Search Results (100)

Most translational work on bacteriophages has focused on antibacterial therapy or food biocontrol. A third use case is scientifically plausible but remains insufficiently defined: the intentional use of characterized phages to modulate gut microbial communities without infection-treatment claims. In this review, the term “phagobiotics” is used for defined, purified and process-controlled bacteriophages or phage cocktails intended for selective gut microbiota modulation. The concept is evaluated across natural human phage exposure, the gut phageome, mechanisms of phage-mediated community modulation, human intervention studies, preclinical models, manufacturing quality and regulatory boundaries. Current evidence supports biological plausibility and indicates that oral phage exposure can be well tolerated and, in some contexts, can selectively affect target bacterial groups without broad microbiota disruption. Generalized clinical efficacy and broad microbiome-support claims, however, remain insufficiently established. Microbiological-modulation claims require target-linked evidence, whereas claims to treat, prevent or cure disease or replace antibiotics fall outside the proposed non-therapeutic category. A proportionate framework is proposed in which natural exposure and food-use precedents inform, but do not determine, the safety rationale; product-specific controls focus on identity, purity, production-host control, manufacturing consistency, stability, genomic characterization and claim-linked evidence. Regulatory classification remains case-specific and depends on intended use, product format, target population and claims. Full article

Background/Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) is a major therapeutic challenge due to its extensive antibiotic resistance. This study examined how bacteriophage exposure affects the genome, proteome and antibiotic susceptibility of a clinical MRSA isolate. Methods: The MRSA isolate was exposed to the PYOFAG bacteriophage cocktail, and small colony variants (SCVs) of the surviving bacteria were compared with the untreated parental strain by phenotypic testing, whole-genome sequencing, comparative proteomics, and transmission electron microscopy. Results: Phage exposure induced marked remodeling in MRSA, including altered growth, colony morphology, and increased susceptibility to various antibiotics, especially β-lactams and aminoglycosides. Genomic analysis identified multiple mutations and the loss of two genomic regions, including changes in tarS, a gene linked to wall teichoic acid glycosylation, phage adsorption, and β-lactam resistance. Proteomic analysis revealed broad changes in metabolic, stress-response, and cell-envelope-associated pathways. Transmission electron microscopy showed a significant reduction in cell wall thickness after phage treatment. Conclusions: Bacteriophage exposure drives phenotypic and molecular adaptation in MRSA and may create evolutionary trade-offs that weaken resistance mechanisms. These findings support the potential of bacteriophages as both direct antibacterial agents and modulators of antibiotic susceptibility. Full article

Prosthetic joint infections (PJIs) remain a major challenge in orthopedic surgery due to the increasing prevalence of antimicrobial-resistant pathogens and their ability to form biofilms on implant surfaces. Local delivery of non-traditional antimicrobials through implant-associated biomaterials represents a promising strategy for preventing bacterial colonization while minimizing systemic antibiotic exposure. This study evaluated the antimicrobial activity and cytocompatibility of two bacteriophages (Phage K and Phage F1) and two antimicrobial peptide dendrimers (AMPDs; TNS18 and G3KL) against clinical isolates of Staphylococcus aureus and Staphylococcus epidermidis recovered from PJIs. Antimicrobial efficacy was assessed using solid and liquid culture assays, while cytocompatibility was evaluated using human osteoblast progenitor cells. Biofilm formation was also investigated under various in vitro conditions. Phages K and F1 demonstrated strong antibacterial activity against S. aureus isolates, whereas TNS18 showed pronounced inhibitory effects against S. epidermidis. All agents exhibited appropriate osteoblast compatibility, except Phage F1, at the highest multiplicity of infection tested. Biofilm formation was observed under several culture conditions, although substantial variability in biofilm stability limited the quantitative assessment of antimicrobial activity. These findings demonstrate complementary antimicrobial activity profiles between bacteriophages and AMPDs and support their further investigation as candidates for implant-associated antimicrobial delivery systems and orthopedic implant coatings. Full article

Bacteriophages are being revisited as programmable platforms for therapy, diagnostics, and biocontrol. Their value, however, depends on the setting. Therapeutic phages must do more than lyse bacteria in vitro: they need to reach infection sites, persist long enough to act, reduce bacterial burden, and limit resistance under clinically relevant conditions. Diagnostic platforms are judged by another standard, including sensitivity, specificity, matrix tolerance, and stable signal readout. Food, agricultural, and environmental applications instead rely on formulation stability, host specificity, scalable delivery, and ecological safety. This review summarizes the biological and engineering principles that support phage-based platforms, and then evaluates therapeutic, diagnostic, and nonclinical uses through an application-specific evidence framework. For therapy, we focus on evidence hierarchy, active phage exposure, immune clearance, persistence, infection spread, and host-resistance-bypass phenotypes. Recent studies on high-persistence and hyper-aggressive phages suggest that dissemination, plaque expansion, and resistance-bypass behavior should be considered during early candidate selection. Phage cocktails, antibiotic combinations, and engineered phages remain useful, but they should be treated as adaptive strategies rather than universal solutions. Overall, phage technologies require validation frameworks that link biological function with manufacturing quality, regulatory feasibility, and meaningful clinical or environmental endpoints. Full article

Background: Bacteriophage-based interventions are increasingly considered antibiotic-sparing tools in poultry production, but target-animal tolerability should be documented before efficacy-oriented field application. Methods: This pilot study evaluated the formulation-level tolerability of the repeated drinking-water administration of Fagovet, a commercial multi-component bacteriophage product, in Ross 308 broiler chickens under non-challenged conditions. According to the manufacturer’s product documentation, the formulation contains a declared mixture of 23 bacteriophages at a concentration of not less than 1 × 10⁶ plaque-forming units per milliliter. However, the concentration of active bacteriophages was not independently confirmed immediately before administration or after dilution in drinking water. A total of 120 birds were allocated to 12 pens, with three replicate pens per treatment, and received untreated water or product-volume-based administration rates corresponding to 1×, 3×, or 5× the manufacturer-recommended rate for 27 days. Body-weight gain and pen-level feed intake were analyzed using linear mixed-effects models with Dunnett-adjusted comparisons against controls. Clinical observations, mortality, diagnostic necropsies, terminal gross postmortem examination of all surviving birds, and descriptive histopathology in eight randomly selected birds, comprising two birds per treatment group, were used as supportive endpoints. Results: Body-weight gain did not differ from controls at 1× (ratio 0.99; 95% CI 0.88–1.10; p = 0.9856), 3× (1.03; 0.92–1.15; p = 0.8273), or 5× (1.01; 0.91–1.13; p = 0.9902). Feed intake showed no significant treatment-related reduction, and no consistent dose-related adverse clinical or pathological pattern was identified. Conclusions: Repeated drinking-water administration of the tested commercial formulation was well tolerated under the conditions of this pilot study. Because individual phage components, genomic safety, actual PFU-based exposure, and drinking-water stability were not independently characterized, the findings apply to the administered formulation and should not be interpreted as a component-level safety or quantitative phage dose–response assessment. Full article

Bacteriophage exposure can impose strong selective pressure on bacterial populations and may alter antimicrobial susceptibility beyond direct lytic effects. However, the persistence of such changes after the removal of phage pressure remains insufficiently characterized in clinical P. aeruginosa isolates. This study evaluated whether short-term exposure to the lytic bacteriophage KPP10 was associated with changes in antimicrobial susceptibility categories and whether these changes remained detectable after serial passage in phage-free medium. Five non-duplicate clinical P. aeruginosa isolates were exposed to KPP10 for 24 h at a multiplicity of infection of 10. Antimicrobial susceptibility testing was performed by disk diffusion at baseline, immediately after exposure (F24) and after four serial passages in phage-free medium. Categories were interpreted according to the EUCAST 2024 clinical breakpoints. Nine categorical susceptibility shifts were detected across six antibiotics: four toward increased susceptibility and five toward decreased susceptibility. Six shifts (66.7%) remained detectable after four serial passages, whereas three shifts (33.3%), involving ciprofloxacin, cefepime, and aztreonam in LBK20, reverted to their baseline categories. Eight of the nine shifts involved β-lactam antibiotics, and cefepime was the most frequently affected agent. These exploratory findings show that short-term KPP10 exposure was associated with isolate-specific and bidirectional changes in categorical antimicrobial susceptibility and support repeated susceptibility monitoring in future phage–antibiotic studies. Full article

The antimicrobial resistance crisis has led to the use of metals and bacteriophages as possible alternatives to antibiotics. Experimental studies have examined interactions between ionic/nano-silver and bacteriophages against multidrug-resistant bacteria. However, these approaches have often failed to examine whether silver affects the stability and infectivity of bacteriophages. Here, we utilized experimental evolution to evolve resistance to ionic silver in bacteriophage T7. High ionic silver concentrations that do not represent physiological exposure conditions were used to impose strong selective pressure. Evolution of ionic silver resistance in phage T7 was rapid, as evidenced by recovery of bacteriophage growth in E. coli following repeated exposures to ionic silver, enhanced infectivity of silver-selected populations relative to parallel control and ancestral populations under increasing ionic silver concentrations, and greater suppression of E. coli growth in standard medium. Furthermore, silver resistance evolved without loss of thermal or pH stability under the conditions tested. The genomic foundation of silver resistance was relatively simple, with positive and negative natural selection differentiating the silver-selected populations from the controls and ancestral populations across serial passages in silver. Support for replication-associated adaptation under ionic silver selection may be reflected in recurrent mutations identified in genes involved in transcription, DNA replication, and genome maintenance, including T7p07 (RNA polymerase), T7p10 (DNA ligase), and T7p29 (DNA polymerase I). These findings highlight the importance of evaluating phage –silver combination strategies within an evolutionary framework that accounts for the adaptive capacity of bacteriophages under silver selection. Full article

Bacteriophages infecting phytopathogenic bacteria represent promising alternatives for plant disease control; however, some groups, such as filamentous bacteriophages, remain comparatively underexplored. In this study, we present a comprehensive characterization of XaF13, a filamentous bacteriophage that infects Xanthomonas vesicatoria, the causal agent of bacterial spot disease in pepper. Morphological analysis revealed a flexible filamentous virion architecture consistent with members of the family Inoviridae. To refine its genomic features, the XaF13 genome was resequenced through a hybrid approach combining newly generated Oxford Nanopore long reads with previously available Illumina data, resulting in a revised genome of 6965 bp. Comparative genomic analysis and intergenomic similarity assessment revealed low nucleotide identity with related inoviruses, supporting the recognition of XaF13 as a putative novel species based on VIRIDIC species-level thresholds. Phylogenetic reconstruction based on the Zot-like protein placed XaF13 within a broader inovirus lineage and showed that it forms a distinct evolutionary branch. In addition, physicochemical assays revealed that XaF13 remains stable across a broad pH range and tolerates brief exposure to elevated temperatures, whereas chloroform treatment and UV-C radiation reduced viral infectivity over time. Overall, these findings highlight the genomic distinctiveness and in vitro physicochemical stability of XaF13, contribute to a better understanding of filamentous bacteriophage diversity and provide a basis for future studies on its ecological role and possible interactions with phytopathogenic bacteria. Full article

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

Lactobacillus crispatus is widely associated with optimal sexual and reproductive health outcomes. While L. crispatus genomes commonly harbor prophages, little is known about their genomic diversity and potential inducibility by clinically relevant compounds. We induced and characterized four bacteriophages from four L. crispatus strains isolated from vaginal secretions of South African adolescents. Sequenced viral DNA from induced phages was assembled, and their respective genomes were annotated and compared to bacteriophage reference genomes. All the phage genomes range in size from 42.9 to 48.3 kbp. Of the four phages, UC101 and UC164 shared <90% pairwise intergenomic similarity to reference phages, suggesting that they represent new species. To explore factors potentially associated with prophage activation, L. crispatus strains were exposed to physiological concentrations of copper ions and tenofovir, selected based on their common use by women in Africa and reported associations with altered vaginal bacterial community composition. The presence of phage-like particles following exposure to copper ions (2.0 × 10⁻⁶ M–3.0 × 10⁻⁶ M) and tenofovir (500 ng/mL) was observed by transmission electron microscopy, suggesting possible prophage activation under these conditions. This study provides new insights into the genomic diversity of inducible L. crispatus phages and presents hypothesis-generating evidence regarding their potential inducibility using copper ions and tenofovir. Full article

Multidrug-resistant Acinetobacter baumannii is a major nosocomial pathogen for which bacteriophages are being explored as alternative antibacterial agents. In this study, we isolated and characterized AUBFM01, a lytic phage active against MDR A. baumannii, and performed an initial assessment of its interaction with PMA-differentiated THP-1 macrophages. AUBFM01 was evaluated by host range testing, adsorption and one-step growth assays, lytic activity, stability testing, biofilm disruption, whole-genome sequencing, and flow cytometry-based macrophage profiling. The phage showed rapid adsorption, a short latent period of approximately 30 min, and a burst size of about 165 phage particles per infected cell. It remained stable under moderate temperature and near-neutral pH conditions and significantly reduced preformed A. baumannii biofilm biomass in vitro. Genomic analysis identified a 41,354-bp double-stranded DNA genome lacking detectable lysogeny-associated genes, antibiotic resistance determinants, and known bacterial virulence factors. In THP-1 macrophages, AUBFM01 exposure was associated with reduced cell viability and with enrichment of a resting/intermediate-like CD86-defined phenotype among the remaining cells, including after endotoxin reduction. These findings identify AUBFM01 as a lytic anti-Acinetobacter phage with antibiofilm activity and notable macrophage-associated effects that warrant further mechanistic and safety investigation. Full article

Antimicrobial resistance has renewed interest in bacteriophage therapy, yet bacterial evolution frequently undermines treatment efficacy. Combination phage therapy is commonly implemented as simultaneous phage cocktails, but whether this is optimal remains in question. Here, we experimentally compared simultaneous versus sequential administration of two phages, an evolved λ called ‘λtrn’ and T2, on Escherichia coli K-12 under controlled laboratory conditions. Across replicated experiments, treatment outcome depended strongly on delivery strategy, dosing order, and timing. Contrary to expectations, sequential delivery consistently achieved greater and more sustained bacterial suppression than simultaneous cocktails, although only when T2 initiated the sequence. Phenotypic assays revealed that treatment differences were driven by the accessibility and timing of cross-resistance evolution. λ-first treatments rapidly selected for cross-resistant bacteria prior to exposure to the second phage, rendering subsequent treatment ineffective. In contrast, T2-first sequential treatments delayed or limited cross-resistance and frequently produced single-phage resistance or collateral sensitivity. Cocktail treatments showed intermediate dynamics, with cross-resistance evolving more slowly but consistently. Whole genome sequencing identified distinct genetic routes to cross-resistance, including regulatory mutations in envZ affecting expression of the phage receptor OmpF, as well as envelope-modifying, mucoidy-associated mutations. Engineering envZ mutations into unevolved backgrounds confirmed the mutation’s sufficiency to confer low-cost cross-resistance. Together, these results demonstrated that phage therapy efficacy depended not only on phage composition but on how selection pressures were ordered in time, highlighting evolutionary steering as a powerful principle for multi-phage therapy design. Full article

Rates of foodborne infectious disease are increasing globally. The One Health zoonoses report shows increasing cases of shigatoxigenic Escherichia coli, campylobacteriosis, salmonellosis and listeriosis in the last 5 years. The ESKAPE pathogens are the top priority due to their alarming rate of resistance to broad-spectrum beta-lactams, carbapenems, glycopeptides, fluoroquinolones, aminoglycosides and biocide solutions. Research assessing alternative biocontrol options highlight the advantages of bacteriophages in the control of resistant bacterial species. Phage formulations including ListShield^TM and SalmoFresh^TM have gained FDA approval for food production. As biocontrol agents, however, phages are limited by their specificity in a multispecies environment, the presence of environmental variables and bacterial resistance mechanisms. Genetic modification and the use of phage cocktails aim to overcome such limitations. Future research is warranted in a harmonised approach supported by a defined legal framework to establish best formulation and exposure protocols. This review discusses phages as biocontrol agents in the control of high-risk pathobionts associated with foodborne illness. Pathobionts associated with bovine livestock are discussed due to the morbidity and incidence of disease associated with such pathogens. Full article

Background: Bacteriophages and phage-derived lytic enzymes are increasingly considered to be targeted antimicrobial tools in aquaculture; however, their compatibility with non-target microbial communities under hatchery-relevant conditions remains insufficiently characterized. Objectives This study evaluates the impact of a lytic phage (CH20) and a phage-derived lysin (LysVp1), applied under previously validated conditions for rapid Vibrio control, on the microbiota associated with seawater, rotifers, and zebrafish larvae challenged with Vibrio alginolyticus GV09. Methods: Treatments were independently applied to each biological matrix using short exposure times representative of hatchery practices, intentionally capturing the critical window during which microbial transfer from live feed to larvae occurs. Microbial communities were analyzed using 16S rRNA gene sequencing, with DNA- and RNA-derived datasets evaluated separately. Results: Alpha diversity indices were compared using appropriate statistical tests, while beta diversity was assessed using Aitchison distance, PERMANOVA, and dispersion analyses, and differential abundance was evaluated using ANCOM-BC2. Alpha diversity metrics showed no significant differences among treatments across all matrices, indicating the preservation of microbial richness and diversity. Beta diversity patterns differed according to the nucleic acid source, with RNA-based analyses revealing treatment-associated shifts in rotifer and water microbiota that were not consistently detected at the DNA level. In zebrafish larvae, neither phage nor lysin treatment significantly altered overall community structure, although dispersion effects reflected limitations related to sample size. Conclusions: Overall, these results indicate that phage CH20 and lysin LysVp1 exert minimal impact on alpha diversity and limited, context-dependent effects on microbial community structure, supporting their microbiota-safe potential for aquaculture applications. Full article

Bone infections, including osteomyelitis, prosthetic joint infections, and fracture-related infections, represent a persistent and growing clinical problem associated with substantial morbidity, mortality, and healthcare costs. Their management is complicated by limited bone vascularization, biofilm formation, intracellular bacterial persistence, dysregulated host immune responses and reduced antibiotic delivery to the infection site, which promote chronic infection and recurrence. The limitations of conventional treatment strategies based on surgical debridement and prolonged systemic antibiotic therapy, together with their association with antimicrobial resistance and systemic toxicity, have led to growing interest in alternative and adjunctive therapeutic approaches. Local antibiotic delivery systems, such as polymethyl methacrylate, calcium sulfate, hydroxyapatite-based composites, hydrogels, antibiotic-impregnated bone grafts, and nanoparticle carriers, enable high local antimicrobial concentrations while minimizing systemic exposure. From a different therapeutic perspective, immunomodulatory strategies, including mesenchymal stem cell-based therapies, cytokine-targeted interventions, bacteriophages, quorum-sensing inhibitors, and non-antibiotic antimicrobials, represent emerging approaches aimed at improving infection control and supporting bone regeneration. Advances in biomarker profiling, molecular diagnostics, and artificial intelligence-assisted analyses further support personalized approaches to diagnosis, monitoring, and treatment. Despite encouraging early results, clinical translation remains limited by methodological and regulatory challenges, underscoring the need for integrated, innovative treatment strategies. Full article