Search Results (148)

Antibiotic resistance is a growing global health threat. However, its evolution cannot be fully understood without considering antibiotic tolerance and persistence. Persister cells are phenotypic variants that survive lethal antibiotic exposure without heritable resistance, primarily through growth arrest, metabolic slowdown, and stress-adaptive states. Although persistence has been viewed as a transient survival phenomenon, increasing evidence suggests that it may also have a genetic basis by preserving populations during antibiotic-induced bottlenecks and enabling regrowth, mutation, and selection under certain conditions. This review examines the molecular mechanisms underlying persister formation, including toxin–antitoxin systems, stringent-response signaling, ATP depletion, translational arrest, and stress-response networks. We discuss how persistence contributes to antibiotic tolerance in biofilms, host environments, and recurrent infections, and how repeated antibiotic exposure may promote stepwise evolution from phenotypic survival to stable resistance in specific contexts. Evidence from experimental evolution, clinical observations, and system-level analyses supports a potential but context-dependent link between persistence and resistance. We also highlight therapeutic strategies targeting persister cells, including antipersister compounds, metabolic activation, combination therapies, bacteriophages, and alternative approaches. Finally, we outline future research directions, emphasizing single-cell technologies, systems biology, longitudinal clinical studies, and evolution-informed treatment design. A comprehensive understanding of persistence and its evolutionary implications is essential for improving treatment efficacy and limiting the emergence of long-term antibiotic resistance. Full article

Bacterial biofilms are structured microbial communities enclosed within a self-produced extracellular polymeric substance matrix composed of polysaccharides, proteins, extracellular DNA, and lipids. This matrix promotes adhesion, structural stability, and the development of heterogeneous microenvironments that restrict antimicrobial penetration and shield bacteria from host immune responses. As a result, biofilms are major contributors to chronic, recurrent, device-related, and difficult-to-treat infections, posing a major challenge for clinical management and antimicrobial stewardship. This review summarizes current understandings of biofilm biology, its clinical relevance, including the stages of biofilm development, the composition and protective roles of the matrix, and the physiological heterogeneity that arises during maturation. It also examines key mechanisms underlying biofilm tolerance and resistance, such as limited antibiotic diffusion, and sequestration, enzymatic inactivation, efflux pump upregulation, persister cell formation, and horizontal gene transfer. In addition, it highlights important clinical settings in which biofilms are implicated, including cystic fibrosis, chronic wounds, osteomyelitis, implant- or device-associated infections, and breast implant illness, in which persistent implant-associated biofilms and the resulting chronic inflammatory milieu have been hypothesized to contribute to local and systemic manifestations in a subset of patients. The review further discusses conventional and emerging approaches for biofilm detection alongwith real-time monitoring. Biofilm-associated infections remain difficult to eradicate because persistence is driven by multiple interconnected protective mechanisms. Effective management therefore requires integrated strategies that combine accurate detection with multifaceted therapies, including antibiotics alongside matrix-disrupting enzymes, quorum-sensing inhibitors, bacteriophages, metabolic reactivators, and nanotechnology-based delivery systems. Advances in multi-omics and system-level modeling will be essential for developing next-generation strategies to prevent, monitor, and treat biofilm-associated disease. Full article

Carbapenem-resistant Gram-negative infections have become one of the most formidable challenges in intensive care units (ICUs). Critically ill patients—often exposed to invasive procedures, prolonged hospitalization, and broad-spectrum antibiotics—are highly susceptible to infections by carbapenem-resistant Enterobacterales (CRE), Pseudomonas aeruginosa (CRPA), and Acinetobacter baumannii (CRAB). These pathogens are associated with mortality exceeding 40%, prolonged ICU stays, and increased healthcare costs. Therapeutic advances have reshaped management in recent years. New β-lactam/β-lactamase inhibitor combinations—ceftazidime–avibactam, meropenem–vaborbactam, imipenem–relebactam, and sulbactam–durlobactam—along with cefiderocol, have provided safer and more effective alternatives to previously used regimens. Yet, none are universally effective, particularly against carbapenemase-producing organisms, especially metallo-β-lactamase (MBL) producers, and resistance may still emerge during treatment. Rapid molecular and phenotypic diagnostics, when integrated into antimicrobial stewardship, have improved early therapy alignment and reduced unnecessary broad-spectrum use. Beyond antibiotics, colonization surveillance and infection control remain pivotal, as colonization often precedes invasive infection. Biofilm formation on devices such as endotracheal tubes and catheters further promotes persistence and relapse. Strategies targeting biofilm disruption, improved dosing guided by pharmacokinetic/pharmacodynamic optimization, and therapeutic drug monitoring are crucial in ICU practice. The future of managing these infections will depend on integrating precision tools—rapid diagnostics, mechanism-based therapy, and stewardship-guided decisions—with emerging treatments and adjunctive options such as immunomodulators, bacteriophages, and AI-driven decision support. Continued research in ICU-specific populations, especially regarding pharmacokinetics in patients on ECMO or CRRT, is urgently needed. In summary, while the therapeutic landscape for carbapenem-resistant Gram-negative infections has evolved substantially, sustained success will rely on a multifaceted strategy combining innovation, precision, and prevention to improve outcomes for the most vulnerable patients. Full article

Infectious diseases remain a major cause of mortality and disability worldwide. This burden is driven, in part, by antimicrobial resistance (AMR) and the re-emergence of epidemic and pandemic threats, underscoring the need for translational research to address knowledge gaps exposed by recent pandemics. Despite significant advances enabled by antibiotics and antivirals, their effectiveness is increasingly constrained by resistance development, limited pathogen spectra, and prolonged development timelines that fail to keep pace with rapidly shifting epidemiology. Diagnostic limitations impede timely pathogen identification and hinder the development of treatment regimens informed by pathogen mechanisms of action. Severe infections frequently involve dysregulated host responses, including hyperinflammation, inflammasome activation, and endothelial or immunothrombotic injury, which may progress to sepsis, immunoparalysis, or chronic sequelae, highlighting the limitations of pathogen-centered paradigms. Conventional biomarkers and culture-based microbiology are often slow or nonspecific, while molecular assays may not reliably distinguish colonization from active infection or capture host-response heterogeneity shaped by age, immune competence, and disease stage. This review synthesizes mechanistic and translational insights across three interrelated axes: (i) host–pathogen interactions, with a focus on innate immune sensing networks (e.g., Toll-like receptors, inflammasomes, RIG-I-like receptors, and cGAS-STING) and microbial replication and immune evasion strategies; (ii) clinical and public health implications, spanning acute organ dysfunction syndromes, post-acute infection syndromes, and AMR-driven health system strain; and (iii) emerging therapeutics along a continuum of pathogen-, virulence-, host-, and immune-directed approaches. Emphasis is placed on anti-virulence therapeutics, bacteriophage therapy, monoclonal antibodies, and engineered immune modalities within frameworks of quantitative translational pharmacology and implementation science. Finally, an integrative conceptual framework encompassing mechanistic phenotypes, host-response diagnostics, and stage-adapted therapeutic combinations is proposed to guide rational intervention across endemic infections and future pandemic preparedness. Full article

Background/Objectives: Colistin, a polymyxin antibiotic introduced in the mid-20th century, has regained clinical importance as a last-resort agent for the treatment of infections caused by multidrug-resistant (MDR) Gram-negative bacteria. The global dissemination of carbapenem-resistant pathogens has intensified colistin use, leading to a concerning rise in resistance. This review aims to provide a comprehensive and up-to-date synthesis of colistin’s pharmacological characteristics, resistance mechanisms, epidemiology, and current and emerging therapeutic strategies. Methods: A narrative review of the literature was conducted, encompassing studies on the chemistry, mechanism of action, pharmacodynamics, clinical use, dosing, and resistance to colistin. Data on chromosomal and plasmid-mediated resistance mechanisms, detection methodologies, epidemiological trends, and clinical outcomes were examined. In addition, evidence on colistin-based treatment strategies and novel non-antibiotic approaches was analyzed. Results: Colistin remains active against many MDR Gram-negative pathogens, including Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii; however, resistance is increasingly reported worldwide. Both chromosomally mediated modifications of lipid A and plasmid-mediated mcr genes contribute to resistance, with heteroresistance posing diagnostic and therapeutic challenges. Carbapenem resistance has emerged as a major driver of colistin use and subsequent resistance selection. Combination therapies, inhaled formulations, and guideline-directed use may improve outcomes, while emerging alternatives such as antimicrobial peptides, bacteriophages, nanoparticles, photodynamic therapy, and CRISPR-based technologies show promise. Conclusions: The escalating prevalence of colistin resistance threatens the effectiveness of this critical last-line antibiotic. Optimized use, robust resistance surveillance, accurate detection methods, and the development of innovative therapeutic strategies are essential to preserve colistin’s clinical utility and address the growing burden of MDR Gram-negative infections. Full article

Bone and joint infections (BJI) remain among the most challenging conditions in orthopaedics due to their complex pathophysiology, frequent association with biofilm formation on bone and implant surfaces, and the rising prevalence of antibiotic-resistant pathogens. Conventional antibiotic therapies, although central to current clinical practice, are often limited by poor biofilm penetration, disruption of the host microbiota, and the increasing emergence of multidrug resistance, particularly in chronic infections such as osteomyelitis and prosthetic joint infections. This review provides a comprehensive exploration of bacteriophage therapy as a targeted, non-antibiotic strategy for the management of BJIs. Bacteriophages exhibit unique biological characteristics, including strict host specificity, self-amplifying antibacterial activity, and the capacity to disrupt biofilms through bacterial lysis and phage-derived enzymes. Evidence from in vitro investigations, animal models, and emerging clinical studies demonstrates the promising efficacy of phages and phage lysins against key BJI pathogens, particularly Staphylococcus aureus, with favourable safety profiles and encouraging rates of infection control, especially when used as adjuncts to surgery and antibiotics. Despite this potential, challenges such as narrow host range, variable pharmacokinetics, immunogenicity, and underdeveloped regulatory frameworks continue to limit widespread clinical adoption. Addressing these barriers through standardized phage selection, improved delivery strategies, combination therapies, and coordinated regulatory efforts will be critical to realizing the full therapeutic potential of phage-based interventions for antibiotic-resistant bone and joint infections. Full article

Lower respiratory tract infections caused by Pseudomonas aeruginosa are a global concern. Patients with chronic lung diseases such as cystic fibrosis and non-cystic fibrosis bronchiectasis often do not receive adequate antibiotic delivery through conventional routes. P. aeruginosa employs several mechanisms, including biofilm formation and efflux pumps to limit the accumulation of bactericidal drug concentrations. Direct drug delivery to the lung epithelial lining fluid can increase antibiotic concentration and reduce treatment failure rates. This review discusses current research and developments in inhaled antibiotic formulations for treating P. aeruginosa infections. Recent studies on particle engineering for the dry powder inhalers of antibiotics emphasized three fundamental principles of development: micro, nano, and nano-in-microparticles. Carrier-free microparticles showed potential for high-dose delivery but suffered from poor aerosolization, which could be improved through a drug–drug combination. Amino acids in a co-spray-dried system improved powders’ aerodynamics and reduced moisture sensitivity while incorporating the chitosan/poly(lactic-co-glycolic acid) (PLGA)-modified release of the drug. Nano-in-microsystems, embedding lipid carriers, showed improved antibiofilm activity and controlled release. We also highlight emerging biologics, including antibacterial proteins/peptides, vaccines, bacteriophages, and probiotics. Research on antibiotics and biologics for inhalation suggests excellent safety profiles and encouraging efficacy for some formulations, including antimicrobial peptides and bacteriophage formulations. Further research on novel molecules and synergistic biologic combinations, supported by comprehensive animal lung safety investigations, will be required in future developments. Full article

Bacteriophage (phage) therapy, including monophage preparations, phage cocktails, engineered phages, and phage-derived enzymes, has re-emerged as a potential option for difficult-to-treat and biofilm-associated infections in the context of rising antimicrobial resistance. Recent scientific and regulatory developments, such as the 2024 World Health Organization Bacterial Priority Pathogens List and the introduction of the European Pharmacopoeia general chapter 5.31 on phage therapy medicinal products, highlight the growing interest in establishing quality, safety, and governance standards for clinical implementation. This narrative review provides an overview of current clinical applications of phage therapy, drawing on published case reports, case series, early-phase clinical studies, and regulatory experiences across different healthcare settings. Clinical use has been reported in respiratory, urinary tract, musculoskeletal, cardiovascular, and device-associated infections, particularly in cases involving multidrug-resistant pathogens, often in combination with antibiotics. At the same time, the biological characteristics of phages, such as strain specificity, adaptive composition of phage cocktails, and the need for individualized formulations, pose significant regulatory and translational challenges. Access to phage therapy currently relies on heterogeneous regulatory mechanisms, including compassionate use programmes, magistral preparations, named-patient pathways, and other national frameworks. Overall, phage therapy represents a promising strategy for selected infections, but its broader clinical adoption will depend on harmonized regulatory approaches, robust quality standards, and the generation of stronger clinical evidence to support safe and scalable use. Full article

Antibiotic resistance is arguably one of the greatest threats to global health today. The worldwide emergence of multidrug-resistant and hypervirulent Klebsiella pneumoniae underscores the urgent need for alternative treatments. Bacteriophages (phages) are considered one of the most promising alternatives to address this crisis. In this review, we summarize current knowledge of phage–host interactions and highlight recent advances in phage therapy against K. pneumoniae, including phage cocktails, antibiotic combination therapy, and treatments based on phage-derived proteins. Despite their tremendous therapeutic potential, significant challenges remain. We therefore also discuss strategies to optimize phage research and recent innovations in the field. Full article

Pseudomonas aeruginosa is a resilient Gram-negative pathogen frequently implicated in healthcare associated infections, particularly among immunocompromised individuals and those with chronic conditions such as cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), or cancer. It is well known for its high resistance to antibiotic treatment. This review briefly mentions P. aeruginosa’s resistance mechanisms, biofilm formation, and virulence factors, while primarily focusing on treatment challenges and recent advancements in therapeutic strategies aimed at overcoming resistance. Covered are novel non-antibiotic interventions such as quorum sensing inhibitors, quorum quenching agents, iron chelators, lectin and efflux pump inhibitors, as well as antimicrobial peptides and nanoparticles. Traditional medicine, phytochemicals, and probiotics are also evaluated. Additionally, this review explores the development of a viable vaccine, bacteriophage therapy, lactoferrin-hypothiocyanite combination, and topical use of electrochemical scaffolds. This review emphasizes the need for extensive safety studies and in vivo validation of these emerging non-antibiotic therapeutic strategies to determine their efficacy, pharmacological behavior, and clinical feasibility before they can be translated into practice. Many of these emerging treatments could play a vital role in future combination therapies by enhancing the efficacy of existing antibiotics and countering resistance and virulence mechanisms. Advancing these approaches from laboratory to clinical application remains a major challenge, making the development of approved therapies or vaccines a critical scientific and public health priority. Full article

Bacteriophages are powerful drivers of microbial evolution and are increasingly explored as alternatives to antibiotics against multidrug-resistant pathogens such as Pseudomonas aeruginosa. Here, we describe the isolation, phenotypic characterization and genomic, structural and evolutionary analysis of Pseudomonas phage Adele, a lytic myovirus representing a novel species within the genus Pakpunavirus (family Vandenendeviridae). Phage Adele exhibits a short latent period of 20 min, a burst size of 59 ± 11 virions per infected cell and a high virulence index, efficiently lysing non-O11 Pseudomonas aeruginosa strains and reducing biofilm biomass. In vivo, Adele confers marked protection in a Galleria mellonella infection model. Phylogenetic reconstruction, synteny analysis and structural modeling demonstrate the relatedness of Vandenendeviridae to phages of the Andersonviridae and Vequintavirinae clades, pointing to a stable, ancestral virion architecture that has undergone lineage-specific elaborations, including the duplication and divergence of tail tube proteins. The tail assembly chaperone gene employs a conserved −1 programmed ribosomal frameshift. Phage Adele encodes an elaborate set of metabolic reprogramming and anti-defense systems, reflecting extensive horizontal gene transfer. The combination of a conserved structural architecture and mosaic genome establishes Adele as an exemplary system for studying modular evolution in phages, alongside its demonstrated therapeutic efficacy. Full article

Background: Periprosthetic joint infections (PJIs) of the hip and knee are one of the most severe complications in arthroplasty, often requiring prolonged antibiotic therapy and multiple revision surgeries. The increasing prevalence of multidrug-resistant organisms and biofilm-associated PJIs has renewed interest in bacteriophage therapy as a targeted, adjunctive treatment option in refractory cases. This investigation systematically reviews and discusses the current evidence regarding the application, outcomes, and safety profile of bacteriophage therapy in the management of PJIs. Methods: This systematic review was conducted in accordance with the 2020 PRISMA statement. PubMed, Google Scholar, EMBASE, and Web of Science were accessed in August 2025. No time constraints were used for the search. All clinical studies investigating bacteriophage therapy for bacterial PJIs were considered for eligibility. Results: A total of 18 clinical studies, comprising 53 patients treated with bacteriophage therapy for PJI, were included. The mean follow-up was approximately 13.6 months. Staphylococcus aureus was the most frequent pathogen (18 cases); phage cocktails were used in 33 patients and monophage preparations in 9, all combined with suppressive antibiotic therapy. Persistent or resistant joint pain was reported in only two patients (3.8%), while signs of ongoing infection despite phage therapy were observed in four patients (7.5%). Adverse events following BT were inconsistently reported. Conclusions: Bacteriophage therapy shows promise as an adjunctive treatment for hip and knee PJIs, especially in refractory or multidrug-resistant cases. Current evidence is limited and methodologically weak, underscoring the need for well-designed clinical trials to clarify efficacy, safety, and optimal integration into existing orthopaedic infection protocols. Full article

Bacteriophage therapy is regarded as a promising alternative for treating and preventing antibiotic-resistant bacterial infections. Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most prevalent and difficult-to-treat pathogens. S. aureus also contributes to the formation of both single- and mixed-species biofilms. Treating biofilms remains a major challenge for antibiotic-based eradication of pathogens, as the biofilm matrix provides a protective barrier for bacteria. The selection of highly active phages targeting S. aureus is therefore crucial for medical applications, given the high prevalence and drug resistance of this pathogen. In this study, S. aureus phage vB_SaS_GE1 (GE1) was isolated and characterized as a potential therapeutic agent. The phage was isolated and propagated, and its host range was determined using standard methods. Whole-genome sequencing and annotation of the phage DNA were performed. A time–kill assay and evaluation of the anti-biofilm activity of the Staphylococcus phage, both alone and in combination with Pseudomonas phage GEC_PNG3 (PNG3) on mixed-species biofilms, were conducted. The results indicated that GE1 is a lytic phage that does not carry virulence-determining genes. The time–kill assay demonstrated sustained lytic activity of GE1 without the emergence of phage-resistant mutants in the tested MRSA strains. Although phage treatment increased biofilm matrix production compared to the control, the viable cell count within the biofilms was reduced. Overall, the characteristics assessed indicate that vB_SaS_GE1 is safe and exhibits strong antibacterial activity against MRSA strains. Full article

Osteoarticular infections (OAIs), including osteomyelitis, septic arthritis, prosthetic joint infections, and facture-related infections, remain a major challenge due to biofilm formation and the prevalence of multidrug-resistant (MDR) pathogens. Although OAIs are predominantly caused by Staphylococcus aureus and coagulase-negative staphylococci, the increasing incidence of MDR Gram-negative infections adds further complexity to their management. Standard approaches, combining surgery and prolonged antibiotic therapy, frequently result in recurrence and poor outcomes. Bacteriophage (phage) therapy has emerged as a promising adjunct or alternative approach, offering high host specificity, replication at the infection site, and activity against biofilm-embedded bacteria. This review highlights recent advances in phage therapy for OAIs, focusing on administration routes (intravenous, intra-articular, topical, and oral) and on novel pharmaceutical delivery systems such as hydrogels, bone cements, microparticles, nanoparticles, and implant coatings. Preclinical and early clinical studies have analyzed phage stability, controlled release, and the synergistic effects of combined phage/antibiotic therapy. However, challenges remain regarding standardization, immunogenicity, and regulatory approval. Nonetheless, phage therapy shows promise for clinical translation as an adjunct or alternative to conventional treatments for OAIs. Well-designed clinical trials are urgently needed to confirm the efficacy of phage therapy, optimize delivery strategies, and integrate the treatments in routine practice. Despite encouraging outcomes for a successful clinical implementation, regulation and standardization of GMP production are required. Full article

The growing prevalence of antimicrobial resistance has significantly compromised the efficacy of conventional antibiotic-based interventions in controlling Salmonella infections across human and veterinary settings. This growing challenge necessitates a strategic rethinking of pathogen control, prompting the integration of next-generation therapeutics capable of disrupting Salmonella pathogenesis through novel, antibiotic-sparing mechanisms. In this context, a diverse array of emerging alternatives, including bacteriophages, antimicrobial peptides, probiotics, prebiotics, short-chain fatty acids, nanoparticles, and host-directed immunomodulators, have gained prominence as a promising frontier in non-antibiotic therapeutics. These modalities offer targeted approaches to inhibit Salmonella colonization, virulence expression, and persistence, while minimizing collateral damage to the microbiota and avoiding the propagation of resistance genes. As Salmonella continues to pose a global threat to animal and public health, the development of scalable, resistance-conscious interventions remains a critical priority. Ongoing research efforts are increasingly focused on optimizing delivery systems, dosage strategies, and synergistic combinations to enhance the clinical and field applicability of these alternatives. By harnessing these innovative modalities, the future of Salmonella control may shift toward precision therapeutics that align with One Health principles and sustainable food safety goals. Full article