Breaking the Spell: Combating Multidrug Resistant 'Superbugs'

Exploiting β-Lactams-Induced Lysis and DNA Fragmentation for Rapid Molecular Antimicrobial Susceptibility Testing of Neisseria Gonorrhoeae via Dual-Digital PCR

The evolution of antimicrobial resistance (AMR) presents substantial challenges to global medical health systems. Neisseria gonorrhoeae (N. gonorrhoeae), in particular, has developed resistance to all currently available antimicrobials. Addressing this issue necessitates not only discovering new antimicrobials but also deepening the understanding of bacterial responses to these agents, which can lead to new markers for rapid antimicrobial susceptibility testing (AST). Such advancements can enhance treatment outcomes and promote antimicrobial stewardship. In this study, single-cell techniques, including live-cell imaging, flow cytometry, and digital polymerase chain reaction (PCR) are utilized, to investigate the lysis dynamics and molecular features of N. gonorrhoeae upon exposure to β-lactam antimicrobials. Distinct patterns of bacterial lysis and DNA fragmentation are uncovered in susceptible strains. Leveraging these discoveries, a microfluidic dual-digital PCR approach that combines single-cell and single-molecule analyses, facilitate rapid and efficient phenotypic molecular AST for N. gonorrhoeae against β-lactams is developed. This proof-of-concept validation demonstrates the effectiveness of the method in accessing antimicrobial susceptibility across a range of bacterial strains, contributing valuable insights for advancing the battle against AMR.

Diversity of culturable bacterial isolates and their potential as antimicrobial against human pathogens from Afar region, Ethiopia

Antimicrobial resistance is a growing global concern exacerbated by the scarcity of new medications and resistance to current antibiotics. Microbes from unexplored habitats are promising sources of natural products to combat this challenge. This study aimed to isolate bacteria producing secondary metabolites and assess their antimicrobial efficacy against human pathogens. Soil and liquid samples were collected from Afar region, Ethiopia. Bacterial isolates were obtained using standard serial dilution techniques. Antimicrobial activity was evaluated using agar plug and well diffusion methods. matrix-assisted laser desorption/ionization time-of-flight-mass spectrometry (MALDI-TOF MS) and whole-genome sequencing (WGS) were conducted for the isolate exhibiting the highest antimicrobial activity. Secondary metabolites were extracted and analyzed using gas chromatography-mass spectra (GC-MS). In this study, 301 bacteria isolates were identified, of which 68 (22.6%) demonstrated antagonistic activity against at least one reference pathogen. Whole-genome sequencing revealed that Sl00103 belongs to the genus Bacillus, designated as Bacillus sp. Sl00103. The extract of Sl00103 showed zones of inhibition ranging between 17.17 ± 0.43 and 26.2 ± 0.4 mm against bacterial pathogens and 19.5 ± 0.44 to 21.0 ± 1.01 mm against Candida albicans. GC-MS analysis of ethyl acetate and n-hexane extracts identified major compounds including (R,R)-butane-2,3-diol; 3-isobutylhexahydropyrrolo[1,2a] pyrazine-1,4-dione; cyclo(L-prolyl-L-valine); and tetradecanoic acid, 12-methyl-, methyl ester; hexadecanoic acid, methyl ester among other. In conclusion, this study isolated several promising bacterial strains from the Afar region in Ethiopia, with strain Sl00103 (Bacillus sp. Sl00103) demonstrating notable antimicrobial and antioxidant activities and warranting further studies.

IMPORTANCE

Antimicrobial resistance (AMR) is an escalating global health threat affecting humans, animals, and the environment, underscoring the urgent need for alternative pathogen control methods. Natural products, particularly secondary metabolites from bacteria, continue to be a vital source of antibiotics. However, microbial habitats and metabolites in Africa remain largely unexplored. In this study, we isolated and screened bacteria from Ethiopia's Afar region, characterized by extreme conditions like high temperatures, volcanic activity, high salinity, and hot springs to identify potential bioactive compounds. We discovered diverse bacterial isolates with antimicrobial activity against various pathogens, including strain Sl00103 (Bacillus sp. Sl00103), which demonstrated significant antimicrobial and antioxidant activities. GC-MS analysis identified several antimicrobial compounds, highlighting strain Sl00103 as a promising source of secondary metabolites with potential pharmaceutical applications and warranting further investigation.

Melanin as a Photothermal Agent in Antimicrobial Systems

Bacterial infection is one of the most problematic issues for human health and the resistance of bacteria to traditional antibiotics is a matter of huge concern. Therefore, research is focusing on the development of new strategies to efficiently kill these microorganisms. Recently, melanin is starting to be investigated for this purpose. Indeed, this very versatile material presents outstanding photothermal properties, already studied for photothermal therapy, which can be very useful for the light-induced eradication of bacteria. In this review, we present antibacterial melanin applications based on the photothermal effect, focusing both on the single action of melanin and on its combination with other antibacterial systems. Melanin, also thanks to its biocompatibility and ease of functionalization, has been demonstrated to be easily applicable as an antimicrobial agent, especially for the treatment of local infections.

Nanoarchitectonics for synergistic activity of multimetallic nanohybrids as a possible approach for antimicrobial resistance (AMR)

The global threat posed by antimicrobial resistance (AMR) to public health is an immensurable problem. The effectiveness of treating infections would be more at risk in the absence of effective antimicrobials. Researchers have shown an amplified interest in alternatives, such as developing advanced metallic nanohybrids as new therapeutic candidates for antibiotics due to their promising effectiveness against resistant microorganisms. In recent decades, the antimicrobial activity of monometallic nanoparticles has received extensive study and solid proof, providing new opportunities for developing multimetallic nanohybrid antimicrobials. Advanced metallic nanohybrids are an emerging remedy for a number of issues that develop in the field of medicine. Advanced metallic nanohybrids have shown a promising ability to combat resistant microorganisms due to their overall synergistic activity. Formulating advanced multimetallic nanohybrids falling under the umbrella of the growing field of nanoarchitectonics, which extends beyond nanotechnology. The underlying theory of nanoarchitectonics involves utilizing nanoscale units that follow the concepts of nanotechnology to architect nanomaterials. This review focuses on a comprehensive description of antimicrobial mechanisms of metallic nanohybrids and their enabling future insights on the research directions of developing the nanoarchitectonics of advanced multimetallic nanohybrids as novel antibiotics through their synergistic activity.

Preparation and characterization of Fe-ZnO cellulose-based nanofiber mats with self-sterilizing photocatalytic activity to enhance antibacterial applications under visible light

Bacterial infections and antibiotic resistance have posed a severe threat to public health in recent years. One emerging and promising approach to this issue is the photocatalytic sterilization of nanohybrids. By utilizing ZnO photocatalytic sterilization, the drawbacks of conventional antibacterial treatments can be efficiently addressed. This study examines the enhanced photocatalytic sterilizing effectiveness of Fe-doped ZnO nanoparticles (Fe-ZnO nanohybrids) incorporated into polymer membranes that are active in visible light. Using the co-precipitation procedure, Fe-ZnO nanohybrids (Fe x Zn100-x O) have been generated using a range of dopant ratios (x = 0, 3, 5, 7, and 10) and characterized. The ability to scavenge free radicals was assessed and the IC50 value was calculated using the DPPH test at different catalytic concentrations. PXRD patterns showed a hexagonal wurtzite structure, which indicated that the particle size of the nanohybrid decreased as the dopant concentration rose. It was demonstrated by UV-vis diffuse reflectance experiments that the band gap of the nanohybrid decreased (redshifted) with Fe doping. The photocatalytic activity under sunlight increased steadily to 87% after Fe was added as a dopant. The Fe 5%-ZnO nanohybrid exhibited the lowest IC50 value of 81.44 μg mL-1 compared to ZnO, indicating the highest radical scavenging activity and the best antimicrobial activity. The Fe 5%-ZnO nanohybrid, which is proven to have the best photocatalytic sterilization activity, was then incorporated into a cellulose acetate polymer membrane by electrospinning. Disc diffusion assay confirmed the highest antimicrobial activity of the Fe 5%-ZnO nanohybrid incorporated electrospun membrane against Staphylococcus aureus (ATCC 25923), Streptococcus pneumoniae (ATCC 49619), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), and Candida albicans (ATCC 10231) under visible light. As a result, Fe 5%-ZnO nanofiber membranes have the potential to be employed as self-sterilizing materials in healthcare settings.

Preparation of Activated Carbon-Reinforced Composite Beads Based on MnO2/MCM-41@Fe3O4 and Calcium Alginate for Efficient Removal of Tetracycline in Aqueous Solutions

Tetracycline (TC) is a common antibiotic; when untreated TC enters the environment, it will cause a negative impact on the human body through the food chain. In the present study, MnO2/MCM-41@Fe3O4 (FeMnMCM) prepared using a hydrothermal and redox method and Camellia oleifera shell-activated carbon (COFAC) prepared through alkali activation were encapsulated using alginate (ALG) and calcium chloride as a cross-linking matrix to give the composite beads COFAC-FeMnMCM-ALG. The resultant COFAC-FeMnMCM-ALG composite beads were then carefully characterized, showing a high immobilization of MnO2/MCM-41@Fe3O4, with porous COFAC as an effective bioadsorbent for enriching the pollutants in the treated samples. These bead catalysts were subsequently applied to the oxidative degradation of TC in a Fenton oxidation system. Several parameters affecting the degradation were investigated, including the H2O2 concentration, catalyst dosage, initial TC concentration, and temperature. A very high catalytic activity towards the degradation of TC was demonstrated. The electron paramagnetic resonance (EPR) and quenching results showed that ·OH and ·O2- were generated in the system, with ·OH as the main radical species. In addition, the COFAC-FeMnMCM-ALG catalyst exhibited excellent recyclability/reusability. We conclude that the as-prepared COFAC-FeMnMCM-ALG composite beads, which integrate MnO2 and Fe3O4 with bioadsorbents, provide a new idea for the design of catalysts for advanced oxidation processes (AOPs) and have great potential in the Fenton oxidation system to degrade toxic pollutants.

A global perspective on microbial risk factors in effluents of wastewater treatment plants

Effective monitoring and management of microbial risk factors in wastewater treatment plants (WWTPs) effluents require a comprehensive investigation of these risks. A global survey on microbial risk factors in WWTP effluents could reveal important insights into their risk features. This study aims to explore the abundance and types of antibiotic resistance genes (ARGs), virulence factor genes (VFGs), the vector of ARG/VFG, and dominant pathogens in global WWTP effluents. We collected 113 metagenomes of WWTP effluents from the Sequence Read Archive of the National Center for Biotechnology Information and characterized the microbial risk factors. Our results showed that multidrug resistance was the dominant ARG type, while offensive virulence factors were the most abundant type of VFGs. The most dominant types of ARGs in the vector of plasmid and phage were both aminoglycoside resistance, which is concerning as aminoglycosides are often a last resort for treating multi-resistant infections. Acinetobacter baumannii was the most dominant pathogen, rather than Escherichia coli, and a weak negative correlation between Escherichia coli and two other dominant pathogens (Acinetobacter baumannii and Bacteroides uniformis) suggests that using Escherichia coli as a biological indicator for all pathogens in WWTP effluents may not be appropriate. The Getah virus was the most dominant virus found in global WWTP effluents. Our study presents a comprehensive global-scale investigation of microbial risk factors in WWTP effluents, providing valuable insights into the potential risks associated with WWTP effluents and contributing to the monitoring and control of these risks.

Antitumor Activity and Mechanism of Terpenoids in Seaweeds Based on Literature Review and Network Pharmacology

Seaweeds are a treasure trove of natural secondary metabolites. Terpenoids extracted from seaweeds are shown to possess a variety of antitumor cellular activities. However, due to the complex and diverse structures of terpenoids, their therapeutic targets and complex mechanisms of action have not been clarified. The present study summarises the research on terpenoids from seaweeds in oncological diseases over the last 20 years. Terpenoids show different degrees of inhibitory effects on different types of tumor cells, suggesting that terpenoids in seaweeds may have potential antitumor disease potential. Terpenoids with potential antitumor activity and their mechanism of action are investigated using network pharmacology. A total of 125 terpenoids and 286 targets are obtained. Proto-oncogene tyrosine-protein kinase Src(SRC), Signal transducer and activator of transcription 3 (STAT3), Mitogen-activated protein kinase (MAPK3, MAPK1), Heat shock protein HSP 90-alpha (HSP90AA1), Phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), and RAC-alpha serine/threonine-protein kinase (AKT1) are defined as core targets. According to GO function and Kyoto encyclopedia of genes and genomes(KEGG) enrichment analysis, terpenoids may affect the Phoshatidylinositol 3'-kinase (PI3K)-Akt signaling pathway, Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor resistance, Prostate cancer, MAPK signaling pathway, and Proteoglycans in cancer. In addition, the molecular docking results show that the selected terpenoids are all able to bind strongly to the active protein. Terpenoids may slow down the progression of cancer by controlling apoptosis, proliferation, and protein and enzyme binding.

The In Vitro Antibacterial Activity of Argirium SUNc against Most Common Pathogenic and Spoilage Food Bacteria

Foodborne diseases are one of the main issues for human health, and antibacterial packaging plays a major role in food security assurance. Silver ultra nanoparticles (Argirium SUNc) are antimicrobial agents that have a wide spectrum of action, including against pathogenic bacteria and spoilage fungi. The aim of the present study was to evaluate the antibacterial activity of Argirium SUNc on the bacteria most commonly found in food: Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Listeria monocytogenes, and Salmonella typhimurium. In this regard, an in vitro study was carried out by assessing the Argirium SUNc effectiveness on different concentrations of each tested microbial strain and at different time intervals. The data showed that the antimicrobial activity of Argirium SUNc was directly related to the microbial concentration and varied depending on the microbial species. Moreover, a greater effectiveness against Gram-negative bacteria than Gram-positive bacteria was observed. These preliminary results provided important information on the silver nanoparticles spectrum of action, and this is an aspect that appears particularly promising for obtaining a viable alternative to traditional antimicrobials to be used against the pathogens and spoilage agents most commonly found in the food chain, harmful both to health and quality aspects.

New broad-spectrum and potent antibacterial agents with dual-targeting mechanism: Promoting FtsZ polymerization and disrupting bacterial membranes

The emergence of multidrug-resistant bacteria and the slow development of new antibacterial agents have led to a growing global health crisis. Here, we identified an antibacterial agent possessing 1-methyl-2,5-diphenylpyridin-1-ium core, MA220607, with a dual-targeting mechanism of action (MOA), which exhibited effective killing activity against both Gram-positive (MIC = 0.062-2 μg/mL) and Gram-negative bacteria (MIC = 0.5-4 μg/mL). Moreover, our study revealed that MA220607 could block the formation of bacterial biofilm, which might be the reason for low frequency of resistance. MOA studies showed that MA220607 not only promoted FtsZ protein polymerization, but also increased the permeability of bacterial membranes and altered their proton gradients. In addition, MA220607 had low hemolytic toxicity and could significantly inhibit the growth of bacteria in mice. Molecular dynamics simulations demonstrated that MA220607 could block the transition from the tense (T) to relaxed (R) state of FtsZ protein, thereby perturbing the stepping mechanism of FtsZ protein. Overall, our findings suggest that integrating the dual mechanisms targeting FtsZ protein and cell membranes of bacteria into a single scaffold represents a promising direction for the development of new antibacterial agents.

Molecular Insight into the Pharmacological Potential of Clerodendrum minahassae Leaf Extract for Type-2 Diabetes Management Using the Network Pharmacology Approach

Background and Objectives: The increasing occurrence and prevalence of type-2 diabetes mellitus (T2DM) have led to a growing interest in researching available treatment alternatives. Clerodendrum minahassae, a native plant species of North Sulawesi, has been a focus of ethnopharmacological studies due to its significance contributions to drug development, particularly its potential antidiabetic properties. This study investigated the pharmacological potential of Clerodendrum minahassae (CM) leaf extract for managing type-2 diabetes (T2DM) using a network pharmacology approach. Materials and Methods: Active compounds were extracted from CM leaves, and their interactions with target proteins in T2DM were explored through various in silico analyses. Results: SAR analysis using Way2Drug Pass Online identified 29 bioactive CM leaf extract compounds with promise as T2DM treatments. Additionally, 26 of these met Ro5 criteria for favorable drug-likeness. Most compounds exhibited positive pharmacodynamic and pharmacokinetic profiles, with 22 considered safe, while 7 posed potential toxicity risks when ingested individually. CM leaf extract targeted 60 T2DM-related proteins, potentially affecting T2DM via cytokine regulation, particularly in proteins linked to metabolic processes, cellular response to angiotensin, and the sphingosine-1-phosphate signaling pathway. The network pharmacology analysis identified five genes targeted by CM leaf extract, namely, STAT3, MAPK1, ESR1, PIK3R1, and NFKB1. Among these genes, PIK3R1's interaction with the insulin receptor (INSR) positions it as a crucial candidate gene due to its pivotal role in insulin signal transduction during T2DM development. Conclusions: This research sheds light on the therapeutic potential of CM leaf extract for treating T2DM. This potential is attributed to the diverse array of bioactive compounds present in the extract, which have the capacity to interact with and inhibit proteins participating in the insulin signal transduction pathway crucial for the progression of T2DM. The findings of this study may open up possibilities for future applications of CM leaf extract in the development of novel T2DM treatments.

Multidrug-Resistant and Extensively Drug-Resistant Escherichia coli in Sewage in Kuwait: Their Implications

In Kuwait, some sewage is discharged into the sea untreated, causing a health risk. Previously, we investigated the presence of pathogenic E. coli among the 140 isolates of E. coli cultured from the raw sewage from three sites in Kuwait. The aim of the current study was to characterize the antimicrobial resistance of these isolates and the implications of resistance. Susceptibility to 15 antibiotic classes was tested. Selected genes mediating resistance to cephalosporins and carbapenems were sought. ESBL and carbapenemase production were also determined. Two virulent global clones, ST131 and ST648, were sought. A total of 136 (97.1%), 14 (10.0%), 128 (91.4%), and 2 (1.4%) isolates were cephalosporin-resistant, carbapenem-resistant, multidrug-resistant (MDR), and extensively drug-resistant (XDR), respectively. Among the cephalosporin-resistant isolates, ampC, blaTEM, blaCTX-M, blaOXA-1, and blaCMY-2 were found. Eighteen (12.9%) samples were ESBL producers. All carbapenem-resistant isolates were negative for carbapenemase genes (blaOXA-48, blaIMP, blaGES, blaVIM, blaNDM, and blaKPC), and for carbapenemase production. Resistance rates in carbapenem-resistant isolates to many other antibiotics were significantly higher than in susceptible isolates. A total of four ST131 and ST648 isolates were detected. The presence of MDR and XDR E. coli and global clones in sewage poses a threat in treating E. coli infections.

Advances in preparation and application of antibacterial hydrogels

Bacterial infections, especially those caused by drug-resistant bacteria, have seriously threatened human life and health. There is urgent to develop new antibacterial agents to reduce the problem of antibiotics. Biomedical materials with good antimicrobial properties have been widely used in antibacterial applications. Among them, hydrogels have become the focus of research in the field of biomedical materials due to their unique three-dimensional network structure, high hydrophilicity, and good biocompatibility. In this review, the latest research progresses about hydrogels in recent years were summarized, mainly including the preparation methods of hydrogels and their antibacterial applications. According to their different antibacterial mechanisms, several representative antibacterial hydrogels were introduced, such as antibiotics loaded hydrogels, antibiotic-free hydrogels including metal-based hydrogels, antibacterial peptide and antibacterial polymers, stimuli-responsive smart hydrogels, and light-mediated hydrogels. In addition, we also discussed the applications and challenges of antibacterial hydrogels in biomedicine, which are expected to provide new directions and ideas for the application of hydrogels in clinical antibacterial therapy.

Fighting Antimicrobial Resistance: Insights on How the Staphylococcus aureus NorA Efflux Pump Recognizes 2-Phenylquinoline Inhibitors by Supervised Molecular Dynamics (SuMD) and Molecular Docking Simulations

The superbug Staphylococcus aureus (S. aureus) exhibits several resistance mechanisms, including efflux pumps, that strongly contribute to antimicrobial resistance. In particular, the NorA efflux pump activity is associated with S. aureus resistance to fluoroquinolone antibiotics (e.g., ciprofloxacin) by promoting their active extrusion from cells. Thus, since efflux pump inhibitors (EPIs) are able to increase antibiotic concentrations in bacteria as well as restore their susceptibility to these agents, they represent a promising strategy to counteract bacterial resistance. Additionally, the very recent release of two NorA efflux pump cryo-electron microscopy (cryo-EM) structures in complex with synthetic antigen-binding fragments (Fabs) represents a real breakthrough in the study of S. aureus antibiotic resistance. In this scenario, supervised molecular dynamics (SuMD) and molecular docking experiments were combined to investigate for the first time the molecular mechanisms driving the interaction between NorA and efflux pump inhibitors (EPIs), with the ultimate goal of elucidating how the NorA efflux pump recognizes its inhibitors. The findings provide insights into the dynamic NorA-EPI intermolecular interactions and lay the groundwork for future drug discovery efforts aimed at the identification of novel molecules to fight antimicrobial resistance.

Drug‑resistant Acinetobacter baumannii: From molecular mechanisms to potential therapeutics (Review)

Bacterial drug resistance is increasingly becoming an important problem that needs to be solved urgently in modern clinical practices. Infection caused by Acinetobacter baumannii is a serious threat to the life and health of patients. The drug resistance rate of Acinetobacter baumannii strains is increasing, thus research on the drug resistance of Acinetobacter baumannii has also seen an increase. When patients are infected with drug-resistant Acinetobacter baumannii, the availability of suitable antibiotics commonly used in clinical practices is becoming increasingly limited and the prognosis of patients is worsening. Studying the molecular mechanism of the drug resistance of Acinetobacter baumannii is fundamental to solving the problem of drug-resistant Acinetobacter baumannii and potentially other 'super bacteria'. Drug resistance mechanisms primarily include enzymes, membrane proteins, efflux pumps and beneficial mutations. Research on the underlying mechanisms provides a theoretical basis for the use and development of antibiotics and the development of novel treatment methods.

Effect of Size, Shape and Surface Functionalization on the Antibacterial Activity of Silver Nanoparticles

Silver nanoparticles (AgNPs) are the most investigated antibacterial agents against multidrug resistant (MDR) pathogens. They can lead to cellular death by means of different mechanisms, damaging several cell compartments, from the external membrane, to enzymes, DNA and proteins; this simultaneous attack amplifies the toxic effect on bacteria with respect to traditional antibiotics. The effectiveness of AgNPs against MDR bacteria is strongly correlated with their chemical and morphological properties, which influence the pathways involved in cellular damage. In this review, AgNPs' size, shape and modification by functional groups or other materials are reported, both to investigate the different synthetic pathways correlated with nanoparticles' modifications and to evaluate the related effect on their antibacterial activity. Indeed, understanding the synthetic conditions for obtaining performing antibacterial AgNPs could help to tailor new and improved silver-based agents to combat multidrug resistance.

Unlocking the Potential of the Antimicrobial Peptide Gomesin: From Discovery and Structure-Activity Relationships to Therapeutic Applications

Gomesin is a cationic antimicrobial peptide which is isolated from the haemocytes of the Brazilian tarantula Acanthoscurria gomesiana and can be produced chemically by Fmoc solid-phase peptide synthesis. Gomesin exhibits a range of biological activities, as demonstrated by its toxicity against therapeutically relevant pathogens such as Gram-positive or Gram-negative bacteria, fungi, cancer cells, and parasites. In recent years, a cyclic version of gomesin has been used for drug design and development as it is more stable than native gomesin in human serum and can penetrate and enter cancer cells. It can therefore interact with intracellular targets and has the potential to be developed as a drug lead for to treat cancer, infectious diseases, and other human diseases. This review provides a perspective on the discovery, structure-activity relationships, mechanism of action, biological activity, and potential clinical applications of gomesin.

Scutellaria baicalensis in the Treatment of Hepatocellular Carcinoma: Network Pharmacology Analysis and Experimental Validation

Objective

The aim of the study was to use a network pharmacological method and experimental validation to examine the mechanism of Scutellaria baicalensis (SB) against hepatocellular carcinoma (HCC).

Methods

The traditional Chinese medicine systems pharmacology database and analysis platform (TCMSP) and GeneCards were used for screening of targets of SB for the treatment of HCC. Cytoscape (3.7.2) software was used to construct the "drug-compound-intersection target interaction" interaction network. The STING database was used to analyze the interactions of the previous intersecting targets. The results were visualized and processed by performing GO (Gene Ontology) enrichment analysis and KEGG (Kyoto Encyclopedia of Genes and Genomes) signaling pathway enrichment analysis at the target sites. The core targets were docked with the active components by AutoDockTools-1.5.6 software. We used cellular experiments to validate the bioinformatics predictions.

Results

A total of 92 chemical components and 3258 disease targets including 53 intersecting targets were discovered. The results showed that wogonin and baicalein, the main chemical components of SB, could inhibit the viability and proliferation of hepatocellular carcinoma cells, promote apoptosis through the mitochondrial apoptotic pathway, and effectively act on AKT1, RELA, and JUN targets.

Conclusion

SB has multiple components and targets in the treatment of HCC, providing possible potential targets for the treatment of HCC and providing a basis for further research.

Droplet Microarray as a Powerful Platform for Seeking New Antibiotics Against Multidrug-Resistant Bacteria

Multidrug-resistant (MDR) bacteria is a severe threat to public health. Therefore, it is urgent to establish effective screening systems for identifying novel antibacterial compounds. In this study, a highly miniaturized droplet microarray (DMA) based high-throughput screening system is established to screen over 2000 compounds for their antimicrobial properties against carbapenem-resistant Klebsiella pneumoniae and methicillin resistant Staphylococcus aureus (MRSA). The DMA consists of an array of hydrophilic spots divided by superhydrophobic borders. Due to the differences in the surface wettability between the spots and the borders, arrays of hundreds of nanoliter-sized droplets containing bacteria and different drugs can be generated for screening applications. A simple colorimetric viability readout utilizing a conventional photo scanner is developed for fast single-step detection of the inhibitory effect of the compounds on bacterial growth on the whole array. Six hit compounds, including coumarins and structurally simplified estrogen analogs are identified in the primary screening and validated with minimum inhibition concentration assay for their antibacterial effect. This study demonstrates that the DMA-based high-throughput screening system enables the identification of potential antibiotics from novel synthetic compound libraries, offering opportunities for development of new treatments against multidrug-resistant bacteria.

Selective isolation of Arctic marine actinobacteria and a down-scaled fermentation and extraction strategy for identifying bioactive compounds

Actinobacteria are among the most prolific producers of bioactive secondary metabolites. In order to collect Arctic marine bacteria for the discovery of new bioactive metabolites, actinobacteria were selectively isolated during a research cruise in the Greenland Sea, Norwegian Sea and the Barents Sea. In the frame of the isolation campaign, it was investigated how different sample treatments, isolation media and sample-sources, such as animals and sediments, affected the yield of actinobacterial isolates to aid further isolation campaigns. Special attention was given to sediments, where we expected spores of spore forming bacteria to enrich. Beside actinobacteria a high share of bacilli was obtained which was not desired. An experimental protocol for down-scaled cultivation and extraction was tested and compared with an established low-throughput cultivation and extraction protocol. The heat-shock method proved suitable to enrich spore-, or endospore forming bacteria such as bacilli. Finally, a group bioactive compounds could be tentatively identified using UHPLC–MS/MS analysis of the active fractions.

Combination of Meropenem and Zinc Oxide Nanoparticles; Antimicrobial Synergism, Exaggerated Antibiofilm Activity, and Efficient Therapeutic Strategy against Bacterial Keratitis

Pseudomonas aeruginosa is an opportunistic gram-negative human pathogen that causes a wide range of infections, including nosocomial infections. Aside from the intrinsic and acquired antimicrobial resistance against many classes of antibiotics, P. aeruginosa can produce an extracellular polymeric matrix called "biofilm" that protects bacteria from antibiotics and harmful factors. Biofilm enables P. aeruginosa to develop chronic infections. This study assessed the inhibitory action of ZnO-nanoparticles against biofilms formed by multidrug-resistant P. aeruginosa strains. A collection of 24 clinical strains of P. aeruginosa were tested for their antimicrobial resistance against different antibiotics using the disk diffusion method. The antibiofilm activity of ZnO-NPs was assessed using the microtiter plate biofilm assay. The application of ZnO-NPs dramatically modulated the resistance profile and biofilm activity of P. aeruginosa. The combination of ZnO-NPs and meropenem showed synergistic antipseudomonal activity with lower MICs. The scanning electron microscope (SEM) micrographs revealed complete inhibition of biofilms treated with the meropenem-ZnO-NPs combination. Reduced expression of biofilm regulating genes lasR, pslA, and fliC was detected, reflecting the enhanced antibiofilm effect of ZnO-NPs. In vivo application of this antimicrobial mixture completely cured P. aeruginosa-induced keratitis in rats. Our findings represent a dual enhancement of antibacterial and antibiofilm activity via the use of meropenem-ZnO-NPs combination against carbapenem-resistant P. aeruginosa infections.

Comprehensive insight into anti-staphylococcal and anti-enterococcal action of brominated and chlorinated pyrazine-based chalcones

The greatest threat and medicinal impact within gram-positive pathogens are posed by two bacterial genera, Staphylococcus and Enterococcus. Chalcones have a wide range of biological activities and are recognized as effective templates in medicinal chemistry. This study provides comprehensive insight into the anti-staphylococcal and anti-enterococcal activities of two recently published brominated and chlorinated pyrazine-based chalcones, CH-0y and CH-0w. Their effects against 4 reference and 12 staphylococcal and enterococcal clinical isolates were evaluated. Bactericidal action, the activity in combination with selected conventional antibiotics, the study of post-antimicrobial effect (PAE, PAE/SME), and in vitro and in vivo toxicity, were included. In CH-0y, anti-staphylococcal activity ranging from MIC = 15.625 to 62.5 μM, and activity against E. faecium from 31.25 to 62.5 μM was determined. In CH-0w, anti-staphylococcal activity ranging from 31.25 to 125 μM, and activity against E. faecium and E. faecalis (62.5 μM) was revealed. Both CH-0y and CH-0w showed bactericidal action, beneficial impact on bacterial growth delay within PAE and PAE/SME studies, and non/low toxicity in vivo. Compared to CH-0w, CH-0y seems to have higher anti-staphylococcal and less toxic potential. In conclusion, chalcones CH-0y and CH-0w could be considered as structural pattern for future adjuvants to selected antibiotic drugs.

Marine Actinomycetes Associated with Stony Corals: A Potential Hotspot for Specialized Metabolites

Microbial secondary metabolites are an important source of antibiotics currently available for combating drug-resistant pathogens. These important secondary metabolites are produced by various microorganisms, including Actinobacteria. Actinobacteria have a colossal genome with a wide array of genes that code for several bioactive metabolites and enzymes. Numerous studies have reported the isolation and screening of millions of strains of actinomycetes from various habitats for specialized metabolites worldwide. Looking at the extent of the importance of actinomycetes in various fields, corals are highlighted as a potential hotspot for untapped secondary metabolites and new bioactive metabolites. Unfortunately, knowledge about the diversity, distribution and biochemistry of marine actinomycetes compared to hard corals is limited. In this review, we aim to summarize the recent knowledge on the isolation, diversity, distribution and discovery of natural compounds from marine actinomycetes associated with hard corals. A total of 11 new species of actinomycetes, representing nine different families of actinomycetes, were recovered from hard corals during the period from 2007 to 2022. In addition, this study examined a total of 13 new compounds produced by five genera of actinomycetes reported from 2017 to 2022 with antibacterial, antifungal and cytotoxic activities. Coral-derived actinomycetes have different mechanisms of action against their competitors.

A Novel Antimicrobial Peptide Derived from Bony Fish IFN1 Exerts Potent Antimicrobial and Anti-Inflammatory Activity in Mammals

Type I interferons (IFN-Is) are critical antiviral cytokine in innate immunity but with limited direct defense ability against bacterial infections in mammals. In bony fish, despite all the IFN-Is (IFN1-4) act in antiviral immunity, studies demonstrate that IFN1 can remarkably contribute to host defense against bacterial infections. In this study, we found that IFN1 from grass carp (Ctenopharyngodon idella) contains an unusual cationic and amphipathic α-helical region (named as gcIFN-20, sequence: SYEKKINRHFKILKKNLKKK). The synthesized peptide gcIFN-20 could form α-helical structure in a membrane environment and exerts potent antimicrobial activity against multiple species of Gram-negative (G-) and Gram-positive (G+) bacteria with negligible toxicity. Mechanism studies showed gcIFN-20 kills G+ bacteria through membrane disruption and cytoplasm outflow while G- bacteria through membrane permeation and protein synthesis inhibition. In two mouse bacterial infection models, gcIFN-20 therapy could significantly reduce tissue bacterial loads and mortalities. In addition to the direct antibacterial activity, we also found that gcIFN-20 could significantly suppress the lipopolysaccharide (LPS)-induced pro-inflammatory cytokines in vitro and in vivo, obviously alleviated lung lesions in a mouse endotoxemia model. The mechanism is that gcIFN-20 interacts with LPS, causes LPS aggregation and neutralization. The antimicrobial and anti-inflammatory activities in vivo of gcIFN-20 in mammalian models suggested a promising agent for developing peptide-based antibacterial therapy. IMPORTANCE Type I interferons play crucial role in antiviral immunity in both vertebrates and invertebrates. The powerful antimicrobial activity is recently reported in nonmammalian vertebrates. The present study identified a novel antimicrobial peptide (gcIFN-20) derived from grass carp interferon 1, found gcIFN-20 exhibits forceful bactericidal and anti-inflammatory activity in mammals, and efficient therapeutic effect against two clinical severe extraintestinal pathogenic Escherichia coli and a mouse endotoxemia models. The antimicrobial mechanisms are membrane disruption and cytoplasm overflow for Gram-positive bacteria, while membrane permeation and protein synthesis inhibition for Gram-negative bacteria. The anti-inflammatory mechanisms can be aggregating and neutralizing lipopolysaccharide to attenuate the binding with receptors and facilitate phagocytosis. The results indicate that gcIFN-20 can be a promising novel therapeutic agent for bacterial diseases and inflammatory disorders, especially as a potential weapon for multidrug resistant strain infections.

Rescue of susceptibility to second-line drugs in resistant clinical isolates of Mycobacterium tuberculosis

Aim: Antibiotic resistance is one of the biggest threats to global health, and this study aimed better understand how the efflux pumps are related to this process in tuberculosis clinical isolates. Results: The combination of antibiotics plus efflux pumps (EP) inhibitors was able to restore the susceptibility of clinical isolates in 100% of aminoglycosides resistance and 33.3% of the fluoroquinolones resistance. The relative expression of EP genes in pre-extensively drug-resistant isolates showed an increase of up to 1000-times. Conclusion: The rescue of susceptibility in the presence of EP inhibitors, the increased of activity and expression of the EP genes alert that the inhibition of EP can reduce the selection of resistant strains and improve treatment.

Impact of novel microbial secondary metabolites on the pharma industry

Microorganisms are remarkable producers of a wide diversity of natural products that significantly improve human health and well-being. Currently, these natural products comprise half of all the pharmaceuticals on the market. After the discovery of penicillin by Alexander Fleming 85 years ago, the search for and study of antibiotics began to gain relevance as drugs. Since then, antibiotics have played a valuable role in treating infectious diseases and have saved many human lives. New molecules with anticancer, hypocholesterolemic, and immunosuppressive activity have now been introduced to treat other relevant diseases. Smaller biotechnology companies and academic laboratories generate novel antibiotics and other secondary metabolites that big pharmaceutical companies no longer develop. The purpose of this review is to illustrate some of the recent developments and to show the potential that some modern technologies like metagenomics and genome mining offer for the discovery and development of new molecules, with different functions like therapeutic alternatives needed to overcome current severe problems, such as the SARS-CoV-2 pandemic, antibiotic resistance, and other emerging diseases. KEY POINTS: • Novel alternatives for the treatment of infections caused by bacteria, fungi, and viruses. • Second wave of efforts of microbial origin against SARS-CoV-2 and related variants. • Microbial drugs used in clinical practice as hypocholesterolemic agents, immunosuppressants, and anticancer therapy.

A network pharmacology study to investigate bioactive compounds and signaling pathways of garlic (Allium sativum L.) husk against type 2 diabetes mellitus

During garlic harvest, much husk has been generated, nearly all husk is discarded as unnecessary by-products. However, in Korean folk remedies, Allium sativum L. husk (ASLH) extracts have been used as a reliever against type 2 diabetes mellitus (T2DM). Currently, its significant mechanisms against T2DM remain unclear. Thus, the aim of this study is to investigate the characteristics of its key signaling pathways, targets, and compounds. The compounds in ASLH were analyzed by gas chromatography-mass spectrum (GC-MS) and confirmed drug-like compounds (DLCs) in silico. Then, protein-protein interaction (PPI) networks and signaling pathways, targets, compounds are constructed, visualized by using RStudio. Finally, we performed a molecular docking test (MDT) to identify the key mechanism(s), target(s), and compound(s) of ASLH on T2DM. A total of 23 compounds in ASLH were identified by GC-MS, and all compounds were accepted by Lipinski's rule. The 23 compounds were associated with 521 targets and retrieved 4,736 T2DM-related targets by Online Mendelian Inheritance in Man (OMIM) and DisGeNET. The final overlapping 87 targets were obtained between compounds-targets and T2DM-related targets. The number of 13 signaling pathways, 33 targets, and 19 compounds of ASLH were associated with T2DM. In parallel, MDT revealed four potential compounds: (1) 9-hexacosene, (2) 2-(([2-ethylhexyl]oxy)carbonyl)benzoic acid, (3) clionasterol, (4) 4-methyl-2-phenylpyrimidine on PPAR signaling pathway. Overall, the four compounds from ASLH might show an anti-T2DM synergistic effect by activating the PPAR signaling pathway or inactivating the phospholipase D signaling pathway. In this study, we suggest that ASLH might be considered a health-promising resource from both nutraceutical and pharmaceutical perspectives. PRACTICAL APPLICATIONS: Allium sativum L. husk (ASLH) has been regarded as wastes that come from garlic (Allium sativum L.). During the harvesting period of garlic, a considerable amount of ASLH is a severe problem in farm communities. Particularly, garlic bioactive compounds are well documented including organosulfur compounds. Conversely, at present, no information is available on chemical compounds of ASLH to use in health industries. Taking this matter into consideration, our analysis approach was to select drug-like compounds (DLCs) from ASLH via GC-MS, thereby we can explore the compounds with high cell permeability. The screened compounds can be used as nutraceutical or medicinal or even cosmetical resources. In this study, we described the significant compounds via the network pharmacology concept to uncover the pharmaceutical mechanism(s) of ASLH against T2DM. Eventually, this work provides nutraceutical or medicinal value of ASLH and suggests that ASLH might be used as an upcycling resource to relieve T2DM.

Thermogenetics: Applications come of age

Temperature is a ubiquitous physical cue that is non-invasive, penetrative and easy to apply. In the growing field of thermogenetics, through beneficial repurposing of natural thermosensing mechanisms, synthetic biology is bringing new opportunities to design and build robust temperature-sensitive (TS) sensors which forms a thermogenetic toolbox of well characterised biological parts. Recent advancements in technological platforms available have expedited the discovery of novel or de novo thermosensors which are increasingly deployed in many practical temperature-dependent biomedical, industrial and biosafety applications. In all, the review aims to convey both the exhilarating recent technological developments underlying the advancement of thermosensors and the exciting opportunities the nascent thermogenetic field holds for biomedical and biotechnology applications.

Drug Resistance Reversal Potential of Nanoparticles/Nanocomposites via Antibiotic's Potentiation in Multi Drug Resistant P. aeruginosa

Bacteria employ numerous resistance mechanisms against structurally distinct drugs by the process of multidrug resistance. A study was planned to discover the antibacterial potential of a graphene oxide nanosheet (GO), a graphene oxide-zinc oxide nanocomposite (GO/ZnO), a graphene oxide-chitosan nanocomposite (GO-CS), a zinc oxide decorated graphene oxide-chitosan nanocomposite (GO-CS/ZnO), and zinc oxide nanoparticles (ZnO) alone and in a blend with antibiotics against a PS-2 isolate of Pseudomonas aeruginosa. These nanocomposites reduced the MIC of tetracycline (TET) from 16 folds to 64 folds against a multidrug-resistant clinical isolate. Efflux pumps were interfered, as evident by an ethidium bromide synergy study with nanocomposites, as well as inhibiting biofilm synthesis. These nanoparticles/nanocomposites also decreased the mutant prevention concentration (MPC) of TET. To the best of our knowledge, this is the first report on nanomaterials as a synergistic agent via inhibition of efflux and biofilm synthesis.

Jiangzhi Granule attenuates non-alcoholic steatohepatitis by suppressing TNF/NFκB signaling pathway-a study based on network pharmacology

Jiangzhi Granule is a commonly used traditional Chinese medicine for treating non-alcoholic fatty liver disease. However, its key ingredients and underlying mechanisms for attenuating nonalcoholic steatohepatitis (NASH) remain unclear. To address this issue, UPLC-TOF-MS based chemical profiling, network pharmacology and animal experimental validation were employed. First, a total of 56 main ingredients of Jiangzhi Granule and 38 ingredients in the blood and liver (after oral administration) were identified. Then, 170 potential targets of the absorbed ingredients and 50 targets of NASH were identified, and 10 overlapped genes were identified as candidate targets of Jiangzhi Granule for NASH treatment. A Jiangzhi Granule-ingredients-targets-disease network was constructed using Cytoscape software, which included eight main ingredients (such as emodin, resveratrol and quercetin) and 10 candidate targets (such as TNF, IL6 and CCL2). Functional enrichment indicated that the candidate targets were enriched in multiple pathways (such as the TNF signaling pathway). Furthermore, a NASH mice model was constructed and intervened with Jiangzhi Granule. The results revealed that Jiangzhi Granule could ameliorate NASH characteristics, such as histopathological changes and liver cholesterol level. Meanwhile, Jiangzhi Granule significantly decreased the mRNA and protein expression of TNFα in NASH mice liver, suppressed NFκB activation, and inhibited the expression of macrophage activation marker F4/80 and M1-type polarization marker CD11b/CD11c. ELISA assay indicated that Jiangzhi Granule reduced pro-inflammatory cytokines (including TNFα, IL-1β and IL-6) in the liver. Collectively, our results suggested that Jiangzhi Granule could attenuate NASH by suppressing TNF/NFκB signaling mediated macrophage M1-type polarization.

Drug resistance reversal potential of multifunctional thieno[3,2-c]pyran via potentiation of antibiotics in MDR P. aeruginosa

We explored the antibacterial potential (alone and combination) against multidrug resistant (MDR) Pseudomonas aeruginosa isolates KG-P2 using synthesized thieno[3,2-c]pyran-2-ones in combination with different antibiotics. Out of 14 compounds, two compounds (3g and 3l) abridged the MIC of tetracycline (TET) by 16 folds. Compounds was killing the KG-P2 cells, in time dependent manner, lengthened post-antibiotic effect (PAE) of TET and found decreased the mutant prevention concentration (MPC) of TET. In ethidium bromide efflux experiment, two compounds repressed the drug transporter (efflux pumps) which is further supported by molecular docking of these compounds with efflux complex MexAB-OprM. In another study, these compounds inhibited the synthesis of biofilm.

Antimicrobial Resistance Determinants in Genomes and Plasmids from Acinetobacter baumannii Clinical Isolates

Acinetobacter baumannii is a Gram-negative coccoid rod species, clinically relevant as a human pathogen, included in the ESKAPE group. Carbapenem-resistant A. baumannii (CRAB) are considered by the World Health Organization (WHO) as a critical priority pathogen for the research and development of new antibiotics. Some of the most relevant features of this pathogen are its intrinsic multidrug resistance and its ability to acquire rapid and effective new resistant determinants against last-resort clinical antibiotics, mostly from other ESKAPE species. The presence of plasmids and mobile genetic elements in their genomes contributes to the acquisition of new antimicrobial resistance determinants. However, although A. baumannii has arisen as an important human pathogen, information about these elements is still not well understood. Current genomic analysis availability has increased our ability to understand the microevolution of bacterial pathogens, including point mutations, genetic dissemination, genomic stability, and pan- and core-genome compositions. In this work, we deeply studied the genomes of four clinical strains from our hospital, and the reference strain ATCC^®19606^TM, which have shown a remarkable ability to survive and maintain their effective capacity when subjected to long-term stress conditions. With that, our aim was presenting a detailed analysis of their genomes, including antibiotic resistance determinants and plasmid composition.

Extracellular metabolites of endophytic fungi from Azadirachta indica inhibit multidrug-resistant bacteria and phytopathogens

Aim: To evaluate antimicrobial activity of extracellular metabolites (EMs) of endophytic fungal isolates (EFIs) from Azadirachta indica. Materials & methods: EFIs were identified by internal transcribed spacer (ITS) sequencing. Antimicrobial activity, and minimum inhibitor concentration (MIC) and minimum bactericidal concentration (MBC) were determined using agar diffusion and microdilution method, respectively. Results: Seventeen EFIs were isolated from different organs of A. indica. Eight of them were identified based on ITS sequencing. The EMs of EFIs inhibited the growth of six multidrug-resistant (MDR) bacterial superbugs and three phytopathogenic fungi. The MDR bacterial superbugs are resistant to six commercial antibiotics of different generations but susceptible to EMs of EFIs. The MIC (0.125-1.0 μg/μl), MBC (0.5-4.0 μg/μl) and minimum fungicidal concentration (1.0-4.0 μg/μl) of the EMs from EFIs are lower enough. Conclusion: The EMs of the EFIs have promising antimicrobial activity against MDR bacteria and phytopathogenic fungi.

Iron Acquisition Systems of Gram-negative Bacterial Pathogens Define TonB-Dependent Pathways to Novel Antibiotics

Iron is an indispensable metabolic cofactor in both pro- and eukaryotes, which engenders a natural competition for the metal between bacterial pathogens and their human or animal hosts. Bacteria secrete siderophores that extract Fe3+ from tissues, fluids, cells, and proteins; the ligand gated porins of the Gram-negative bacterial outer membrane actively acquire the resulting ferric siderophores, as well as other iron-containing molecules like heme. Conversely, eukaryotic hosts combat bacterial iron scavenging by sequestering Fe3+ in binding proteins and ferritin. The variety of iron uptake systems in Gram-negative bacterial pathogens illustrates a range of chemical and biochemical mechanisms that facilitate microbial pathogenesis. This document attempts to summarize and understand these processes, to guide discovery of immunological or chemical interventions that may thwart infectious disease.

Consolidation of network and experimental pharmacology to divulge the antidiabetic action of Ficus benghalensis L. bark

A total of 21 different bioactives were identified from F. benghalensis in which 3 molecules, i.e., apigenin, 3',4',5,7-tetrahydroxy-3-methoxyflavone, and kaempferol were predicted to target the highest number of proteins involved in diabetic pathogenesis in which protein tyrosine phosphatase 1b was primarily targeted. Similarly, a docking study identified ursolic acid to have the highest binding affinity with protein tyrosine phosphatase 1b. The combined synergic network analysis identified PI3K/Akt signaling pathway to be primarily modulated followed by the calcium signaling pathway. Similarly, in oral glucose tolerance test, we observed the efficacy of hydroalcoholic extract of F. benghalensis to lower the total area under the curve of glucose and increase total area under curve of insulin for 2 hours. Likewise, hydroalcoholic extract reversed the altered homeostatic hepatic enzymes after 28 days of treatments. Similarly, the extract also enhanced the antioxidant enzymes level like catalase and superoxide dismutase in liver homogenate. In summary, hydroalcoholic extract of F. benghalensis bark may act as an antidiabetic agent by enhancing the glycolysis, decreasing gluconeogenesis, promoting glucose uptake, enhancing insulin secretion, and maintaining pancreatic β-cell mass via PI3K/Akt signaling pathway and downregulating the function of  protein tyrosine phosphatase 1b.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-02788-7.

Fresh Molecular Concepts to Extend the Lifetimes of Old Antimicrobial Drugs

Antimicrobial drug development generally initiates with target identification and mode of action studies. Often, emergence of resistance and/or undesired side effects that are discovered only after prolonged clinical use, result in discontinuation of clinical use. Since the cost and time required for improvement of existing drugs are considerably lower than those required for the development of novel drugs, academic and pharmaceutical company researchers pursue this direction. In this account we describe selected examples of how chemical probes generated from antimicrobial drugs and chemical and enzymatic modifications of these drugs have been used to modify modes of action, block mechanisms of resistance, or reduce side effects, improving performance. These examples demonstrate how new and comprehensive mechanistic insights can be translated into fresh concepts for development of next-generation antimicrobial agents.

Polymeric approach to combat drug-resistant methicillin-resistant Staphylococcus aureus

ABSTRACT

The current global death rate has threatened humans due to increase in deadly unknown infections caused by pathogenic microorganisms. On the contrary, the emergence of multidrug-resistant bacteria is also increasing which is leading to elevated lethality rate worldwide. Development of drug-resistant bacteria has become one of the daunting global challenges due to failure in approaching to combat against them. Methicillin-resistant Staphylococcus aureus (MRSA) is one of those drug-resistant bacteria which has led to increase in global mortality rate causing various lethal infections. Polymer synthesis can be one of the significant approaches to combat MRSA by fabricating polymeric coatings to prevent the spread of infections. This review provides last decade information in the development of various polymers against MRSA.

GRAPHICAL ABSTRACT

Trauma and Antimicrobial Resistance Are Independent Predictors of Inadequate Empirical Antimicrobial Treatment of Ventilator-Associated Pneumonia in Critically Ill Patients

Background: We aimed to assess independent risk factors for inadequate initial antimicrobial treatment (IAT) in critically ill patients with ventilator-associated pneumonia (VAP) treated in intensive care units (ICU) and to determine whether IAT is associated with adverse outcomes in patients with VAP. Patients and Methods: A prospective cohort study was performed and included 152 patients with VAP treated in an ICU for more than 48 hours. The main outcomes of interest were all-cause ICU mortality and VAP-related mortality. Other outcomes considered were: intra-hospital mortality, VAP-related sepsis, relapse, re-infection, length of stay in ICU (ICU LOS), and number of days on mechanical ventilation (MV). Results: One-third of patients (35.5%) received inadequate antimicrobial therapy. Trauma (odds ratio [OR], 3.55; 95% confidence interval [CI], 1.25-10.06) and extensively drug-resistant (XDR) causative agent (OR, 3.09; 95% CI, 1.23-7.74) were independently associated with inadequate IAT. Inadequate IAT was associated with a higher mortality rate (OR, 3.08; 95% CI, 1.30-7.26), VAP-related sepsis (OR, 2.39; 95% CI, 1.07-5.32), relapse (OR, 3.25; 95% CI, 1.34-7.89), re-infection (OR, 6.06; 95% CI, 2.48-14.77), and ICU LOS (β 4.65; 95% CI, 0.93-8.36). Acinetobacter spp., Pseudomonas aeruginosa and Klebsiella/Enterobacter spp. were the most common bacteria in patients with IAT and those with adequate antimicrobial therapy. Conclusions: This study demonstrated that inadequate IAT is associated with a higher risk of the majority of adverse outcomes in patients with VAP treated in ICUs. Trauma and XDR strains of bacteria are independent predictors of inadequate IAT of VAP in critically ill patients.

Design, synthesis and drug resistance reversal potential of novel curcumin mimics Van D: Synergy potential of curcumin mimics

Being crucial part of plant-based novel discovery of drug from natural resources, a study was done to explore the antibacterial potential of curcumin mimics in combination with antibiotics against multidrug resistant isolates of Pseudomonas aeruginosa. The best candidate Van D, a curcumin mimics reduced the MIC of tetracycline (TET) up to 16 folds against multidrug resistant clinical isolates. VanD further inhibited the efflux pumps as evident by ethidium bromide efflux and by in-silico docking studies. In another experiment, it was also found that Van D inhibits biofilm synthesis. This derivative kills the KG-P2, an isolate of P. aeruginosa in a time dependent manner, the post-antibiotic effect (PAE) of tetracycline was extended as well as mutant prevention concentration (MPC) of TET was also decreased. In Swiss albino mice, Van D reduced the proinflammatory cytokines concentration. In acute oral toxicity study, this derivative was well tolerated and found to be safe up to 1000 mg/kg dose. To the best of our knowledge, this is the first report on curcumin mimics as synergistic agent via inhibition of efflux pump.

Atomic Force Microscopy (AFM) As a Surface Mapping Tool in Microorganisms Resistant Toward Antimicrobials: A Mini-Review

The worldwide emergence of antimicrobial resistance (AMR) in pathogenic microorganisms, including bacteria and viruses due to a plethora of reasons, such as genetic mutation and indiscriminate use of antimicrobials, is a major challenge faced by the healthcare sector today. One of the issues at hand is to effectively screen and isolate resistant strains from sensitive ones. Utilizing the distinct nanomechanical properties (e.g., elasticity, intracellular turgor pressure, and Young’s modulus) of microbes can be an intriguing way to achieve this; while atomic force microscopy (AFM), with or without modification of the tips, presents an effective way to investigate such biophysical properties of microbial surfaces or an entire microbial cell. Additionally, advanced AFM instruments, apart from being compatible with aqueous environments—as often is the case for biological samples—can measure the adhesive forces acting between AFM tips/cantilevers (conjugated to bacterium/virion, substrates, and molecules) and target cells/surfaces to develop informative force-distance curves. Moreover, such force spectroscopies provide an idea of the nature of intercellular interactions (e.g., receptor-ligand) or propensity of microbes to aggregate into densely packed layers, that is, the formation of biofilms—a property of resistant strains (e.g., Staphylococcus aureus, Pseudomonas aeruginosa). This mini-review will revisit the use of single-cell force spectroscopy (SCFS) and single-molecule force spectroscopy (SMFS) that are emerging as powerful additions to the arsenal of researchers in the struggle against resistant microbes, identify their strengths and weakness and, finally, prioritize some future directions for research.

Bacterial signaling as an antimicrobial target

Antibiotics profoundly reduced worldwide mortality. However, the emergence of resistance to the growth inhibiting effects of these drugs occurred. New approaches to treat infectious disease that reduce the likelihood for resistance are needed. In bacterial pathogens, complex signaling networks regulate virulence. Anti-virulence therapies aim to disrupt these networks to attenuate virulence without affecting growth. Quorum-sensing, a cell-to-cell communication system, represents an attractive anti-virulence target because it often activates virulence. The challenge is to identify druggable targets that inhibit virulence, while also minimizing the likelihood of mutations promoting resistance. Moreover, given the ubiquity of quorum-sensing systems in commensals, any potential effects of anti-virulence therapies on microbiome function should also be considered. Here we highlight the efficacy and drawbacks of anti-virulence approaches.

Anti-bacterial activity of inorganic nanomaterials and their antimicrobial peptide conjugates against resistant and non-resistant pathogens

This review details the antimicrobial applications of inorganic nanomaterials of mostly metallic form, and the augmentation of activity by surface conjugation of peptide ligands. The review is subdivided into three main sections, of which the first describes the antimicrobial activity of inorganic nanomaterials against gram-positive, gram-negative and multidrug-resistant bacterial strains. The second section highlights the range of antimicrobial peptides and the drug resistance strategies employed by bacterial species to counter lethality. The final part discusses the role of antimicrobial peptide-decorated inorganic nanomaterials in the fight against bacterial strains that show resistance. General strategies for the preparation of antimicrobial peptides and their conjugation to nanomaterials are discussed, emphasizing the use of elemental and metallic oxide nanomaterials. Importantly, the permeation of antimicrobial peptides through the bacterial membrane is shown to aid the delivery of nanomaterials into bacterial cells. By judicious use of targeting ligands, the nanomaterial becomes able to differentiate between bacterial and mammalian cells and, thus, reduce side effects. Moreover, peptide conjugation to the surface of a nanomaterial will alter surface chemistry in ways that lead to reduction in toxicity and improvements in biocompatibility.

Nanoparticles as antibiotic-delivery vehicles (ADVs) overcome resistance by MRSA and other MDR bacterial pathogens: The grenade hypothesis

Objectives:

The aim of this study was to examine how the concentrated delivery of less effective antibiotics, such as the β-lactam penicillin G, by linkage to nanoparticles (NPs), could influence the killing efficiency against various pathogenic bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and other multidrug resistant (MDR) strains.

Methods:

The β-lactam antibiotic penicillin G (PenG) was passively sorbed to fluorescent polystyrene NPs (20 nm) that were surface-functionalized with carboxylic acid (COO⁻-NPs) or sulfate groups (SO₄⁻-NPs) to form a PenG-NP complex. Antimicrobial activities of PenG-NPs were evaluated against Gram-negative and Gram-positive bacteria, including antibiotic resistant strains. Disc diffusion, microdilution assays and live/dead staining were performed for antibacterial assessments.

Results:

The results showed that bactericidal activities of PenG-NP complexes were statistically significantly (P < 0.05) enhanced against Gram-negative and Gram-positive strains, including MRSA and MDR strains. Fluorescence imaging verified that NPs comigrated with antibiotics throughout clear zones of MIC agar plate assays. The increased bactericidal abilities of NP-linked antibiotics are hypothesized to result from the greatly increased densities of antibiotic delivered by each NP to a given bacterial cell (compared with solution concentrations of antibiotic), which overwhelms the bacterial resistance mechanism(s).

Conclusions:

As a whole, PenG-NP complexation demonstrated a remarkable activity against different pathogenic bacteria, including MRSA and MDR strains. We term this the ‘grenade hypothesis’. Further testing and development of this approach will provide validation of its potential usefulness for controlling antibiotic-resistant bacterial infections.

ACD: Antimicrobial chemotherapeutics database

Antimicrobial resistance is becoming a growing health problem, which has become a challenge for the physicians to control infection and also an economic burden on the healthcare. This increase in resistance to the present antimicrobial agents led the researchers to find some alternative and more efficient drugs which can fight with the resistant microorganisms more effectively. Hence, in silico approach is used to design some novel drugs against various targets of microorganisms. For effective virtual screening of the drugs, there is a need to know about the chemical structure and properties of the antimicrobial agents. Therefore, we have prepared a comprehensive database as a platform for the researcher to search for possible lead molecules. Antimicrobial chemotherapeutics database (ACD) is comprised of ~4100 synthetic antimicrobial compounds as well as ~1030 active antimicrobial peptides. The Antimicrobial peptides are mainly from biological sources but some of them are synthetic in nature. Only those compounds, which are found to be active against either bacteria (both Gram-positive and negative) or fungus, are selected for this database.The ACD database is freely available at URL: http://amdr.amu.ac.in/acd, and it is compatible with desktops, smartphones, and tablets.

Anthracycline Shunt Metabolites From Philippine Marine Sediment-Derived Streptomyces Destroy Cell Membrane Integrity of Multidrug-Resistant Staphylococcus aureus

The rise of antibiotic resistance (ABR) and the drying up of the pipeline for the development of new antibiotics demands an urgent search for new antibiotic leads. While the majority of clinically available antibiotics were discovered from terrestrial Streptomyces, related species from marine sediments as a source of antibiotics remain underexplored. Here, we utilized culture-dependent isolation of thirty-five marine sediment-derived actinobacterial isolates followed by a screening of their antibacterial activity against multidrug-resistant S. aureus ATCC BAA-44. Our results revealed that the crude extract of Streptomyces griseorubens strain DSD069 isolated from marine sediments collected in Romblon, Philippines displays the highest antibacterial activity, with 96.4% growth inhibition. The S. aureus ATCC BAA-44 cells treated with crude extract of Streptomyces griseorubens strain DSD069 showed cell membrane damage as demonstrated by (a) leakage and loss of vital cell constituents, including DNA and proteins, (b) irregular shrinkage of cells, and (c) increase membrane permeability. The antibiotic compounds were identified as Bisanhydroaklavinone and 1-Hydroxybisanhydroaklavinone with MIC value of 6.25 μg/mL and 50.00 μg/mL, respectively. Bisanhydroaklavinone and 1-Hydroxybisanhydroaklavinone are shunt metabolites in the biosynthesis of anticancer anthracycline derivatives namely doxorubicin, daunorubicin, and cinerubins. It is rare, however, that shunt metabolites are accumulated during fermentation of marine sediment-derived Streptomyces strain without genetic modification. Thus, our study provides evidence that natural bacterial strain can produce Bisanhydroaklavinone and 1-Hydroxybisanhydroaklavinone as antibiotic leads to combat ABR.

Experimental Evidence Reveals Both Cross-Infection and Cross-Contamination Risk of Embryo Storage in Liquid Nitrogen Biobanks

Simple Summary

This study was conducted to demonstrate the potential hazards of cross-infection and cross-contamination of embryos during storage in liquid nitrogen biobanks. For the harmless and successful cryopreservation of embryos, the vitrification method must be chosen meticulously to guarantee not only a high post-thaw survival of embryos, but also to reduce the risk of disease transmission when those embryos are in storage for long periods.

Abstract

In recent decades, gamete and embryo cryopreservation have become routine procedures in livestock and human assisted reproduction. However, the safe storage of germplasm and the prevention of disease transmission continue to be potential hazards of disease transmission through embryo transfer. This study aimed to demonstrate the potential risk of cross-infection of embryos from contaminated liquid nitrogen, and cross-contamination of sterile liquid nitrogen from infected embryos in naked and closed devices. Additionally, we examined the effects of antibiotic-free media on culture development of infected embryos. The study was a laboratory-based analysis using rabbit as a model. Two experiments were performed to evaluate both cross-infection (liquid nitrogen to embryos) and cross-contamination (embryos to liquid nitrogen) of artificially inoculated Salmonella Typhimurium, Staphylococcus aureus, Enterobacter aerogenes, and Aspergillus brasiliensis. Rapid cooling through vitrification was conducted on rabbit embryos, stored for a year, thawed, and cultured. In vivo produced late morulae–early blastocyst stages (72 h) embryos were used (n = 480). Embryos were cultured for 1 h in solutions with and without pathogens. Then, the embryos were vitrified and stored in naked and closed devices for one year in two liquid nitrogen biobanks (one pathogen-free and the other artificially contaminated). Embryos were warmed and cultured for a further 48 h, assessing the development and the presence of microorganism (chromogenic media, scanning electron microscopy). Embryos stored in naked devices in artificially contaminated liquid nitrogen became infected (12.5%), while none of the embryos stored in closed devices were infected. Meanwhile, storage of artificially infected embryos incurred liquid nitrogen biobank contamination (100%). Observations by scanning electron microscopy revealed that all the microorganisms were caught in the surface of embryos after the vitrification-thawed procedure. Nevertheless, embryos cultured in antibiotics and antimycotic medium developed to the hatched blastocyst stage, while artificially infected embryos cultured in antibiotic-free medium failed to develop. In conclusion, our findings support that both cross-contamination and cross-infection during embryo storage in liquid nitrogen biobanks are plausible. So, to ensure biosafety for the cryogenic storage, closed systems that avoid direct contact with liquid nitrogen must be used. Moreover, it seems essential to provide best practice guidelines for the cryogenic preservation and storage of gametes and embryos, to define appropriate quality and risk management procedures.

How Phages Overcome the Challenges of Drug Resistant Bacteria in Clinical Infections

Nowadays the most important problem in the treatment of bacterial infections is the appearance of MDR (multidrug-resistant), XDR (extensively drug-resistant) and PDR (pan drug-resistant) bacteria and the scarce prospects of producing new antibiotics. There is renewed interest in revisiting the use of bacteriophage to treat bacterial infections. The practice of phage therapy, the application of phages to treat bacterial infections, has been around for approximately a century. Phage therapy relies on using lytic bacteriophages and purified phage lytic proteins for treatment and lysis of bacteria at the site of infection. Current research indicates that phage therapy has the potential to be used as an alternative to antibiotic treatments. It is noteworthy that, whether phages are used on their own or combined with antibiotics, phages are still a promising agent to replace antibiotics. So, this review focuses on an understanding of challenges of MDR, XDR, and PDR bacteria and phages mechanism for treating bacterial infections and the most recent studies on potential phages, cocktails of phages, and enzymes of lytic phages in fighting these resistant bacteria.

Considerations and Caveats in Combating ESKAPE Pathogens against Nosocomial Infections

ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) are among the most common opportunistic pathogens in nosocomial infections. ESKAPE pathogens distinguish themselves from normal ones by developing a high level of antibiotic resistance that involves multiple mechanisms. Contemporary therapeutic strategies which are potential options in combating ESKAPE bacteria need further investigation. Herein, a broad overview of the antimicrobial research on ESKAPE pathogens over the past five years is provided with prospective clinical applications.

Carbapenem-Resistant Enterobacteriaceae Posing a Dilemma in Effective Healthcare Delivery

The emergence and spread of Carbapenem-resistant Enterobacteriaceae (CRE) is seriously posing threats in effective healthcare delivery. The aim of this study was to ascertain the emergence of CRE at Chukwuemeka Odumegwu Ojukwu University Teaching Hospital (COOUTH) Awka. Biological samples were collected from 153 consenting patient from 5 clinics in the hospital. The isolates were identified using standard microbiological protocols. Susceptibility to meropenem was done using Kirby-Bauer disc diffusion method on Mueller Hinton Agar. A total of 153 patients were recruited in this study. About one half of those from rural, 63.64% from Sub-urban and 42.27% from urban areas had significant E. coli and Klebsiella spp infections. The male: female ratio of the Enterobacteriaceae infection was 1:1. Almost as much inpatient as outpatient study participants had the infections. The infections were observed mostly on participants with lower educational status. The unmarried individuals were most infected compared to their married counterparts. Enterobacteriaceae infection rate was 50.98%. Of this, 28.21% had CRE infection while the overall prevalence of the CRE in the studied population was 14.38% (22/153). This study shows that CRE is quickly emerging in both community and hospital environments. Klebsiella spp was the most common CRE in this hospital especially Klebsiella oxytoca. Hospitalization was a strong risk factor in the CRE infections. Rapid and accurate detection is critical for their effective management and control.