Search Results (226)

Background: Enterococcus faecalis is a major cause of complicated urinary tract infections (UTIs), characterized by intrinsic resistance and pronounced biofilm formation. Nitroxoline (NTX), a metal-chelating uroantiseptic, accumulates in urine and exhibits antibiofilm activity. Hydroquinone (HQ), the active urinary metabolite of arbutin-containing herbal preparations, is also excreted into urine and may contribute to antimicrobial activity in situ. This study investigated the antimicrobial and antibiofilm effects of NTX and HQ, individually and in combination, against uropathogenic E. faecalis isolates. Methods: Minimum inhibitory (MIC), bactericidal (MBC), and anti-adhesion (MAC) concentrations were determined using broth microdilution. Interaction was assessed by the checkerboard method and expressed as the fractional inhibitory concentration index (FICI). Biofilm inhibition was quantified by colony-forming unit (CFU) enumeration following exposure to subinhibitory concentrations. Ultrastructural alterations of E. faecalis following exposure to NTX and HQ were examined by transmission electron microscopy (TEM). Results: NTX demonstrated MIC values ranging from 0.002–0.016 mg/mL (MIC50/MIC90: 0.004/0.008 mg/mL), while HQ exhibited MIC values of 0.78–1.56 mg/mL (MIC50/MIC90: 0.78/1.56 mg/mL). Synergistic interactions (FICI ≤ 0.5) were observed in selected isolates, with up to eightfold and sixteenfold reductions in NTX and HQ concentrations, respectively. Additive effects predominated in the remaining isolates without antagonism. The combination achieved 3–5 log₁₀ reductions in adherent bacterial counts compared to untreated controls and up to 4 log₁₀ reductions compared to single-agent exposure. In several strains, complete inhibition of adhesion was observed. TEM analysis revealed marked envelope disruption, cytoplasmic condensation, and structural collapse following combined treatment. Conclusions: Given that both NTX and HQ are active within the urinary environment, their combination may represent a pharmacologically relevant strategy targeting both bacterial growth and early biofilm establishment in enterococcal UTIs. These findings support further in vivo and pharmacokinetic investigations to evaluate the clinical applicability of this combination. 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

Bacterial membrane vesicles (BMVs) are non-replicative, bilayered nanostructures secreted by both Gram-negative and Gram-positive bacteria. Rather than being passive byproducts of cell envelope turnover, BMVs are increasingly recognized as regulated particles that selectively package proteins, lipids, nucleic acids, and other bioactive molecules. Through these cargos, BMVs mediate a wide range of biological processes, including bacterial stress adaption, intercellular communication, virulence delivery, and host immune modulation. In this review, we integrate recent advancements in understanding the molecular mechanisms underlying BMV biogenesis and composition and discuss how their heterogeneity contributes to their functional diversity. Beyond their biological roles, we critically examine the translational potential of BMVs in vaccine development, targeted drug delivery, cancer therapy, diagnostic tools, and biotechnological applications. However, significant challenges related to their safety, efficacy, and large-scale production must be addressed to realize their full clinical potential. We review recent progress and ongoing obstacles in the use of BMVs across various biomedical applications and propose strategies for their clinical translation. Full article

Staphylococcus aureus is a major cause of skin and soft tissue infections, necessitating the development of new topical agents with rapid bactericidal activity and low resistance potential. Here, we evaluated the antibacterial activity of a pyrazolone copper complex (P-FAH-Cu-phen) against S. aureus, investigated its in vitro mode of action, and its assessed therapeutic efficacy in a murine model of S. aureus-infected skin trauma. P-FAH-Cu-phen exhibited potent bactericidal activity (minimum inhibitory concentration [MIC] 1.4 μg/mL; minimum bactericidal concentration [MBC] 2.8 μg/mL) and rapid killing (>91% eradication within 2.5 min), with no detectable MIC increase under the tested serial passaging conditions. Cell-envelope dysfunction was evidenced by increased supernatant alkaline phosphatase activity, elevated leakage of nucleic acids and proteins, and reduced membrane-associated Na⁺/K⁺- and Ca²⁺/Mg²⁺-ATPase activities. At sub-inhibitory concentrations, P-FAH-Cu-phen reduced haemolytic and coagulase activities, modulated virulence gene expression (sea, hla, agrA), and inhibited biofilm formation and biofilm-associated metabolic activity. In vivo, topical treatment accelerated wound closure and histopathological repair, increased hydroxyproline content, reduced bacterial burden, and lowered TNF-α and IL-10 levels in wound tissues. Collectively, P-FAH-Cu-phen shows multi-faceted anti-infective activity and exhibits further development as a topical candidate for S. aureus-infected skin wounds. Full article

Background/Objectives: The mycobacterial complex cell envelope serves as a formidable barrier against host immunity and antibiotics. Lipomannan (LM) and lipoarabinomannan (LAM) are key structural components of the mycobacterial envelope and potent immunomodulators. The mycobacterial lipoarabinomannan biosynthesis mannosyltransferase MptC modifies the multiple α-(1→2)-linked branched mannan residues of LAM in the mycobacteria. However, the role of MptC in mycobacterial infectivity, antibiotic susceptibility and host immune regulation remains poorly understood. Methods: An mptC (also named MSMEG_4247) knockout Mycobacterium smegmatis mc²-155 (M. smeg) strain (designated as M. smegΔmptC) was generated using CRISPR–Cas12a technology. The effects of MptC on bacterial physiology, cell wall permeability, drug sensitivity, immune cell function, and survival during infection are analyzed through glycogen staining, drug sensitivity tests, and cellular and mouse infection models. Results: MptC deficiency results in a loss of LM and increase in LAM synthesis. The M. smegΔmptC mutant strain exhibits enhanced cell wall permeability and reduces hydrophobicity. Functionally, the mptC knockout strain increases the intracellular cytokines (IFN-γ, TNF-a and IL-17) production of T cells in mice. Consequently, results based on both macrophage and mouse infection models demonstrate that the M. smegΔmptC strain has less bacterial loads and higher susceptibility to antibiotic rifampicin. Conclusions: Mannosyltransferase MptC plays an important role in maintaining cell wall integrity (via LM/LAM synthesis), regulating T cell responses, and influencing antibiotic susceptibility in mycobacteria. Full article

Lipopolysaccharides (LPSs) are key components of the bacterial outer envelope, determining its structural integrity, barrier properties, and interactions with the surrounding environment. This review analyzes the relationship between the molecular architecture of LPSs and their physicochemical properties. Particular attention is being paid to the organization of LPS-containing supramolecular assemblies, including bacterial outer membranes, bilayers, micelles, and LPS brushes. The review further focuses on theoretical frameworks employed to describe LPS layers and discusses the physical meaning of the parameters involved in these models. The simulations involve a wide range of approaches starting from all-atom molecular treatment and up to polymer and colloidal approaches. When considering these models, we focus on the relationships between parameters that are addressed at each level of modeling. It is shown that biological functions such as membrane stability and bacterial adhesion are largely governed by the molecular organization of LPS. This structure–property relationship provides a basis for predicting the performance of anti-adhesive biomaterials, antimicrobial strategies, and bactericidal agents. Full article

The persistent emergence of infectious diseases has underscored the critical demand for next-generation vaccine technologies that are safe, effective, and scalable. This review explores virus biomimetic delivery systems, focusing on virus-like particles (VLPs) and virosomes as promising platforms for vaccine and therapeutic development. VLPs are self-assembled nanostructures composed of viral structural proteins that mimic native virions without carrying genetic material, while virosomes are reconstituted viral envelopes that retain functional glycoproteins but lack a nucleocapsid. Both systems provide strong immunogenicity and safety by mimicking viral architecture while eliminating the risk of replication. The paper examines various expression platforms for VLP production, including bacterial, yeast, insect, mammalian, and plant-based systems, highlighting their respective advantages, challenges, and optimization strategies. Mechanistic insights into antigen presentation, immune activation, and cellular uptake pathways are discussed to explain their superior performance in eliciting humoral and cellular immune responses. Furthermore, current applications of VLPs and virosomes in vaccines against major pathogens such as SARS-CoV-2, influenza, Newcastle disease virus, malaria, hepatitis, and respiratory syncytial virus are reviewed, demonstrating their versatility and clinical potential. By integrating molecular engineering, nanotechnology, and biofabrication strategies, virus biomimetic systems represent a transformative frontier in vaccinology, immunotherapy, and targeted drug delivery. Full article

The multiple-transferable resistance protein (MtrR) is a transcriptional repressor of the mtrCDE-encoded drug efflux pump and Type IV pilus biosynthesis (pilM), and an activator of penicillin-binding protein 1 (ponA) expression in Neisseria gonorrhoeae. Previously published microarray data suggested that MtrR is also an activator of ltgA expression in the gonococcus. LtgA is a lytic transglycosylase responsible for approximately half of recycled peptidoglycan fragments and released peptidoglycan-derived cytotoxins, which cause ciliary damage and induce specific inflammatory responses. The fragments generated by LtgA during peptidoglycan remodeling can either be recognized by the permease AmpG for uptake into the bacterial cytoplasm and recycled for new cell wall growth and general metabolism or released into the external milieu. Therefore, we sought to define the capacity of MtrR to regulate LtgA expression in gonococci. We show that MtrR binds to the ltgA promoter region in a concentration-dependent manner, and that this binding results both in increased ltgA mRNA transcription and LtgA protein levels during exponential growth. Deletion of mtrR in N. gonorrhoeae decreased peptidoglycan monomer release from growing cells and increased autolysis. These results suggest that MtrR regulation of ltgA impacts peptidoglycan-derived cytotoxin release and autolysis in the gonococcus. This study suggests a central role of MtrR in coordinating aspects of the cellular envelope that may contribute to gonococcal pathogenesis. Full article

The global challenge of antimicrobial resistance (AMR) has been framed primarily in terms of genetic resistance mechanisms. Nevertheless, bacteria can also survive antimicrobial stress through phenotypic plasticity, resulting in transient, non-genetic states such as tolerance, persistence, and population-level resilience. These phenotypic states complicate diagnostic efforts, diminish antibiotic efficacy, and contribute to the chronic nature of infections even in the absence of heritable resistance. This review evaluates phenotypic plasticity as a significant yet underrecognized factor in AMR, with a focus on responses to oxidative and photodynamic stress. Key manifestations of plasticity are discussed, including morphological and metabolic remodeling such as filamentation, small-colony variants, and metabolic rewiring, as well as envelope- and biofilm-associated heterogeneity and regulatory flexibility mediated by gene networks and horizontal regulatory transfer. The review highlights plastic responses elicited by reactive oxygen species-mediated stress and antimicrobial photodynamic inactivation, where single-cell heterogeneity, biofilm and mucus barriers, and light-dependent cues influence bacterial survival. Case studies are presented to demonstrate how photodynamic strategies can induce transient protective states and act synergistically with antibiotics, revealing mechanisms of action that extend beyond conventional single-target therapeutic models. Drawing on evidence from single-cell analyses, biofilm ecology, and experimental evolution, this review establishes phenotypic plasticity as a central element in the chemical biology of AMR. Enhanced understanding of plasticity is essential for advancing diagnostics, informing the development of adjuvant therapies, and predicting bacterial responses to novel antimicrobial interventions. Full article

Gloves, used in conjunction with hand hygiene, are designed to protect healthcare personnel from direct contact with blood, body fluids, and other potentially infectious materials, which is critical for reducing the transmission of microorganisms. The aim of this systematic review was to analyze available studies on the disinfection of disposable, non-sterile gloves as a method of reducing the risk of microbial contamination in everyday clinical practice. A systematic review was conducted in the fourth quarter of 2025. A total of 317 records were initially retrieved from the five databases (EBSCO, PubMed, Scopus, Web of Science, Ovid). Interventions included alcohol-based hand rubs (ABHR), sodium hypochlorite wipes or solutions, quaternary ammonium wipes, and sporicidal ethanol. Across all studies, glove disinfection consistently reduced bacterial, viral, and spore contamination. Hypochlorite-based agents and sporicidal ethanol demonstrated the highest efficacy against spore-forming organisms such as Clostridioides difficile. Alcohol-based hand rubs were effective against bacteria and enveloped viruses but showed reduced activity against non-enveloped viruses and spores. Conclusions from studies conducted in both laboratory and clinical conditions clearly emphasize the key role of hand hygiene after removing gloves, even when using multiple layers of protection, while also indicating that glove disinfection can be a useful supplement to protection against particularly virulent pathogens (EVD, CDI). Full article

Background: Vibrio harveyi is a major bacterial pathogen threatening turbot aquaculture, necessitating the development of more effective vaccines. Bacterial ghosts (BGs), which are empty bacterial envelopes with preserved surface antigens, offer a promising alternative to traditional formaldehyde-killed vaccines that often suffer from reduced immunogenicity. Methods: We developed an optimized BGs vaccine for V. harveyi by combining the nonionic surfactant NP-40 with sodium hydroxide (NaOH). This NP-40/NaOH combination demonstrated a synergistic lytic effect, halving the minimum inhibitory concentration of NaOH required for complete inactivation. Results: The resulting BGs exhibited intact cellular morphology with transmembrane pores, efficient removal of cytoplasmic contents, and significantly better preservation of lipopolysaccharide structure compared to NaOH-alone treatment. Vaccination trials in turbot demonstrated that the NP-40/NaOH BGs provided the highest relative percent survival (RPS = 58.8%) upon challenge, outperforming both NaOH-alone BGs (RPS = 55.0%) and a traditional formaldehyde-killed vaccine (RPS = 34.8%). The superior protection was correlated with the induction of a more robust and sustained immune response, characterized by significantly higher levels of specific IgM antibodies, elevated lysozyme activity, and increased total serum protein. Conclusions: This study establishes the NP-40/NaOH protocol as an effective strategy for producing high-quality BGs with enhanced immunogenicity, presenting a potent vaccine candidate for controlling vibriosis in aquaculture. Full article

Background: The current rise in multidrug-resistant pathogens highlights the urgent need for the discovery of novel antibacterial agents with potential clinical applications. A considerable proportion of these developed resistances may be attributable to the intrinsic response of bacteria to antibiotic-induced stress conditions in the environment. Consequently, the identification and characterization of genetic alterations in physiological processes in response to antibiotics represent promising strategies for the discovery and characterization of naturally produced novel antibacterial agents. This study investigated the antimicrobial activity of an antimicrobial active isolate Actinomadura coerulea derived from a meerkat fecal sample. Methods: The production of secondary metabolites that potentially compromise bacterial cell wall integrity was confirmed by the induction of promoter activity in whole-cell biosensors in which an antibiotic-inducible promoter was fused to the luciferase cassette. During plate-based biosensor assays, we identified naturally resistant Bacillus subtilis colonies growing in the zone of inhibition around A. coerulea colonies. After these successive rounds of selection, highly resistant spontaneous B. subtilis mutants had evolved that were subjected to whole-genome sequencing. Results: Non-silent mutations were identified in pssA, which encodes a phosphatidylserine synthase; mdtR, as a gene for the repressor of multidrug resistance proteins, and yhbD, whose function is still unknown. A new cinnamycin-like molecule, coerumycin, was discovered based on the physiological role of PssA and comprehensive genomic analysis of A. coerulea. Additional experiments with cell extracts containing coerumycin as well as the cinnamycin-like compound duramycin confirmed that the interaction between coerumycin and the bacterial cell envelope is inhibited by a loss-of-function mutation in pssA. Conclusion: Our approach demonstrates that combining the exploration of niche habitats for actinomycetes with whole-cell biosensor screening and characterization of natural resistance development provides a promising strategy for identifying novel antibiotics. Full article

Klebsiella oxytoca has emerged as an important opportunistic pathogen in nosocomial infections, particularly during the COVID-19 pandemic, due to its capacity to acquire and disseminate resistance and virulence genes through horizontal gene transfer (HGT). This study presents a genome-based comparative analysis of K. oxytoca within the genus Klebsiella, aimed at exploring the evolutionary plausibility of outer membrane vesicle (OMV) associated processes in bacterial adaptation. Using publicly available reference genomes, we analyzed pangenome structure, phylogenetic relationships, and the distribution of mobile genetic elements, resistance determinants, virulence factors, and genes related to OMV biogenesis. Our results reveal a conserved set of envelope associated and stress responsive genes involved in vesiculogenic pathways, together with an extensive mobilome and resistome characteristic of the genus. Although these genomic features are consistent with conditions that may favor OMV production, they do not constitute direct evidence of functional OMV mediated horizontal gene transfer. Instead, our findings support a hypothesis generating evolutionary framework in which OMVs may act as a complementary mechanism to established gene transfer routes, including conjugation, integrative mobile elements, and bacteriophages. Overall, this study provides a genomic framework for future experimental and metagenomic investigations into the role of OMV-associated processes in antimicrobial resistance dissemination and should be interpreted as a recently identified evolutionary strategy inferred from genomic data, rather than a novel or experimentally validated mechanism. Full article

Astroviruses are non-enveloped, positive-sense single-stranded RNA viruses known to infect various mammals and birds, including humans, often causing gastrointestinal disorders. In recent years, astroviruses have also been linked to neurological and respiratory diseases across several species, including ruminants, mink, deer, and other mammals. Notably, astrovirus infections in goats have been documented in countries such as Switzerland and China, where novel genotypes have been identified in fecal samples. However, their role in the context of disease remains unclear, and reports focusing solely on goat astrovirus in the United States have not been published. A necropsy case of a Boer goat kid with a history of diarrhea was submitted for investigation following death in January 2025. Fresh tissues were received and used for histopathology and enteric pathogen testing, including parasitic, bacterial, and viral workups. Metagenomic-based next-generation sequencing (mNGS) was also applied for this case. Histological examination revealed severe necrotizing enterocolitis. The small intestine exhibited epithelial ulcerations, villus atrophy, hyperplastic and dilated crypts with necrotic debris, few intraenterocytic coccidian parasites, and increased inflammatory cells in the lamina propria. The large intestine showed similar findings with pleomorphic crypt enterocytes. Standard enteric pathogen tests were negative except for aerobic culture that identified Escherichia.coli and Enterococcus hirae. mNGS and bioinformatic analysis identified a novel astrovirus in the intestinal content that showed the highest nucleotide identity (86%) to the sheep strain Mamastrovirus 13 sheep/HA3 from China based on BLAST analysis. Phylogenetic analysis indicated that the newly identified caprine astrovirus IL90175 clustered with astrovirus strains from small ruminants in Asia and Europe. This research reports the discovery, histopathologic features, and genetic characteristics of a gastrointestinal disease-causing astrovirus in a goat kid, which had not been previously described in the United States. Full article

Salmonella typhimurium is a global foodborne pathogen, and controlling its persistence is critical for public health. This study investigated the regulatory role of the PhoP/PhoQ two-component system (TCS) in biofilm formation under the acid adaptation condition. A phoP deletion strain (ΔphoP) was constructed and compared with the wild type (WT) after acid induction (pH 5.4). Without acid adaptation, ΔphoP and WT showed similar acid tolerance and biofilm formation. However, after acid induction, ΔphoP exhibited markedly reduced biofilm formation, swimming ability, metabolic activity, and extracellular polymer production. RNA-seq analysis further revealed defects in ΔphoP under acid-induced conditions: (i) first leads to downregulation of lipopolysaccharide biosynthesis, peptidoglycan synthesis, and cationic antimicrobial peptide resistance pathways, thereby weakening the bacteria’s envelope modification capacity and structural stability; (ii) it also disrupts signal regulations in acidic environments, further impairing energy metabolism, flagellar function, and chemotaxis, thereby affecting bacterial adhesion capacity and environmental adaptability. These results demonstrate that under acid adaptation, the PhoP/PhoQ TCS is critical for coordinating cell envelope remodelling, energy metabolism, and motility to support biofilm formation in S. typhimurium. Understanding the contribution of this system to biofilm formation is essential for addressing the stress resistance and persistence of Salmonella in the food industry. Full article