with a strong antibacterial effect.

[This corrects the article DOI: 10.1371/journal.pone.0282742.].

The proliferation of drug-resistant pathogens continues to increase, giving rise to serious public health concerns. Many researchers have formulated metal oxide nanoparticles for use as novel antibacterial agents. In the present study, copper oxide (CuO) was synthesized by simple hydrothermal synthesis, and doping was performed to introduce different polymers onto the NP surface for bacteriostasis optimization. The polymer-modified CuO NPs were analyzed further with XRD, FTIR, TEM, DLS and zeta potential to study their morphology, size, and the charge of the substrate. The results indicate that polymer-modified CuO NPs had a significantly higher bacteriostatic rate than unmodified CuO NPs. In particular, polydopamine (PDA)-modified CuO (CuO-PDA) NPs, which carry a weakly negative surface charge, exhibited excellent antibacterial effects, with a bacteriostatic rate of up to 85.8 ± 0.2% within 3 h. When compared to other polymer-modified CuO NPs, CuO-PDA NPs exhibited superior bacteriostatic activity due to their smaller size, surface charge, and favorable van der Waals interactions. This may be attributed to the fact that the CuO-PDA NPs had relatively lipophilic structures at pH 7.4, which increased their affinity for the lipopolysaccharide-containing outer membrane of the Gram-negative bacterium Escherichia coli.

The antibacterial activity of Cinnamaldehyde against Methicillin-resistant Staphylococcus aureus in Bovine Mastitis is investigated in this study, providing insights into inhibition mechanisms and elucidating the effects on bacterial cell membranes. The Minimum Inhibitory Concentration and Minimum Bactericidal Concentration were determined in this study. In addition, growth curves and a time-kill assay were constructed to assess the antibacterial activity of Cinnamaldehyde. The study revealed that the MIC values ranged from 62.5 to 125 μg/mL, and the MBC values ranged from 125 to 250 μg/mL. The presence of sublethal concentrations of Cinnamaldehyde impeded bacterial growth, while high concentrations demonstrated a significant and rapid bactericidal effect. Subsequently, we examined cell morphology using SEM and TEM, evaluated membrane integrity via laser confocal fluorescence microscopy, and measured levels of β-galactosidase, extracellular DNA release, LDH activity, and ROS, to assess the antibacterial mechanism of Cinnamaldehyde. The findings indicated that with higher concentrations of Cinnamaldehyde, Methicillin-resistant Staphylococcus aureus demonstrated significant morphological alterations and disruption of both the cell wall and membrane. Furthermore, Cinnamaldehyde disrupted the integrity of membranes and increased permeability of the outer membrane in a manner dependent on its concentration. Cinnamaldehyde notably triggered the release of β-galactosidase, extracellular DNA, and LDH, in addition to elevating cellular ROS levels. Finally, the effect of Cinnamaldehyde on the transcription levels of genes related to cell membrane synthesis was assessed using RT-qPCR, and the effect of Cinnamaldehyde on the total protein content of Methicillin-resistant Staphylococcus aureus cells was assessed using WB. The RT-qPCR results showed that Cinnamaldehyde at 1xMIC notably upregulated the transcription levels of genes related to fatty acid biosynthesis in Methicillin-resistant Staphylococcus aureus cell membranes, with a significant or highly significant effect. The WB results showed that Cinnamaldehyde exerts its antibacterial action by suppressing protein expression in Methicillin-resistant Staphylococcus aureus. These findings illustrate that Cinnamaldehyde exerts a potent inhibitory effect on Methicillin-resistant Staphylococcus aureus, establishing a fundamental foundation for the potential use of Cinnamaldehyde essential oil as an antibacterial agent in the treatment of bovine mastitis, in accordance with established scientific standards.

Quinolinones, also called quinolones, are a group of heterocyclic compounds with a broad spectrum of biological activities. These compounds occur naturally in plants and microorganisms but can also be obtained synthetically. The first synthesis of quinolinones took place at the end of the 19th century, and the most recent methods were published just a few years ago. They allow for obtaining an unlimited number of analogs differing in biological properties. In this review, we described the plethora of methods leading to quinolin-4-ones. Several of these compounds have been used as antibiotics for over four decades, but recently, their antiproliferative effects have been of particular interest to researchers. This review summarizes the experimental progress made in the synthetic development of various routes leading to quinoline-4-ones and presents an overview of the structures, their evolution, and their relation to activity.

Dayak tribes indigenous to the Indonesian island of Borneo has been using Bajakah Kalalawit ( Uncaria gambir Roxb . ) as traditional medicine for ages. This inspired us to develop phenolic from Bajakah Kalalawit extract as antibacterial agent. The extraction was done through decoction method and the determination of phenolic concentration was done using a visible spectrophotometer and Folin–Ciocalteu reagent (mixture of phosphotungstic and phosphomolybdic acids). We investigated the possibility of developing phenolic nanoparticle for future work. Kirby-Bauer method was used to assess antibacterial activity of phenolic against Staphylococcus aureus and the results were compared to Chloramphenicol in terms of its efficacy and duration of inhibition. This study contributes to the ongoing effort to address antibiotic resistance through the development of innovative antibacterial agents derived from natural sources. The results provide valuable insights into the potential of Bajakah Kalalawit phenolic extracts as a promising avenue for combating bacterial infections in the future.