Mechanisms of Antibiotic Resistance. Microbiol Spectr. 2016;4. [PMID: 27227291 DOI: 10.1128/microbiolspec.vmbf-0016-2015]

A review of the human microRNA and the Mycobacterium tuberculosis epigenetic effects on the emergence drug resistance

AIMS

Mycobacterium tuberculosis (MTB) uses epigenetics to avoid the hostile host immune defence systems and also mount resistance to chemotherapy when exposed to antibiotic stress. MTB's epigenetic survival tool-kit includes genomic DNA histone acetylation/deacetylation, methylation, phosphorylation, ubiquitylation, etc. The non-coding host microRNAs (miRNAs) as genomic products of epigenetic control of drug extrusion processes, drug permeability barrier formation or metabolism, and target alteration are hijacked by MTB to mount multi-drug resistance. The miRNAs involved and the mechanisms used are not yet completely understood. The role of MTB genome-derived miRNA are currently indeterminate as the current studies are only focused on the host miRNA biogenesis in MTB pathogenesis. However, the contribution of host miRNA to drug resistance in MTB chemotherapy is largely unknown.

MATERIALS AND METHODS

We have comprehensively searched online databases for medical, health, and nanotechnology for articles published in English between 2020 and 2024 using search words "MTB", "Epigenetics", "microRNA", "TB Chemotherapy" to compile this narrative review.

KEY FINDINGS

MTB epigenetic tool-kit of DNA methylation, histone acetylation/deacetylation, cell membrane impermeability, drug metabolism and target mimicry are mediated by the hijacked host cell microRNAs in the development of drug resistance. Antisense oligomers or mimetics can therefore, be used as miRNA antagonists/silencers or agomirs, respectively, depending on the pattern of miRNA expression, to combat resistance to MTB chemotherapy.

CONCLUSIONS

This review discusses microRNAs as epigenetic agents in the emergence of Multi-Drug Resistance TB (MDR-TB) and their potential role in chemotherapeutics.

Environmental sulfonamides pollution and microbial adaptation: Genome, transcriptome, and toxicology reveal Bacillus sp. HC-1 biotransformation and antibiotic resistance mechanisms

Sulfonamides (SAs) residue in the environment presents significant challenges to both environmental safety and medical security. Currently, the reaction and transformation mechanisms of microorganisms in the presence of SAs remain unclear. This study employed multiomics to investigate the gene response and enzymatic transformation mechanisms of Bacillus sp. HC-1 under SAs exposure conditions. Strain HC-1 demonstrated the ability to transform sulfaquinoxaline (SQX), sulfamethoxazole (SMX), and sulfamethazine (SMZ) into their respective N4-acetylated products. Within 12 hours, the transformation rates of SQX, SMX, and SMZ reached 51.7 %, 44.7 %, and 42.70 % respectively. Transcriptome analysis revealed that differentially expressed genes (DEGs) related to cellular transport, membrane channel activity, and various metabolic pathways were significantly enriched in strain HC-1 exposed to SQX. Through genomic analysis, we identified three types of arylamine N-acetyltransferases (NATs), which were named BaNATA, BaNATB, and BaNATC. Their highest homologies with reported NATs were 35.29 %, 40.82 %, and 35.32 %, respectively. Resistance and toxicological assessments indicated that NATs functioned as resistance genes against SAs, and the toxicity of transformation products to microorganisms and plant seeds was diminished. This study offers a valuable reference for a more in-depth understanding of microbial reactions, potential resistance, and transformation mechanisms in antibiotic-contaminated environments.

Exploring the intricacies of antimicrobial resistance: Understanding mechanisms, overcoming challenges, and pioneering innovative solutions

Antimicrobial resistance (AMR) poses a growing global threat. This review examines AMR from diverse angles, tracing the story of antibiotic resistance from its origins to today's crisis. It explores the rise of AMR, from its historical roots to the urgent need to counter this escalating menace. The review explores antibiotic classes, mechanisms, resistance profiles, and genetics. It details bacterial resistance mechanisms with illustrative examples. Multidrug-resistant bacteria spotlight AMR's resilience. Modern AMR control offers hope through precision medicine, stewardship, combination therapy, surveillance, and international cooperation. Converging traditional and innovative treatments presents an exciting frontier as novel compounds seek to enhance antibiotic efficacy. This review calls for global unity and proactive engagement to address AMR collectively, emphasizing the quest for innovative solutions and responsible antibiotic use. It underscores the interconnectedness of science, responsibility, and action in combatting AMR. Humanity faces a choice between antibiotic efficacy and obsolescence. The call is clear: unite, innovate, and prevail against AMR.

Harnessing advances in mechanisms, detection, and strategies to combat antimicrobial resistance

Antimicrobial resistance (AMR) is a growing global health crisis, threatening the effectiveness of antibiotics and other antimicrobial agents, leading to increased morbidity, mortality, and economic burdens. This review article provides a comprehensive analysis of AMR, beginning with a timeline of antibiotics discovery and the year of first observed resistance. Main mechanisms of AMR in bacteria, fungi, viruses, and parasites are summarized, and the main mechanisms of bacteria are given in detail. Additionally, we discussed in detail methods for detecting AMR, including phenotypic, genotypic, and advanced methods, which are crucial for identifying and monitoring AMR. In addressing AMR mitigation, we explore innovative interventions such as CRISPR-Cas systems, nanotechnology, antibody therapy, artificial intelligence (AI), and the One Health approach. Moreover, we discussed both finished and ongoing clinical trials for AMR. This review emphasizes the urgent need for global action and highlights promising technologies that could shape the future of AMR surveillance and treatment. By integrating interdisciplinary research and emerging clinical insights, this study aims to guide individuals toward impactful solutions in the battle against AMR.

Novel Approaches for Treatment of Intraoral Microbial Infections

Historically, broad-spectrum antibiotics have represented a major component of the therapeutic armamentarium used to treat common oral diseases associated with a bacterial etiology. The fact that these diseases are due to the accumulation of multispecies biofilms composed of ever-increasing numbers of resistant organisms has dramatically affected the efficacy of many of these drugs. Furthermore, it is now appreciated that repeated use of broad-spectrum antibiotics also affects the composition of the host commensal microbiota, which can have both local and systemic implications. In recognition of the limitations of classical antibiotics, alternative chemical, physical, and mechanical strategies are either in use or development. These include novel narrow-spectrum antimicrobials such as antitoxins, bacteriophages, and antibody-conjugated drugs that can target specific microbes while minimizing the emergence of resistant organisms and preserving eubiotic microbes. Other approaches, such as new broad-spectrum non-antibiotic strategies and probiotics, are aimed at disrupting or altering the composition of oral biofilms and their extracellular matrices to facilitate the elimination of overt pathogens by the host response and/or adjunctive antimicrobials. This critical review describes the use and limitations of broad- and narrow-spectrum strategies currently being used to treat common bacterially induced oral diseases as well as alternative methods in development.

Ciprofloxacin-resistant Salmonella Typhimurium demonstrates cross-tolerance to heat treatments in liquid food matrices

The alarming occurrence of antimicrobial resistance (AMR) in human bacterial isolates indicates that prevention and control protocols are not adequately managing this global threat. The agri-food chain plays a noteworthy role in the dissemination of AMR via the handling and consumption of contaminated food products. However, it remains unclear whether acquisition of AMR in bacteria might indirectly enhance bacterial tolerance to food preservation methods (i.e., cross-tolerance), resulting in defective pathogen reduction. In this study, five ciprofloxacin (CIP) resistant variants (RVs) were generated after exposing Salmonella Typhimurium LT2 (SeT) to an upward CIP gradient. We thereupon observed up to 125-fold increases in the minimum inhibitory concentration to CIP in all five RVs. Moreover, two RVs showed reduced sensitivity to heat in laboratory media compared to SeT. The most tolerant strain displayed mutations in genes previously implicated in AMR, coding for RNA polymerase subunits (rpoD), regulatory protein RamR (ramR) and enzyme adenylate cyclase (cyaA). Validation in liquid food matrices revealed enhanced thermotolerance of the RV to treatments performed at 50 °C in orange juice (×986.7 survival risk after 15 min of treatment), and 54 °C in milk (more than ×10,000 survival risk after 30 min) and liquid-whole egg (×976.7 survival risk after 40 min). Furthermore, virulence assays in nematode Caenorhabditis elegans showed mutations conferring AMR and cross-tolerance did not result in a substantial loss of pathogenicity. Hence, exposures to CIP might lead to the selection of S. Typhimurium variants that pose limits to heat treatment efficacy, thereby increasing their survival risk and ultimately allowing them to reach the end consumer - thus also limiting the scope of antibiotic action during eventual infection.

Gene expressions of clinical Pseudomonas aeruginosa harboring RND efflux pumps on chromosome and involving a novel integron on a plasmid

The clinical strain of Pseudomonas aeruginosa XM8 harbored multiple RND-type antibiotic efflux pump genes and a novel integron In4881 on its plasmid pXM8-2, rendering it resistant to nearly all conventional antibiotics except colistin. The resistance was primarily attributed to the inactivation of the oprD gene and overexpression of several efflux pump genes, including mexAB-oprM, mexCD-oprJ, oprN-mexFE, and mexXY. In this study, the XM8 strain was comprehensively characterized using various methods. Antimicrobial susceptibility testing was performed using the BioMerieux VITEK2 system and manual double dilution methods. Gene expression levels of efflux pump-related genes were analyzed via quantitative real-time PCR. The bacterial chromosome and plasmid were sequenced using both Illumina and Nanopore platforms, and bioinformatics tools were employed to analyze mobile genetic elements associated with antibiotic resistance. The pXM8-2 plasmid containsed multiple mobile genetic elements, including integrons (In4881, In334, In413) and transposons (Tn3, TnAs1, TnAs3). Notably, In4881 was reported for the first time in this study. The presence of these elements highlights the potential for horizontal gene transfer and further spread of antibiotic resistance. Given the strong resistance profile of the XM8 strain, effective measures should be implemented to prevent the dissemination and prevalence of such multidrug-resistant bacteria.

Exploring molecular mechanisms of drug resistance in bacteria and progressions in CRISPR/Cas9-based genome expurgation solutions

Antibiotic resistance in bacteria is a critical global health challenge, driven by molecular mechanisms such as genetic mutations, efflux pumps, enzymatic degradation of antibiotics, target site modifications, and biofilm formation. Horizontal gene transfer (HGT) further accelerates the spread of resistance genes across bacterial populations. These mechanisms contribute to the emergence of multidrug-resistant (MDR) strains, rendering conventional antibiotics ineffective. Recent advancements in CRISPR/Cas9-based genome editing offer innovative solutions to combat drug resistance. CRISPR/Cas9 enables precise targeting of resistance genes, facilitating their deletion or inactivation, and provides a potential method to eliminate resistance-carrying plasmids. Furthermore, phage-delivered CRISPR systems show promise in selectively killing resistant bacteria while leaving susceptible strains unaffected. Despite challenges such as efficient delivery, off-target effects, and potential bacterial resistance to CRISPR itself, ongoing research and technological innovations hold promise for using CRISPR-based antimicrobials to reverse bacterial drug resistance and develop more effective therapies. These abstract highlights the molecular mechanisms underlying bacterial drug resistance and explores how CRISPR/Cas9 technology could revolutionize treatment strategies against resistant pathogens.

First report of Stemphylium lycopersici keratitis, a complex corneal infection case

Filamentous fungi are among the emerging causes of infections, although corneal infections caused by these fungi are rare, they can lead to severe clinical outcomes. In this report, we present the first documented case of keratitis caused by Stemphylium lycopersici, a filamentous hemipteran fungus of the Pleosporaceae family. A 66-year-old man presented conjunctival redness, irritation, and visual deterioration in his left eye, following a stone chip injury that occurred five months earlier. Despite multiple treatments, the causative pathogen remained unidentified, leading to worsening symptoms and significant vision loss. This deterioration led the patient to seek care at our hospital. An in vivo confocal microscopy (IVCM) examination suggested a fungal infection. Consequently, antifungal medications were administered, but the condition did not improve. Metagenomic next-generation sequencing (mNGS) examination of corneal scrapings revealed a mixed infection with S. lycopersici and human alphaherpesvirus 1. This definitive diagnosis facilitated the implementation of targeted therapy, leading to progressive symptomatic improvement. Early and rapid pathogen identification using mNGS analysis of corneal scrapings enables accurate management of infectious keratitis, contributing to visual recovery and reducing the risk of resistance to corneal pathogenic microbes.

Serum-Stable, Cationic, α-Helical AMPs to Combat Infections of ESKAPE Pathogens and C. albicans

Expedition in the rate of development of antimicrobial resistance accompanied by the slowdown in the development of new antimicrobials has led to a dire necessity to develop an alternate class of antimicrobial agents. Antimicrobial peptides (AMPs), available in nature, are effective molecules that can combat microbial infections. However, due to several inherent shortcomings such as salt sensitivity of their potency, short systemic half-lives owing to protease and serum degradation, and cytotoxicity, their commercial success is limited. Inspired by α helical AMPs present in nature, here in this work, we have developed two short, cationic, helical AMPs RR-12 and FL-13. Both peptides exhibited high broad-spectrum antimicrobial activity, salt tolerance, prompt bactericidal activity, considerable serum stability, remaining non-cytotoxic and non-hemolytic at relevant microbicidal concentrations. The designed AMPs were membranolytic toward the microbial strains, though there were subtle differences in the mechanism owing to the variation in the composition of the cell membranes in different microbes. Rigorous experimental techniques and molecular dynamics (MD) simulations were performed to understand the structure, activity, and their mechanisms in detail. Positive charge, balanced hydrophobicity-hydrophilicity, and helical conformation were the different attributes that led to the development of the superior performance of the AMPs, making them valuable additions to the repertoire of therapeutically promising antimicrobials.

Dynamics of bacterial operons during genome-wide stresses is influenced by premature terminations and internal promoters

Bacterial gene networks have operons, each coordinating several genes under a primary promoter. Half of the operons in Escherichia coli have been reported to also contain internal promoters. We studied their role during genome-wide stresses targeting key transcription regulators, RNA polymerase (RNAP) and gyrase. Our results suggest that operons' responses are influenced by stress-related changes in premature elongation terminations and internal promoters' activity. Globally, this causes the responses of genes in the same operon to differ with the distance between them in a wave-like pattern. Meanwhile, premature terminations are affected by positive supercoiling buildup, collisions between elongating and promoter-bound RNAPs, and local regulatory elements. We report similar findings in E. coli under other stresses and in evolutionarily distant bacteria Bacillus subtilis, Corynebacterium glutamicum, and Helicobacter pylori. Our results suggest that the strength, number, and positioning of operons' internal promoters might have evolved to compensate for premature terminations, providing distal genes similar response strengths.

Metabolic byproduct utilization and the evolution of mutually beneficial cooperation in Escherichia coli

Understanding how cooperation evolves in microbial populations, particularly under environmental stress such as antibiotic exposure, remains a key topic in evolutionary biology. Here, we investigate cooperative interactions between antibiotic-resistant and antibiotic-sensitive strains of Escherichia coli. Under antibiotic stress, a small number of antibiotic-sensitive strains rapidly evolve into antibiotic-resistant strains. Resistant E. coli produce indole, which induces a protective response in sensitive cells, enabling them to survive in antibiotic stress conditions. In turn, antibiotic-sensitive E. coli could help reduce toxic accumulation of indole, indirectly benefiting the resistant strain. Indole is harmful to the growth of the antibiotic-resistant strain but benefits the antibiotic-sensitive strain by helping turn-on the multi-drug exporter to neutralize the antibiotic. This mutual exchange leads to increased fitness for both strains in cocultures, demonstrating a mechanism by which mutually beneficial cooperation can evolve in bacterial communities. Our findings provide insight into how mutualism can emerge under antibiotic pressure through metabolic byproduct exchange, revealing new dynamics in the evolution of bacterial cooperation.

AmrProfiler: a comprehensive tool for identifying antimicrobial resistance genes and mutations across species

Antimicrobial resistance (AMR) remains a critical challenge in public health and research. AmrProfiler is a comprehensive tool with three specialized modules: identifying acquired AMR genes, resistance-associated mutations, and ribosomal RNA (rRNA) gene mutations across nearly 18 000 bacterial species. By integrating and refining data from established databases, it provides a robust framework for AMR analysis. AmrProfiler is the first to systematically report mutations in rRNA genes, offering in-depth analysis of rRNA copy numbers and mutations-key for identifying potential rRNA-associated resistance mechanisms. Its curated database includes 7600 unique AMR gene entries and over 4300 resistance-related mutations. Supporting genome assemblies in multiple formats, AmrProfiler allows users to customize detection thresholds for AMR genes, mutations, and rRNA analysis. Validation with Acinetobacter baumannii,Escherichia coli,Klebsiella pneumoniae,Staphylococcus aureus, and Staphylococcus epidermidis demonstrated that AmrProfiler accurately identified all AMR genes and mutations reported by other tools while also detecting additional resistance markers and mutations not previously recognized. By bridging AMR genotypes and phenotypes, AmrProfiler provides actionable insights that advance both research and clinical applications in AMR. AmrProfiler is freely available as an open-access web server without login at https://dianalab.e-ce.uth.gr/amrprofiler.

Flies as Vectors of Foodborne Pathogens Through Food Animal Production: Factors Affecting Pathogen and Antimicrobial Resistance Transmission

Flies play an important role in the transmission of antimicrobial-resistant (AMR) and multidrug-resistant (MDR) foodborne pathogens in animal production systems, posing risks to food safety and public health. Synanthropic fly species, including house flies (Musca domestica), face flies (Musca autumnalis), blow flies (Calliphoridae), and flesh flies (Sarcophagidae), mechanically and/or biologically transmit bacterial pathogens such as Salmonella enterica, Escherichia coli, Listeria monocytogenes, Klebsiella, and Campylobacter spp. Their frequent contact with manure, animal waste, and processing environments enables the transfer of AMR pathogens across food production systems. This review synthesizes recent research on the interactions between flies and foodborne pathogens, highlighting the role of fly physiology, behavior, and microbial associations in pathogen transport. Additionally, it introduces the influence of environmental factors on pathogen dissemination and evaluates current Integrated Pest Management (IPM) strategies, including biological, chemical, and physical control methods, for mitigating fly-mediated pathogen transmission. Understanding these systems is essential for developing targeted interventions to reduce the burden of AMR pathogens in food production and enhance public health protection.

From resistance to treatment: the ongoing struggle with Acinetobacter baumannii

Acinetobacter baumannii (A. baumannii) has become a major hospital-acquired pathogen, well-known for its rapid development of resistance to multiple antibiotics. The rising incidence of antibiotic-resistant A. baumannii presents a significant global public health challenge. Gaining a deep understanding of the mechanisms behind this resistance is essential for creating effective treatment options. This comprehensive review explores the understanding of various antibiotic resistance mechanisms in A. baumannii. It covers intrinsic resistance, acquired resistance genes, efflux pumps, changes in outer membrane permeability, alterations in drug targets, biofilm formation, and horizontal gene transfer. Additionally, the review investigates the role of mobile genetic elements and the clinical implications of antibiotic resistance in A. baumannii infections. The insights provided may inform the development of new antimicrobial agents and the design of effective infection control strategies to curb the spread of multidrug-resistant (MDR) A. baumannii strains in healthcare environments. Unlike previous reviews, this study offers a more integrative perspective by also addressing the pathogen's environmental resilience, with particular emphasis on its resistance to desiccation and the formation of robust biofilms. It further evaluates both established and emerging therapeutic strategies, thereby expanding the current understanding of A. baumannii persistence and treatment.

LPS-enriched interaction drives spectrum conversion in antimicrobial peptides: Design and optimization of AA16 derivatives for targeting gram-negative bacteria

The increasing prevalence of antibiotic-resistant Gram-negative bacteria necessitates the development of novel antimicrobial agents with targeted specificity. In this study, we designed and optimized derivatives of the antimicrobial peptide AA16, which truncated from CD14 protein α-helical region, to selectively target Gram-negative bacteria by enhancing lipopolysaccharide (LPS)-enriched interactions, thereby achieving antibacterial spectrum conversion. Starting from the parent peptide AA16 (Ac-AARIPSRILFGALRVL-Amide), we performed strategic amino acid substitutions based on structure-activity relationship analysis. This led to the identification of AA16-10R, a derivative with a specific substitution at position 10, which demonstrated significantly enhanced antibacterial activity against Gram-negative strains such as Escherichia coli and Pseudomonas aeruginosa, while maintaining low hemolytic activity. Mechanistic studies revealed that AA16-10R exhibited a strong binding affinity to LPS (Kd = 0.15 μM), and its interaction with LPS induced the formation of an α-helical structure. This conformational change facilitated its accumulation on the bacterial outer membrane and disrupted membrane integrity. Our innovative approach of exploiting LPS-enriched interactions successfully converted the antimicrobial spectrum of AA16 derivatives from broad-spectrum to Gram-negative-specific. This study highlights a novel strategy for the rational design of antimicrobial peptides based on specific protein-protein interactions, offering a promising avenue for targeted antimicrobial therapy against Gram-negative pathogens.

Tiny but Mighty: Small RNAs-The Micromanagers of Bacterial Survival, Virulence, and Host-Pathogen Interactions

Bacterial pathogens have evolved diverse strategies to infect hosts, evade immune responses, and establish successful infections. While the role of transcription factors in bacterial virulence is well documented, emerging evidence highlights the significant contribution of small regulatory RNAs (sRNAs) in bacterial pathogenesis. These sRNAs function as posttranscriptional regulators that fine-tune gene expression, enabling bacteria to adapt rapidly to challenging environments. This review explores the multifaceted roles of bacterial sRNAs in host-pathogen interactions. Firstly, it examines how sRNAs regulate pathogenicity by modulating the expression of key virulence factors, including fimbriae, toxins, and secretion systems, followed by discussing the role of sRNAs in bacterial stress response mechanisms that counteract host immune defenses, such as oxidative and envelope stress. Additionally, this review investigates the involvement of sRNAs in antibiotic resistance by regulating efflux pumps, biofilm formation, and membrane modifications, which contribute to multi-drug resistance phenotypes. Lastly, this review highlights how sRNAs contribute to intra- and interspecies communication through quorum sensing, thereby coordinating bacterial behavior in response to environmental cues. Understanding these regulatory networks governed by sRNAs is essential for the development of innovative antimicrobial strategies. This review highlights the growing significance of sRNAs in bacterial pathogenicity and explores their potential as therapeutic targets for the treatment of bacterial infections.

Molecular epidemiology and antibiotic resistance profiling of Staphylococcus aureus isolates from camel mastitis

Mastitis is considered one of milk-producing animals' most widespread infectious diseases. The present study evaluated the prevalence of antibiotic-resistant isolates of Staphylococcus aureus (S. aureus) including methicillin-resistant S. aureus (MRSA), β-lactam-resistant S. aureus (BRSA), aminoglycoside-resistant S. aureus (ARSA), and tetracycline-resistant S. aureus (TRSA) from the udder of dromedary camels along with the associated risk factors and the antibiogram of resistant isolates. Phylogenetic analysis of antibiotic-resistant genes with NCBI sequences was performed to check their homology. A total of 384 milk samples were collected and subjected to standard microbiological procedures to isolate S. aureus. The results revealed that 177 milk samples were found positive for subclinical mastitis (SCM) out of which 101 milk samples were found positive for S. aureus. The molecular assay found the prevalence of MRSA, BRSA, ARSA, and TRSA as 48.51 %, 46.53 %, 42.57 %, and 39.60 % by targeting the mecA, blaZ, accA-aphD, and tetK genes respectively. The study isolates significant similarities to each other and to previously reported sequences from other countries that were found by in-silico analysis, indicating the possibility of pathogen transboundary transmission. This study also revealed potential risk factors that aid in the spread of mastitis in camels. Among various risk factors, the most significant were farm hygiene, physiological status of animals, type of mastitis, teat injury, use of teat dips, and milk leakage (p < 0.05). The antibiogram of antibiotic-resistant isolates of S. aureus revealed that the highest resistance was observed against penicillin followed by amoxicillin and oxytetracycline while levofloxacin was the most sensitive drug. This study highlights the high prevalence of antimicrobial-resistant S. aureus in camel mastitis. Identified risk factors provide valuable insights into management practices that contribute to disease occurrence, aiding in the development of targeted control strategies. Additionally, antimicrobial susceptibility findings offer guidance for optimizing treatment protocols to effectively manage S. aureus-induced mastitis in camels and mitigate the spread of antimicrobial resistance.

Artificial intelligence in drug resistance management

This review highlights the application of artificial intelligence (AI), particularly deep learning and machine learning (ML), in managing antimicrobial resistance (AMR). Key findings demonstrate that AI models, such as Naïve Bayes, Decision Trees (DT), Random Forest (RF), Support Vector Machines (SVM), and Artificial Neural Networks (ANN), have significantly advanced the prediction of drug resistance patterns and the identification of novel antibiotics. These algorithms have effectively optimized antibiotic use, predicted resistance phenotypes, and identified new drug candidates. AI has also facilitated the detection of AMR-associated mutations, offering new insights into the spread of resistance and potential interventions. Despite data privacy and algorithm transparency challenges, AI presents a promising tool in combating AMR, with implications for improving patient outcomes, enhancing disease management, and addressing global public health concerns. However, realizing its full potential requires overcoming issues related to data scarcity, ethical considerations, and fostering interdisciplinary collaboration.

Antibiofilm action of phytochemicals on Enterobacteriaceae

The biofilm-associated infections pose a great threat to human health. The available drugs are not effective due to the formation of biofilm and limited access to underlying pathogens. The initiation of biofilm formation occurs through adhesion, facilitated by the adhesin protein MrkD1P in the fimbriae tip. This study targeted the MrkD1P protein and employed plant phenols to inhibit biofilm formation in Escherichia coli, Salmonella typhi, and Klebsiella pneumoniae, as major Enterobacteriaceae species. A homology model was constructed for the MrkD1P protein, and 44 phenolic derivatives were assessed for their interaction with this protein. Caffeic acid and 3-hydroxybenzoic acid exhibited the best binding-free energies of 29.61 kcal/mol and 24.24 kcal/mol, respectively. Using a microtiter plates-based minimum biofilm inhibitory concentration assay, it was found that doses of these compounds ranging from 2 to 256 mg/mL effectively reduced biofilm formation. The biofilm inhibition assay demonstrated over 80 % reduction of biofilms in all tested species at inhibitory doses. Further analysis through field emission gun scanning electron micrographs revealed that the compounds disintegrated fimbriae on cell surfaces. Additionally, the re-formation assay demonstrated the inability of biofilm-associated cells to re-form the biofilm on fresh surfaces due to fimbriae inhibition. This study highlights the antibiofilm capabilities of caffeic acid and 3-hydroxybenzoic acid, indicating their potential as effective treatments for illnesses caused by Enterobacteriaceae biofilms.

Biocides as drivers of antibiotic resistance: A critical review of environmental implications and public health risks

The widespread and indiscriminate use of biocides poses significant threats to global health, socioeconomic development, and environmental sustainability by accelerating antibiotic resistance. Bacterial resistance development is highly complex and influenced significantly by environmental factors. Increased biocide usage in households, agriculture, livestock farming, industrial settings, and hospitals produces persistent chemical residues that pollute soil and aquatic environments. Such contaminants contribute to the selection and proliferation of resistant bacteria and antimicrobial resistance genes (ARGs), facilitating their dissemination among humans, animals, and ecosystems. In this review, we conduct a critical assessment of four significant issues pertaining to this topic. Specifically, (i) the role of biocides in exerting selective pressure within the environmental resistome, thereby promoting the proliferation of resistant microbial populations and contributing to the global spread of antimicrobial resistance genes (ARGs); (ii) the role of biocides in triggering transient phenotypic adaptations in bacteria, including efflux pump overexpression, membrane alterations, and reduced porin expression, which often result in cross-resistance to multiple antibiotics; (iii) the capacity of biocides to disrupt bacteria and make the genetic content accessible, releasing DNA into the environment that remains intact under certain conditions, facilitating horizontal gene transfer and the spread of resistance determinants; (iv) the capacity of biocides to disrupt bacterial cells, releasing intact DNA into the environment and enhancing horizontal gene transfer of resistance determinants; and (iv) the selective interactions between biocides and bacterial biofilms in the environment, strengthening biofilm cohesion, inducing resistance mechanisms, and creating reservoirs for resistant microorganisms and ARG dissemination. Collectively, this review highlights the critical environmental and public health implications of biocide use, emphasizing an urgent need for strategic interventions to mitigate their role in antibiotic resistance proliferation.

Characterization of novel phages KPAФ1, KP149Ф1, and KP149Ф2 for lytic efficiency against clinical MDR Klebsiella pneumoniae infections

Phage therapy offers a promising approach to the increasing antimicrobial resistance of Klebsiella pneumoniae. This study highlights three novel lytic bacteriophages-KPAФ1, KP149Ф1, and KP149Ф2- targeting multidrug-resistant (MDR) K. pneumoniae. These phages belong to the Myoviridae and Podoviridae family and demonstrate their efficacy and stability across a wide range of temperatures (up to 60°C) and pH levels (pH 4 to 11). Genomic analysis reveals that they are free from virulence, toxicity, and antimicrobial resistance genes, making them promising candidates for therapeutic use. Among these phages, KPAФ1 showed the highest lytic activity with a 26.15% lysis against MDR K. pneumoniae isolates. Additionally, a phage cocktail comprising all three phages improved lytic efficacy to 32.30%. This study also examined the antimicrobial resistance profiles of K. pneumoniae isolates, emphasizing the critical need for alternative treatments. By effectively targeting resistant strains, these phages offer a potential candidacy to be used as a viable alternative or a complementary antimicrobial agent to traditional antibiotics, opening up the possibility for advanced phage-based therapies. The promising results from this study pave the way for developing new treatments that could significantly improve patient care and outcomes from the growing issue of resistant bacterial infections.

Food, Health, and Environmental Impact of Lactic Acid Bacteria: The Superbacteria for Posterity

Lactic acid bacteria (LAB) are Gram-positive cocci or rods that do not produce spores or respire. Their primary function is to ferment carbohydrates and produce lactic acid. The two primary forms of LAB that are currently recognized are homofermentative and heterofermentative. This review discusses the evolutionary diversity and the biochemical and biophysical conditions required by LAB for their metabolism. Next, it concentrates on the applications of these bacteria in gut health, cancer prevention, and overall well-being and food systems. There are numerous uses for LAB, including the food and dairy sectors, as probiotics to improve human and animal gut-health, as anti-carcinogenic agents, and in food safety as biopreservatives, pathogen inhibitors, and reducers of anti-nutrients in foods. The group included many genera, including Aerococcus, Carnobacterium, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Streptococcus, Tetragenococcus, Vagococcus, and Weissella. Numerous species of Lactobacillus and Bifidobacterium genera as well as other microbes have been suggested as probiotic strains, or live microorganisms added to meals to improve health. LAB can colonize the intestine and take part in the host's physiological processes. This review briefly highlights the role of these bacteria in food safety and security as well as aspects of regulation and consumer acceptance. Finally, the recent innovations in LAB fermentations and the limitations and challenges of the applications of LAB in the food industry are discussed. Notwithstanding recent developments, the study of LAB and their functional components is still an emerging topic of study that has not yet realized its full potential.

Impact of multidrug-resistant microorganisms in bile on postoperative outcomes and long-term survival in patients with periampullary malignancies

Preoperative biliary drainage (PBD) and antibiotic therapy due to cholangitis contribute toward bile contamination with multidrug-resistant organisms (MDROs) and increase the risk of infectious complications. However, little is known about the impact of MDROs in bile on postoperative outcomes and long-term survival in patients with periampullary malignancies. This retrospective single-center study investigated the impact of bile contamination with MDROs on the incidence, postoperative outcomes, and long-term survival in periampullary malignancies in a German tertiary pancreatic center between 2011 and 2015. A total of 428 patients underwent curative and palliative surgery for periampullary malignancies. At least one multidrug-resistant organism in bile was detected in 72 cases (16.8%). Patients with MDROs were significantly older, had a higher frequency of PBD, preoperative antibiotic therapies, non-standard single-shot antibiotics perioperatively, and prolonged antibiotic therapy postoperatively as opposed to the non-MDRO group. The incidence of surgical site infection was significantly higher in the MDRO group. Survival in papillary cancer was significantly worse in the MDRO group compared to the non-MDRO group. Patients with postoperative sepsis had significantly higher risk (hazard ratio 4.59) for postoperative death. Bile contamination with MDROs is associated with a significant increase of surgical site infection, leading to high mortality and poor long-term survival. Tailored antibiotic therapy may improve the survival rate.

Synergistic activity of menadione in combination with colistin against colistin-susceptible and colistin-resistant Gram-negative bacteria

OBJECTIVE

Antibiotic resistance poses a formidable challenge, especially with the emergence of multidrug-resistant Gram-negative bacteria. Colistin serves as a last-resort antibiotic to combat multidrug-resistance, but it is limited by its nephrotoxicity and rising resistance. This study introduces menadione, a synthetic form of vitamin K, as a potential adjuvant to enhance colistin's efficacy against both susceptible and resistant strains of Gram-negative bacteria.

METHODS

Through checkerboard dilution assays, we demonstrate that menadione significantly lowers the MICs of colistin, with fractional inhibitory concentration indices ranging from 0.031 to 0.375. Furthermore, synergistic effects were confirmed via time-kill kinetics, indicating effective bacterial growth inhibition. The study also explores the mechanism underlying this synergy, revealing that menadione in combination with colistin disrupts the bacterial outer membrane, reduces the proton motive force and adenosine triphosphate content, and amplify the production of reactive oxygen species, contributing to bacterial cell death.

RESULTS

Menadione was shown to prevent the evolution of colistin resistance.

CONCLUSIONS

This research highlights the potential of using menadione as a colistin adjuvant to combat antibiotic-resistant Gram-negative bacteria, providing a promising approach to extend the utility of existing antibiotics in clinical settings.

Emerging antibiotic resistance by various novel proteins/enzymes

BACKGROUND

The emergence and dissemination of antibiotic resistance represents a significant and ever-increasing global threat to human, animal, and environmental health. The explosive proliferation of resistance has ultimately been seen in all clinically used antibiotics. Infections caused by antibiotic-resistant bacteria have been associated with an estimated 4,950,000 deaths annually, with extremely limited therapeutic options and only a few new antibiotics under development. To combat this silent pandemic, a better understanding of the molecular mechanisms of antibiotic resistance is immensely needed, which not only helps to improve the efficacy of current drugs in clinical use but also design new antimicrobial agents that are less susceptible to resistance.

RESULTS

The past few years have witnessed a number of new advances in revealing the molecular mechanisms of AMR. Following five sophisticated mechanisms (efflux pump, antibiotics inactivation by enzymes, alteration of membrane permeability, target modification, and target protection), the roles of various novel proteins/enzymes in the acquisition of antibiotic resistance are constantly being described. They are widely used by clinical bacterial strains, playing a key role in the emergence of resistance.

CONCLUSION

While most of these have so far received less attention, expanding our understanding of these emerging resistance mechanisms is of crucial importance to combat the antibiotic resistance crisis in the world. This review summarizes recent advances in our knowledge of emerging resistance mechanisms in bacteria, providing an update on the current antibiotic resistance threats and encouraging researchers to develop critical strategies for overcoming the resistance.

Synergistic Antibacterial Effects of Plant Extracts and Essential Oils Against Drug-Resistant Bacteria of Clinical Interest

Infectious diseases, the second leading cause of death worldwide, have traditionally been treated with antimicrobials. However, the emergence of drug-resistant microorganisms has driven the need for alternative therapies. This study aimed to assess the antibacterial efficacy of Capparis spinosa crude extracts and five essential oils (EOs) derived from Salvia officinalis, Eucalyptus globulus, Micromeria barbata, Origanum vulgare, and Juniperus excelsa. The EOs were extracted using hydro-distillation, and C. spinosa extracts were obtained using ethanol and acetone solvents. Microdilution assays revealed that O. vulgare EO exhibited the strongest activity against Listeria monocytogenes, Escherichia coli, Salmonella spp., and Brucella melitensis, while C. spinosa demonstrated significant antibacterial effects against L. monocytogenes and notable inhibition of Pseudomonas aeruginosa. The combination of EOs with antibiotics, including M. barbata, J. excelsa, S. officinalis, and E. globulus, enhanced the efficacy of the antibiotics against recalcitrant bacterial strains. The synergistic effects were evaluated through Fractional Inhibitory Concentration Index (FICI) analysis. These findings confirm that the antibacterial efficacy observed in the tested EOs, especially when used in synergy with antibiotics, offers a promising therapeutic strategy to combat antimicrobial resistance.

Frog Skin Peptides Hylin-a1, AR-23, and RV-23: Promising Tools Against Carbapenem-Resistant Escherichia coli and Klebsiella pneumoniae Infections

BACKGROUND/OBJECTIVES

One of the pressing challenges in global public health is the rise in infections caused by carbapenem-resistant Enterobacteriaceae. Growing bacterial drug resistance, coupled with the slow development of new antibiotics, highlights the critical need to explore and develop new broad-spectrum antimicrobial agents able to inhibit bacterial growth efficiently. In recent years, antimicrobial peptides (AMPs) have gained significant attention as a promising alternative to conventional drugs, owing to their antimicrobial potency, low toxicity, and reduced propensity for fostering resistance. Our research aims to investigate the antibacterial ability of three amphibian AMPs, namely Hylin-a1, AR-23, and RV-23, against both antibiotic-sensitive and carbapenem-resistant strains of Escherichia coli and Klebsiella pneumoniae.

METHODS

A 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT) was performed to identify non-cytotoxic concentrations of peptides. A microdilution assay evaluated the antibacterial effect, determining the peptides' minimum inhibitory concentration (MIC). In addition, the checkerboard test analyzed the compounds' synergistic effect with meropenem.

RESULTS

We demonstrated that peptides with low toxicity profile and resistance to proteolytic activity exhibited strong antibacterial activity, with MIC ranging from 6.25 to 25 μM. The antibiofilm mechanism of action of peptides was also investigated, suggesting that they had a crucial role during the biofilm formation step by inhibiting it. Finally, we highlighted the synergistic effects of peptides with meropenem.

CONCLUSIONS

Our study identifies Hylin-a1, AR-23, and RV-23 as promising candidates against Gram-negative bacterial infections with a favorable therapeutic profile. This effect could be related to their great flexibility, as evidenced by circular dichroism data, confirming that the peptides could assume an α-helical conformation interacting with bacterial membranes.

Identification of 6,8-ditrifluoromethyl halogenated phenazine as a potent bacterial biofilm-eradicating agent

Bacterial biofilms are surface-attached communities consisting of non-replicating persister cells encased within an extracellular matrix of biomolecules. Unlike bacteria that have acquired resistance to antibiotics, persister cells enable biofilms to demonstrate innate tolerance toward all classes of conventional antibiotic therapies. It is estimated that 50-80% of bacterial infections are biofilm associated, which is considered the underlying cause of chronic and recurring infections. Herein, we report a modular three-step synthetic route to new halogenated phenazine (HP) analogues from diverse aniline and nitroarene building blocks. The HPs were evaluated for antibacterial and biofilm-killing properties against a panel of lab strains and multidrug-resistant clinical isolates. Several HPs demonstrated potent antibacterial (MIC ≤ 0.39 μM) and biofilm-eradicating activities (MBEC < 10 μM) with 6,8-ditrifluoromethyl-HP 15 demonstrated remarkable biofilm-killing potencies (MBEC = 0.15-1.17 μM) against Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus clinical isolates. Confocal microscopy showed HP 15 induced significant losses in the polysaccharide matrix in MRSA biofilms. In addition, HP 15 showed increased antibacterial activities against dormant Mycobacterium tuberculosis (Mtb, MIC = 1.35 μM) when compared to replicating Mtb (MIC = 3.69 μM). Overall, this new modular route has enabled rapid access to an interesting series of potent halogenated phenazine analogues to explore their unique antibacterial and biofilm-killing properties.

A computational investigation of potential plant-based bioactive compounds against drug-resistant Staphylococcus aureus of multiple target proteins

Drug-resistant Staphylococcus aureus (DRSA) poses a significant global health threat, like bacteremia, endocarditis, skin, soft tissue, bone, and joint infections. Nowadays, the resistance against conventional drugs has been a prompt and focused medical concern. The present study aimed to explore the inhibitory potential of plant-based bioactive compounds (PBBCs) against effective target proteins using a computational approach. We retrieved and verified 22 target proteins associated with DRSA and conducted a screening process that involved testing 87 PBBCs. Molecular docking was performed between screened PBBCs and reference drugs with selected target proteins via AutoDock. Subsequently, we filtered the target proteins and top PBBCs based on their binding affinity scores. Furthermore, molecular dynamic simulation was carried out through GROMACS for a duration of 100 ns, and the binding free energy was calculated using the gmx_MMPBSA. The result showed consistent hydrogen bonding interactions among the amino acid residues Ser 149, Arg 151, Thr 165, Thr 216, Glu 239, Ser 240, Ile 14, as well as Asn 18, Gln 19, Lys 45, Thr 46, Tyr 109, with their respective target proteins of the penicillin-binding protein and dihydrofolate reductase complex. Additionally, we assessed the pharmacokinetic properties of screened PBBCs via SwissADME and AdmetSAR. The findings suggest that β-amyrin, oleanolic acid, kaempferol, quercetin, and friedelin have the potential to inhibit the selected target proteins. In future research, both in vitro and in vivo, experiments will be needed to establish these PBBCs as potent antimicrobial drugs for DRSA.

RND/HAE-1 members in the Pseudomonadota phylum: exploring multidrug resistance

The hydrophobe/amphiphile efflux-1 (HAE-1) family, part of the Resistance-Nodulation-Division (RND) superfamily, plays a critical role in the development of multidrug resistance (MDR) in bacteria. Known for its broad substrate transport capacity, this family of efflux pumps can actively expel a wide range of molecules, including antibiotics, salts, and dyes, thereby reducing the intracellular concentration of toxic substances. These transporters, which form efflux systems, are primarily found in bacteria within the phylum Pseudomonadota (Proteobacteria), where they are strongly associated with increased resistance and enhanced virulence, thus contributing to bacterial survival in hostile environments. In addition, efflux systems are composed of two other protein components: Membrane Fusion Proteins (MFPs) and Outer Membrane Factors (OMFs). Notably, several bacterial species identified by the World Health Organization (WHO) as urgent priorities for new antibiotic development, such as Escherichia coli and Pseudomonas aeruginosa, have well-studied HAE-1 efflux systems, such as AcrAB-TolC and MexAB-OprM. These systems efficiently transport molecules from the periplasm to the extracellular space, facilitating bacterial persistence. In this review, we examined the current knowledge of HAE-1 efflux transporters and their roles in the physiology and survival of bacteria in the Pseudomonadota phylum.

Antibiotic Use in Livestock Farming: A Driver of Multidrug Resistance?

Antimicrobial resistance (AMR) constitutes a pressing and intensifying global health crisis, significantly exacerbated by the inappropriate utilization and excessive application of antibiotics in livestock agriculture. The excessive use of antibiotics, including prophylactic and metaphylactic administration as well as growth-promotion applications, exacerbates selective pressures, fostering the proliferation of multidrug-resistant (MDR) bacterial strains. Pathogens such as Escherichia coli, Salmonella spp., and Staphylococcus aureus can be transmitted to humans through direct contact, contaminated food, and environmental pathways, establishing a clear link between livestock farming and human AMR outbreaks. These challenges are particularly pronounced in regions with limited veterinary oversight and weak regulatory frameworks. Addressing these issues requires the implementation of sustainable practices, enhanced antibiotic stewardship, and strengthened interdisciplinary collaboration. This review underscores the critical need for a One Health approach to mitigate AMR, recognizing the interconnectedness of human, animal, and environmental health in safeguarding global public health.

Systematic All-Hydrocarbon Stapling Analysis for Cecropin A Generates a Potent and Stable Antimicrobial Peptide

As an evolutionarily conserved family of antimicrobial peptides (AMPs), cecropins play an important role in innate immunity. But their inevitable weaknesses, including poor proteolytic stability and unpredictable cytotoxicity, severely hindered their clinical applications. Considering their two-helical structure, all-hydrocarbon stapling was performed on cecropin A, successfully generating 27 (i, i + 4) stapled derivatives. By evaluating antimicrobial and hemolytic activities, CEC-2-9 with the C-terminus threonine and lysine being stapled was identified as the optimal one. It exerted significantly enhanced antibacterial potency with more severe bacterial membrane damage capacity. Compared to cecropin A, its increased helicity and hydrophobicity as well as the decreased net charge also enabled its improved stability and biocompatibility, facilitating its enhanced antibacterial and anti-inflammatory efficacy for the effective treatment of mice with peritonitis sepsis. These results have proven that the systematic all-hydrocarbon stapling of AMPs was a feasible approach for the future development of antibacterial therapeutics.

Polyacrylamide-Based Antimicrobial Copolymers to Replace or Rescue Antibiotics

Antibiotics save countless lives each year and have dramatically improved human health outcomes since their introduction in the 20th century. Unfortunately, bacteria are now developing resistance to antibiotics at an alarming rate, with many new strains of "superbugs" showing simultaneous resistance to multiple classes of antibiotics. To mitigate the global burden of antimicrobial resistance, we must develop new antibiotics that are broadly effective, safe, and highly stable to enable global access. In this manuscript, we report the development of polyacrylamide-based copolymers as a class of broad-spectrum antibiotics with efficacy against several critical pathogens. We demonstrate that these copolymer drugs are selective for bacteria over mammalian cells, indicating a favorable safety profile. We show that they kill bacteria through a membrane disruption mechanism, which allows them to overcome traditional mechanisms of antimicrobial resistance. Finally, we demonstrate their ability to rehabilitate an existing small-molecule antibiotic that is highly subject to resistance development by improving its potency and eliminating the development of resistance in a combination treatment. This work represents a significant step toward combating antimicrobial resistance.

Oral care medications for the prevention and treatment of ventilator-associated pneumonia in intensive care unit

This study aims to ameliorate the management of VAP in clinical practice and deliver more precise care in the ICU. Study selection using the appropriate critical appraisal tools was undertaken by three authors. This review provides an overview of empirical antibiotics, chlorhexidine, and povidone-iodine, which are currently commonly used in critical care. It also discusses oral medications and preparations that may be used to prevent and treat ICU ventilator-associated pneumonia, including new antibiotics, hydrogen peroxide solutions, sodium bicarbonate, octenidine, and oral herbal medicines. It also discusses ongoing research and potential applications, such as the antimicrobial effects of these agents in ICU oral hygiene. Pharmaceuticals and formulations used in oral hygiene are effective or have huge application potential in the prevention and treatment of VAP, but further research is needed to standardize oral health assessment and care practices to develop evidence-based personalized oral hygiene for critically ill patients.

Two-Component System Sensor Kinase Inhibitors Target the ATP-Lid of PmrB to Disrupt Colistin Resistance in Acinetobacter baumannii

Two-component systems serve as ubiquitous communication modules that enable bacteria to detect and respond to various stimuli by regulating cellular processes such as growth, viability, and, most notably, antimicrobial resistance. Classical two-component systems consist of two proteins: an initial membrane-bound sensor histidine kinase and a DNA-binding response regulator that induces the appropriate response within the cell. Numerous studies have implicated the PmrAB two-component system in facilitating resistance to the last-resort antibiotic polymyxin E (colistin) in Acinetobacter baumannii. As initiators of the signaling pathways that elicit resistance, histidine kinases present ideal targets for developing antibiotic adjuvant drugs. Despite this, due to the membrane-bound nature of the histidine kinase PmrB, in vitro studies on PmrAB have been predominantly limited to the response regulator PmrA. In this work, we counter these limitations by producing a recombinant truncation of the cytosolic portion of PmrB (PmrBc) that retains its ATP binding, autophosphorylation, and phosphotransfer functions. Subsequently, in vivo phosphorylation assays using this protein construct allowed for the evaluation of five compounds (IMD-0354, NDM-265, NDM-455, NDM-463, and NDM-497) that act as PmrBc inhibitors capable of preventing autophosphorylation and phosphotransfer independently. These compounds have been shown to eliminate colistin resistance in vivo. Finally, these results, paired with mass spectrometry and limited proteolysis investigations, enabled us to determine the mechanism of action of these compounds as well as their likely binding site on the ATP-lid of PmrB.

Effect of temperature on the activity of efflux pumps in selected species of human opportunistic bacterial pathogens

BACKGROUND

Efflux pumps represents one of the most important mechanisms of antibiotic resistance. They allow bacteria to expel antibiotics from their cells before they reach the target site.

OBJECTIVES

The main objective of this work was to examine how cultivation temperature and its variations affect the activity of efflux pumps in Acinetobacter junii, Bacillus cereus, and Enterobacter cloacae isolated from a skin swab.

METHODS

The isolation and purification of bacterial colonies were done through the streak plate method. For the identification of bacterial species, MALDI-TOF was utilised. To detect the activity of efflux pumps, agar-ethidium bromide cartwheel method was implemented.

FINDINGS

The accumulation of ethidium bromide (EtBr) in bacterial cells was higher at 43ºC than at 30ºC, so the activity of efflux pumps was reduced at 43ºC in all isolates. A temperature of 7ºC also caused increased cumulation of EtBr in the cells, hence decreasing the activity of efflux pumps in isolated bacteria. Moreover, B. cereus was more sensitive to meropenem at 43ºC than at 36ºC.

MAIN CONCLUSIONS

The activity of efflux pumps and antibiotic resistance can be strongly affected by changes in incubation temperature in vitro in tested human opportunistic bacterial pathogens.

Bacterial etiology and antimicrobial resistance in bloodstream infections at the University of Gondar Comprehensive Specialized Hospital: a cross-sectional study

Background

Bacterial bloodstream infections are a major global health concern, particularly in resource-limited settings including Ethiopia. There is a lack of updated and comprehensive data that integrates microbiological data and clinical findings. Therefore, this study aimed to characterize bacterial profiles, antimicrobial susceptibility, and associated factors in patients suspected of bloodstream infections at the University of Gondar Comprehensive Specialized Hospital.

Methods

A cross-sectional study analyzed electronic records from January 2019 to December 2021. Sociodemographic, clinical, and blood culture data were analyzed. Descriptive statistics and binary logistic regression were employed to identify factors associated with bloodstream infections. Descriptive statistics such as frequency and percentage were computed. Furthermore, a binary and multivariable logistic regression model was fitted to determine the relationship between BSI and associated factors. Variables with p-values of <0.05 from the multivariable logistic regression were used to show the presence of statistically significant associations.

Results

A total of 4,727 patients' records were included in the study. Among these, 14.8% (701/4,727) were bacterial bloodstream infections, with Gram-negative bacteria accounting for 63.5% (445/701) of cases. The most common bacteria were Klebsiella pneumoniae (29.0%), Staphylococcus aureus (23.5%), and Escherichia coli (8.4%). The study revealed a high resistance level to several antibiotics, with approximately 60.9% of the isolates demonstrating multidrug resistance. Klebsiella oxytoca, Klebsiella pneumoniae, and Escherichia coli exhibited high levels of multidrug resistance. The study identified emergency OPD [AOR = 3.2; (95% CI: 1.50-6.74)], oncology ward [AOR = 3.0; (95% CI: 1.21-7.17)], and surgical ward [AOR = 3.3; (95% CI: 1.27-8.43)] as factors associated with increased susceptibility to bloodstream infections.

Conclusion

The overall prevalence of bacterial isolates was high with concerning levels of multi-drug resistance. The study identified significant associations between bloodstream infections with age groups and presentation in specific clinical settings, such as the emergency OPD, oncology ward, and surgical ward. Strict regulation of antibiotic stewardship and the implementation of effective infection control programs should be enforced.

Recent advances and challenges in metal-based antimicrobial materials: a review of strategies to combat antibiotic resistance

Despite the availability of a series of classical antibiotic drugs, bacterial infections continue to represent a significant and urgent threat to global human health. The emergence of drug-resistant bacteria and the slow pace of antibiotic development have rendered current treatment methods inadequate in meeting the clinical demands of bacterial infections. Consequently, there is an increasingly urgent and vital need for the development of safe, efficient, and alternative novel antimicrobial agents in the medical and healthcare field. Over the past five years, there has been a notable expansion in the field of nanomedicine with regard to the prevention and control of infectious diseases. The objective of this article is to provide a comprehensive review of the latest research developments in the field of metal nanomaterials for medical antimicrobial therapy. We begin by delineating the gravity of the bacterial infection crisis, subsequently undertaking a comprehensive examination of the potential mechanisms through which nanoparticles may combat bacterial infections and the specific applications of these nanomaterials in the treatment of diverse infectious diseases. In conclusion, we eagerly anticipate the future development directions of metal nanomaterials in the field of antimicrobial therapy. We believe that with continuous technological advancements and innovations, this field will make even more outstanding contributions to safeguarding human health and well-being.

Self-responsive biomimetic short lipopeptide-based delivery systems for enhanced antibiotic efficacy against drug-resistant infections

Biocompatible short peptide amphiphile nanostructures were developed as an innovative platform for the efficient delivery of meropenem. These nanostructures exhibit self-responsive behavior, specifically targeting infection sites and releasing the antibiotic in a controlled manner. Testing against clinically relevant bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Staphylococcus aureus (VRSA), demonstrated their ability to enhance antibiotic concentration at the site of infection, significantly improving therapeutic efficacy. By reducing the required dosages, this approach minimizes systemic cytotoxicity and mitigates the side effects associated with higher drug concentrations. The study highlights the potential of these nanostructures as a promising strategy to combat drug-resistant bacterial infections, addressing a critical global health challenge.

Antimicrobial Resistance and Molecular Characterization of Escherichia coli from Healthy Chickens in Shandong, China from 2009 to 2014

Antimicrobial resistance (AMR) is a great threat to animal and public health. Here, we conducted a surveillance of Escherichia coli isolated from healthy chickens during 2009-2014 to identify the characteristics of AMR. A total of 351 (95.64%) E. coli isolates were obtained from 367 healthy chicken fecal samples collected from 6 farms located in Shandong Province, China. The susceptibility to 10 antimicrobials, the prevalence of antibiotic resistance genes (ARGs), phylogenetic clustering, and multilocus sequence typing were evaluated. The isolates exhibited high resistant rates (>95%) to ampicillin, cefotaxime, ciprofloxacin, ceftiofur, and enrofloxacin. The most prevalent ARGs were blaCTX-M (36.36%), aac(6')-Ib-cr (30.79%), qnrS (29.62%), oqxAB (27%), mcr-1 (15.83%), blaTEM (9.09%), qnrC (3.52%), qnrD (0.88%), and qepA (0.29%). Phylogenetic clustering analysis indicated that the most prevalent group was group D (37.89%), followed by group B1 (34.76%), A (24.22%), and B2 (3.13%). Fifty-seven sequence types (STs) were identified among the 124 blaCTX-M-positive strains, and the dominant STs were ST354 (13.71%), ST117 (5.65%), ST155, ST2309, and ST2505 (4.84% each). There was a significant association between 17 pairs of AMR phenotypes, 14 pairs of ARGs, and 11 pairs of AMR-ARGs. The strongest association was found between ST602 and qnrC (odds ratios: 22.2). This study implied that E. coli isolated from healthy chickens could potentially serve as a reservoir of AMR and ARGs, and significant associations exist among AMR, ARGs, phylogenetic groups, and STs. Our study highlighted the need for routine surveillance of AMR in healthy chickens, and promoting appropriate antibiotic use and implementing regular monitoring of resistance in broilers are crucial for fostering the development of the poultry industry and safeguarding public health.

Understanding and mapping the antibiotic prescribing and administration process in assisted living facilities

Objective

Inappropriate prescribing practices significantly contribute to antibiotic resistance which poses a significant public health challenge. While antibiotic prescribing and administration process has been widely studied in various settings including nursing homes, little is known about Assisted Living Facilities (ALFs). This study aims to map the antibiotic prescribing and administration processes in ALFs.

Design

A qualitative descriptive study using the Systems Engineering Initiative for Patient Safety (SEIPS) 2.0 model.

Methods

Seven semi-structured interviews were conducted with staff from five ALFs located in a mid-western state. Participating staff were either involved in or knowledgeable about the process. The interviews were analyzed in NVivo using SEIPS 2.0 model as a theoretical framework.

Results

The analysis informed the mapping of a 33-step antibiotic prescribing and administration process for residents in ALFs. They were grouped into five sections: admission, resident having a change in condition, antibiotic prescribing, obtaining the prescription from the pharmacy, and antibiotic administration and follow-up. Pharmacies played critical role in delivery of prescriptions to ALFs and are uniquely positioned to support antibiotic stewardship efforts.

Conclusions and implications

This study is among the first to systematically map the antibiotic prescribing and administration process in ALFs. Insights gathered regarding the use of preferred pharmacies highlight opportunities for pharmacists in stewardship practices. Comparison of the process to that of nursing homes, suggests that several pharmacist-led stewardship interventions used there could be adapted effectively in ALFs. Further research is essential to assess the impact of antibiotic prescribing and pharmacist-driven stewardship interventions tailored specifically for ALFs.

Impact of Antibiotic Duration on Gut Microbiome Composition and Antimicrobial Resistance: A Substudy of the BALANCE Randomized Controlled Trial

Background

Maintaining a diverse gut microbiome and minimizing antimicrobial resistance gene (ARG) carriage through reduced antibiotic utilization may decrease antimicrobial resistance. We compared gut microbiome disruption and ARG carriage following 7 or 14 days of antibiotics for treatment of bacteremia in a substudy of the BALANCE randomized controlled trial.

Methods

The BALANCE randomized controlled trial enrolled 3631 participants with bacteremia, who were randomized 1:1 to receive 7 or 14 days of antibiotics. Rectal swabs were collected from 131 participants and analyzed with metagenomic sequencing to characterize the gut microbiome and ARGs. The primary outcome was change in gut microbiome diversity at day 7 vs 14.

Results

Forty-one participants (n = 28 in the 14-day group, n = 13 in the 7-day group) had samples available for the primary analysis, with an imbalance in piperacillin-tazobactam exposure between groups. Change in gut microbiome diversity at day 7 vs 14 was comparable between the 14-day group (median, 0.07; IQR, -0.46 to +0.51) and 7-day group (median, 0.19; IQR, -0.77 to +0.22; P = .49). Change in ARG abundance at day 7 vs 14 did not differ by treatment duration, nor did the abundance of individual ARGs. We did not observe any change in gut microbiome diversity or ARG carriage at enrollment vs day 7.

Conclusions

In this subset of patients from the BALANCE randomized controlled trial, we did not detect greater gut microbiome disruption or ARG carriage among participants who received 14 vs 7 days of antibiotics, but we were limited by small sample size and imbalances between groups.

Aurovertins from a Marine-Derived Penicillium Species and Nonenzymatic Reactions in Their Formation

Six new aurovertins (1-6) and a new citreoviridin derivative (7), together with six known analogues (8-13), were isolated from the marine-derived Penicillium sp. OUCMDZ-5930. Their structures were determined based on detailed spectroscopic analysis and ECD calculations. The putative nonenzymatic formation from citreoviridin to various aurovertins was presented, which was confirmed by chemical transformations. These results provide new insights into the formation mechanism of the 2,6-dioxabicyclo[3.2.1]octane ring system present in aurovertin-type natural products.

Mechanisms of Salmonella typhimurium Resistance to Cannabidiol

The emergence of multi-drug resistance (MDR) poses a huge risk to public health globally. Yet these recalcitrant pathogens continue to rise in incidence rate with resistance rates significantly outpacing the speed of antibiotic development. This therefore presents related health issues such as untreatable nosocomial infections arising from organ transplants and surgeries, as well as community-acquired infections that are related to people with compromised immunity, e.g., diabetic and HIV patients, etc. There is a global effort to fight MRD pathogens spearheaded by the World Health Organization, thus calling for research into novel antimicrobial agents to fight multiple drug resistance. Previously, our laboratory demonstrated that Cannabidiol (CBD) is an effective antimicrobial against Salmonella typhimurium (S. typhimurium). However, we observed resistance development over time. To understand the mechanisms S. typhimurium uses to develop resistance to CBD, we studied the abundance of bacteria lipopolysaccharide (LPS) and membrane sterols of both CBD-susceptible and CBD-resistant S. typhimurium strains. Using real-time quantitative polymerase chain reaction (rt qPCR), we also analyzed the expression of selected genes known for aiding resistance development in S. typhimurium. We found a significantly higher expression of blaTEM (over 150 mRNA expression) representing over 55% of all the genes considered in the study, fimA (over 12 mRNA expression), fimZ (over 55 mRNA expression), and integron 2 (over 1.5 mRNA expression) in the CBD-resistant bacteria, and these were also accompanied by a shift in abundance in cell surface molecules such as LPS at 1.76 nm, ergosterols at 1.03 nm, oleic acid at 0.10 nm and MPPSE at 2.25nm. For the first time, we demonstrated that CBD-resistance development in S. typhimurium might be caused by several structural and genetic factors. These structural factors demonstrated here include LPS and cell membrane sterols, which showed significant differences in abundances on the bacterial cell surfaces between the CBD-resistant and CBD-susceptible strains of S. typhimurium. Specific key genetic elements implicated for the resistance development investigated included fimA, fimZ, int2, ompC, blaTEM, DNA recombinase (STM0716), leucine-responsive transcriptional regulator (lrp/STM0959), and the spy gene of S. typhimurium. In this study, we revealed that blaTEM might be the highest contributor to CBD-resistance, indicating the potential gene to target in developing agents against CBD-resistant S. typhimurium strains.

Uncovering the potent antimicrobial activity of squaramide based anionophores - chloride transport and membrane disruption

Antimicrobial resistance (AMR) - often referred to as a silent pandemic, is at present the most serious threat to medicine, and with constantly emerging resistance to novel drugs, combined with the paucity of their development, is likely to worsen. To circumvent this, supramolecular chemists have proposed the applicability of synthetic anion transporters in the fight against AMR. In this article we discuss the synthesis, supramolecular characterisation and biological profiling of six structurally simple squaramide anion transporters. Through a combination of spectroscopic techniques, and cellular assays we have deduced the mode of action of these antimicrobial agents to be as a result of both anion transport and membrane disruption. Furthermore, through the synthesis of two fluorescent analogues we verified this membrane-localised activity using Super-Resolution nanoscopy methods. These compounds represent particularly active antimicrobial anionophores and compliment similar reports showing the applicability of agents such as these in the fight against AMR.

Bacteriophage P1 protein Icd inhibits bacterial division by targeting FtsZ

The study of bacteriophage (phage) gene products and their effects on the host helps to better understand the phage-host relationship and provides clues for the development of new antimicrobial proteins. In this study, we focused on a small protein named Icd with 73 amino acids from phage P1. It inhibits the growth of Escherichia coli and rapidly blocks the formation of Z-ring. The results of bacterial two-hybrid and pull-down experiments showed that Icd directly targets FtsZ, a key protein in bacterial division. Furthermore, we identified the core region of Icd as amino acids 12-51; this 40-amino acid protein had similar antibacterial activity to the full-length Icd, inhibiting bacterial growth and division.

Acquired Bacterial Resistance to Antibiotics and Resistance Genes: From Past to Future

The discovery, commercialization, and regular administration of antimicrobial agents have revolutionized the therapeutic paradigm, making it possible to treat previously untreatable and fatal infections. However, the excessive use of antibiotics has led to develop resistance soon after their use in clinical practice, to the point of becoming a global emergency. The mechanisms of bacterial resistance to antibiotics are manifold, including mechanisms of destruction or inactivation, target site modification, or active efflux, and represent the main examples of evolutionary adaptation for the survival of bacterial species. The acquirement of new resistance mechanisms is a consequence of the great genetic plasticity of bacteria, which triggers specific responses that result in mutational adaptation, acquisition of genetic material, or alteration of gene expression, virtually producing resistance to all currently available antibiotics. Understanding resistance processes is critical to the development of new antimicrobial agents to counteract drug-resistant microorganisms. In this review, both the mechanisms of action of antibiotic resistance (AMR) and the antibiotic resistance genes (ARGs) mainly found in clinical and environmental bacteria will be reviewed. Furthermore, the evolutionary background of multidrug-resistant bacteria will be examined, and some promising elements to control or reduce the emergence and spread of AMR will be proposed.

The role of bacterial metabolism in antimicrobial resistance

The relationship between bacterial metabolism and antibiotic treatment is complex. On the one hand, antibiotics leverage cell metabolism to function. On the other hand, increasing research has highlighted that the metabolic state of the cell also impacts all aspects of antibiotic biology, from drug efficacy to the evolution of antimicrobial resistance (AMR). Given that AMR is a growing threat to the current global antibiotic arsenal and ability to treat infectious diseases, understanding these relationships is key to improving both public and human health. However, quantifying the contribution of metabolism to antibiotic activity and subsequent bacterial evolution has often proven challenging. In this Review, we discuss the complex and often bidirectional relationships between metabolism and the various facets of antibiotic treatment and response. We first summarize how antibiotics leverage metabolism for their function. We then focus on the converse of this relationship by specifically delineating the unique contribution of metabolism to three distinct but related arms of antibiotic biology: antibiotic efficacy, AMR evolution and AMR mechanisms. Finally, we note the relevance of metabolism in clinical contexts and explore the future of metabolic-based strategies for personalized antimicrobial therapies. A deeper understanding of these connections is crucial for the broader scientific community to address the growing crisis of AMR and develop future effective therapeutics.

Comprehensive genomic insights into a highly pathogenic clone ST656 of mcr8.1 containing multidrug-resistant Klebsiella pneumoniae from Bangladesh

Antimicrobial resistance (AMR) is a pressing global health issue, intensified by the spread of resistant pathogens like Klebsiella pneumoniae (K. pneumoniae), which frequently causes hospital-acquired infections. This study focuses on a multidrug-resistant K. pneumoniae sequence type (ST) 656 strain, isolated from canal water in Bangladesh. Whole-genome sequencing and comparative genomic analysis revealed extensive resistance mechanisms and genetic elements underlying its adaptability. The strain exhibited resistance to colistin and multiple β-lactam antibiotics, containing key resistance genes such as mcr8.1, blaLAP-2, blaTEM-1, blaSHV-11 and blaOXA-1, alongside genes for copper, zinc, and silver resistance, indicating survival capability in metal-rich environments. Virulence factor analysis identified genes supporting adhesion, biofilm formation, and immune evasion, amplifying its pathogenic potential. Plasmid and phage analyses revealed mobile genetic elements, highlighting the role of horizontal gene transfer in AMR dissemination. The study included a pangenome analysis using a dataset of 32 publicly available K. pneumoniae sequence type (ST) 656 genomes, demonstrating evidence of an expanding pangenome for K. pneumoniae ST656. This study emphasized the role of environmental sources in AMR spread and the importance of continued surveillance, particularly in settings with intensive antibiotic usage, to mitigate the spread of high-risk, multidrug-resistant clones like K. pneumoniae ST656.