Search Results (3,973)

Conventional antibiotic susceptibility testing (AST) primarily assesses planktonic bacteria. However, the three-dimensional architecture and barrier properties of biofilms mean that the minimum inhibitory concentration (MIC) for planktonic cells is typically far lower than the antibiotic exposure required for biofilm eradication. In this study, gelatin methacryloyl (GelMA) microspheres were used to create a three-dimensional biofilm microenvironment for the quantitative evaluation of biofilm tolerance. Escherichia coli K-12 MG1655 was immersed in GelMA microspheres and subjected to a series of antibiotic concentration gradients. Bacterial viability was inferred from time-dependent changes in microsphere diameter. The results demonstrated substantial tolerance of the resulting biofilms to ampicillin, ciprofloxacin, and ceftriaxone, with biofilm antibiotic tolerance values exceeding 200 μg/mL, 10–50 μg/mL, and 20–50 μg/mL, respectively. Relative to planktonic MICs, these tolerance levels are elevated by one to two orders of magnitude and surpass the standard clinical breakpoint thresholds. This methodology includes a high-throughput platform, involving only several hundred microspheres and achieving completion within 24 h, thereby offering a useful platform for investigating biofilm resistance mechanisms and guiding antibiotic treatment strategies. Full article

With accelerating urbanization, rivers have been severely polluted, resulting in widespread black and odorous waterways. The coagulation–sedimentation and contact oxidation bypass treatment process is characterized by low operational cost and simple operation and management. In this study, a coagulation–sedimentation–contact oxidation biofilter process was developed to treat heavily polluted malodorous blackwater. Among the tested biofilm carriers, rigid aramid fiber exhibited the fastest biofilm formation and the best pollutant removal performance. Based on a comprehensive evaluation of effluent quality and treatment capacity, the optimal operating conditions of the proposed process were identified as a PAC dosage of 50 mg/L, an air-to-water ratio of 7:1, and a hydraulic retention time (HRT) of 2 h. Under these conditions, the effluent concentrations of chemical oxygen demand (COD), ammonia nitrogen (NH₄⁺-N), and suspended solids (SSs) were consistently maintained below 30, 5, and 5 mg/L, respectively. Moreover, the optimized system demonstrated strong resistance to shock loading, maintaining stable operation at influent COD and SS concentrations of approximately 150 mg/L and 40 mg/L, respectively, while complying with the Class A Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants. This study provides an efficient treatment strategy for malodorous blackwater remediation. Full article

The intensification of aquaculture practices has been accompanied by an increased incidence of bacterial diseases, leading to a greater reliance on antibiotics for disease control. Consequently, the widespread and often indiscriminate use of these compounds has contributed to the emergence and dissemination of antibiotic-resistant bacteria within aquaculture systems, posing a serious threat to animal health, environmental sustainability, and public health. In this regard, research efforts have focused on developing alternative strategies to reduce antibiotic use. Natural compounds have gained particular attention due to their well-documented antimicrobial and antibiofilm activities. In this context, the combined application of antibiotics and natural compounds has emerged as a promising approach to enhance antimicrobial efficacy while potentially mitigating the development of resistance. This review synthesizes the current knowledge on antibiotic resistance in aquaculture, highlights the role of biofilm formation as a key resistance mechanism, and critically examines the potential of antibiotic–natural compound combinations against major aquaculture pathogens, with particular emphasis on bacterial growth inhibition, biofilm disruption, and virulence attenuation. Collectively, the evidence discussed underscores the potential of synergistic strategies as a sustainable tool for improving disease management in aquaculture while supporting efforts to limit antibiotic resistance. 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

Zinc (Zn), a ubiquitous environmental transition metal primarily existing as Zinc ions (Zn²⁺), plays a critical role in various biological processes. Its extensive application in agriculture, industry, and healthcare has led to significant environmental contamination. However, the mechanistic contribution of Zn²⁺ to bacterial antibiotic resistance and virulence remains insufficiently understood. This review explores the sources, cycling, and environmental accumulation of Zn²⁺ in a One Health context, emphasizing their impact on bacterial antibiotic resistance and virulence. Zn²⁺ promote bacterial antibiotic resistance by regulating efflux pumps, biofilm formation, expression and transfer of antibiotic resistance genes, as well as synergistic effects with other heavy metals and antibiotics. Meanwhile, Zn²⁺ promote bacterial virulence by regulating quorum sensing, secretion and metal homeostasis systems, as well as oxidative stress response and virulence factor expression. Additionally, it highlights the potential of targeting Zn homeostasis as a strategy to combat environmental antibiotic resistance. Collectively, these findings provide key insights into the mechanisms by which Zn²⁺ regulate bacterial antibiotic resistance and pathogenicity, offering valuable guidance for developing strategies to mitigate the global threat of antibiotic resistance. Full article

Staphylococcus aureus is a major opportunistic pathogen responsible for a wide spectrum of human infections, including severe and difficult-to-treat cases. The emergence of multidrug-resistant strains limits the efficacy of conventional antibiotic therapies and poses a significant global public health challenge. In this context, the search for novel antibiotics has intensified, with increasing interest in marine resources, an ecosystem still largely underexplored. Marine bacteria produce a vast array of secondary metabolites with unique structures and potentially novel modes of antibacterial action. Several compounds isolated from marine bacterial strains have demonstrated promising activity against multidrug-resistant S. aureus, including antivirulence effects such as biofilm formation and Quorum-Sensing inhibition. This review explores the potential of marine bacteria as a source of new antibiotics against S. aureus, discusses both classical and advanced strategies for the discovery of bioactive molecules, and highlights the scientific and technological challenges involved in translating these findings into clinical applications. Full article

Bifidobacterium animalis subsp. lactis is a widely used probiotic, yet its efficacy is highly strain-specific, and growing antibiotic resistance necessitates rigorous safety evaluations. We used whole-genome sequencing and in vitro assays to characterize the safety and probiotic traits of infant feces-sourced strain BD1, which shows preliminary mood-modulating and anti-inflammatory potential. The BD1 genome showed a favorable safety profile. VFDB analysis identified 139 low-similarity homologs, with no major toxins detected. Only four chromosomally encoded antibiotic resistance genes were found; phenotypic testing confirmed resistance solely to tetracycline and mupirocin. Although the tetracycline resistance gene tet(W) was identified in genomic island GI01, the absence of associated mobile genetic elements results in a negligible risk of its mobilization. Functional annotation highlighted a dominant metabolic capacity for carbohydrate and amino acid metabolism. BD1 is rich in CAZymes, enabling superior utilization of diverse substrates (starch, sucrose, galactose). Enrichment in lipid metabolism pathways (glycerolipid, sphingolipid) further suggests potential for enhancing fermented product flavor. In vitro assessment demonstrated moderate gastrointestinal tolerance and strong bile salt tolerance. Surface properties showed pronounced cell surface hydrophobicity and confirmed biofilm-forming potential. In conclusion, BD1 exhibits robust safety, metabolic versatility, and strong probiotic characteristics, supporting its development as a functional probiotic strain. Full article

Background/Objectives: Stenotrophomonas maltophilia is an opportunistic pathogen causing severe infections, particularly in patients with cystic fibrosis (CF). Its intrinsic multidrug resistance and biofilm-forming capacity complicate treatment. Although biofilms are generally associated with antimicrobial tolerance, the relationship between biofilm formation and planktonic antibiotic resistance in S. maltophilia remains poorly understood. This study investigated the association between antibiotic resistance profiles and biofilm production in clinical isolates from CF and non-CF patients. Methods: A total of 86 clinical isolates (40 from CF airways and 46 from non-CF patients) were analyzed. Susceptibility to seven antibiotics was assessed by disk diffusion, and multidrug resistance profiles were defined using standard criteria. Biofilm formation was quantified after 24 h using a crystal violet microtiter plate assay and categorized by using a semiquantitative scale. Results: High resistance rates were observed, particularly to meropenem (87.2%), ciprofloxacin (80.2%), and rifampicin (72.1%). CF isolates exhibited significantly higher resistance to piperacillin/tazobactam and a greater prevalence of multidrug resistance. Biofilm formation was detected in 94.2% of isolates, with strong or powerful producers predominating. However, CF isolates formed significantly less biofilm than non-CF isolates. Notably, resistance to piperacillin/tazobactam and meropenem was associated with reduced biofilm biomass and a lower proportion of high biofilm producers. Across all isolates, an inverse correlation was observed between the number of antibiotic resistances and biofilm biomass. These trends persisted after stratification by clinical origin, although some comparisons did not reach statistical significance. Conclusions: This study reveals an unexpected inverse relationship between planktonic antibiotic resistance and biofilm-forming capacity in S. maltophilia. Enhanced biofilm production may represent an alternative persistence strategy in more antibiotic-susceptible strains, with important implications for infection management and therapeutic failure. Full article

Adherent-invasive E. coli (AIEC) is closely related to inflammatory bowel disease (IBD). However, its pathogenic mechanism has not yet been fully elucidated. Using a BLASTP search, we discovered that the amino acid sequence of a putative protein (UFP37798.1) in the AIEC LF82 strain is highly homologous to some regulators in the SlyA family. We named it EruA. We displayed the secondary structures of EruA using bioinformatics, overexpressed the His₆-tagged EruA protein using SDS-PAGE, and dissected the genetic organization of the eruA chromosomal region using 5′RACE. We constructed an eruA deletion mutant (ΔeruA) and a complementary strain (CΔeruA) of the LF82 strain. The transcriptomes of wild-type (WT) and ΔeruA bacteria were compared using RNA sequencing and qRT-PCR, thereby identifying 32 differentially expressed genes (DEGs). Based on YASARA software and EMSA analysis, EruA directly binds to the consensus sequences (P_fimA and P_tnaB) in the promoter region of the fimA and tnaB genes from these DEGs. By using a super-resolution confocal microscope (SCM), counting CFUs of colonies on plates, indole quantification, and crystal violet staining of biofilms adhered to tubes or 96-well plates, we found that EruA activates the fimA to promote bacterial adhesion to intestinal epithelial cells and activates the tnaB to enhance bacterial indole production and biofilm formation. Moreover, EruA helps AIEC resist environmental stress and enhances bacterial survival within macrophages as well as loading in mouse tissues. Notably, EruA promotes AIEC colonization in the colons of mice and exacerbates intestinal inflammation caused by bacterial infection in mice with DSS-induced inflammatory colitis, manifested by weight loss, colon length shortening, and pathological changes in colon tissues. Therefore, EruA plays a key role in the pathogenicity of AIEC. Full article

Background: Antifungal resistance among Candida species and related genera, coupled with the lack of new drugs, poses a significant threat to public health. Several studies have demonstrated a relationship between virulence factors and resistance. Current objectives include identifying new targets and searching for new natural molecules. Carvacrol, a natural phenolic compound, has been shown to have antimicrobial properties; however, its impact on the virulence of species other than Candida albicans and related yeast genera remains underexplored. Methods: The antifungal activity of carvacrol was evaluated against clinical isolates of Candidozyma auris, Meyerozyma guilliermondii, and Candida dubliniensis, as well as its effect on adhesion, hydrophobicity, biofilm formation and osmotic stress tolerance. In vivo activity was assessed using the Galleria mellonella infection model at MIC concentrations. Results: Carvacrol inhibited adherence and significantly reduced both early and preformed biofilms in M. guilliermondii and C. dubliniensis. In C. auris, the compound produced a modest reduction in biofilm activity but significantly enhanced larval survival in the in vivo model (~20%, p < 0.01). Carvacrol also induced increased tolerance of C. auris to osmotic stress, suggesting activation of adaptive pathways. Conclusions: Carvacrol exhibits species-specific effects, acting as an antivirulence modulator in M. guilliermondii and C. dubliniensis and attenuating virulence in vivo in C. auris. These findings support the potential of carvacrol as an adjuvant antifungal strategy, particularly against C. auris, and highlight the relevance of targeting virulence traits to reduce selective pressure and limit antifungal resistance. Full article

Currently, the increased incidence of invasive fungal infections globally is posing a significant challenge to public health. Due to drug resistance issues, the clinical efficacy of existing antifungal drugs is seriously insufficient, while new drug development progresses slowly. Consequently, there is an urgent need to discover and develop novel antifungal therapeutics. Natural products have the characteristics of wide sources and few adverse reactions and are one of the sources for developing antifungal drugs. Numerous studies have shown that many compounds isolated from plants and traditional Chinese medicine have antifungal activity and diverse antifungal mechanisms. Thymol, a monoterpene phenol compound from thyme (Lamiaceae), has multiple biological functions such as antibacterial, antioxidant, and anti-inflammatory. Recent research has found that thymol has strong antifungal activity, and its molecular mechanisms involve cell membrane rupture, interference with cell wall synthesis, disruption of mitochondrial function and energy metabolism, inhibition of biofilm, inhibition of virulence factor expression, inhibition of key enzymes, and induction of cell apoptosis. This review aimed to summarize the antifungal activity of thymol and the underlying molecular mechanisms, safety, and potential clinical applications. Emerging technologies in thymol delivery systems and future research directions are also discussed. The comprehensive analysis aims to provide a detailed understanding of fungal infections and the role of thymol in antifungal treatment, offering insights for further research and clinical practice. Full article

Background/Objectives: Bacterial biofilms formed by Escherichia coli pose a significant challenge in veterinary medicine due to their intrinsic resistance to antibiotics. Antimicrobial peptides (AMPs) represent a promising alternative. AMPs exert their bactericidal activity by binding to negatively charged phospholipids in bacterial membranes via electrostatic interactions, leading to membrane disruption and rapid cell lysis. Methods: In vitro assays including MIC determination, biofilm eradication testing (crystal violet, colony counts, and CLSM), swimming motility, and EPS quantification were performed. CRISPR/Cas9 was used to construct and complement a kduD mutant. A transposon mutagenesis library was screened for biofilm-defective mutants. In an in vivo murine excisional wound infection model treated with the mouse cathelicidin-related antimicrobial peptide (CRAMP-34), wound closure and bacterial burden were monitored. Gene expression changes were analyzed via RT-qPCR. Results: CRAMP-34 effectively eradicated pre-formed biofilms of a clinically relevant, porcine-origin E. coli strain and promoted wound healing in the murine infection model. We conducted a genome-wide transposon mutagenesis screen, which identified kduD as a critical gene for robust biofilm formation. Functional characterization revealed that kduD deletion drastically impairs flagellar motility and alters exopolysaccharide production, leading to defective biofilm architecture without affecting growth. Notably, the anti-biofilm activity of CRAMP-34 phenocopied aspects of the kduD deletion, including motility inhibition and transcriptional repression of a common set of biofilm-related genes. Conclusions: This research highlights CRAMP-34 as a potent anti-biofilm agent and unveils kduD as a previously unrecognized regulator of E. coli biofilm development, which is also targeted by CRAMP-34. Full article

Changes in preservation conditions act as an important environmental filter driving shifts in microbial communities. However, the precise identities, functional traits, and ecological mechanisms of the dominant agents driving stage-specific deterioration remain insufficiently characterized. This study investigated microbial communities and dominant fungal degraders in waterlogged versus dried bamboo slips using amplicon sequencing, multivariate statistics, and microbial isolation. Results revealed compositionally distinct communities, with dried slips sharing only a small proportion of operational taxonomic units (OTUs) with waterlogged slips, while indicating the persistence of a subset of taxa across preservation states. A key discovery was the dominance of Fonsecaea minima (92% relative abundance) at the water-solid-air interface of partially submerged slips. Scanning electron microscopy (SEM) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) indicate that this fungus forms melanin-rich, biofilm-like surface structures, suggesting enhanced surface colonization and stress resistance. In contrast, the fungal community isolated from dried slips was characterized by Apiospora saccharicola associated with detectable xylanase activity. Meanwhile, the xerophilic species Xerogeomyces pulvereus dominated (99% relative abundance) the storage box environment. Together, these results demonstrate that preservation niches select for fungi with distinct functional traits, highlighting the importance of stage-specific preservation strategies that consider functional traits rather than taxonomic identity alone. Full article

Methicillin-resistant Staphylococcus aureus (MRSA), a major global public health threat due to its broad resistance, urgently requires the development of new antibiotic alternatives. (‒)‒Epigallocatechin-3-gallate (EGCG) is considered a natural bioactive compound with anti-MRSA properties. The L-Lectin module of serine-rich adhesin for platelets (SraP) is considered an important target for blocking MRSA-infected hosts. This study aims to investigate the mechanism of action of EGCG against MRSA. Surface plasmon resonance (SPR), cell adhesion and invasion, biofilm formation, checkerboard assays, RNA sequencing (RNA-seq) and quantitative real-time polymerase chain reaction (qRT-PCR) were performed. The results showed that EGCG bound to SraP L Lectin with high affinity and effectively inhibited MRSA colonization. Additionally, EGCG significantly suppressed pyrimidine metabolism and downregulated related genes, thereby potentially inhibiting bacterial growth. It also markedly reduced the expression of multiple genes associated with β-lactam resistance and inhibited biofilm formation. A strong synergistic effect was observed between EGCG and the bactericidal agent ceftriaxone (CRO). When combined with 10 μg/mL EGCG, CRO required 75% less dosage and exhibited a prolonged antimicrobial effect. In conclusion, EGCG exerts anti-MRSA effects through multiple pathways and represents a promising candidate as an alternative therapeutic agent against MRSA infections. 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