Search Results (335)

Salmonella is a major foodborne pathogen, yet real-time data on duck-derived strains in China remain scarce. This study investigated the epidemiology, antimicrobial resistance (AMR), gene profiles, and PFGE patterns of 114 Salmonella isolates recovered from 397 deceased ducks (2021–2024) across nine provinces (isolation rate: 28.72%). Fourteen serotypes were identified, with S. Typhimurium (23.68%), S. Indiana (21.93%), S. Kentucky (18.42%), and S. Enteritidis (12.28%) being predominant. Most isolates showed high resistance to β-lactams, tetracyclines, quinolones, and sulfonamides, with extensive multidrug resistance (MDR) observed—especially in S. Indiana, S. Typhimurium, and S. Kentucky. Among the 23 detected resistance genes, tet(B) had the highest prevalence (75.44%), particularly in S. Indiana. Biofilm formation was observed in 99.12% of isolates, with 84.21% demonstrating moderate to strong capacity. Eighteen virulence genes were detected; S. Enteritidis carried more spvB/C, sipB, and sodC1, while S. Indiana had higher cdtB carriage. PFGE revealed substantial genetic diversity among strains. This comprehensive analysis highlights the high AMR and biofilm potential of duck-derived Salmonella in China, emphasizing the urgent need for enhanced surveillance and control measures to mitigate public health risks. Full article

Background/Objectives: Hemodialysis catheter-related bloodstream infection (HD-CRBSIs) is a main cause of morbidity in hemodialysis. New preventive strategies have emerged, such as using lock solutions with antiseptic or antibiotic capacity. In this study, the antimicrobial effect was analyzed in vitro and with a catheter model of lock solutions of gentamicin (LSG), gentamicin/heparin (LSG/H), and gentamicin/citrate (LSG/C) in clinical and ATCC strains of Pseudomonas aeruginosa and Staphylococcus aureus. Methods: The formation, minimum inhibitory concentration, and minimum inhibitory concentration of the biofilm and minimum biofilm eradication concentration of the lock solutions were determined. Additionally, colony-forming unit assays were performed to evaluate the antimicrobial efficacy of the lock solutions in a hemodialysis catheter inoculation model. Results: The minimum inhibitory concentration (MIC) of planktonic cells of both P. aeruginosa and S. aureus for LSG/H and LSG/C was 4 µg/mL. In the minimum biofilm inhibitory concentration (MBIC) tests, the LSG/H was less effective than LSG/C, requiring higher concentrations for inhibition, contrary to the minimum biofilm eradication concentration (MBEC), where LSG/H was more effective. All lock solutions eradicated P. aeruginosa biofilms in the HD catheter model under standard conditions. Nevertheless, under modified conditions, the lock solutions were not as effective versus ATCC and clinical strains of S. aureus. Conclusions: Our analysis shows that the lock solutions studied managed to eradicate intraluminal mature P. aeruginosa in non-tunneled HD catheters under standard conditions. Biofilm inhibition and eradication were observed at low gentamicin concentrations, which could optimize the gentamicin concentration in lock solutions used in HD catheters. Full article

Heavy metal pollution represents a pervasive environmental challenge that significantly exacerbates the ever-increasing crisis of antimicrobial resistance and the capacity of microorganisms to endure and proliferate despite antibiotic interventions. This review examines the intricate relationship between heavy metals and AMR, with an emphasis on the underlying molecular mechanisms and ecological ramifications. Common environmental metals, including arsenic, mercury, cadmium, and lead, exert substantial selective pressures on microbial communities. These induce oxidative stress and DNA damage, potentially leading to mutations that enhance antibiotic resistance. Key microbial responses include the overexpression of efflux pumps that expel both metals and antibiotics, production of detoxifying enzymes, and formation of protective biofilms, all of which contribute to the emergence of multidrug-resistant strains. In the soil environment, particularly the rhizosphere, heavy metals disrupt plant–microbe interactions by inhibiting beneficial organisms, such as rhizobacteria, mycorrhizal fungi, and actinomycetes, thereby impairing nutrient cycling and plant health. Nonetheless, certain microbial consortia can tolerate and detoxify heavy metals through sequestration and biotransformation, rendering them valuable for bioremediation. Advances in biotechnology, including gene editing and the development of engineered metal-resistant microbes, offer promising solutions for mitigating the spread of metal-driven AMR and restoring ecological balance. By understanding the interplay between metal pollution and microbial resistance, we can more effectively devise strategies for environmental protection and public health. Full article

Salmonella is one of the main causes of food-borne illness worldwide. In most cases, Salmonella contamination can be traced back to food processing plants and/or to cross-contamination during food preparation. To avoid food-borne diseases, food processing plants use sanitizers and biocidal to reduce bacterial contaminants below acceptable levels. Despite these preventive actions, Salmonella can survive and consequently affect human health. This study investigates the adaptive capacity of the main Salmonella enterica serotypes isolated from the poultry production line, focusing on their replication, antimicrobial resistance, and biofilm formation under stressors such as acidic conditions, oxidative environment, and high osmolarity. Using growth curve analysis, crystal violet staining, and microscopy, we assessed replication, biofilm formation, and antimicrobial resistance under acidic, oxidative, and osmotic stress conditions. Disinfectant tolerance was evaluated by determining the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of sodium hypochlorite. The antibiotic resistance was assessed using the Kirby–Bauer method. The results indicate that, in general, acidic and osmotic stress reduce the growth of Salmonella. However, no significant differences were observed specifically for serotypes Infantis, Heidelberg, and Corvallis. The S. Infantis isolates were the strongest biofilm producers and showed the highest prevalence of multidrug resistance (71%). Interestingly, S. Infantis forming biofilms required up to 8-fold higher concentrations of sodium hypochlorite for eradication. Furthermore, osmotic and oxidative stress significantly induced biofilm production in industrial S. Infantis isolates compared to a reference strain. Understanding how Salmonella responds to industrial stressors is vital for designing strategies to control the proliferation of these highly adapted, multi-resistant pathogens. Full article

Objectives: Cefideroccol (FDC) is a siderophore cephalosporin with potent antibacterial activity against a wide range of Gram-negative multidrug-resistant (MDR) microorganisms. We investigated the anti-biofilm capacity of FDC against clinical strains. Methods: This multicenter study was conducted on 28 selected strains of MDR Gram-negative bacilli isolated from clinical samples of Pseudomonas aeruginosa (n = 5), Acinetobacter baumannii (n = 11), and Klebsiella pneumoniae (n = 12). We first determined the minimum inhibitory concentration (MIC) of each strain using the microdilution method. We also defined the minimum biofilm inhibitory concentration (MBIC) as a ≥50% reduction in tetrazolium salt (XTT) (as recommended in the 2017 Spanish Microbiology Protocols [SEIMC] for the microbiological diagnosis of infections related to the formation of biofilms). We also analyzed the reduction in the following biofilm variables after an 8 mg/mL FDC treatment: the CFU count, the cell viability, the biomass, the metabolic activity, and extracellular α or β polysaccharides. Results: The MIC₅₀ and MBIC₅₀ of FDC were 0.5 mg/L and 64 mg/L, respectively. We observed a mean (SD) fold increase in the susceptibility to FDC between planktonic and sessile cells for P. aeruginosa, A. baumannii, and K. pneumoniae of 9.60 (0.55), 6.27 (2.28), and 6.25 (2.80), respectively. When 8 mg/mL of FDC was tested, we observed that the best median (IQR) percentage reductions were obtained for cell viability and the extracellular matrix (73.1 [12.4–86.5] and 79.5 [37.3–95.5], respectively), particularly for P. aeruginosa. The lowest percentage reduction rates were those obtained for biomass. Conclusions: We demonstrated that the susceptibility to FDC was significantly reduced when strains were in a biofilm state. The best percentage reduction rates for all biofilm-defining variables were observed for P. aeruginosa. Our results need to be validated using a larger collection of clinical samples. Full article

Background/Objectives: There is an increasing incidence of fungal infections in conjunction with the rise in resistance to medical treatment. Antimicrobial resistance is frequently associated with virulence factors such as adherence and the capacity of biofilm formation, which facilitates the evasion of the host immune response and resistance to drug action. Novel therapeutic strategies have been developed to overcome antimicrobial resistance, including the use of different type of nanomaterials: metallic (Au, Ag, Fe₃O₄ and ZnO), organic (e.g., chitosan, liposomes and lactic acid) or carbon-based (e.g., quantum dots, nanotubes and graphene) materials. The objective of this study was to evaluate the action of nanoparticles of different synthesis and with different coatings on fungi of medical interest. Methods: Literature research was conducted using PubMed and Google Scholar databases, and the following terms were employed in articles published up to June 2025: ‘nanoparticles’ in combination with ‘fungal biofilm’, ‘Candida biofilm’, ‘Aspergillus biofilm’, ‘Cryptococcus biofilm’, ‘Fusarium biofilm’ and ‘dermatophytes biofilm’. Results: The utilization of nanoparticles was found to exert a substantial impact on the reduction in fungal biofilm, despite the presence of substantial variability in minimum inhibitory concentration (MIC) values attributable to variations in nanoparticle type and the presence of capping agents. It was observed that the MIC values were lower for metallic nanoparticles, particularly silver, and for those synthesized with polylactic acid compared to the others. Conclusions: Despite the limited availability of data concerning the stability and biocompatibility of nanoparticles employed in the treatment of fungal biofilms, it can be posited that these results constitute a significant initial step. Full article

Klebsiella pneumoniae, a zoonotic pathogen of global concern, poses significant threats to both veterinary and public health. Here, a comparative study characterized 14 clinical isolates (7 avian-derived, 7 human-derived) from Jiangsu, China, through integrated genomic and phenotypic analyses. Firstly, multilocus sequence typing (MLST) revealed distinct epidemiological patterns: the same ST type in avian isolates was circulating between different species and different regions, whereas it was not found in human isolates. In addition, hypervirulent Klebsiella pneumoniae (hvKP) phenotypes confirmed by string test were exclusive to two human isolates (KP15, KP20). Secondly, biofilm detection demonstrated 78.6% (11/14) of isolates possessed biofilm-forming capacity, with cellulose but not curli as the predominant matrix component. Human-derived KP15 and KP20 had the strongest biofilm formation ability in all isolates. Antimicrobial susceptibility profiling identified serious multidrug resistance in both avian and human isolates. Virulence gene analysis revealed striking disparities, with human isolates harboring 10–20 virulence factors (median 15) versus 6–7 (median 6.5) in avian counterparts. Finally, functional pathogenesis assessments demonstrated human-derived strains exhibited stronger epithelial cell adhesion (2-fold higher) and invasion (1.97-fold higher) in Calu-3 cell models and paradoxically showed reduced macrophage phagocytosis (2.85-fold lower at 2 h) for immune escape. In vivo models confirmed dose-dependent mortality, with human isolates demonstrating higher lethality in both Galleria mellonella and mice. Virulence gene burden positively correlated with mortality outcomes. These findings delineate critical host adaptation differences in Klebsiella pneumoniae populations and provide empirical evidence for pathogen transmission dynamics at the human-animal interface. Full article

Cystic fibrosis (CF) is a life-limiting autosomal recessive disorder affecting a large number of individuals in Europe. The disease arises from mutations in the CFTR gene encoding the cystic fibrosis transmembrane conductance regulator, a chloride ion channel crucial for maintaining epithelial ion and fluid homeostasis. Dysfunctional CFTR disrupts mucociliary clearance, particularly in the respiratory tract, resulting in persistent bacterial colonization, chronic inflammation, and progressive pulmonary damage—ultimately leading to respiratory failure, the principal cause of mortality in CF patients. Early diagnosis and advances in therapy have substantially improved both survival and quality of life. A hallmark of CF pathology is the establishment of polymicrobial infections within the thickened airway mucus. Pseudomonas aeruginosa is the dominant pathogen in chronic CF lung infections and demonstrates a remarkable capacity for adaptation via biofilm formation, metabolic reprogramming, and immune evasion. Biofilms confer increased tolerance to antimicrobial agents and facilitate long-term persistence in hypoxic, nutrient-limited microenvironments. P. aeruginosa exhibits a wide range of virulence factors, including exotoxins (e.g., ExoU, ExoS), pigments (pyoverdine, pyochelin), and motility structures (flagella and pili), which contribute to tissue invasion, immune modulation, and host damage. During chronic colonization, P. aeruginosa undergoes significant genotypic and phenotypic changes, such as mucoid conversion, downregulation of acute virulence pathways, and emergence of hypermutator phenotypes that facilitate rapid adaptation. Persistent cells, a specialized subpopulation characterized by metabolic dormancy and antibiotic tolerance, further complicate eradication efforts. The dynamic interplay between host environment and microbial evolution underlies the heterogeneity of CF lung infections and presents significant challenges for treatment. Elucidating the molecular mechanisms driving persistence, hypermutability, and biofilm resilience is critical for the development of effective therapeutic strategies targeting chronic P. aeruginosa infections in CF. Full article

Staphylococcus aureus is one of the aetiological agents of mastitis in dairy cattle. Their biofilms are relevant for human and veterinary medicine. It has been shown that some antibiotics at low concentrations can stimulate the production of biofilms, but there is little information on the effects of low concentrations of nisin, which is considered a therapeutic agent and has been added to food products for years as a biopreservative. In our study, we used Staphylococcus aureus strains (n = 28) isolated from dairy cattle. The MIC of nisin were determined using the broth microdilution method. Based on the minimum inhibitory concentration (MIC) results, the following concentrations were selected for further analyses: nisin at 39, 19, 9 IU/mL; nisin in combination with tetracycline at 39 IU/mL + 0.06 μg/mL, 18 IU/mL + 0.06 μg/mL, and 9 IU/mL + 0.06 μg/mL; and tetracycline alone at 0.06 μg/mL. The biofilm-forming capacity was determined via crystal violet staining in 96-well plates, icaD gene expression was determined using the 2−ΔΔCt method, and microscopic evaluation was carried out using scanning electron microscopy. Results: The MICs were 156 IU/mL (46%) and 312 IU/mL (43%) for most strains. Due to large statistical deviations, there were no statistically significant changes in the biofilm-forming capacity or icaD gene expression despite a visible increasing trend. Despite the absence of statistically significant differences, it was observed that for all concentrations analysed biofilm formation was noticeably greater for both nisin alone and for tetracycline and its mixtures than for untreated cells. Conclusions: In our opinion, the effects of nisin, especially at low concentrations, on biofilm structure show a certain worrying trend that may pose a future threat. Full article

Background: During the COVID-19 pandemic, the emergence of multidrug-resistant (MDR) pathogens, driven by heightened antibiotic usage and device-associated infections, has posed significant challenges to healthcare. This study reports an outbreak of Proteus mirabilis producing NDM-5 and CTX-M-15 β-lactamases in a hospital in Buenos Aires, Argentina, from October 2020 to April 2021. To our knowledge, this represents the first documented outbreak of NDM-5-producing P. mirabilis in the country. Methods: A total of 82 isolates were recovered from 40 patients, with 41.5% from blood cultures and 18.3% from respiratory and urinary samples, among others. Antimicrobial susceptibility testing, PCR-based methods, and MALDI-TOF MS cluster analysis were conducted. Whole genome sequencing (WGS) was performed to characterize the MLST, resistome and plasmid content. Biofilm formation assays and in vitro rifampicin susceptibility tests were also conducted. Result: Most isolates exhibited resistance to carbapenems, cephalosporins, aminoglycosides, and fluoroquinolones, while retaining susceptibility to aztreonam. Genetic analysis confirmed the co-presence of the bla_NDM-5 and bla_CTX-M-15 genes. Clonal relationships was supported by PCR-based typing and MALDI-TOF MS cluster analysis. WGS revealed a resistome comprising 25 resistance genes, including rmtB and both β-lactamases, as well as the presence of an incomplete IncQ1 replicon associated with multiple resistance determinants. MLST classified this clone as belonging to ST135. Despite the biofilm-forming capacity observed across strains, rifampicin demonstrated potential for disrupting established biofilms at concentrations ≥32 µg/mL in vitro. The MDR profile of the outbreak strain significantly limited therapeutic options. Conclusions: This study highlights the growing threat of NDM-producing P. mirabilis in Argentina. The absence of surveillance cultures from the index case limits insights into the outbreak’s origin. These findings underscore the importance of integrating genomic surveillance into infection control protocols to mitigate the spread of MDR pathogens. Full article

This article investigates the antifungal activity of clove essential oil (CEO) against Candida albicans, as well as its inhibitory effects on C. albicans biofilm formation and the associated developmental processes. Furthermore, it evaluates the therapeutic efficacy of CEO in a mouse model of intestinal C. albicans infection and explores its impact on intestinal microbiota. Additionally, 16S rRNA high-throughput sequencing was conducted to analyze the alterations in the intestinal microbiota. The findings indicate that the administration of CEO in mice infected with C. albicans resulted in a normalization of body weight and an improvement in their symptoms. Histological analysis utilizing HE and PAS staining demonstrated that CEO exerted beneficial effects on the intestinal mucosal status of these infected mice. Furthermore, ELISA results revealed a dose-dependent reduction in the levels of IL-6, IL-8, and IL-17A within the small intestinal tissues of C. albicans-infected mice. Additionally, 16S rRNA gene analysis indicated that CEO effectively enhanced the richness and diversity within the intestinal microbiota of CEO treatment groups of mice that were investigated. Overall, CEO exhibits therapeutic potential against inflammation induced by intestinal C. albicans infection in mice. This effect can be attributed to its anti-inflammatory properties as well as its capacity to regulate the composition of intestinal flora. Full article

Overgrazing (OG) is an important driver of grassland ecosystem degradation and productivity decline. Plants may effectively cope with OG stress by regulating their synergistic interactions with plant growth-promoting rhizobacteria (PGPR) through root exudates. However, the synergistic regulatory mechanisms remain unclear. Under OG stress, Leymus chinensis recruited the specific PGPR strain Paraburkholderia graminis (B24) by regulating specific root exudate compounds, including amino acids, alkaloids, and organic acids, which enhance B24 chemotaxis and biofilm formation. The B24 inoculation systematically regulated the transcription of key plant growth and development genes, including those involved in nutrient transport and cell wall expansion, which enhanced nutrient uptake and promoted the overall growth of L. chinensis. Furthermore, B24 regulated the homeostasis of endogenous L. chinensis through the synergistic effects of hormones and the trade-off between growth and defense. Integrated transcriptomic and metabolomic analyses revealed that B24 regulation enhanced carbon and nitrogen metabolism, and energy supply after mowing, forming a holistic adaptive mechanism that enabled L. chinensis to effectively recover from mowing-induced stress, thereby improving its adaptability and regenerative capacity. This study provides a scientific basis and support for elucidating the response mechanisms of how grassland plants cope with OG stress, optimizing grassland management, and rapidly restoring and enhancing grassland productivity. Full article

Climate change and ocean warming have a huge impact on microbial communities, leading to an increased prevalence of Vibrio parahaemolyticus infections in northern America. V. parahaemolyticus is an inhabitant of aquatic environments and is associated with fishes and shellfishes, particularly with oysters. It causes gastrointestinal infection through consumption of contaminated seafood, as well as wound infections or septicemia. Temperature is known to affect virulence and persistence factors in V. parahaemolyticus. In this study, twenty clinical strains isolated form sick patients in Quebec, Canada, were characterized for persistence and virulence factor production at different temperatures to assess the impact of a switch from sea water to the human body on them. Their capacity to produce biofilm, hemolysins, and membrane vesicles as well as their motility and antibiotic resistance at 20 °C and 37 °C were assessed. Our results revealed that while temperature had little effect on vesicle production, it significantly influenced their growth, antimicrobial resistance, biofilm formation, and motility. Additionally, all V. parahaemolyticus strains produced hemolysins at 37 °C but not under environmental conditions. Full article

The antimicrobial and antibiofilm efficacy of two Ocimum basilicum L., essential oils sourced from Colombia (BEOC) and Italy (BEOI), was evaluated against multidrug-resistant fish isolates of Salmonella enterica subsp. salamae, Bacillus thuringiensis, and Bacillus oceanisediminis—species for which such activity has not been previously reported. Using a fish-based model system (FBMS), we found that BEOI, rich in linalool (69.86%), exhibited stronger antimicrobial activity than camphor-dominated BEOC (24.61%). The antimicrobial effects of both EOs were strain- and concentration-dependent, with minimum bactericidal concentration (MBC) 3.75–15.0 µL/mL for BEOI and 15.0–30.0 µL/mL for BEOC. Pure linalool showed even greater potency (MBC: 0.0125 to 0.025 µL/mL). Confocal laser scanning microscopy revealed that BEOI induced severe membrane damage (27% of the cells within 1 h), ultimately leading to the death of 96% of the cells after 24 h. Biofilm formation, assessed in both FBMS and tryptone soy broth (TSB), was strain-dependent, with FBMS promoting higher biofilm production than TSB. Moreover, significant differences in biofilm morphotypes were observed, with the morphotype PDAR (pink dry and rough), characterized by only cellulose, being the most frequently exhibited by the strains (7/15), while BDAR (brown dry and rough), characterized by only curli, was the least expressed (7/15); the remaining strains presented morphotype RDAR. In addition, the strains in polystyrene surfaces accumulated more biomass than stainless steel 304. Notably, BEOI and linaool significantly reduced biofilm formation across all strains, with a reduction of 90% in S. enterica subsp. salamae strains (TJC19 and TJC21. These strains with the RDAR phenotype likely contribute to their strong biofilm-forming capacity. Our findings highlight BEOI’s potential as a natural anti-biofilm agent in food processing environments, offering a promising strategy to combat multidrug-resistant bacteria biofilm-related challenges in the food industry. Full article

The treatment of proctological conditions, including hemorrhoids, anal fissures, and perianal abscesses, is often complicated by bacterial infections, particularly those involving multidrug-resistant Escherichia coli. This study presents the synthesis, characterization, and biological evaluation of the newly designed synthetic peptide AMPEC4, inspired by cytotoxin 5 from Naja ashei snake venom. AMPEC4 demonstrated potent antimicrobial properties with MIC values of 100 and 200 µg/mL, effectively inhibiting biofilm formation (up to 84%) and eradicating the pre-formed biofilm by up to 35%. The antibacterial activity of AMPEC4 was further supported by a membrane permeabilization assay, demonstrating its capacity to disrupt bacterial membrane integrity in a dose-dependent manner. Furthermore, AMPEC4 significantly promoted fibroblast migration, a critical step in tissue regeneration, while exhibiting notable biocompatibility, as evidenced by the absence of hemolytic, cytotoxic, and genotoxic effects. By addressing both infection control and tissue regeneration, AMPEC4 represents a promising therapeutic strategy for managing chronic wounds, particularly in the challenging environment of the anorectal region. Its ability to target Escherichia coli reference and clinical strains while accelerating the wound-healing process underscores its potential for future clinical applications. Full article