The resistance mechanisms of bacteria against ciprofloxacin and new approaches for enhancing the efficacy of this antibiotic

Integration of dual drugs into a collagen scaffold by a combination of apatite coating and impregnation with apatite particles for periodontal regeneration

Bioresorbable porous scaffolds capable of promoting osteoregeneration while preventing bacterial infection are needed for regenerative periodontal therapy. Previously, a porous collagen sponge coated with low-crystalline apatite has been shown to possess superior bioresorption and osteogenic properties compared to the uncoated sponge. In this study, we integrated osteogenic and antibacterial dual drugs into the sponge utilizing two types of apatite matrices to achieve further functionalization. First, the collagen sponge was coated with apatite loaded with an osteogenic drug, l-ascorbic acid 2-phosphate (AS), using a metastable supersaturated calcium phosphate (CaP) solution supplemented with AS. Second, the coated sponge was impregnated with apatite particles loaded with an antibacterial drug, ciprofloxacin (CF), which were fabricated using a labile supersaturated CaP solution supplemented with CF. The resulting dual drug-immobilized sponge demonstrated biological activities arising from both AS and CF; it enhanced proliferation of osteoblastic MC3T3-E1 cells and exhibited antibacterial activity against the oral bacterium Actinomyces naeslundii. The proposed technique to fabricate multifunctional scaffolds would offer a solution to provide more effective, patient-tailored regenerative periodontal therapy.

Mechanistic investigation of ciprofloxacin degradation using NiFe2O4/CA-cellulose acetate composite films in a novel dielectric barrier discharge plasma system

Conventional wastewater treatments often exhibit limited efficiency in removing antimicrobial residues, thus requiring innovative methods to tackle antimicrobial contamination in the environment. This study employed a dielectric barrier discharge (DBD) plasma reactor with NiFe2O4-cellulose acetate (CA) composite films for ciprofloxacin (CIP) degradation in water. The catalytic efficiency of NiFe2O4/CA films was tested across the degradation rate of CIP in synthesized wastewater, reaction kinetics, energy utilization, and reductions in total organic carbon (TOC) and chemical oxygen demand (COD), both with and without the films in the DBD system. Optimal degradation conditions of 10 mg/L CIP concentration, 195 V, 6.5 Hz, 9% catalyst loading, and 4.32 L/min flow rate achieved 89.63% CIP removal within 60 min, with alkaline pH further enhancing degradation. UV-Vis analysis confirmed that extending DBD treatment time improved degradation rates. Variations in solution conductivity, pH, and concentrations of H2O2 and O3 were tracked to verify the catalytic role of NiFe2O4/CA films. Moreover, radical scavengers such as tert-butanol (TBA), benzoquinone (BQ), and triethylenediamine (TEDA) were introduced to the system which identified that •OH, ·O2-, and 1O2 were the key reactive oxygen species responsible for CIP degradation. Liquid chromatography-mass spectrometry (LC-MS) was used to determine the intermediate and by-products of the CIP degradation and four potential degradation pathways were proposed. Pathway III was considered the prominent route involving hydroxylation and piperazine ring cleavage, producing fewer toxic intermediates supported by density functional theory (DFT) calculations. Toxicity assessment showed most intermediates had reduced developmental toxicity and bioaccumulation potential compared to CIP. This highlights the environmental safety of the DBD plasma and NiFe2O4/CA system, as a promising, eco-friendly alternative to traditional methods, with reduced toxicity, minimal bioaccumulation, and potential for sustainable, large-scale application.

Phage therapy: A novel approach to combat drug-resistant pathogens

Antibiotic-resistant infections, such as those caused by the overuse of antibiotics, have greatly strained healthcare systems. Among them, drug-resistant bacteria ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) are typical and common. Enterococcus faecalis and Escherichia coli are of equal concern. These pathogens often have higher pathogenicity than the same strains, and resistance has reduced treatment options, so new treatment options are needed to address these pathogens. This review analyzes recent studies related to phage therapy for the treatment of bacterial infections in various parts of the human body (e.g., alcoholic liver disease, skin, and soft tissues, respiratory tract, gastrointestinal tract, urinary system, etc.), to better understand the potential role of phage therapy as a non-antibiotic strategy for the treatment of infections caused by drug-resistant bacteria. In addition, this review introduces a series of products related to phage therapy and points out potential research directions for phage therapy in clinical applications. This paper elucidates the basic mechanism of human infection by some drug-resistant bacteria and the therapeutic effect of phage therapy against drug-resistant bacteria. It popularizes the understanding of phage therapy and provides a reference for research on its use for drug-resistant bacterial infections.

Antimicrobial Resistant Staphylococcus spp., Escherichia coli, and Salmonella spp. in Food Handlers: A Global Review of Persistence, Transmission, and Mitigation Challenges

Antimicrobial resistance in foodborne pathogens represents a critical global health challenge, with food handlers serving as key contributors in their transmission. This comprehensive review synthesizes evidence on the prevalence, transmission dynamics, and antimicrobial resistance patterns of three major pathogens, Staphylococcus spp., Escherichia coli, and Salmonella spp., among food handlers worldwide. Analysis of studies across diverse geographical regions reveals considerable variation in colonization rates, with Staphylococcus spp. prevalence ranging from 19.5% to 95.0%, Escherichia coli from 2.8% to 89.3%, and Salmonella spp. from 0.07% to 9.1%. Resistance profiles demonstrate alarming trends, including widespread β-lactam resistance and emerging resistance to last-resort antibiotics like carbapenems. Particularly concerning is the high occurrence of multidrug resistant (MDR) strains and extended spectrum β-lactamase (ESBL) producers in low- and middle-income countries. This review identified inadequate handwashing, poor hygiene infrastructure, and asymptomatic carriage as critical factors facilitating the transmission of antimicrobial resistant strains. These findings underscore the urgent need for enhanced surveillance systems, targeted decolonization strategies, improved hygiene protocols, and food handler education to mitigate the spread of resistant pathogens through the food chain.

Phage-antibiotic synergy to combat multidrug resistant strains of Gram-negative ESKAPE pathogens

Bacteriophage-antibiotic-synergy (PAS) was investigated to target Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii and Enterobacter cloacae. Whole genome sequencing indicated that bacteriophage KPW17 targeting K. pneumoniae, clustered with genus Webervirus, ECSR5 targeting E. cloacae clustered with Eclunavirus, PAW33 targeting P. aeruginosa clustered with Bruynoghevirus, while ABTW1 targeting A. baumannii clustered with Vieuvirus. PAS analysis showed that the combination of ciprofloxacin (CIP) and levofloxacin (LEV) with PAW33 resulted in the synergistic eradication of all tested P. aeruginosa strains. Similarly, the combined use of doripenem (DOR) and LEV with KPW17 resulted in the synergistic eradication of the environmental and clinical K. pneumoniae strains, while the combined use of DOR and gentamicin (CN) with ECSR5 was synergistic against the clinical E. cloacae NCTC 13406. Gentamicin with ECSR5, however, only exhibited an additive effect for E. cloacae 4L, while ABTW1 with piperacillin-tazobactam (TZP) and imipenem (IPM) resulted in an indifferent interaction between the bacteriophage and tested antibiotics against the clinical A. baumannii AB3, i.e., the activity of the combination is equal to the activity of most active agent. Thus, while the observed PAS may offer an opportunity for the re-introduction or more efficient application of certain antibiotics to combat antibiotic resistance, extensive research is required to determine the optimal phage-antibiotic combinations, dosages and treatment regiments.

Staphylococcus aureus: A Review of the Pathogenesis and Virulence Mechanisms

Staphylococcus aureus is a formidable human pathogen responsible for infections ranging from superficial skin lesions to life-threatening systemic diseases. This review synthesizes current knowledge on its pathogenesis, emphasizing colonization dynamics, virulence mechanisms, biofilm formation, and antibiotic resistance. By analyzing studies from PubMed, Scopus, and Web of Science, we highlight the pathogen's adaptability, driven by surface adhesins (e.g., ClfB, SasG), secreted toxins (e.g., PVL, TSST-1), and metabolic flexibility in iron acquisition and amino acid utilization. Nasal, skin, and oropharyngeal colonization are reservoirs for invasive infections, with biofilm persistence and horizontal gene transfer exacerbating antimicrobial resistance, particularly in methicillin-resistant S. aureus (MRSA). The review underscores the clinical challenges of multidrug-resistant strains, including vancomycin resistance and decolonization strategies' failure to target single anatomical sites. Key discussions address host-microbiome interactions, immune evasion tactics, and the limitations of current therapies. Future directions advocate for novel anti-virulence therapies, multi-epitope vaccines, and AI-driven diagnostics to combat evolving resistance. Strengthening global surveillance and interdisciplinary collaboration is critical to mitigating the public health burden of S. aureus.

Application of a Two-Phase Experiment Design and Optimization Method to Formulate Ciprofloxacin-Loaded Bovine Serum Albumin Nanoparticles with High-Entrapment Efficiency for Targeting Urinary Tract Infections

Urinary tract infections (UTIs), predominantly caused by uropathogenic Escherichia coli (UPEC), pose a global health concern due to rising antibiotic resistance and biofilm formation. Albumin nanoparticles (NPs) offer a promising strategy for UTI treatment, with site-specific selectivity, improved bioavailability, and sustained drug release. This study focused on developing an optimized method for formulating ciprofloxacin-loaded albumin nanoparticles (CPF-loaded BSA NPs) to treat UPEC and its biofilms effectively. A desolvation method was used to synthesize the nanoparticles, and a two-phase experimental design was used for optimization. Evaluation parameters included size, polydispersity index, zeta potential, morphology, encapsulation efficiency, drug release, storage stability, cytotoxicity, and effectiveness against UPEC. The optimized CPF-loaded BSA NPs exhibited desirable characteristics such as small particle size (123 nm), low polydispersity index (0.178), optimum zeta potential (-31.8), and high encapsulation efficiency (> 80%). They also exhibited low cytotoxicity, high stability, and sustained drug release, making them an ideal drug delivery system. Critically, they demonstrated effectiveness against UPEC and its biofilm. This study suggests that the optimized CPF-loaded BSA NPs, synthesized using our optimized desolvation technique, hold the potential for effectively treating UTIs caused by UPEC.

Antimicrobial peptides: evolving soldiers in the battle against drug-resistant superbugs

The discovery of antibiotics was one of the greatest achievements in human history, however, antibiotic resistance evolved no later than the introduction of antibiotics. The rapid evolution of antibiotic-resistant pathogens soon became frightening and remained a global healthcare threat. There is an urgent need to have new alternatives or new strategies to combat the multi-drug resistant superbugs such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), carbapenem-resistant Pseudomonas aeruginosa (CR-PA), extended-spectrum β-lactamases (ESBL) bearing multidrug-resistant Acinetobacter baumannii (MDR-AB), Escherichia coli (E. coli), and Klebsiella pneumoniae (K. pneumoniae). Antimicrobial peptides (AMPs) have been considered promising agents equipped with unique mechanisms of action along with several other benefits to fight the battle against drug-resistant superbugs. Overall, the current review summarizes the mechanisms of drug-resistant development, the mechanism of action adopted by AMPs to combat drug-resistant pathogens, and the immunomodulatory properties of AMPs. Additionally, we have also reviewed the synergistic potential of AMPs with conventional antibiotics along with the associated challenges and limitations of AMPs in the way of pharmacological development for therapeutic applications in clinical settings.

Synergistic Activity of Gloeophyllum striatum-Derived AgNPs with Ciprofloxacin and Gentamicin Against Human Pathogenic Bacteria

Silver nanoparticles (AgNPs) are used in a variety of different fields due to their excellent antimicrobial potential. Despite clear advantages, concerns about their toxicity have arisen, also concerning biogenic nanoparticles. Simultaneously, global healthcare is facing a problem of spreading antimicrobial resistance towards existing antibiotics. Using combined therapies involving AgNPs and antibiotics seems to be a promising solution to the above problems. The aim of this study was to evaluate the enhancement of the effectiveness of AgNPs, ciprofloxacin, and gentamicin against Staphylococcus aureus and Pseudomonas aeruginosa. The research involved the assessment of antimicrobial and antibiofilm-forming activities and the analysis of phospholipid and fatty acid profiles. Our results showed that combining the tested antimicrobials can enhance their activity against the tested bacterial strains. However, no effect was observed while mixing AgNPs with ciprofloxacin against P. aeruginosa. The most significant effect was obtained by combining 3.125 µg/mL of AgNPs with 0.125 µg/mL of gentamicin against S. aureus. It was also shown that the tested antimicrobials applied in combination exhibited an increased inhibitory activity towards bacterial biofilm formation by S. aureus. Lipidomic analysis revealed that under the influence of the tested antimicrobials, the properties of the cell membrane were altered in different ways depending on the bacterial strain.

Review on application of silk fibroin hydrogels in the management of wound healing

Wounds are regarded as disruptions in the integrity of human skin tissues, and the process of wound healing is often characterized as protracted and complex, primarily due to the potential infection or inflammation caused by microorganisms. The quest for innovative solutions that accelerate wound healing while prioritizing patient safety and comfort has emerged as a focal point. Within this pursuit, silkworm silk fibroin-a natural polymer extracted from silk cocoons-exhibits a distinctive combination of properties including biocompatibility, biodegradability, superior mechanical strength, water absorption, and low immunogenicity, which align closely with the demands of contemporary wound care. Its remarkable biocompatibility facilitates seamless integration with host tissues, thereby minimizing the risk of rejection or adverse reactions. Furthermore, its intrinsic degradability permits controlled release of therapeutic agents, promoting an optimal microenvironment conducive to healing. This review investigates the multifaceted potential of silk fibroin specifically as a wound dressing material and examines the intricate nuances associated with its application in hydrogels for wound healing, aiming to furnish a thorough overview for both researchers and clinicians. By scrutinizing underlying mechanisms, current applications, and prospective directions, we aspire to cultivate new insights and inspire innovative strategies within this rapidly evolving field.

Drug susceptibility profiles of Mycobacterium abscessus isolated in the state of São Paulo, 2008-2024

Introduction. Infections caused by Mycobacterium abscessus, an environmentally prevalent, rapidly growing mycobacteria, are increasingly frequent in developed countries.Objective. To analyse the drug susceptibility profiles of M. abscessus isolated in the state of São Paulo from 2008 to 2024.Methods. Of the 2,402 M. abscessus isolates identified during those 17 years, 558 (23.2%) met the American Thoracic Society's microbiologic and clinical criteria for drug susceptibility testing (DST), which was performed for five agents - clarithromycin, amikacin, cefoxitin, ciprofloxacin, and doxycycline.Results. Clarithromycin showed a dramatic increase in resistance phenotype from ≤10% in the early period to 73-90% over the last 8 years. Over half those isolates demonstrated inducible resistance. Resistance to amikacin was found in fewer than 5% of isolates from 2016 to 2021. In 2022, that result increased to 13%, but for 2023 and 2024, it had fallen back to 2%. Over the past decade, cefoxitin DST has reported the majority of isolates as intermediate, a problematic result in M. abscessus group (MAG) infections, which typically require long-term treatment for successful outcomes. Since 2018, the annual susceptibility rate has been ≤18%, and in five of the 7 years, ≤7%. Ciprofloxacin was typically assessed as susceptible from 2009 to 2011, then decreased sharply to ≤20% over the next several years, and since 2018, the rate has been less than 5%. Through the entire study, doxycycline resistance has remained consistently high; in the years since 2018, ≤6% of isolates have been susceptible.Conclusion. This study demonstrates wide variation among MAG clinical isolates in the frequency of susceptibility, both across different agents and within individual agents over time. These results emphasize the importance of performing high-quality DST on MAG clinical isolates and suggest the need to consider revising the standard panel of drugs tested.

Antibiotic-Modified Nanoparticles Combined with Lysozyme for Rapid Extraction of Pathogenic Bacteria DNA in Blood

Rapid and precise identification of the pathogens causing sepsis remains a significant diagnostic challenge. Blood culture is time-consuming and insensitive, while molecular diagnostic techniques, such as the polymerase chain reaction (PCR), are fast but greatly influenced by template quality. Here, we present a new approach to separate trace amounts of pathogen DNA from blood, which utilizes lysozyme to destroy bacteria and release DNA, followed by enrichment and purification using magnetic nanoparticles (MNPs) modified with kanamycin (Kan) or tobramycin (TM). We demonstrate that the prepared Kan@MNPs and TM@MNPs can efficiently adsorb DNA, with the mechanism involving interaction with the minor groove of DNA. Notably, the adoption of lysozyme ensures bacterial lysis while avoiding damage to blood cells, minimizing the interference from human genomic DNA background and inhibitory components, thereby obtaining relatively pure bacterial DNA. For artificially infected whole blood samples, our method shortens the sample processing time to 35 min and achieves a 10-fold improvement in PCR sensitivity compared to a commercial kit. Through clinical evaluation of blood samples collected from suspected infected patients, we identified positive samples that were 100% consistent with the clinical practice. Therefore, this method holds promising potential for clinical application in advancing rapid sepsis diagnosis and earlier interventions.

High incidence of multidrug-resistant organisms and modifiable risk factors associated with surgical site infections: a cohort study in a tertiary medical center in Kuala Lumpur, Malaysia from 2020 to 2023

BACKGROUND

Surgical site infections (SSIs) are a persistent challenge in healthcare, contributing significantly to patient morbidity, mortality, and healthcare costs. Despite advancements in preventive measures, SSIs remain prevalent, especially in countries like Malaysia where rates are higher than in high-income nations.

METHODS

A prospective, cohort study was conducted at the University Malaya Medical Center (UMMC), Malaysia, from November 2020 to May 2023. Clinical and microbiological data were collected, and logistic regression were performed to identify risk factors associated with SSIs.

RESULTS

A total of 1,815 patients undergoing orthopedic, neurosurgical, and general surgical procedures were monitored for SSIs. The incidence rate of SSIs was 3.23 per 100 procedures (n = 71) with significant associations observed between SSI occurrence and prolonged surgical duration > 100 min, extended hospitalization > 5 days, trauma-to-surgery interval > 8 days, and presence of implants. Common pathogens isolated included Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Multidrug-resistant organisms (MDROs) were identified in 42.1% of the total isolates.

CONCLUSIONS

In this study, a high rate of MDRO and risk factors for SSI were identified. It emphasises the need for ongoing surveillance to guide infection prevention strategies and antimicrobial stewardship programs. Future research should prioritize evaluating the impact of targeted interventions tailored to identified risk factors to optimize surgical patient outcomes.

Exploring the Impact of Chemotherapy on the Emergence of Antibiotic Resistance in the Gut Microbiota of Colorectal Cancer Patients

With nearly half of colorectal cancer (CRC) patients diagnosed at advanced stages where surgery alone is insufficient, chemotherapy remains a cornerstone for this cancer treatment. To prevent infections and improve outcomes, antibiotics are often co-administered. However, chemotherapeutic interactions with the gut microbiota cause significant non-selective toxicity, affecting not only tumor and normal epithelial cells but also the gut microbiota. This toxicity triggers the bacterial SOS response and loss of microbial diversity, leading to bacterial mutations and dysbiosis. Consequently, pathogenic overgrowth and systemic infections increase, necessitating broad-spectrum antibiotics intervention. This review underscores how prolonged antibiotic use during chemotherapy, combined with chemotherapy-induced bacterial mutations, creates selective pressures that drive de novo antimicrobial resistance (AMR), allowing resistant bacteria to dominate the gut. This compromises the treatment efficacy and elevates the mortality risk. Restoring gut microbial diversity may mitigate chemotherapy-induced toxicity and improve therapeutic outcomes, and emerging strategies, such as fecal microbiota transplantation (FMT), probiotics, and prebiotics, show considerable promise. Given the global threat posed by antibiotic resistance to cancer treatment, prioritizing antimicrobial stewardship is essential for optimizing antibiotic use and preventing resistance in CRC patients undergoing chemotherapy. Future research should aim to minimize chemotherapy's impact on the gut microbiota and develop targeted interventions to restore microbial diversity affected during chemotherapy.

ADP-MoA-Pa: a platform for screening antibiotic activity and their mechanism of action in Pseudomonas aeruginosa

AIMS

The emergence of multidrug-resistant bacteria poses a significant threat to global public health. To address this crisis, there is an urgent need to identify and characterize novel antibacterial molecules. This study aimed to develop the ADP-MoA-Pa platform to facilitate the discovery of new antibiotics and provide preliminary insights into their mechanisms of action (MoA).

METHODS AND RESULTS

The ADP-MoA-Pa platform enables the simultaneous visualization of antibiotic activity (growth inhibition) alongside one of three classic MoA in Pseudomonas aeruginosa: DNA damage/inhibition of DNA replication, protein synthesis inhibition, or cell wall damage. To construct the platform, the promoter regions of recA, ampC, and armZ of P. aeruginosa PA14 strain were each amplified and fused to a promoterless luxCDABE operon in vector pUC18T-mini-Tn7T-lux-Gm. The constructs were electrotransformed into strain PA14 where they integrated in the chromosome. Each promoter fusion was activated by the expected antibiotics on plates and in liquid media, thereby demonstrating proof of concept. The armZ::luxCDABE fusion responded to protein synthesis inhibitors such as macrolides, chloramphenicol, tetracyclines, and aminoglycosides. The ampC::luxCDABE fusion was induced by β-lactams, while the recA::luxCDABE fusion was activated by quinolones and nitrofurantoin. Interestingly, under some conditions, ciprofloxacin also activated ampC and armZ, though to a lesser extent.

CONCLUSIONS

The ADP-MoA-Pa platform is a low-cost, readily implementable tool with significant potential for high-throughput screening of antimicrobials. It offers a promising avenue for identifying and characterizing novel antibiotics against P. aeruginosa and other bacterial species, contributing to the global effort to combat multidrug-resistant pathogens.

Impact of meropenem exposure on fluoroquinolone and carbapenem resistance in Pseudomonas aeruginosa infection in inpatients in a Japanese university hospital: Insights into oprD mutations and efflux pump overexpression

OBJECTIVES

In Pseudomonas aeruginosa isolates, emerging meropenem resistance beyond imipenem resistance has become a problem. In this study, we aimed to investigate the relationship between the in vivo acquisition of antimicrobial resistance in fluoroquinolone- and carbapenem-resistant P. aeruginosa clinical isolates, the underlying molecular mechanisms, and exposure to antimicrobial agents.

METHODS

Pulsed-field gel electrophoreses were performed to study the molecular relatedness of nine clinical isolates from a Japanese hospital. The minimal inhibitory concentrations of clinically relevant antibiotics were determined. Quantitative PCR was performed to analyze oprD, mexB, mexC, mexE, and mexY expression. DNA sequencing was performed to identify mutations.

RESULTS

Eight of nine strains were metallo-β-lactamase (MBL) negative, and one strain was MBL positive. All eight non-MBL-resistant strains harbored mutations in the quinoline-resistance-determining regions (QRDR) of gyrA, gyrB, or parC. Five of the eight non-MBL strains had T83I, two had D87N, and one had both T83I and D87N mutations in gyrA. Of these eight strains, three carrying gyrA mutations had another QRDR mutation in subunits, gyrB or parC, associated with mexY overexpression. Additionally, seven of eight dual fluoroquinolone and carbapenem-resistant isolates carried a premature termination codon within oprD, containing either F170L or L7 shortening.

CONCLUSIONS

In dual fluoroquinolone- and carbapenem-resistant P. aeruginosa, alterations in the OprD porin and the presence of an active EP are primary resistance mechanisms. Meropenem exposure within the past 59 days may have contributed to the selection of the oprD mutant overexpressing mexB, and meropenem exposure within the past 6 months may have contributed to meropenem resistance.

Characterization of enterotoxin, antibiotic resistance genes, and antimicrobial susceptibility profiling of Staphylococcus aureus isolated from table eggs: Implications for food safety and public health

Background

Staphylococcus aureus is a significant pathogen in both clinical and food safety contexts, capable of contaminating table eggs, which are a common dietary staple worldwide.

Aim

This study aimed to assess the prevalence, molecular characteristics, and antibiotic resistance profiles of S. aureus isolated from table eggs. The focus was on identifying methicillin-resistant S. aureus (MRSA) strains that produce enterotoxin (seb), resistance to β-lactam antibiotics (blaTEM), tetracycline (tetA), and vancomycin-resistant S. aureus.

Methods

A total of 200 egg samples were collected from various retail sources in Mymensingh City Corporation, Bangladesh. Swab samples (n = 100) were collected from eggshells, and another 100 samples were collected from the inner membrane, egg white, and yolk. Samples were enriched in trypticase soy broth and cultured on mannitol salt agar. Staphylococcus aureus was isolated through conventional culture techniques, confirmed by polymerase chain reaction targeting the nuc, and further screened for the mecA, seb, blaTEM, tetA, vanA, and vanC genes. Antibiotic susceptibility testing was conducted using the disc diffusion method against 13 antibiotics. Bivariate analysis is used to assess the strong and significant correlations between virulence genes and the pairs of any of two antibiotic-resistant S. aureus.

Results

Staphylococcus spp. and S. aureus were detected in 53% and 21% of eggshell samples, respectively, and 41% and 13% of egg content samples. Among 34 coagulase-positive isolates, 12 (57.14%) from eggshells and 4 (30.78%) from egg contents were positive for the nuc gene. Resistance was observed in eggshell isolates for mecA (33.33%), blaTEM (85.71%), tetA (33.33%), vanA (19.04%), vanC (33.33%), and seb (20.50%), whereas egg content isolates showed resistance to blaTEM (46.15%) and vanC (7.80%). All coagulase-positive isolates exhibited significant resistance to β-lactam antibiotics, cephalosporins, and glycopeptides, especially vancomycin. Notably, 19 (90.47%) and 12 (92.30%) eggshell and egg content isolates, respectively, were multidrug-resistant, with multiple antibiotic resistance indices ranging from 0.23 to 0.76.

Conclusion

The study revealed a high prevalence of multidrug-resistant S. aureus in table eggs, indicating a significant public health risk. The presence of MRSA and strains with enterotoxins and resistance genes underscores the need for enhanced monitoring, stricter biosecurity measures, and robust control strategies for egg production and distribution to ensure food safety.

A systematic review of recent outbreaks and the efficacy and safety of drugs approved for the treatment of Salmonella infections

A systematic review was conducted to critically analyze the outbreaks, efficacy, and safety of drugs used to treat various Salmonella infections. Four drugs-azithromycin, ceftriaxone, ciprofloxacin, and amoxicillin-are commonly used to treat Salmonella infections, and all four drugs were included in this review. This review found that, of these, azithromycin and ceftriaxone were more effective in treating Salmonella infections based on the patient's length of stay in the hospital and the rate at which the fever was resolved. Fluoroquinolones are also effective in treating Salmonella infection but are not approved for use in children. Azithromycin was found to be the physicians' preferred choice of medication for Salmonella infection due to its less resistance development. Almost all these drugs produce varying degrees of adverse events, but they are mild to moderate. However, azithromycin was shown to be comparatively safer than the other three drugs in terms of side effects, adverse events, and relapse associated with Salmonella treatment. Developing effective and safe therapies for all strains of Salmonella remains a priority, especially given the increasing prevalence of antibiotic-resistant variants.

Drug susceptibility of uropathogens isolated from patients treated at the Mazovian Specialized Hospital in Radom

Urinary tract infections (UTI) are a significant problem among populations worldwide. It is mainly associated with the increasing incidence of recurrence, complications and the increasing drug resistance of uropathogens. The aim of this study was to demonstrate the prevalence of resistance among pathogens causing urinary tract infections. The material for the study was data obtained from the Mazovian Specialized Hospital (M.S.H) in Radom over a period of 2 years. Urine was collected from hospitalized patients with UTI. Statistical calculations were performed using statistical software. During the study period, 3,917 patients underwent microbiological examination of urine, and almost 15% of them were found to be infected with UTI. Based on statistical analysis of drug susceptibility of the most common uropathogens, it was shown that urinary tract infections caused by Escherichia coli or Klebsiella pneumoniae, among others, often show high resistance to fluoroquinolones and β-lactam antibiotics. Proteus mirabilis strains have been shown to be more resistant to aminoglycosides and fluoroquinolones than to beta-lactams. In the case of Pseudomonas aeruginisa, resistance to fluoroquinolones predominates. On the other hand, UTI caused by Acientobacter baumannii should be treated based on the results of drug susceptibility testing due to the increasing prevalence of multidrug-resistant strains.

Genomic analysis of multidrug-resistant Escherichia coli isolated from dairy cows in Shihezi city, Xinjiang, China

Introduction

Dairy farming plays a vital role in agriculture and nutrition; however, the emergence of antimicrobial resistance (AMR) among bacterial pathogens poses significant risks to public health and animal welfare. Multidrug-resistant (MDR) Escherichia coli strains are of particular concern due to their potential for zoonotic transmission and resistance to multiple antibiotics. In this study, we investigated the prevalence of AMR and analyzed the genomes of two MDR E. coli isolated from dairy cows in Shihezi City.

Methods

Fecal samples were collected from dairy cows, and E. coli strains were isolated. Antibiotic susceptibility testing was conducted using the Kirby-Bauer disk diffusion method against 14 antibiotics. Two MDR isolates (E.coli_30 and E.coli_45) were selected for whole-genome sequencing and comparative genomic analysis. The Comprehensive Antibiotic Resistance Database (CARD) was used to identify AMR genes, and virulence factors were analyzed. Phylogenetic analysis was performed to determine the evolutionary relationships of the isolates, and a pangenome analysis of 50 E. coli strains was conducted to assess genetic diversity. The presence of mobile genetic elements (MGEs), including insertion sequences (IS) and transposons, was also examined.

Results

Among the E. coli isolates, 22.9% exhibited MDR, with high resistance to imipenem and ciprofloxacin, while gentamicin and tetracycline remained the most effective antibiotics. Genomic analysis revealed key AMR genes, including mphA, qnrS1, and bla CTX-M-55 (the latter found only in E.coli_45), conferring resistance to macrolides, quinolones, and beta-lactams, respectively. Virulence genes encoding type III secretion systems (TTSS) and adhesion factors were identified, indicating pathogenic potential. Phylogenetic analysis showed that E.coli_30 and E.coli_45 originated from distinct ancestral lineages. The presence of two extended-spectrum β-lactamase (ESBL) genes in E.coli_45 was noticeable, so we studied their global and national distribution using evolutionary analysis. We found that they are endemic in E. coli, Salmonella enterica, and Klebsiella pneumoniae. Pangenome analysis revealed significant genetic diversity among E. coli strains, with unique genes related to metabolism and stress response. This indicates the bacteria's adaptation to various environments. MGEs were identified as key contributors to genetic variability and adaptation.

Discussion

This study highlights the growing threat of MDR E. coli in dairy farms, emphasizing the critical role of MGEs in the spread of resistance genes. The genetic diversity observed suggests strong adaptive capabilities, justifying the need for continuous AMR surveillance in livestock. Effective monitoring and mitigation strategies are essential to prevent the dissemination of MDR bacteria, thereby protecting both animal and public health.

A Comprehensive Overview of Antibacterial Agents for Combating Multidrug-Resistant Bacteria: The Current Landscape, Development, Future Opportunities, and Challenges

Background/Objectives: Antimicrobial resistance poses a major public health challenge. The World Health Organization has identified 15 priority pathogens that require prompt development of new antibiotics. This review systematically evaluates the antibacterial resistance of the most significant bacterial pathogens, currently available treatment options, as well as complementary approaches for the management of infections caused by the most challenging multidrug-resistant (MDR) bacteria. For carbapenem-resistant Gram-negative bacteria, treatment options include combinations of beta-lactam antibiotics and beta-lactamase inhibitors, a novel siderophore cephalosporin, known as cefiderocol, as well as older antibiotics like polymixins and tigecycline. Treatment options for Gram-positive bacteria are vancomycin, daptomycin, linezolid, etc. Although the development of new antibiotics has stagnated, various agents with antibacterial properties are currently in clinical and preclinical trials. Non-antibiotic strategies encompass antibiotic potentiators, bacteriophage therapy, antivirulence therapeutics, antimicrobial peptides, antibacterial nanomaterials, host-directed therapy, vaccines, antibodies, plant-based products, repurposed drugs, as well as their combinations, including those used alongside antibiotics. Significant challenges exist in developing new antimicrobials, particularly related to scientific and technical issues, along with policy and economic factors. Currently, most of the alternative options are not part of routine treatment protocols. Conclusions and Future Directions: There is an urgent need to expedite the development of new strategies for treating infections caused by MDR bacteria. This requires a multidisciplinary approach that involves collaboration across research, healthcare, and regulatory bodies. Suggested approaches are crucial for addressing this challenge and should be backed by rational antibiotic use, enhanced infection control practices, and improved surveillance systems for emerging pathogens.

Ciprofloxacin-encapsulated solid lipid nanoparticles: a comprehensive biochemical analysis of cytotoxic effects, proliferation inhibition, and apoptotic induction in KG1-a leukemia cells

As a fundamental approach to the treatment of acute myeloid leukemia (AML), chemotherapeutic agents face significant clinical challenges, including poor solubility and low bioavailability. In this context, solid lipid nanoparticles (SLNs) have emerged as a promising drug delivery system in oncologic therapies, owing to their advantageous characteristics, such as enhanced physical stability and controlled drug-release profiles. This study focuses on the synthesis of ciprofloxacin (CP)-loaded SLNs, aiming to enhance the anticancer efficacy of CP, an antibiotic recognized for its potential anticancer properties, while simultaneously reducing its associated side effects. Characterization of blank SLN and CP-SLN was conducted using dynamic light scattering (DLS), atomic force microscopy (AFM), UV-Vis spectrophotometry, and Fourier transform infrared spectroscopy (FTIR). In vitro release was carried out using dialysis bag method in isotonic phosphate buffer (pH = 7.4). The anticancer and pro-apoptotic effects of the CP-SLN formulation were assessed through cell viability assays, Hoechst staining, and Annexin V/PI flow cytometry. Additionally, expression levels of Bax, Bcl2, and p53 were analyzed via Real-Time PCR. The synthesized CP-SLN formulation exhibited optimal characteristics, including a particle size of 340-360 nm, a polydispersity index (PDI) of 0.4, and an entrapment efficiency of 90%. The in vitro drug release showed an initial burst release in the time points 4-10 h. Both CP and the CP-SLN formulations demonstrated significant anti-proliferative and pro-apoptotic effects on KG1-a cells, as indicated by the upregulation of the Bax/Bcl2 ratio and p53, resulting in G0/G1 cell cycle arrest and apoptosis induction. The results suggest that encapsulating CP in SLN enhances its anticancer and pro-apoptotic effects in KG1-a stem-like leukemia cells. Thus, CP-SLN may serve as a promising formulation for leukemia treatment and could improve the efficacy of other therapeutic agents.

Assessment of phytochemical screening, antibacterial, analgesic, and antipyretic potentials of Litsea glutinosa (L.) leaves extracts in a mice model

BACKGROUND

Litsea glutinosa (LG) leaves have been traditionally used in ethnomedicine for the treatment of various ailments, including pain, fever, and microbial infections. This study aims to scientifically evaluate the therapeutic potential of cold methanol extracts of LG leaves, specifically focusing on their analgesic, antipyretic, and antibacterial activities. In addition, the research includes preliminary phytochemical screening to identify key bioactive compounds and an acute toxicity test to assess the safety profile of the extract.

METHODS

In this study, we conducted an initial investigation of the major phytochemical groups present in L. glutinosa leaves using both modern chromatographic techniques, specifically High-Performance Liquid Chromatography (HPLC), and conventional phytochemical screening methods applied to cold methanol extracts. Both approaches consistently identified phenols and flavonoids as the predominant bioactive compounds. Following this phytochemical characterization, we assessed the analgesic efficacy of the extracts using acetic acid-induced writhing and electrical heat-induced nociceptive pain stimuli, evaluated antipyretic effects through Brewer's yeast-induced pyrexia, and determined antibacterial activity via the disc diffusion method. Additionally, the toxicity of the extracts was evaluated through preclinical testing.

RESULTS

In hot plate method, the highest pain inhibitory activity was found at a dose of 500 mg/kg of crude extract (3.37 ± 0.31 sec) which differed significantly (P < 0.01 and P < 0.001) with that of the standard drug morphine (6.47 ± 0.23 sec). The extract significantly prolonged reaction latency to thermal-induced pain in hotplate model. Analgesic activity at 500 mg/kg, LG extract produced a 70% suppression of writhing in mice, which was statistically significant (p < 0.001) compared to standard morphine's (77.5%) inhibition. In antipyretic activity assay, the crude extract showed notable reduction in body temperature (36.17 ±  0.32 °C) at dose of 300 mg/kg-body weight, when the standard (at dose 100 mg/kg-body weight) exerted (36.32 ±  0.67 °C) after 3 h of administration. In antibacterial studies, results showed that inhibition of bacterial growth at 400 μg dose of each extract clearly inhibited growth of bacteria from 11 to 22 mm. The extractives carbon tetrachloride fraction, chloroform soluble fraction, ethyl acetate fraction demonstrated notably greater inhibitory zone widths (p < 0.05) against tested strains.

CONCLUSION

Overall, the cold methanol extract of LG leaves demonstrates the therapeutic potential in preclinical settings. Future research is warranted to isolate the specific bioactive compounds and elucidate their mechanisms of action to further support the development of new treatments and contributing to modern medicinal practices based on this plant leaves.

Fluoroquinolone-Mediated Tendinopathy and Tendon Rupture

The fluoroquinolone (FQ) class of antibiotics includes the world's most prescribed antibiotics such as ciprofloxacin, levofloxacin, and ofloxacin that are known for their low bacterial resistance. This is despite their potential to trigger severe side effects, such as myopathy, hearing loss, tendinopathy, and tendon rupture. Thus, healthcare organizations around the world have recommended limiting the prescription of FQs. Tendinopathy is a common name for maladies that cause pain and degeneration in the tendon tissue, which can result in tendon rupture. Whilst there are several identified effects of FQ on tendons, the exact molecular mechanisms behind FQ-mediated tendon rupture are unclear. Previous research studies indicated that FQ-mediated tendinopathy and tendon rupture can be induced by changes in gene expression, metabolism, and function of tendon resident cells, thus leading to alterations in the extracellular matrix. Hence, this review begins with an update on FQs, their mode of action, and their known side effects, as well as summary information on tendon tissue structure and cellular content. Next, how FQs affect the tendon tissue and trigger tendinopathy and tendon rupture is explored in detail. Lastly, possible preventative measures and promising areas for future research are also discussed. Specifically, follow-up studies should focus on understanding the FQ-mediated tendon changes in a more complex manner and integrating in vitro with in vivo models. With respect to in vitro systems, the field should move towards three-dimensional models that reflect the cellular diversity found in the tissue.

Dynamics of Salmonella Dublin infection and antimicrobial resistance in a dairy herd endemic to salmonellosis

Salmonella Dublin is a serovar that causes severe infections and cattle. Despite the importance of this agent, research on achieving its elimination from dairy farms is limited, which complicates risk mitigation and control efforts. This study thus aimed to assess the prevalence of S. Dublin on a farm with a history of outbreaks, to understand the dynamics of the infection, characterize the antimicrobial resistance of the isolates, and evaluate their genetic similarity. Multiparous cows in the postpartum phase are nearly five times more likely to shed Salmonella sp. A total of 39 cases of fatal septicemic salmonellosis caused by S. Dublin were confirmed in calves aged 3-5 months. Antimicrobial susceptibility was evaluated in 45 strains of S. Dublin, with 48.9% of the isolates classified as multidrug resistant, including resistance to penicillin (48.9%), tetracyclines (42.2%), and fluoroquinolones (33.3%). Seven multidrug-resistant isolates were selected for genomic sequencing. Among the resistance determinants identified, a mutation in the gyrA gene, present in all sequenced isolates, was notable. Analyses of cgMLST and SNPs revealed that the isolates from healthy animals were closely related to those found in animals with confirmed cases of S. Dublin, confirming that the agent was circulating among healthy animals across various categories. A high similarity was also found between the isolates in this study and strains causing salmonellosis in humans in Brazil, thus reinforcing the zoonotic nature and possible epidemiological link between cattle, and the occurrence of this disease in humans.

In Vitro Insights into Bacteriocin-Mediated Modulation of Chicken Cecal Microbiota

Reducing the use of antibiotics in animal husbandry is essential to limit the spread of resistance. A promising alternative to antibiotics resides in bacteriocins, which are antimicrobial peptides produced by bacteria showing a great diversity in terms of spectrum of activity, structure, and mechanism of action. In this study, the effects of diverse bacteriocins on the composition and metabolic activity of chicken cecal microbiota were examined in vitro, in comparison with antibiotics. Different impacts on microbiota composition were revealed by 16S metabarcoding, with colistin having the most dramatic impact on diversity. Bacteriocins produced by Gram-negative bacteria, microcins J25 and E492, did not significantly influence the microbiota composition. In contrast, bacteriocins from Gram-positive bacteria impacted the abundance of lactic acid bacteria, with nisin Z showing the most impact while pediocin PA-1 (M31L) exhibited a moderate effect at the highest concentration tested. This study emphasizes the potential of bacteriocins as alternatives to antibiotics in poultry to protect from pathogens such as Salmonella, Clostridium, and Enterococcus.

Injectable gelatin-pectin hydrogel for dental tissue engineering: Enhanced angiogenesis and antibacterial efficacy for pulpitis therapy

Pulpitis is inflammation of the dental pulp, often caused by bacterial infection from untreated cavities, leading to pain. The main challenge in treatment is eliminating infection while preserving tooth vitality. This study aims to address this challenge by developing a hydrogel for convenient insertion into the root canal system, securely attaching to dentin walls. An injectable hydrogel system is developed by chemically cross-linking natural polysaccharide pectin with gelatin (GPG) through reversible Schiff base reaction. The GPG system was then used to encapsulate and release drugs, such as ciprofloxacin (CIP) for infection prevention and deferoxamine (DFO) for promoting blood vessel proliferation and reducing inflammatory reactions. The GPGs absorbed significant amounts of CIP and DFO, enabling sustained release over a nearly ten-day period. When subcutaneously implanted, the GPGs formed stable gel depots, with only 50 % of the gels degrading after 3 weeks, indicating a sustained biodegradation pattern. Additionally, the GPG system demonstrated excellent antibacterial activity against both gram-negative and gram-positive bacteria. Results from in vitro scratch healing tests and in ovo chorioallantoic membrane chick model tests showed promising biocompatibility and promotion of vascular proliferation by the GPG. This study heralds a novel frontier in endodontic therapeutics, poised to potentially enable dental pulp regeneration.

Combining with matrine restores ciprofloxacin efficacy against qnrS producing E. coli in vitro and in vivo

The exposure risk of plasmid-mediated quinolone resistance (PMQR) genes increases the incidence of resistant bacterial infections, has resulted in clinical treatment failures with ciprofloxacin, necessitating urgent implementation of novel strategies for controlling this situation. Matrine serves as the principal constituent of the traditional Chinese herb Sophora flavescens Ait. and exhibits pharmacological activities including anti-inflammatory, antibacterial, anti-tumor, and hepatoprotective effects. However, the precise mechanism by which matrine exhibits antibacterial activity remains incompletely elucidated. This study investigated the antibacterial potential and synergistic mechanism of matrine in combination with ciprofloxacin against qnrS-carrying E. coli. The clinical ciprofloxacin-resistant E. coli carrying the qnrS and the recombinant E. coli DE3 (pET28a-qnrS) were evaluated for their antibacterial activity in vitro, it was found that the combination of matrine/ciprofloxacin exhibited a significant synergistic, reducing the MIC value of ciprofloxacin against qnrS-positive E. coli by 4-fold, and it effectively reduced the bacterial load to undetectable levels within 10 h without obvious cytotoxicity. Moreover, consistent findings were observed in significantly reducing bacterial load within the mouse infection model. Molecular docking revealed that matrine was localized in the large loop B of the qnrS crystal structure, establishing hydrogen bonds with Thr-102 and Arg-101, thereby disrupting the activity of qnrS. Interaction analysis further confirmed that matrine could significantly inhibit the protective effect of qnrS on gyrase and restore the activity of ciprofloxacin against qnrS-positive E. coli. Matrine may serve as a qnrS inhibitor to restore the efficacy of ciprofloxacin, suggesting its potential as a novel antibiotic adjuvant for controlling bacterial infections.

Can α-Mangostin and Photodynamic Therapy Support Ciprofloxacin in the Inactivation of Uropathogenic Escherichia coli and Staphylococcus aureus Strains?

Multidrug-resistant bacteria represent a significant challenge in the treatment of bacterial infections, often leading to therapeutic failures. This issue underlines the need to develop strategies that improve the efficacy of conventional antibiotic therapies. In this study, we aimed to assess whether a plant-derived compound, α-mangostin, and photodynamic therapy (PDT) could enhance the antibacterial activity of ciprofloxacin against uropathogenic strains of Escherichia coli and Staphylococcus aureus. Using nanopore sequencing technology, we confirmed that the clinical strains tested were classified as multidrug-resistant. Digital holotomography (DHT) was used to examine α-mangostin-induced changes in the bacterial cells' penetration by a photosensitizer. A scanning confocal fluorescence microscope was used to visualize photosensitizer penetration into bacterial cells and validate DHT results. A synergistic effect between α-mangostin and ciprofloxacin was observed exclusively in S. aureus strains, while no enhancement of ciprofloxacin's antibacterial activity was detected in E. coli strains when combined with α-mangostin. Notably, photodynamic therapy significantly potentiated the antibacterial effects of ciprofloxacin and its combination with α-mangostin compared to untreated controls. In addition, morphological changes were observed in bacterial cells exposed to these antimicrobials. In conclusion, our findings suggest that α-mangostin and PDT may serve as valuable adjuncts to ciprofloxacin, improving the eradication of uropathogens.

Gram Negative Biofilms: Structural and Functional Responses to Destruction by Antibiotic-Loaded Mixed Polymeric Micelles

Biofilms are a well-known multifactorial virulence factor with a pivotal role in chronic bacterial infections. Their pathogenicity is determined by the combination of strain-specific mechanisms of virulence and the biofilm extracellular matrix (ECM) protecting the bacteria from the host immune defense and the action of antibacterials. The successful antibiofilm agents should combine antibacterial activity and good biocompatibility with the capacity to penetrate through the ECM. The objective of the study is the elaboration of biofilm-ECM-destructive drug delivery systems: mixed polymeric micelles (MPMs) based on a cationic poly(2-(dimethylamino)ethyl methacrylate)-b-poly(ε-caprolactone)-b-poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA35-b-PCL70-b-PDMAEMA35) and a non-ionic poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO100-b-PPO65-b-PEO100) triblock copolymers, loaded with ciprofloxacin or azithromycin. The MPMs were applied on 24 h pre-formed biofilms of Escherichia coli and Pseudomonas aeruginosa (laboratory strains and clinical isolates). The results showed that the MPMs were able to destruct the biofilms, and the viability experiments supported drug delivery. The biofilm response to the MPMs loaded with the two antibiotics revealed two distinct patterns of action. These were registered on the level of both bacterial cell-structural alterations (demonstrated by scanning electron microscopy) and the interaction with host tissues (ex vivo biofilm infection model on skin samples with tests on nitric oxide and interleukin (IL)-17A production).

Controlled bioorthogonal catalyst self-assembly and activity using rationally designed polymer scaffolds

Polymer-based nanocatalysts have been extensively utilized in advanced drug delivery due to their versatility and high reactivity. Incorporating bioorthogonal transition metal catalysts (TMCs) into polymers generates bioorthogonal nanocatalysts capable of producing therapeutic agents in situ, minimizing off-target effects. The supramolecular interactions within the polymer matrix, including hydrophobic interactions and aromatic stacking, play a crucial role in catalytic properties. Our study focuses on co-engineering the host polymer structure and the catalyst encapsulation process to achieve precise control over the supramolecular interactions within the nanoenvironment. By carefully engineering these interactions, we successfully generate thermo-responsive nanocatalysts with a resolution of 6 °C. These nanocatalysts demonstrate thermal activation of the catalytic deprotection of a pro-antibiotic, with concomitant external control of bacterial biofilm eradication.

Ringing medicinal chemistry: The importance of 3-membered rings in drug discovery

Scaffold-based drug design has become increasingly prominent in the pharmaceutical field due to the systematic and effective approach through which it facilitates the development of novel drugs. The identification of key scaffolds provides medicinal chemists with a fundamental framework for subsequent research. With mounting evidence suggesting that increased aromaticity could impede the chances of developmental success for oral drug candidates, there is an imperative need for a more thorough exploration of alternative ring systems to mitigate attrition risks. The unique characteristics exhibited by three-membered rings have led to their application in medicinal chemistry. This review explores the use of cyclopropane-, aziridine-, thiirane-, and epoxide-containing compounds in drug discovery, focusing on their roles in approved medicines and drug candidates. Specifically, the importance of the three-membered ring systems in rending biological activity for each drug molecule was highlighted. The undeniable therapeutic value and intriguing features presented by these compounds suggest significant pharmacological potential, providing justification for their incorporation into the design of novel drug candidates.

Bacteriophage as a novel therapeutic approach for killing multidrug-resistant Escherichia coli ST131 clone

The emergence of the multidrug-resistant (MDR) Escherichia coli ST131 clone has significantly impacted public health. With traditional antibiotics becoming less effective against MDR bacteria, there is an urgent need for alternative treatment options. This study aimed to isolate and characterize four lytic phages (EC.W2-1, EC.W2-6, EC.W13-3, and EC.W14-3) from hospital sewage water and determine their effectiveness against the ST131 clone. These phages demonstrated a broad host range, effectively lysing 94.4% of highly pathogenic E. coli ST131 isolates. Morphological observations and phylogenetic analysis indicate that EC.W2-1, and EC.W13-3 belong to the Tequatrovirus genus in the Straboviridae family, while EC.W2-6 and EC.W14-3 are part of the Kuravirus genus in the Podoviridae family. Phages remained stable at pH 2-10 for 4 h and below 80°C for 1 h. These four phages showed in vitro bacterial lytic activity at various MOIs (0.1-0.001). The one-step growth curve of phages exhibited a short latent period of approximately 10-20 min and a moderate burst size of 50-80 (pfu/cell). Phages' genome size ranged from 46,325-113,909 bp, with G + C content of 35.1 -38.3%. No virulence or drug resistance genes were found, which enhanced their safety profile. In vivo, EC.W2-6 and EC.W13.3, along with their cocktail, fully protected against the ESBL-producing E. coli ST131 infection model in vivo. Combining these phages and a 3-day repeated single phage, EC.W13-3 significantly enhanced the survival rate of E. coli ST131 infected mice at low MOI (0.01-0.001). The in vivo effectiveness of the isolated phages and the EC.W2-6 and EC.W14-3 cocktail in highly reducing bacterial load CFU/g in multiple organs strongly supports their potential efficacy. Based on in vivo, in vitro, and genomic analyses, phages have been proposed as novel and suitable candidates for killing the pandemic ST131 clone.

Fluoroquinolones and Biofilm: A Narrative Review

Background: Biofilm-associated infections frequently span multiple body sites and represent a significant clinical challenge, often requiring a multidisciplinary approach involving surgery and antimicrobial therapy. These infections are commonly healthcare-associated and frequently related to internal or external medical devices. The formation of biofilms complicates treatment, as they create environments that are difficult for most antimicrobial agents to penetrate. Fluoroquinolones play a critical role in the eradication of biofilm-related infections. Numerous studies have investigated the synergistic potential of combining fluoroquinolones with other chemical agents to augment their efficacy while minimizing potential toxicity. Comparative research suggests that the antibiofilm activity of fluoroquinolones is superior to that of beta-lactams and glycopeptides. However, their activity remains less effective than that of minocycline and fosfomycin. Noteworthy combinations include fluoroquinolones with fosfomycin and aminoglycosides for enhanced activity against Gram-negative organisms and fluoroquinolones with minocycline and rifampin for more effective treatment of Gram-positive infections. Despite the limitations of fluoroquinolones due to the intrinsic characteristics of this antibiotic, they remain fundamental in this setting thanks to their bioavailability and synergisms with other drugs. Methods: A comprehensive literature search was conducted using online databases (PubMed/MEDLINE/Google Scholar) and books written by experts in microbiology and infectious diseases to identify relevant studies on fluoroquinolones and biofilm. Results: This review critically assesses the role of fluoroquinolones in managing biofilm-associated infections in various clinical settings while also exploring the potential benefits of combination therapy with these antibiotics. Conclusions: The literature predominantly consists of in vitro studies, with limited in vivo investigations. Although real world data are scarce, they are in accordance with fluoroquinolones' effectiveness in managing early biofilm-associated infections. Also, future perspectives of newer treatment options to be placed alongside fluoroquinolones are discussed. This review underscores the role of fluoroquinolones in the setting of biofilm-associated infections, providing a comprehensive guide for physicians regarding the best use of this class of antibiotics while highlighting the existing critical issues.

Fluoroquinolones tackling antimicrobial resistance: Rational design, mechanistic insights and comparative analysis of norfloxacin vs ciprofloxacin derivatives

Antimicrobial resistance poses a global health concern and develops a need to discover novel antimicrobial agents or targets to tackle this problem. Fluoroquinolone (FN), a DNA gyrase and topoisomerase IV inhibitor, has helped to conquer antimicrobial resistance as it provides flexibility to researchers to rationally modify its structure to increase potency and efficacy. This review provides insights into the rational modification of FNs, the causes of resistance to FNs, and the mechanism of action of FNs. Herein, we have explored the latest advancements in antimicrobial activities of FN analogues and the effect of various substitutions with a focus on utilizing the FN nucleus to search for novel potential antimicrobial candidates. Moreover, this review also provides a comparative analysis of two widely prescribed FNs that are ciprofloxacin and norfloxacin, explaining their rationale for their design, structure-activity relationships (SAR), causes of resistance, and mechanistic studies. These insights will prove advantageous for new researchers by aiding them in designing novel and effective FN-based compounds to combat antimicrobial resistance.

Evaluating the Antimicrobial Efficacy of a Designed Synthetic peptide against Pathogenic Bacteria

Recent research has focused on discovering peptides that effectively target multidrug-resistant bacteria while leaving healthy cells unharmed. In this work, we describe the antimicrobial properties of RK8, a peptide composed of eight amino acid residues. Its activity was tested against multidrug-resistant Gram-negative and Gram-positive bacteria. RK8's efficacy in eradicating mature biofilm and increasing membrane permeability was assessed using Sytox Green. Cytotoxicity assays were conducted both in vitro and in vivo models. Circular dichroism analysis revealed that RK8 adopted an extended structure in water and sodium dodecyl sulfate (SDS). RK8 exhibited MICs of 8-64 μM and MBCs of 4-64 μM against various bacteria, with higher effectiveness observed in Methicillin-resistant Staphylococcus aureus (MRSA) and E. coli KPC+ strains than others. Ciprofloxacin and Vancomycin showed varying MIC and MBC values lower than RK8 for Gram-positive bacteria, but competitive for Gram-negative bacteria. The combination of RK8 and ciprofloxacin showed a synergistic effect. The RK8 peptides could reduce 38% of the mature Acinetobacter baumannii biofilm. Sytox Green reagent achieved 100% membrane permeation of Gram-positive and Gram-negative bacteria. The RK8 peptide did not show cytotoxic effects against murine macrophages (64 μM), erythrocytes (100 μM) or Galleria mellanella larvae (960 μM). In the stability test against peptidases, the RK8 peptide was stable, maintaining around 60% of the molecule intact after 120 min of incubation. These results highlight the potential of RK8 to be a promising strategy for developing a new antimicrobial and antibiofilm agent, inspiring and motivating further research in antimicrobial peptides.

Combined Antibiotic and Photodynamic Therapies in Pseudomonas aeruginosa: From Synergy to Antagonism

Background: Antibiotics remain the most effective option for combating infections. However, the situation has shifted from ideal to concerning, as bacterial resistance to antibiotics is increasing in both prevalence and strength. Objectives: This study explores the synergistic/antagonistic potential of combining antibiotic and photodynamic therapy (PDT) against Pseudomonas aeruginosa. Methods: We conducted in vitro experiments to observe the effect of the sequential application of antibiotics and photodynamic therapy with a time interval between them. The antibiotics used were ciprofloxacin, ceftriaxone, and gentamicin, and Photodithazine was employed as the photosensitizer, with the PDT performed at different light doses of 660 nm radiation. Results: The combined effect was highly dependent on the antibiotic. While for gentamicin, the combination of antibiotic and PDT treatment was always synergistic, for ciprofloxacin, it could be severely antagonistic. Each antibiotic exhibited a distinctive pattern of interaction with PDT. Gentamicin resulted in the largest enhancement in bactericidal activity combined with PDT, requiring lower antibiotic concentrations to achieve significant bacterial reduction. Ceftriaxone's bactericidal action was less influenced by PDT intensity, maintaining a stable efficacy regardless of different PDT dosages. Conversely, the outcome of ciprofloxacin was highly dependent on the antibiotic concentration changing from synergic to antagonistic action. Conclusions: The findings advocate for the development of treatment protocols that combine antibiotics and PDT and necessitate the establishment of the criterion for the dosage and periodicity of administration of such combination protocols. The demonstrated results open the doors wide to new applications and opportunities to combat infectious diseases through the combined use of photodynamic therapy and antibiotics.

Comparison of the antibiotic resistance mechanisms in a gram-positive and a gram-negative bacterium by gene networks analysis

Nowadays, the emergence of some microbial species resistant to antibiotics, both gram-positive and gram-negative bacteria, is due to changes in molecular activities, biological processes and their cellular structure in order to survive. The aim of the gene network analysis for the drug-resistant Enterococcus faecium as gram-positive and Salmonella Typhimurium as gram-negative bacteria was to gain insights into the important interactions between hub genes involved in key molecular pathways associated with cellular adaptations and the comparison of survival mechanisms of these two bacteria exposed to ciprofloxacin. To identify the gene clusters and hub genes, the gene networks in drug-resistant E. faecium and S. Typhimurium were analyzed using Cytoscape. Subsequently, the putative regulatory elements were found by examining the promoter regions of the hub genes and their gene ontology (GO) was determined. In addition, the interaction between milRNAs and up-regulated genes was predicted. RcsC and D920_01853 have been identified as the most important of the hub genes in S. Typhimurium and E. faecium, respectively. The enrichment analysis of hub genes revealed the importance of efflux pumps, and different enzymatic and binding activities in both bacteria. However, E. faecium specifically increases phospholipid biosynthesis and isopentenyl diphosphate biosynthesis, whereas S. Typhimurium focuses on phosphorelay signal transduction, transcriptional regulation, and protein autophosphorylation. The similarities in the GO findings of the promoters suggest common pathways for survival and basic physiological functions of both bacteria, including peptidoglycan production, glucose transport and cellular homeostasis. The genes with the most interactions with milRNAs include dpiB, rcsC and kdpD in S. Typhimurium and EFAU004_01228, EFAU004_02016 and EFAU004_00870 in E. faecium, respectively. The results showed that gram-positive and gram-negative bacteria have different mechanisms to survive under antibiotic stress. By deciphering their intricate adaptations, we can develop more effective therapeutic approaches and combat the challenges posed by multidrug-resistant bacteria.

Antibiotic resistance mediated by gene amplifications

Apart from horizontal gene transfer and sequence-altering mutational events, antibiotic resistance can emerge due to the formation of tandem repeats of genomic regions. This phenomenon, also known as gene amplification, has been implicated in antibiotic resistance in both laboratory and clinical scenarios, where the evolution of resistance via amplifications can affect treatment efficacy. Antibiotic resistance mediated by gene amplifications is unstable and consequently can be difficult to detect, due to amplification loss in the absence of the selective pressure of the antibiotic. Further, due to variable copy numbers in a population, amplifications result in heteroresistance, where only a subpopulation is resistant to an antibiotic. While gene amplifications typically lead to resistance by increasing the expression of resistance determinants due to the higher copy number, the underlying mechanisms of resistance are diverse. In this review article, we describe the various pathways by which gene amplifications cause antibiotic resistance, from efflux and modification of the antibiotic, to target modification and bypass. We also discuss how gene amplifications can engender resistance by alternate mutational outcomes such as altered regulation and protein structure, in addition to just an increase in copy number and expression. Understanding how amplifications contribute to bacterial survival following antibiotic exposure is critical to counter their role in the rise of antimicrobial resistance.

Analyzing the causal role of blood cells in aging: a Mendelian randomization study

Blood cells are crucial components of the human body, closely linked to the aging process. This study aims to explore the causal relationship between 91 blood cell phenotypes and aging through Mendelian randomization (MR) analysis. Exposure data from genome-wide association studies (GWAS) was extracted from the GWAS of blood cell perturbation phenotypes in 2,600 European individuals. Initial analysis utilized GWAS data related to aging from the GWAS Catalog database GCST90014288, with inverse-variance weighting as the primary method for causal analysis. Sensitivity analyses included Cochran's Q test, MR-Egger intercept test, MR-PRESSO, and leave-one-out analysis. For significant associations, replication and meta-analysis were conducted using independent aging GWAS data from GCST90014300. Initial analysis revealed that environmental peroxide-impacted red blood cells and ciprofloxacin-impacted reticulocytes accelerated aging. Additionally, elevated neutrophil levels were found to accelerate aging, while LiCl-impacted neutrophils reduced aging risk. Replication and meta-analysis showed consistent results: ciprofloxacin-impacted reticulocytes and elevated neutrophil levels increased the risk of aging, while LiCl-impacted neutrophils reduced the risk. RBCs showed no significant impact on aging progression. Sensitivity analyses confirmed the robustness and reliability of these positive findings. Our study provides evidence of a causal relationship between three blood cell disturbance phenotypes and human aging.

Development of Low-Toxicity Antimicrobial Polycarbonates Bearing Lysine Residues

Antibiotic resistance has been threatening public health for a long period, while the COVID pandemic aggravated the scenario. To combat antibiotic resistance strains, host defense peptides (HDPs) mimicking molecules have attracted considerable attention. Herein, we reported a series of polycarbonates bearing cationic lysine amino acid residues that could mimic the mechanism of action of HDPs and possess broad-spectrum antimicrobial activity. Moreover, those polymers had negligible toxicity toward red blood cells and mammalian cells. The membrane-disruption mechanism endows the lysine-containing polycarbonates with low possibility of resistance development and the fast killing kinetics, making them promising candidates for antimicrobial development.

Method Validation for the Determination of Ciprofloxacin in Lucilia sericata Larvae via Capillary Electrophoresis Combined With Mass Spectrometry

Substances derived from insects can serve therapeutic functions due to their diverse biological properties. This article focuses on the species Lucilia sericata and the benefits of larval therapy in patients who, due to hospitalization, have developed pressure ulcers and other difficult-to-heal wounds. Larval therapy, also known as maggot debridement therapy, employs sterile fly larvae to treat chronic, non-healing wounds by enzymatically degrading necrotic tissue and decreasing bacterial colonization. The larvae are applied to the wound for a period of 48-72 h, during which they effectively clean the wound and stimulate tissue regeneration. This therapeutic approach is particularly efficacious for recalcitrant wounds, such as diabetic foot ulcers and pressure sores, which have not responded to conventional treatments. Larvae may also constitute an alternative material in entomotoxicological studies to detect substances ingested at not only toxic but also therapeutic doses. The present work describes a method for assaying ciprofloxacin in L. sericata larvae using capillary electrophoresis coupled to mass spectrometry. The developed method features high sensitivity with a limit of quantification of 100 ± 0.018 ng/mL, as well as accuracy and precision estimated within 87%-103% and 1%-4%, respectively. An application of a simple and fast precipitation of proteins procedure for sample cleaning resulted in a highly satisfactory recovery of the analyte (90%-104%). The method was linear in a range of 100-1000 ng/mL with a determination coefficient higher than 0.9973. The method was used to determine ciprofloxacin in larval homogenate after antibiotic administration to the patient at a dose of 500 mg twice daily per os during application of the larvae dressing. Ciprofloxacin was shown to distribute from the patient's circulation to the larvae at a concentration of 150 ng/mL (750 ng/g).

Potential of silver nanoparticles synthesized from Justicia adhatoda metabolites for inhibiting biofilm on urinary catheters

In the present study, we investigated the anti-biofilm effect of urinary catheters fabricated with biogenic nanoparticles synthesized from metabolites of Justicia adhatoda under in vitro conditions against human pathogenic bacteria. Silver nanoparticles were synthesized in the reaction mixture composed of 2 % w/v of 0.1 M of precursor (silver nitrate) and 0.2 g of the metabolites obtained from ethanolic extract of Justicia adhatoda. Characterization of the nanoparticles was done by UV visible spectroscopy, fourier infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X ray diffraction (XRD) to confirm the structural and functional properties. Primary conformation of nanoparticles synthesis by UV visible spectroscopy revealed the notable absorption spectra at 425 nm with a wavelength shift around 450 nm, likely due to surface plasmon resonance excitation. SEM analysis showed spherical, monodisperse, nano scale particles with a size range of 50-60 nm. Crystaline phase of the synthesized nanoparticles was confirmed by x ray diffraction studies which showed the distinct peaks at (2θ) 27.90, 32.20, 46.30, 54.40, and 67.40, corresponding to (111), (200), (220), (222), and (311) planes of nano scale silver. The biocompatibility of these nanoparticles was assessed through zebrafish embryonic toxicity study which showed more than 90 % of embryos were alive and healthy. No marked changes on the blood cells also confirmed best hemocompatibility of the nanoparticles. Synthesized nanoparticles thus obtained were fabricated on the urinary catheter and the fabrication was confirmed by FTIR and SEM analysis. Notable changes in the absorption peaks, uniform coating and embedding of silver nanoparticles studied by FTIR and SEM analysis confirmed the fabrication of silver nanoparticles. The coated catheters demonstrated significant antibacterial activity against pathogenic bacterial strains, including E. coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853. Anti-biofilm studies, conducted using a modified microtiter plate crystal violet assay, revealed effective inhibition of both bacterial adhesion and biofilm development. 85 % of biofilm inhibition was recorded against both the tested strains. The coating method presented in this study shows promise for enhancing infection resistance in commonly used medical devices like urinary catheters, thus addressing device-associated infections.

Mechanism of staphylococcal resistance to clinically relevant antibiotics

Staphylococcus aureus, a notorious pathogen with versatile virulence, poses a significant challenge to current antibiotic treatments due to its ability to develop resistance mechanisms against a variety of clinically relevant antibiotics. In this comprehensive review, we carefully dissect the resistance mechanisms employed by S. aureus against various antibiotics commonly used in clinical settings. The article navigates through intricate molecular pathways, elucidating the mechanisms by which S. aureus evades the therapeutic efficacy of antibiotics, such as β-lactams, vancomycin, daptomycin, linezolid, etc. Each antibiotic is scrutinised for its mechanism of action, impact on bacterial physiology, and the corresponding resistance strategies adopted by S. aureus. By synthesising the knowledge surrounding these resistance mechanisms, this review aims to serve as a comprehensive resource that provides a foundation for the development of innovative therapeutic strategies and alternative treatments for S. aureus infections. Understanding the evolving landscape of antibiotic resistance is imperative for devising effective countermeasures in the battle against this formidable pathogen.

Exploring the potential of naturally occurring antimicrobials for managing orthopedic-device-related infections

Orthopedic-device-related infections (ODRIs) are challenging clinical complications that are often exacerbated by antibiotic resistance and biofilm formation. This review explores the efficacy of naturally occurring antimicrobials - including agents sourced from bacteria, fungi, viruses, animals, plants and minerals - against pathogens common in ODRIs. The limitations of traditional antibiotic agents are presented, and innovative naturally occurring antimicrobials, such as bacteriophage therapy and antimicrobial peptides, are evaluated with respect to their interaction with conventional antibiotics and antibiofilm efficacy. The integration of these natural agents into clinical practice could revolutionize ODRI treatment strategies, offering effective alternatives to conventional antibiotics and mitigating resistance development. However, the translation of these compounds from research into the clinic may require the substantial investment of intellectual and financial resources.

Design, synthesis, and biological evaluation of pyrazole-ciprofloxacin hybrids as antibacterial and antibiofilm agents against Staphylococcus aureus

In our continued efforts to tackle antibiotic resistance, a new series of pyrazole-ciprofloxacin hybrids were designed, synthesized, and evaluated for their antibacterial activity against Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa), and Mycobacterium tuberculosis (Mtb). Most of the compounds exhibited good to excellent activities against S. aureus, and six compounds (7a, 7b, 7d, 7g, 7k, and 7p) exhibited higher or comparable activity (MIC = 0.125-0.5 μg mL-1) to ciprofloxacin (0.125 μg mL-1). Further, these selected compounds were non-toxic (CC50 ≥ 1000 μg mL-1) when evaluated for cell viability test against the Hep-G2 cell line. Three compounds (7a, 7d, and 7g) demonstrated excellent activity against ciprofloxacin-resistant S. aureus with MIC values ranging from 0.125-0.5 μg mL-1 and good antibiofilm activity. Among them, 7g displayed remarkable antibiofilm activity with an MBIC50 value of 0.02 μg mL-1, which is 50 times lower than ciprofloxacin (MBIC50 = 1.06 μg mL-1). A time-kill kinetics study indicated that 7g showed both concentration and time-dependent bactericidal properties. In addition, 7g effectively inhibited DNA-gyrase supercoiling activity at 1 μg mL-1 (8× MIC). Two compounds 7b and 7d exhibited the highest activity against Mtb with a MIC of 0.5 μg mL-1, while 7c showed the highest activity against P. aeruginosa with a MIC value of 2 μg mL-1. Molecular docking studies revealed that 7g formed stable interactions at the DNA active site.

Molecular mechanism of a triazole-containing inhibitor of Mycobacterium tuberculosis DNA gyrase

Antimicrobial resistance remains a persistent and pressing public health concern. Here, we describe the synthesis of original triazole-containing inhibitors targeting the DNA gyrase, a well-validated drug target for developing new antibiotics. Our compounds demonstrate potent antibacterial activity against various pathogenic bacteria, with notable potency against Mycobacterium tuberculosis (Mtb). Moreover, one hit, compound 10a, named BDM71403, was shown to be more potent in Mtb than the NBTI of reference, gepotidacin. Mechanistic enzymology assays reveal a competitive interaction of BDM71403 with fluoroquinolones within the Mtb gyrase cleavage core. High-resolution cryo-electron microscopy structural analysis provides detailed insights into the ternary complex formed by the Mtb gyrase, double-stranded DNA, and either BDM71403 or gepotidacin, providing a rational framework to understand the superior in vitro efficacy on Mtb. This study highlights the potential of triazole-based scaffolds as promising gyrase inhibitors, offering new avenues for drug development in the fight against antimicrobial resistance.

Antibacterial and anti-biofilm activities of new fluoroquinolone derivatives coupled with nitrogen-based heterocycles

We report the design, synthesis, and antimicrobial evaluation of a series of ciprofloxacin (CP) conjugates coupled with nitrogen-containing heterocycles. In vitro screening of these new hybrid compounds (1-13) against a panel of planktonic bacterial strains highlighted thiazolyl homologs 6 and 7 as the most promising candidates for further investigation. These derivatives demonstrated potent growth-inhibitory activity against various standard and clinical isolates, with minimum inhibitory concentrations (MICs) ranging from 0.05 to 0.4 µg/ml, which are higher or comparable to the reference fluoroquinolone. Both compounds effectively inhibited biofilm formation by selected staphylococci across all tested concentrations (1-8 x MIC), displaying greater efficacy at higher doses compared to CP alone. Notably, conjugate 7 also significantly eradicated existing biofilms formed by S. aureus of various origin. Molecular docking studies revealed that conjugate 7 engages in a broader range of interactions with DNA gyrase and DNA topoisomerase IV than CP, suggesting stronger binding affinity and enhanced flexibility. This may contribute to its potential in overcoming bacterial resistance mechanisms. The above findings indicate compound 7 as a promising candidate for clinical development.

Clinically relevant mutations in regulatory regions of metabolic genes facilitate early adaptation to ciprofloxacin in Escherichia coli

The genomic landscape associated with early adaptation to ciprofloxacin is poorly understood. Although the interplay between core metabolism and antimicrobial resistance is being increasingly recognized, mutations in metabolic genes and their biological role remain elusive. Here, we exposed Escherichia coli to increasing gradients of ciprofloxacin with intermittent transfer-bottlenecking and identified mutations in three non-canonical targets linked to metabolism including a deletion (tRNA-ArgΔ414-bp) and point mutations in the regulatory regions of argI (ARG box) and narU. Our findings suggest that these mutations modulate arginine and carbohydrate metabolism, facilitate anaerobiosis and increased ATP production during ciprofloxacin stress. Furthermore, mutations in the regulatory regions of argI and narU were detected in over 70% of sequences from clinical E. coli isolates and were overrepresented among ciprofloxacin-resistant isolates. In sum, we have identified clinically relevant mutations in the regulatory regions of metabolic genes as a central theme that drives physiological changes necessary for adaptation to ciprofloxacin stress.

GLNNMDA: a multimodal prediction model for microbe-drug associations based on global and local features

Microbes have been demonstrated to be closely linked to diseases that pose a major threat to human health. Computing technologies can help researchers find potential microbe-drug associations more quickly and precisely. In this study, we introduced a novel computational prediction model called GLNNMDA based on global and local features of microbes and drugs to infer possible microbe-drug correlations. In GLNNMDA, we first constructed a heterogeneous network based on known microbe-drug relationships by integrating multiple similarity metrics of drugs and microbes. Subsequently, low-dimensional features will be extracted for nodes in the heterogeneous network by adopting the graph attention encoder. Next, based on combining these low-dimensional features with multiple properties of microbes and drugs to form a new comprehensive feature matrix, we would utilize the GLF module to extract the global and local features for microbes and drugs respectively, and then, we would further fuse these global and local features to come up with predictions of possible microbe-drug associations. Moreover, in order to evaluate the prediction performance of GLNNMDA, under the framework of fivefold cross-validation, intensive comparative experiments and case studies were done on different well-known public databases. The results showed that GLNNMDA obtained the highest AUC values as well as AUPR values of 0.9802 ± 0.0011, 0.9773 ± 0.0021 and 0.8586 ± 0.0004, 0.8008 ± 0.0031 in the two databases, MDAD and aBiofilm, respectively, compared to the state-of-the-art competing prediction methods. In addition, case studies of well-known microorganisms and drugs have demonstrated the effectiveness of GLNNMDA in inferring potential microbial drug associations, which implies that GLNNMDA may be a useful tool for microbe-drug association prediction in the future. The source code is available at: " https://github.com/KuangHaiYue/GLNNMDA.git ".