Search Results (7,809)

Antimicrobial resistance is a serious global public health concern, with Acinetobacter baumannii recognized as one of the most problematic multidrug-resistant (MDR) pathogens. This Gram-negative bacterium is highly persistent in the environment, possesses a remarkably adaptable cell envelope, and forms biofilms. As the effectiveness of conventional antibiotics declines, alternative strategies are being actively explored, particularly membrane-targeting approaches based on synthetic copolymers. These compounds mimic antimicrobial peptides, offer enhanced stability and structural tunability, and have a lower propensity to develop resistance. Recent advances in polymer chemistry have led to the design of antibacterial polymers with activity against MDR A. baumannii. Some of these act synergistically with existing antibiotics, restoring bacterial susceptibility or disrupting biofilms. However, their non-degradability remains a concern due to its potential implications for body/environment accumulation and related toxicity and/or selection of resistant strains. This review examines the biology of the A. baumannii cell envelope, its resistance mechanisms, and treatment limitations, while emphasizing the promise of membrane-active copolymers. By bridging materials science and microbiology, these approaches offer promising strategies for combating World Health Organization priority pathogens. Full article

Background: The increasing prevalence of multidrug-resistant bacterial infections highlights the need for drug-delivery strategies that improve antimicrobial exposure and sustain therapeutic activity. In this study, ciprofloxacin-loaded nanostructured lipid carriers (NLC-CIP) were developed and evaluated to better understand how formulation-dependent release behavior influences antibacterial performance against Escherichia coli. Methods: NLC-CIP were prepared and characterized in terms of size, polydispersity, encapsulation efficiency, and colloidal stability. In vitro release profiles were evaluated across different pH conditions, followed by kinetic modeling. Stability under refrigerated storage was assessed. Antibacterial performance was determined through IC₅₀ measurements and dynamic growth-kinetic analyses, while cytotoxicity was evaluated in HepG2 cells. Results: Ciprofloxacin incorporation increased hydrodynamic diameter (~116 to 194 nm) while preserving low polydispersity (PdI~0.04), high colloidal stability, and encapsulation efficiency (96%). Release studies showed medium-dependent behavior, with rapid release at pH 1.2, 4.5, and 7.4, and more sustained profile at pH 6.8, consistent with diffusion-controlled kinetics (Weibull model). Refrigerated storage preserved release profiles while slowing early-stage kinetics. NLC-CIP showed improved apparent antibacterial activity, reducing the IC₅₀ from 4.9 to 1.2 ng/mL, and sustained bacterial suppression by decreasing growth rates and prolonging doubling times. Unloaded NLCs showed no antibacterial activity, and cytotoxicity assays confirmed favorable biocompatibility. Conclusion: Overall, these results show that NLC-based encapsulation can modulate ciprofloxacin release and reshape drug exposure over time, thereby improving antibacterial performance under the tested conditions. This study supports integrated release and growth-kinetic analyses as a more informative framework for evaluating lipid-based antibiotic delivery systems. Full article

Baicalin, a natural plant-derived compound, holds promise in addressing clinical bacterial resistance when combined with antibiotics. This study evaluated the antibacterial activity of the combination of baicalin and cefotaxime and explored its mechanism of action on the cell wall and biofilm of multidrug-resistant Pseudomonas aeruginosa (MRPA). The results showed that the combination of baicalin and cefotaxime exerted a synergistic inhibitory effect on the growth of MRPA, with a fractional inhibitory concentration index (FICI) of 0.28. Mechanistically, compared with cefotaxime alone, the combination of baicalin and cefotaxime enhanced the permeability of the cell membrane and cell wall of MRPA, thereby increasing cell damage. It also exhibited stronger antibiofilm activity by inhibiting numerous virulence factors (pyocyanin, elastase, lectin), reducing cellular metabolic activity, and downregulating the expression of biofilm genes (pslA, pelA, algD) and quorum-sensing genes (lasl, lasR, rhll, rhlR, pqsA, pqsR). The molecular docking results revealed that baicalin could stably bind to wbpE, LasR, and RhlR. Therefore, this interaction may indirectly influence the processes related to antibiotic resistance and biofilm formation in bacterial cells. Metabolomic analysis revealed that the combination of baicalin and cefotaxime upregulated 863 metabolites and downregulated 587 metabolites. These metabolites mainly included amino acids, lipids, nucleotides, carbohydrates, and secondary metabolites. The combination primarily enriched key pathways such as amino acid metabolism, lipid metabolism (sphingolipid metabolism) and secondary metabolite biosynthesis. Through these pathways, it triggers significant metabolic reprogramming, thereby interfering with the supply of cell wall synthesis precursors, membrane structural stability, and the generation of biomembrane matrix. Ultimately, it synergistically enhances the effects of cell wall damage and biomembrane inhibition. In conclusion, this study confirms that the combination of baicalin and cefotaxime exerts significant synergistic antibacterial activity against MRPA. It also reveals the mechanism of action of the combination on the cell wall and biofilm of MRPA at the metabolic level, providing theoretical support for the development of novel strategies to combat MRPA. Full article

In 2023, the European Centre for Disease Prevention and Control surveillance report highlighted an increasing number of carbapenem-resistant Escherichia coli isolates carrying the less common bla_NDM-5 variant in Europe. The aim of this study was to investigate the molecular epidemiology of NDM-producing (New Delhi metallo-β-lactamase) E. coli isolates collected in Croatia over a one-year period. A total of 160 carbapenemase-producing E. coli isolates were reported through national surveillance in Croatia between March 2023 and March 2024. Whole-genome sequencing was performed on 22 NDM-producing E. coli isolates. Phylogenetic analysis identified 17 sequence types, indicating high diversity and polyclonal spread. High variability in resistome profiles and co-occurrence of resistance genes across multiple antimicrobial classes indicate multidrug resistance. The predominant bla_NDM variant was bla_NDM-1 (77.27%), followed by bla_NDM-5 (22.73%). Co-occurrence of bla_NDM with extended-spectrum β-lactamase (ESBL) encoding genes was detected in 12/22 isolates (54.55%). Plasmid analysis identified 22 different replicon types, with IncFII (54.54%) and IncA/C2 (45.45%) being the most frequent. Our findings provide insights into the molecular epidemiology of NDM-producing E. coli at the national level, highlighting the presence of the bla_NDM-5 variant. These results emphasize the need for genomic surveillance and strengthened infection control strategies to better understand and limit its spread. Full article

Background/Objectives: Central line-associated bloodstream infections (CLABSIs) remain a leading healthcare-associated infection in intensive care units (ICUs), yet independent risk factors and evidence-based catheter duration thresholds have not been defined through analytical study designs in settings with endemic multidrug-resistant organisms (MDROs). Methods: A retrospective case–control study was conducted in the ICU of a tertiary teaching university hospital in western Türkiye (January 2019–December 2024). Cases (n = 74) were patients with confirmed CLABSIs per CDC/NHSN criteria; controls (n = 148) were randomly selected central venous catheter (CVC)-bearing patients without CLABSIs. A reduced multivariate logistic regression model (seven variables; events-per-variable ratio 10.6) identified independent risk factors. Results: In multivariate analysis, catheter duration (adjusted OR: 1.19 per day; 95% CI: 1.13–1.24; p < 0.001), renal replacement therapy (aOR: 3.66; 95% CI: 1.68–7.95; p = 0.001), vasopressor support (aOR: 3.04; 95% CI: 1.50–6.17; p = 0.002), APACHE-II score (aOR: 1.07 per point; 95% CI: 1.02–1.11; p = 0.002), lower Glasgow Coma Scale (aOR: 0.86 per point; 95% CI: 0.78–0.94; p = 0.002), mechanical ventilation (aOR: 2.48; 95% CI: 1.24–4.95; p = 0.010), and total parenteral nutrition (aOR: 2.33; 95% CI: 1.12–4.86; p = 0.024) were independently associated with CLABSI. The model demonstrated good discrimination (C-statistic: 0.864) and calibration (Hosmer–Lemeshow p = 0.425). Kaplan–Meier analysis showed CLABSI-free survival declining from 98.9% at day 7 to 42.9% at day 21 (log-rank p < 0.001); these within-study estimates reflect relative risk patterns given the artificial 1:2 case-to-control ratio. Receiver operating characteristic (ROC) analysis identified day 13 as an exploratory optimal cutoff (AUC: 0.818; 95% CI: 0.762–0.874; sensitivity: 77.0%; specificity: 74.3%). CLABSI-attributable ICU mortality was 20.3% (47.3% vs. 27.0%; p = 0.004). Late-onset CLABSIs (>10 days) were dominated by Gram-negative pathogens (68.3%) versus 35.7% in early-onset infections (Fisher’s exact p = 0.012), with Acinetobacter baumannii as the predominant organism (27.0%; 83.3% carbapenem-resistant). Conclusions: Each additional catheter-day is independently associated with a 19% increment in CLABSI odds, with an exploratory critical threshold at day 13 beyond which enhanced surveillance measures should be considered, pending external validation. Full article

The rapid emergence of antibiotic-resistant bacteria represents one of the most critical challenges in modern healthcare and has stimulated intense research into alternative antimicrobial strategies. Antibacterial hydrogels have emerged as versatile biomaterials due to their high water content, tunable physicochemical properties, and ability to function as multifunctional platforms for drug delivery and tissue regeneration. This review analyzes recent advances in antibacterial hydrogel systems through a conceptual framework based on three complementary pillars: biological antibacterial agents, inorganic functional components, and structural material engineering. Biological strategies, particularly bacteriophage-based approaches, provide highly specific antibacterial activity capable of targeting multidrug-resistant pathogens and disrupting bacterial biofilms. Inorganic components such as hydroxyapatite nanoparticles contribute additional functionalities including drug adsorption, modulation of the ionic microenvironment, and osteoconductive behavior relevant for bone-related infections. Structural design strategies based on electrospinning enable the fabrication of fibrous architectures that enhance mechanical stability, regulate therapeutic release, and mimic extracellular matrix organization. The integration of these three pillars within multifunctional hydrogel platforms offers promising opportunities for developing advanced antibacterial biomaterials capable of addressing infection control while supporting tissue regeneration. Full article

Antimicrobial resistance (AMR) represents one of the major threats to global health, driven by the indiscriminate use of antibiotics and decline in the development of new therapeutic agents. In this context, essential oils (EOs) have emerged as innovative natural alternatives due to their broad-spectrum antimicrobial activity and low potential to induce bacterial resistance. However, their clinical application is limited by their volatility, low chemical stability, and rapid degradation. The incorporation of EOs into electrospun natural polymer fibers has emerged as an effective strategy to overcome these limitations, improving their stability, enabling controlled release, and enhancing their antimicrobial efficiency. This review focuses on the use of electrospun natural polymers for biomedical applications, highlighting their biocompatibility, biodegradability, and ability to mimic the extracellular matrix, thereby promoting cell interaction. Additionally, their high surface area and porous structure facilitate efficient encapsulation and controlled release of bioactive compounds. Recent advances in the development of these systems against clinically relevant multidrug-resistant pathogens are analyzed, along with the antimicrobial mechanisms of EOs. Finally, the factors influencing encapsulation and release efficiency, as well as the main challenges and future perspectives for clinical translation, are discussed. Full article

Polyamines, putrescine, spermidine and spermine, are essential polycationic metabolites present in all eukaryotic cells, where they regulate fundamental processes including nucleic acid stabilization, translation, and stress responses. Spermidine synthase (SPDS), a member of the aminopropyltransferase (APT) family, catalyzes the transfer of an aminopropyl group from decarboxylated S-adenosylmethionine (dc-SAM) to putrescine to form spermidine. Although genomic analyses predict the presence of SPDS homologs in multiple fungal species, polyamine biosynthesis has not been experimentally characterized in the multidrug-resistant fungal pathogen Candidozyma auris. Here, we report the biochemical and functional characterization of the C. auris spermidine synthase, CauSpe3. The CauSPE3 gene complemented a Saccharomyces cerevisiae spe3Δ mutant demonstrating conserved function in vivo. Recombinant CauSpe3 was expressed in Escherichia coli, purified and analyzed using the fluorescence-based DAB-APT assay, which uses 1,2-diacetylbenzene (DAB) for polyamine detection. CauSpe3 catalyzed efficient conversion of putrescine to spermidine in the presence of dc-SAM, with K_half values of 65.5 ± 7.11 µM for putrescine and 66.9 ± 2.09 µM for dc-SAM, and V_max values of 7.1 ± 0.57 and 7.9 ± 0.12 nmol·µg⁻¹·min⁻¹, respectively. A catalytic-site mutant and heat-inactivated enzyme showed no detectable activity, and product formation was confirmed by means of thin-layer chromatography and mass spectrometry. These findings establish CauSpe3 as a functional spermidine synthase. 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

Background/Objectives: The emergence of antimicrobial-resistant (AMR) pathogens in aquaculture ecosystems poses a significant risk to both food security and human health. Shewanella species are recognized as significant AMR reservoirs, yet their prevalence and resistance mechanisms within a shrimp-related ecosystem remain poorly characterized. This study aimed to perform a genotypic and phenotypic characterization of S. algae VK101, isolated from wild-caught black tiger shrimp (Penaeus monodon) broodstock. Methods: A complete 5.21 Mb genome was generated using a hybrid Illumina and Oxford Nanopore sequencing approach. Antimicrobial susceptibility was evaluated for 21 antibiotics via Minimum Inhibitory Concentration (MIC) testing. Comparative pangenomics and genome-wide association studies (GWAS) across 125 S. algae genomes were conducted to identify novel resistance determinants. Results: MIC analysis revealed that VK101 was resistant to ampicillin (>16 µg/mL) and colistin (8 µg/mL), while showing intermediate susceptibility to imipenem and ciprofloxacin. In silico analysis identified 205 antimicrobial resistance genes (ARGs), including a perfect hit for the fluoroquinolone resistance gene qnrA3. Notably, no mcr genes were detected. Although VK101 exhibited moderate resistance (8 µg/mL), GWAS across the broader S. algae population linked a specific lptA mutation (K140N) to high-level resistance (64 µg/mL). Other GWAS-identified genes (e.g., czcA, ampC, and oprM) likely represent indirect associations driven by genetic linkage or clade-specific markers rather than direct causal factors. Conclusions: These findings highlighted the presence of multidrug-resistant S. algae in wild-caught P. monodon broodstock, reflecting the occurrence of antimicrobial resistance in aquatic environments. Colistin resistance in these isolates was primarily mediated by chromosomal variants rather than mobile mcr elements, indicating the need for integrated genomic surveillance within the aquaculture value chain. Full article

The high prevalence of biofilm-associated multidrug-resistant (MDR) Escherichia coli infections in older adults calls for novel control strategies. This study compared fecal E. coli carriage, antimicrobial resistance, and biofilm formation among community-dwelling older adults with different self-reported immune statuses (lower vs. normal), and evaluated the antibiofilm activity of five Lactobacillus cell-free supernatants (CFSs). Fecal samples from 20 older adults were analyzed. E. coli was enumerated, and isolates were characterized for antimicrobial susceptibility and biofilm formation. Five Lactobacillus strains were screened for antibiofilm activity using crystal violet assay, with further evaluation of extracellular polymeric substance (EPS) production and biofilm morphology. After removing the redundant isolates, 70 isolates were reported, with significantly higher counts in the lower-immunity group (7.89 vs. 6.04 log MPN/g). The lower-immunity group had significantly higher antimicrobial resistance (97.3% vs. 60.6%), and higher MDR prevalence (91.7% vs. 24.2%). Biofilm formation was observed in 62.9% of isolates, with significantly higher prevalence among MDR isolates and in the lower-immunity group. L. paracasei L475 CFS showed the strongest antibiofilm activity against a representative MDR isolate (L5-1), with inhibition and eradication rates of 82.9% and 75.0%, respectively. Mechanistically, L475 CFS reduced extracellular polymeric substance components, with a 92.3% reduction in proteins and 41.3% in polysaccharides. Microscopy confirmed disrupted biofilm architecture, membrane damage, and cell lysis. In conclusion, these preliminary findings indicate a potential association between self-reported immune function and E. coli resistance/biofilm formation in older adults. L. paracasei L475 CFS demonstrates promising in vitro antibiofilm activity against an MDR E. coli isolate from this population, supporting its potential as a postbiotic candidate. Full article

Camel-associated antimicrobial resistance (AMR) is an underrecognized component of the One Health landscape, particularly in the Gulf Cooperation Council (GCC) and North Africa. Available evidence demonstrates the presence of clinically significant resistance mechanisms in camel populations, including extended-spectrum beta-lactamases, carbapenemases, colistin resistance genes, and multidrug-resistant clones. Molecular similarities between camel and human isolates suggest potential cross-species transmission and highlight camels as possible reservoirs within interconnected human–animal–environment systems. Despite documented resistance patterns, camel production systems remain largely excluded from national AMR surveillance and stewardship frameworks. This gap reflects limited camel-specific data on antimicrobial usage and structural challenges related to pastoral mobility, cross-border trade, and emerging commercial intensification. Strengthening diagnostic capacity, implementing tailored antimicrobial stewardship strategies, and integrating camels into national AMR action plans are essential to mitigate potential public health risks. Proactive inclusion of camel systems within regional AMR governance frameworks is necessary to prevent further amplification of resistance. Full article

Silver nanoparticles (AgNPs) are widely recognized for their potent antibacterial properties and diverse biomedical applications. While conventional synthesis methods typically rely on chemical-reducing agents that may pose risks to human health and the environment, this study proposes an eco-friendly green synthesis approach utilizing porcine skin extracts. The extracts were prepared through thermal treatment and filtration to serve as a biological reducing agent. Successful synthesis was validated using dynamic light scattering, Fourier transform infrared (FTIR) spectroscopy, UV–Vis spectroscopy, and scanning electron microscopy (SEM). Furthermore, the antimicrobial efficacy of the synthesized AgNPs was evaluated against multidrug-resistant microorganisms, demonstrating significant growth inhibition across various antibiotic-resistant strains. These findings suggest that porcine skin—a readily available bioresource—is a promising precursor for the sustainable production of AgNPs with broad-spectrum antimicrobial potential. Full article

Multidrug-resistant (MDR) Salmonella enteritidis infections cause high mortality and devastating economic losses in poultry, pose severe threats to animal health and food safety, and create an urgent demand for effective antibiotic alternatives. Herein, we developed a cationic liposome-encapsulated bacteriophage endolysin Lys40 (designated Lys40-Lip), and systematically evaluated its therapeutic efficacy in a chick model challenged with Salmonella enteritidis strain S4. Recombinant Lys40 was encapsulated into cationic liposomes with an encapsulation efficiency (EE) of 34.83%. The resulting Lys40-Lip nanoparticles had a hydrodynamic diameter of 137.3 ± 4.1 nm, a high positive zeta potential of +42.5 ± 0.3 mV, and excellent stability, retaining 78.52% of its initial bactericidal activity after 56 days of storage at 4 °C. Following a three-day oral treatment in Salmonella enteritidis S4-infected chicks, Lys40-Lip significantly increased survival rates in a dose-dependent manner (72.22% to 88.89% for low-to-high dose vs. 44.44% in infected controls, p < 0.05) and reduced ileal Salmonella enteritidis S4 colonization by 28.8% compared to free Lys40. Histopathology revealed Lys40-Lip restored duodenal villus integrity and reduced jejunal and ileal inflammation. Serum cytokine analysis confirmed that Lys40-Lip effectively regulated the host inflammatory response, significantly downregulating the pro-inflammatory cytokines IL-1β and IL-6, and upregulating the anti-inflammatory cytokine IL-10. Crucially, liposomal encapsulation overcame the outer membrane barrier of Gram-negative bacteria via charge-driven fusion mediated by its high positive surface potential (+42.5 ± 0.3 mV), enabling targeted delivery of Lys40 without the need for EDTA or other outer membrane permeabilizers. Lys40-Lip significantly improved the therapeutic outcomes of avian salmonellosis via synergistic direct bactericidal activity, intestinal barrier protection and inflammatory response regulation, offering a promising nanotherapeutic strategy for the control of this disease in veterinary practice. Full article

To date, the problem of mastitis in cattle remains relevant for both the industrial sector and scientific research. Despite numerous active investigations, the causes of this disease have not been fully established. It is postulated that several factors may be involved, such as bacterial pathogens, animal husbandry practices, and weather and climatic conditions. In this study, we selected cows from farms in Yakutia to investigate microbial isolates present in the milk of cows affected by mastitis and treated with antibiotics. Five identified Staphylococcus aureus isolates were investigated using whole-genome sequencing (Illumina sequencing and nanopore sequencing), followed by analysis of virulence factors in the genomes and cultural properties of the isolates. The profile of S. aureus virulence genes (exotoxins, cytotoxins, superantigen-like proteins, adhesins) was identified via WGS. Hemolysin gene (hla) was detected in all isolates. An investigation of the cultural properties of the isolates, specifically through hemolysis of rabbit erythrocytes and Western blot analysis of the culture liquid of S. aureus, revealed different expression levels of alpha-hemolysin among the strains. One isolate (17-21) exhibited the highest secretion level of about 320 ± 37 ng, both in the hemolysis test and immunoblotting assay. An investigation of the isolates’ antibiotic resistance showed that all isolates exhibited multidrug resistance, as confirmed by the presence of antibiotic resistance genes in these isolates. One isolate (7-7) exhibited the broadest range of phenotypic resistance and was resistant to all tested antibiotics (except clindamycin). Phylogenetic analysis suggested that the evolution of these isolates occurred independently in their respective ecological niches, although their transfer from cattle to humans, and vice versa, is possible. Isolates 7-7, 18-22, 33-40, and 35-42 are most typical to Yakutian cattle, while isolate 17-21 might have been introduced from a different region. To the best of our knowledge, this is the first in-depth study into a range of S. aureus isolates associated with mastitis infection in Yakutian cattle. Full article