Antibiotic-resistant Strains Research Articles

Antibacterial activity of copper-coated carbon nanotubes synthesized by plasma-enhanced chemical vapor deposition against Escherichia coli and Staphylococcus aureus

The increase of antibiotic-resistant strains has necessitated the generation of antibacterial agents that do not induce microbial resistance. The present study was conducted to evaluate the antibacterial effect of copper-coated carbon nanotubes (Cu/CNTs) synthesized by plasma-enhanced chemical vapor deposition (PECVD) on two strains of gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria. First, the PECVD method was used to deposit carbon nanotubes (CNTs) on high-resistivity silicon wafers previously decorated with nickel catalyst by an electron beam gun. These nanotubes were then coated with copper thin films (Cu, 0– 60 nm) in a vacuum evaporator using the Direct Current (DC) Magnetron Sputtering method. The morphology of PECVD-grown Cu/CNTs was investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). The antibacterial properties of as-synthesized Cu/CNTs against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were determined using Standard Plate Count (SPC). The results showed that increasing the coating thickness of Cu/CNTs had intensified their antibacterial activity. The SEM and TEM images confirmed the morphological modification of the samples after coating with copper.

Effective degradation of various bacterial toxins using ozone ultrafine bubble water.

Infectious and foodborne diseases pose significant global threats, with devastating consequences in low- and middle-income countries. Ozone, derived from atmospheric oxygen, exerts antimicrobial effects against various microorganisms, and degrades fungal toxins, which were initially recognized in the healthcare and food industries. However, highly concentrated ozone gas can be detrimental to human health. In addition, ozonated water is unstable and has a short half-life. Therefore, ultrafine-bubble technology is expected to overcome these issues. Ultrafine bubbles, which are nanoscale entitles that exist in water for considerable durations, have previously demonstrated bactericidal effects against various bacterial species, including antibiotic-resistant strains. This present study investigated the effects of ozone ultrafine bubble water (OUFBW) on various bacterial toxins. This study revealed that OUFBW treatment abolished the toxicity of pneumolysin, a pneumococcal pore-forming toxin, and leukotoxin, a toxin that causes leukocyte injury. Silver staining confirmed the degradation of pneumolysin, leukotoxin, and staphylococcal enterotoxin A, which are potent gastrointestinal toxins, following OUFB treatment. In addition, OUFBW treatment significantly inhibited NF-κB activation by Pam3CSK4, a synthetic triacylated lipopeptide that activates Toll-like receptor 2. Additionally, OUFBW exerted bactericidal activity against Staphylococcus aureus, including an antibiotic-resistant strain, without displaying significant toxicity toward human neutrophils or erythrocytes. These results suggest that OUFBW not only sterilizes bacteria but also degrades bacterial toxins.

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

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

Antibacterial Activity of Brass against Antibiotic-Resistant Bacteria following Repeated Exposure to Hydrogen Peroxide/Peracetic Acid and Quaternary Ammonium Compounds.

Copper-containing materials are attracting attention as self-disinfecting surfaces, suitable for helping healthcare settings in reducing healthcare-associated infections. However, the impact of repeated exposure to disinfectants frequently used in biocleaning protocols on their antibacterial activity remains insufficiently characterized. This study aimed at evaluating the antibacterial efficiency of copper (positive control), a brass alloy (AB+®) and stainless steel (negative control) after repeated exposure to a quaternary ammonium compound and/or a mix of peracetic acid/hydrogen peroxide routinely used in healthcare settings. A panel of six antibiotic-resistant strains (clinical isolates) was selected for this assessment. After a short (5 min) exposure time, the copper and brass materials retained significantly better antibacterial efficiencies than stainless steel, regardless of the bacterial strain or disinfectant treatment considered. Moreover, post treatment with both disinfectant products, copper-containing materials still reached similar levels of antibacterial efficiency to those obtained before treatment. Antibiotic resistance mechanisms such as efflux pump overexpression did not impair the antibacterial efficiency of copper-containing materials, nor did the presence of one or several genes related to copper homeostasis/resistance. In light of these results, surfaces made out of copper and brass remain interesting tools in the fight against the dissemination of antibiotic-resistant strains that might cause healthcare-associated infections.

Determination of Aminoglycosides by Ion-Pair Liquid Chromatography with UV Detection: Application to Pharmaceutical Formulations and Human Serum Samples.

Aminoglycosides (AGs) represent a prominent class of antibiotics widely employed for the treatment of various bacterial infections. Their widespread use has led to the emergence of antibiotic-resistant strains of bacteria, highlighting the need for analytical methods that allow the simple and reliable determination of these drugs in pharmaceutical formulations and biological samples. In this study, a simple, robust and easy-to-use analytical method for the simultaneous determination of five common aminoglycosides was developed with the aim to be widely applicable in routine laboratories. With this purpose, different approaches based on liquid chromatography with direct UV spectrophotometric detection methods were investigated: on the one hand, the use of stationary phases based on hydrophilic interactions (HILIC); on the other hand, the use of reversed-phases in the presence of an ion-pairing reagent (IP-LC). The results obtained by HILIC did not allow for an effective separation of aminoglycosides suitable for subsequent spectrophotometric UV detection. However, the use of IP-LC with a C18 stationary phase and a mobile phase based on tetraborate buffer at pH 9.0 in the presence of octanesulfonate, as an ion-pair reagent, provided adequate separation for all five aminoglycosides while facilitating the use of UV spectrophotometric detection. The method thus developed, IP-LC-UV, was optimized and applied to the quality control of pharmaceutical formulations with two or more aminoglycosides. Furthermore, it is demonstrated here that this methodology is also suitable for more complex matrices, such as serum, which expands its field of application to therapeutic drug monitoring, which is crucial for aminoglycosides, with a therapeutic index ca. 50%.

Decreased susceptibility to viscosin in Streptococcus pneumoniae.

Growing numbers of infections caused by antibiotic-resistant Streptococcus pneumoniae strains are a major concern for healthcare systems that will require new antibiotics for treatment as well as preventative measures that reduce the number of infections. Lipopeptides are antimicrobial molecules, of which some are used as antibiotics, including the last resort antibiotics daptomycin and polymyxins. Here we have studied the antimicrobial effect of the cyclic lipopeptide viscosin on S. pneumoniae growth and morphology. Most lipopeptides function as surfactants that create pores in membrane layers, which is regarded as their main antimicrobial activity. We show that viscosin can inhibit growth of S. pneumoniae without disintegration of the cytoplasmic membrane. Instead, the cells developed abnormal shapes and misplaced new division sites. The cell wall of these bacteria appeared less dense in electron microscopy images, suggesting that viscosin interfered with normal cell wall synthesis. Corroborating this observation, a luciferase reporter assay was used to show that the two-component systems LiaFSR and CiaRH, which are known to be activated upon cell wall stress, were strongly induced by viscosin. Furthermore, a mutant displaying 1.8-fold decreased susceptibility to viscosin was generated by sequential exposure to increasing concentrations of the lipopeptide. The mutant suffered from significant fitness loss and had mutations in genes involved in fatty acid synthesis, teichoic acid synthesis, and cell wall synthesis as well as transcription and translation. How these mutations might be linked to decreased viscosin susceptibility is discussed.IMPORTANCEStreptococcus pneumoniae is a leading cause of bacterial pneumonia, sepsis, and meningitis in children, and the incidence of infections caused by antibiotic-resistant strains is increasing. Development of new antibiotics is therefore necessary to treat these types of infections in the future. Here, we have studied the activity of the antimicrobial lipopeptide viscosin on S. pneumoniae and show that in addition to having the typical membrane destabilizing activity of lipopeptides, viscosin inhibits pneumococcal growth by obstructing normal cell wall synthesis. This suggests a more specific mode of action than just the surfactant activity. Furthermore, we show that S. pneumoniae does not easily acquire resistance to viscosin, which makes it a promising molecule to explore further, for example, by synthesizing less toxic derivates that can be tested for therapeutic potential.

Identifying antibiotic-resistant strains via cell sorting and elastic-light-scatter phenotyping

The proliferation and dissemination of antimicrobial-resistant bacteria is an increasingly global challenge and is attributed mainly to the excessive or improper use of antibiotics. Currently, the gold-standard phenotypic methodology for detecting resistant strains is agar plating, which is a time-consuming process that involves multiple subculturing steps. Genotypic analysis techniques are fast, but they require pure starting samples and cannot differentiate between viable and non-viable organisms. Thus, there is a need to develop a better method to identify and prevent the spread of antimicrobial resistance. This work presents a novel method for detecting and identifying antibiotic-resistant strains by combining a cell sorter for bacterial detection and an elastic-light-scattering method for bacterial classification. The cell sorter was equipped with safety mechanisms for handling pathogenic organisms and enabled precise placement of individual bacteria onto an agar plate. The patterning was performed on an antibiotic-gradient plate, where the growth of colonies in sections with high antibiotic concentrations confirmed the presence of a resistant strain. The antibiotic-gradient plate was also tested with an elastic-light-scattering device where each colony’s unique colony scatter pattern was recorded and classified using machine learning for rapid identification of bacteria. Sorting and patterning bacteria on an antibiotic-gradient plate using a cell sorter reduced the number of subculturing steps and allowed direct qualitative binary detection of resistant strains. Elastic-light-scattering technology is a rapid, label-free, and non-destructive method that permits instantaneous classification of pathogenic strains based on the unique bacterial colony scatter pattern.Key points• Individual bacteria cells are placed on gradient agar plates by a cell sorter• Laser-light scatter patterns are used to recognize antibiotic-resistant organisms• Scatter patterns formed by colonies correspond to AMR-associated phenotypes

Transformation of antibiotics to non-toxic and non-bactericidal products by laccases ensure the safety of Stropharia rugosoannulata

The substantial use of antibiotics contributes to the spread and evolution of antibiotic resistance, posing potential risks to food production systems, including mushroom production. In this study, the potential risk of antibiotics to Stropharia rugosoannulata, the third most productive straw-rotting mushroom in China, was assessed, and the underlying mechanisms were investigated. Tetracycline exposure at environmentally relevant concentrations (<500 μg/L) did not influence the growth of S. rugosoannulata mycelia, while high concentrations of tetracycline (>500 mg/L) slightly inhibited its growth. Biodegradation was identified as the main antibiotic removal mechanism in S. rugosoannulata, with a degradation rate reaching 98.31 % at 200 mg/L tetracycline. High antibiotic removal efficiency was observed with secreted proteins of S. rugosoannulata, showing removal efficiency in the order of tetracyclines > sulfadiazines > quinolones. Antibiotic degradation products lost the ability to inhibit the growth of Escherichia coli, and tetracycline degradation products could not confer a growth advantage to antibiotic-resistant strains. Two laccases, SrLAC1 and SrLAC9, responsible for antibiotic degradation were identified based on proteomic analysis. Eleven antibiotics from tetracyclines, sulfonamides, and quinolones families could be transformed by these two laccases with degradation rates of 95.54–99.95 %, 54.43–100 %, and 5.68–57.12 %, respectively. The biosafety of the antibiotic degradation products was evaluated using the Toxicity Estimation Software Tool (TEST), revealing a decreased toxicity or no toxic effect. None of the S. rugosoannulata fruiting bodies from seven provinces in China contained detectable antibiotic-resistance genes (ARGs). This study demonstrated that S. rugosoannulata can degrade antibiotics into non-toxic and non-bactericidal products that do not accelerate the spread of antibiotic resistance, ensuring the safety of S. rugosoannulata production.

Iron/Molybdenum Sulfide Nanozyme Cocatalytic Fenton Reaction for Photothermal/Chemodynamic Efficient Wound Healing.

The issue of bacterial infectious diseases remains a significant concern worldwide, particularly due to the misuse of antibiotics, which has caused the emergence of antibiotic-resistant strains. Fortunately, the rapid development of nanomaterials has propelled significant progress in antimicrobial therapy, offering promising solutions. Among them, the utilization of nanoenzyme-based chemodynamic therapy (CDT) has become a highly hopeful approach to combating bacterial infectious diseases. Nevertheless, the application of CDT appears to be facing certain constraints for its low efficiency in the Fenton reaction at the infected site. In this study, we have successfully synthesized a versatile nanozyme, which was a composite of molybdenum sulfide (MoS2) and iron sulfide (FeS2), through the hydrothermal method. The results showed that iron/molybdenum sulfide nanozymes (Fe/Mo SNZs) with desirable peroxidase (POD) mimic activity can generate cytotoxic reactive oxygen species (ROS) by successfully triggering the Fenton reaction. The presence of MoS2 significantly accelerates the conversion of Fe2+/Fe3+ through a cocatalytic reaction that involves the participation of redox pairs of Mo4+/Mo6+, thereby enhancing the efficiency of CDT. Additionally, based on the excellent photothermal performance of Fe/Mo SNZs, a near-infrared (NIR) laser was used to induce localized temperature elevation for photothermal therapy (PTT) and enhance the POD-like nanoenzymatic activity. Notably, both in vitro and in vivo results demonstrated that Fe/Mo SNZs with good broad-spectrum antibacterial properties can help eradicate Gram-negative bacteria like Escherichia coli and Gram-positive bacteria like Staphylococcus aureus. The most exciting thing is that the synergistic PTT/CDT exhibited astonishing antibacterial ability and can achieve complete elimination of bacteria, which promoted wound healing after infection. Overall, this study presents a synergistic PTT/CDT strategy to address antibiotic resistance, providing avenues and directions for enhancing the efficacy of wound healing treatments and offering promising prospects for further clinical use in the near future.

Temporal trends in indoor bioaerosols: implications for dental healthcare environments

ABSTRACT Antibiotic resistance, a significant public health hazard, is predicted to cause 10 million deaths worldwide by 2050. The study aimed to identify culturable bioaerosols in the indoor air of dental units in Lahore and assess their antibiotic resistance. Air samples were collected from 10 dental unit locations at different distances, with average concentrations of fungi and bacteria falling within intermediate ranges, per the Global Index of Microbial Contamination (GIMC/m3) index. The study found higher antibiotic-resistant strains in hospital dental units, particularly during winter. The most vigorous strain, S.aureus-NAJIH18, exhibited 70% resistance to ceftazidime. The research highlights the importance of quantifying microbial pollutants for evaluating their source and complexity. It suggests proactive mitigation techniques, such as focused cleaning and air filtration, to improve indoor air quality can mitigate the spread of antibiotic-resistant strains. These insights offer hope in combating the growing public health threat of antibiotic resistance.

Deciphering the Potential Therapeutic Effects of Hydnocarpus wightianus Seed Extracts using in vitro and in silico approaches

Phytocompounds possess the potential to treat a broad spectrum of disorders due to their remarkable bioactivity. Naturally occurring compounds possess lower toxicity profiles, which making them attractive targets for drug development. Hydnocarpus wightianus seeds were extracted using ethanol, acetone, and hexane solvents. The extracts were evaluated for phytochemicals screening and other therapeutic characteristics, such as free radicals scavenging, anti α-amylase, anti α-glucosidase, and anti-bacterial activities. The ethanolic extract exhibited noteworthy antibacterial characteristics and demonstrated considerable antioxidant, and anti-diabetic effects. The IC50 value of the ethanolic extract for Dpph, α-amylase, and α-glucosidase were found to be 77.299 ± 3.381 μg/mL, 165.56 2.56 μg/mL, and 136.58 ± 5.82 μg/mL, respectively. The ethanolic extract was effective against Methicillin resistant Staphylococcus aureus (26 mm zone of inhibition at 100 μL concentration). Molecular docking investigations revealed the phytoconstituent's inhibitory mechanisms against diabetic, free radicals, and bacterial activity. Docking score for phytocompounds against targeted protein varies from −7.2 to −5.1 kcal/mol. The bioactive compounds present in the ethanolic extract were identified by Gas chromatography/Mass spectrometry analysis, followed by molecular docking and molecular dynamic simulation studies to further explore the phytoconstituent's inhibitory mechanism of α-glucosidase, ∝-amylase, radical scavenging, and bacterial activity. The electronic structure and possible pharmacological actions of the phytocompound were revealed through the use of Density Functional Theory (DFT) analysis. Computational and in vitro studies revealed that these identified compounds have anti-diabetic, anti-oxidant, and anti-bacterial activities against antibiotic-resistant strain of Staphylococcus aureus.

Antibiotic resistance alters the ability of Pseudomonas aeruginosa to invade bacteria from the respiratory microbiome.

The emergence and spread of antibiotic resistance in bacterial pathogens is a global health threat. One important unanswered question is how antibiotic resistance influences the ability of a pathogen to invade the host-associated microbiome. Here we investigate how antibiotic resistance impacts the ability of a bacterial pathogen to invade bacteria from the microbiome, using the opportunistic bacterial pathogen Pseudomonas aeruginosa and the respiratory microbiome as our model system. We measure the ability of P. aeruginosa spontaneous antibiotic-resistant mutants to invade pre-established cultures of commensal respiratory microbes in an assay that allows us to link specific resistance mutations with changes in invasion ability. While commensal respiratory microbes tend to provide some degree of resistance to P. aeruginosa invasion, antibiotic resistance is a double-edged sword that can either help or hinder the ability of P. aeruginosa to invade. The directionality of this help or hindrance depends on both P. aeruginosa genotype and respiratory microbe identity. Specific resistance mutations in genes involved in multidrug efflux pump regulation are shown to facilitate the invasion of P. aeruginosa into Staphylococcus lugdunensis, yet impair invasion into Rothia mucilaginosa and Staphylococcus epidermidis. Streptococcus species provide the strongest resistance to P. aeruginosa invasion, and this is maintained regardless of antibiotic resistance genotype. Our study demonstrates how the cost of mutations that provide enhanced antibiotic resistance in P. aeruginosa can crucially depend on community context. We suggest that attempts to manipulate the microbiome should focus on promoting the growth of commensals that can increase the fitness costs associated with antibiotic resistance and provide robust inhibition of both wildtype and antibiotic-resistant pathogen strains.

ASSESSMENT OF BIOTECHNOLOGICAL POTENTIAL OF MICROORGANISMS CULTURES PROMISSING FOR SUPRESSING ANTIBIOTIC-RESISTANT STRAINS

One of the problems in global practical medicine is antibiotic-resistant strains. The problem is that pathogens are resistant to a number of antibacterial drugs and this makes treatment difficult, which can be long and/or ineffective. One solution is to develop drugs based on bacterial lysates. In this article, the objects of study are producers of extended spectrum β-lactamases - Enterobacteriaceae, Acinetobacter, Pseudomonas, Staphylococcus, Haemophilus, Streptococcus. We assessed the survival, antibiotic resistance and biological compatibility of 25 microbial cultures. Cultures have acceptable viability numbers reguired for industrially valuable strains: more than 106 CFU/ml (109 – 1010 CFU/ml). Antibiotic resistance to various groups of is antibiotics was studied: carbapenems, fluoroguinolones, cephalosporins, macrolides, aminoglycosides, penicillins, chloramphenicols. The choise of antibacterial drugs is based on the freguent use of these antibiotics. The spectrum of antibiotic resistance of each strain is different, from one antibiotic (Ps. aeruginosa 13) to ten antibiotics (S. pneumoniae 5). Cultures are resistant to amoxicillin, ampicillin, benzylpenicillin, erythromycin and cephalosporins. The strains are mostly biocompatible with each other and have antibiotic resistance to a number of antibacterial drugs.

Обзор эффективности и безопасности препарата Канефрон® Н при лечении и профилактике инфекций мочевыводящих путей у различных групп пациентов.

Introduction. The growth of antibiotic-resistant strains of microorganisms that cause urological infections, especially uropathogenic Escherichia coli, the main causative agent of uncomplicated urinary tract infections, requires the search for alternative antimicrobial treatment methods. The discovery of the urine microbiome explains the concept of «asymptomatic bacteriuria», which in most cases does not require the use of antibiotics. The effectiveness of herbal preparations in the treatment and prevention of urinary tract infections has been proven by their traditional use over many years, as well as by scientific research in recent decades. Materials and methods. The presented review summarizes the results of the use of the drug Canephron® N over the past decade, published in the international databases PubMed, Embase, Cochrane Library, ClinicalTrials.gov, articles in Russian from the eLibrary.ru database and their bibliography. Data from randomized, observational clinical studies in adult patients and children are presented. The studies were conducted in patients with infectious and inflammatory diseases of the kidneys, bladder and urinary tract. Results. 32 publications in both Russian and English were analyzed. Publications are grouped together: the use of Canephron® N in the treatment and prevention of urinary tract infections (cystitis and pyelonephritis) in adults; in children; in pregnant women; after urological interventions. The quality of the studies and side effects after using Canephron® N were discussed. Conclusions. The effectiveness and safety of Canephron® N in the treatment and prevention of urological diseases has been proven.

The scourge of carbapenem resistant Enterobacteriaceae: how to fight back

The Enterobacteriaceae species cause both community acquired and health care associated infections like bloodstream infections, ventilator-associated pneumonia, intra-abdominal infections and urinary tract infections. Carbapenem-resistant Enterobacteriaceae (CRE) have been included in the list of global priority pathogens (GPP) declared by WHO in 2017. These infections pose a serious threat due to the associated significant morbidity and mortality. The mechanisms of antimicrobial resistance in these organisms are numerous; however, β-lactamase genes carried on mobile genetic elements are a key mechanism for the rapid spread of these antibiotic-resistant strains on a global scale. The carbapenem resistance (CR) in Enterobacteriaceae has been recognized for the past two decades, but the carbapenemase-producing Enterobacteriaceae (CPE) has been a more recent issue and is spreading at an alarming pace worldwide. In this article, we conducted a systematic literature search of the PubMed, Embase, Web of Science and Cochrane Library databases to identify relevant studies that reported the epidemiology and the outcomes for hospitalised patients with confirmed infections due to CRE and carbapenem-susceptible Enterobacteriaceae (CSE) published between 1 January 2010 and 30 August 2023.The results emphasize that patients with CRE infection still face a greater risk of mortality and need an urgent need for newer antibiotics and appropriate treatment regimens to reduce the risk of morbidity and mortality.

Phytochemical characterization and antibacterial evaluation of crude saps from medicinal plants in Palestinian cuisine

The emergence and evolution of antibiotic-resistant bacterial strains has shifted interest in herbal therapy. Plants have long been a source of anti-infective compounds. This study investigated the antibacterial activity and phytochemical composition of various Palestinian plants against five human pathogenic bacteria. Antibacterial activity was determined using the Agar Diffusion Method (ADM), as well as the Minimal Inhibitory Concentration (MIC) and Broth Microdilution (BMD) assays. The successful ADM bacterial inhibition zones employing plant extracts were Eucalyptus camaldulensis Dehn. (E. camaldulensis) 9.35 mm, Allium sativum L. (A. sativum) 8.35 mm, Ceratonia siliqua L. (C. siliqua) 7.85 mm, and Amygdalus communis L. (A. communis) 7.85 mm. The MIC50 values against the tested microorganisms varied from 5.69 to 398.5 mg/mL. Furthermore, the MIC50 values for Gram-positive bacteria varied from 5.69 to 233.88 mg/mL, whereas the values for Gram-negative bacteria ranged from 28.65 to 398.5 mg/mL. Most species of bacteria were effectively inhibited by E. camaldulensis and A. sativum extracts. For Gram-positive and Gram-negative bacteria, the MIC50 values for E. camaldulensis were 39.01-40.38 and 31.60-85.37 mg/mL, respectively. The MIC50 values for A. sativum against Gram-positive and Gram-negative bacteria were 5.69-14.85 mg/mL and 38.98-200.11 mg/mL, respectively. The phytochemicals such as flavonoids, steroids, proteins, carbohydrates, and alkaloids in varying amounts, may explain their diverse capability to inhibit bacteria. The present study showed that E. camaldulensis, A. sativum, C. siliqua and A. communis are valuable Palestinian medicinal plants that contain antibacterial agents against the tested bacterial species. However, this study serves as a foundation for further pharmaceutical studies.

Whole-Genome Analysis of Extensively Drug-Resistant Enterobacter hormaechei Isolated from a Patient with Non-Hodgkin's Lymphoma.

Currently, the Enterobacteriaceae species are responsible for a variety of serious infections and are already considered a global public health problem, especially in underdeveloped countries, where surveillance and monitoring programs are still scarce and limited. Analyses were performed on the complete genome of an extensively antibiotic-resistant strain of Enterobater hormaechei, which was isolated from a patient with non-Hodgkin's lymphoma, who had been admitted to a hospital in the city of Manaus, Brazil. Phenotypical identification and susceptibility tests were performed in automated equipment. Total DNA extraction was performed using the PureLink genomic DNA mini-Kit. The genomic DNA library was prepared with Illumina Microbial Amplicon Prep and sequenced in the MiSeq Illumina Platform. The assembly of the whole-genome and individual analyses of specific resistance genes extracted were carried out using online tools and the Geneious Prime software. The analyses identified an extensively resistant ST90 clone of E. hormaechei carrying different genes, including blaCTX-M-15, blaGES-2, blaTEM-1A, blaACT-15, blaOXA-1 and blaNDM-1, [aac(3)-IIa, aac(6')-Ian, ant(2″)-Ia], [aac(6')-Ib-cr, (qnrB1)], dfrA25, sul1 and sul2, catB3, fosA, and qnrB, in addition to resistance to chlorhexidine, which is widely used in patient antisepsis. These findings highlight the need for actions to control and monitor these pathogens in the hospital environment.

Influence of CO2 and Dust on the Survival of Non-Resistant and Multi-Resistant Airborne E. coli Strains.

The airborne transmission of bacterial pathogens poses a significant challenge to public health, especially with the emergence of antibiotic-resistant strains. This study investigated environmental factors influencing the survival of airborne bacteria, focusing on the effects of different carbon dioxide (CO2) and dust concentrations. The experiments were conducted in an atmospheric simulation chamber using the non-resistant wild-type E. coli K12 (JM109) and a multi-resistant variant (JM109-pEC958). Different CO2 (100 ppm, 800 ppm, 3000 ppm) and dust concentrations (250 µg m-3, 500 µg m-3, 2000 µg m-3) were tested to encompass a wide range of CO2 and dust levels. The results revealed that JM109-pEC958 exhibited greater resilience to high CO2 and dust concentrations compared to its non-resistant counterpart. At 3000 ppm CO2, the survival rate of JM109 was significantly reduced, while the survival rate of JM109-pEC958 remained unaffected. At the dust concentration of 250 µg m-3, JM109 exhibited significantly reduced survival, whereas JM109-pEC958 did not. When the dust concentration was increased to 500 and 2000 µg m-3, even the JM109-pEC958 experienced substantially reduced survival rates, which were still significantly higher than those of its non-resistant counterpart at these concentrations. These findings suggest that multi-resistant E. coli strains possess mechanisms enabling them to endure extreme environmental conditions better than non-resistant strains, potentially involving regulatory genes or efflux pumps. The study underscores the importance of understanding bacterial adaptation strategies to develop effective mitigation approaches against antibiotic-resistant bacteria in atmospheric environments. Overall, this study provides valuable insights into the interplay between environmental stressors and bacterial survival, serving as a foundational step towards elucidating the adaptation mechanisms of multi-resistant bacteria and informing strategies for combating antibiotic resistance in the atmosphere.

Novel approaches for bacterial toxin neutralization; current advances and future perspectives

Summary This review outlines diverse strategies for neutralizing bacterial toxins which are a significant threat to human health. Effective toxin neutralization is crucial in preventing and treating bacterial infections, especially those caused by antibiotic-resistant strains. Promising approaches include using monoclonal antibodies that target toxins and combining them with agents that directly target bacteria. Aptamers, synthetic molecules that bind to specific targets, provide a rapid and tailored method for inhibiting toxin activity and detecting pathogens. Cell-membrane-coated nanoparticles mimic host cells and effectively neutralize toxins by diverting them and stimulating immune responses. These advancements have the potential to combat bacterial infections and alleviate the associated public health burden.

Fabrication of photo-induced molecular superoxide radical generator for highly efficient therapy against bacterial wound infection

The pressing need for highly efficient antibacterial strategies arises from the prevalence of microbial biofilm infections and the emergence of rapidly evolving antibiotic-resistant strains of pathogenic bacteria. Photodynamic therapy represents a highly efficient and compelling antibacterial approach, offering promising prospects for effective control of the development of bacterial resistance. However, the effectiveness of many photosensitizers is limited due to the reduced generation of reactive oxygen species (ROS) in hypoxic microenvironment, which commonly occur in pathological conditions such as inflammatory and bacteria-infected wounds. Herein, we designed and prepared two phenothiazine-derived photosensitizers (NB-1 and NB-2), which can effectively generate superoxide anion radicals (O2●–) through the type I process. Both photosensitizers demonstrate significant efficacy in vitro for the eradication of broad-spectrum bacteria. Moreover, NB-2 possesses distinct advantages including strong membrane binding and strong generation of O2●–, rendering it an exceptionally efficient antibacterial agent against mature biofilms. In addition, laser activated NB-2 could be applied to treat MRSA-infected wound in vivo, which offers new opportunities for potential practical applications.