Strategies to combat Gram-negative bacterial resistance to conventional antibacterial drugs: a review

A comprehensive investigation of the anion inhibition profile of a β-carbonic anhydrase from Acinetobacter baumannii for crafting innovative antimicrobial treatments

This study refers to the intricate world of Acinetobacter baumannii, a resilient pathogenic bacterium notorious for its propensity at antibiotic resistance in nosocomial infections. Expanding upon previous findings that emphasised the bifunctional enzyme PaaY, revealing unexpected γ-carbonic anhydrase (CA) activity, our research focuses on a different class of CA identified within the A. baumannii genome, the β-CA, designated as 𝛽-AbauCA (also indicated as CanB), which plays a crucial role in the resistance mechanism mediated by AmpC beta-lactamase. Here, we cloned, expressed, and purified the recombinant 𝛽-AbauCA, unveiling its distinctive kinetic properties and inhibition profile with inorganic anions (classical CA inhibitors). The exploration of 𝛽-AbauCA not only enhances our understanding of the CA repertoire of A. baumannii but also establishes a foundation for targeted therapeutic interventions against this resilient pathogen, promising advancements in combating its adaptability and antibiotic resistance.

Isolation, derivatization, and anti-microbial evaluation of secondary metabolites from Garcinia dryobalanoides

A detailed study on secondary metabolites from the stem bark of Garcinia dryobalanoides has yielded one triterpenoid and four xanthones. Along with that, five novel rubraxanthone derivatives had been successfully synthesised via Williamson etherification with various alkyl halides. The antibacterial evaluation on crude extract, isolated secondary metabolites (1-5), and synthesised compounds (6-9) against Lactiplantibacillus plantarum, Enterobacter cloacae, Pseudomonas aeruginosa, and Serratia marcescens demonstrated moderate to active activities outlining their bacteriostatic potential. The structure-activity relationship (SAR) study conducted revealed the presence of prenyl and hydroxy groups on the xanthone attributed to good bacterial inhibition. The introduction of the alkyl chain to the hydroxy part eventually decreases the antibacterial activity of the compound which is probably due to the bulkiness that causes steric hindrances, therefore limiting the ability to bind to its target site within the bacterial cell.

Evaluation of Plant-Based Silver Nanoparticles for Antioxidant Activity and Promising Wound-Healing Applications

The current research focuses on the green synthesis of silver nanoparticles (AgNPs) using a polar extract of taro corms and the evaluation of its antioxidant properties and wound-healing applications. Taro corm extract (100 mL) was treated with a 5 mM AgNO3 solution (100 mL) at room temperature for the formation of AgNPs, and a color change was observed. The surface plasmon resonance (SPR) peaks in their UV-visible spectra appeared at a range of 438-445 nm. Fourier transform infrared, scanning electron microscopy, energy-dispersive X-ray, dynamic light scattering, and X-ray diffraction were used for the characterization of the taro corms extract-mediated AgNPs (TCE-AgNPs). The synthesized AgNPs were crystalline and spherical, with an average size of 244.9-272.2 nm with a polydispersity index of 0.530 and zeta potential of -18.8 mV, respectively. The antibacterial potential of TCE-AgNPs was tested, and the inhibition zones detected against Cronobacter sakazakii, Pseudomonas aeruginosa, Listeria monocytogenes, and Enterococcus faecalis were 28, 26, 18, and 13 mm, respectively. Furthermore, the antioxidant activity of TCE-AgNPs showed significant radical-scavenging activity compared to the standard used. Collagen content data collected from regenerated tissue and higher collagen content indicated rapid wound healing compared to others, which was seen in a group treated with TCE-AgNP film bandages.

Efficacy of new generation biosorbents for the sustainable treatment of antibiotic residues and antibiotic resistance genes from polluted waste effluent

Antimicrobials are frequently used in both humans and animals for the treatment of bacterially-generated illnesses. Antibiotic usage has increased for more than 40% from last 15 years globally per day in both human populations and farm animals leading to the large-scale discharge of antibiotic residues into wastewater. Most antibiotics end up in sewer systems, either directly from industry or healthcare systems, or indirectly from humans and animals after being partially metabolized or broken down following consumption. To prevent additional antibiotic compound pollution, which eventually impacts on the spread of antibiotic resistance, it is crucial to remove antibiotic residues from wastewater. Antibiotic accumulation and antibiotic resistance genes cannot be effectively and efficiently eliminated by conventional sewage treatment plants. Because of their high energy requirements and operating costs, many of the available technologies are not feasible. However, the biosorption method, which uses low-cost biomass as the biosorbent, is an alternative technique to potentially address these problems. An extensive literature survey focusing on developments in the field was conducted using English language electronic databases, such as PubMed, Google Scholar, Pubag, Google books, and ResearchGate, to understand the relative value of the available antibiotic removal methods. The predominant techniques for eliminating antibiotic residues from wastewater were categorized and defined by example. The approaches were contrasted, and the benefits and drawbacks were highlighted. Additionally, we included a few antibiotics whose removal from aquatic environments has been the subject of extensive research. Lastly, a few representative publications were identified that provide specific information on the removal rates attained by each technique. This review provides evidence that biosorption of antibiotic residues from biological waste using natural biosorbent materials is an affordable and effective technique for eliminating antibiotic residues from wastewater.