Search Results (4,669)

Listeria monocytogenes is a high-risk pathogenic bacterium associated with ready-to-eat foods and poses a potential threat to consumer health. This study aimed to investigate the prevalence, characterization and genetic diversity of L. monocytogenes in ready-to-eat raw salmon and trout products obtained from physical stores and online stores in China. Out of 150 samples analyzed, 23 (15.3%) were positive for L. monocytogenes. Among these positive samples, three (12%) were from Japanese restaurants, four (16%) from farmers markets, one (2.9%) from large supermarkets and fifteen (30%) from e-commerce platforms, and only one sample showed a contamination level exceeding 100 most probable number (MPN)/g. The isolates from positive samples demonstrated a concrete public health risk through several findings: twenty-three L. monocytogenes exhibited varying degrees of cytotoxicity, ranging from 7.6% to 71.8%. Compared with the reference strain ATCC 19115, five of these isolates were highly cytotoxic, a result that was validated by mouse survival rate experiment, which also confirmed their high virulence at tested dose. All isolates were resistant to cefuroxime sodium, ceftriaxone, cefepime and nalidixic acid, and 13% showed resistance to sulphamethoxazole-trimethoprim. Three serogroups were identified, with serogroup Ⅰ.1 (1/2a, 3a) being the most prevalent (65.2%). These isolates were grouped into eight sequence types, with ST8 (34.8%) and ST87 (30.4%) dominating. All isolates carried virulence genes associated with LIPI-1 andmultiple internalin genes (inlA, inlB, inlJ and inlK), confirming their potential pathogenicity. Additionally, the isolates harbored antimicrobial resistance genes lin and FosX. The five highly virulent isolates exhibited the highest genetic similarity to J2-031 (GCA_000438645.1) and C1-387 (GCA_000438605.1). The results provided valuable information for Chinese regulatory authorities to strengthen the risk monitoring of L. monocytogenes in ready-to-eat raw salmon and trout products. Full article

The human skin microbiome has gained considerable attention as a resource for the development of innovative probiotics for cosmetic purposes or promoting skin health. However, the evaluation of new probiotic strains to ensure their “generally recognized as safe” (GRAS) status remains challenging. Here, we have subjected the annotated draft genome sequences of four human skin-derived bacterial strains, namely Bacillus subtilis MBF10-19J, Micrococcus luteus MBF05-19J, Staphylococcus hominis MBF12-19J, and Staphylococcus warneri MBF02-19J, to bioinformatic analyses to detect the genes associated with important probiotic traits, as well as undesirable characteristics such as antibiotic resistance, virulence factors, and toxic metabolites. Each bacterium harbors at least one type of adhesin-encoding gene, while only S. hominis MBF12-19J and S. warneri MBF02-19J contain the putative genes encoding enzymes for metabolism improvement. In vitro assays, including antibiotic susceptibility and antimicrobial activity testing, revealed strain-specific safety characteristics that complement the genomic findings. With regard to antibiotic resistance determinants, S. hominis MBF12-19J showed the most favorable profile, S. warneri MBF02-19J and M. luteus MBF05-19J appeared suitable when used with appropriate caution, and B. subtilis MBF10-19J exhibited amoxicillin resistance, i.e., warrants careful evaluation. Further in vivo validation is needed to determine whether these strains do indeed comply with GRAS evaluation frameworks. Full article

Animal-derived E. faecium poses a public health risk due to its capacity to acquire antimicrobial resistance (AMR) and virulence genes. However, the pathogenicity and cross-host transmission potential of strains originating from unique environments, such as the Qinghai–Tibet Plateau, remain poorly understood. In this study, a strain of E. faecium was isolated from yak feces. We constructed a phylogenetic tree and identified AMR and virulence genes via whole-genome sequencing. Antimicrobial susceptibility testing was performed to determine its resistance phenotype. An in vivo mouse infection model was established to assess pathogenicity, and transcriptomic analysis was utilized to investigate the host’s molecular response mechanisms in infected intestinal tissue. The results indicated that this yak-derived strain is closely related to human clinical isolates, suggesting a risk of cross-host transmission. The strain harbored the AMR genes AAC(6′)-Ii, msrC, and eatAv and exhibited resistance to penicillin, kanamycin, erythromycin, and clindamycin. The strain harbored key virulence genes, such as bopD, Acm, and ClpP. Infection with this strain caused characteristic inflammatory damage in mouse intestinal tissue, as revealed by histopathological examination, including epithelial necrosis, vascular congestion, and inflammatory cell infiltration. Transcriptomics further delineated a complete “Recognition–Response–Damage” signaling axis: pathogen recognition through Toll-like receptors and NOD-like receptors activates the NF-κB and MAPK signaling pathways. This activation is accompanied by significant upregulation of various inflammatory factors and recruits immune cells via chemokine signaling, ultimately leading to tissue damage. Our findings provide insights into the pathogenic pathway of this strain from genetic determinants to phenotypic manifestations, providing a theoretical foundation for assessing the public health risk posed by animal-derived E. faecium and for developing targeted intervention strategies. Full article

Pseudomonas aeruginosa is an opportunistic pathogen commonly associated with nosocomial infections and environmental dissemination. Among its high-risk clones, ST244 is notable for its global distribution and distinctive genomic traits. This study reports whole-genome sequencing of ten ST244 isolates from hospitalized patients and wastewater in a healthcare complex in Southeastern Brazil. Genomic comparisons revealed a highly conserved clonal group, with nine isolates forming a tight monophyletic cluster based on rMLST, SNP phylogeny, and average nucleotide identity (>99.5%). One isolate showed close phylogenetic proximity to strains from Asia and North America, suggesting international dissemination. Serotype analysis revealed both O5 and O12 variants, indicating intra-lineage antigenic diversity. Resistance profiling identified multidrug-resistant phenotypes carrying carbapenemase genes (bla_OXA-494, bla_OXA-396) and diverse insertion sequences (ISPa1, ISPa6, ISPa22, ISPa32, and ISPa37), facilitating horizontal gene transfer. Virulence gene analysis showed conserved elements related to adhesion, iron uptake, secretion systems, and quorum sensing, while the cytotoxin gene exoU was absent. These results highlight clonal persistence, possible intra-hospital transmission, and links to globally circulating ST244 sublineages. Our findings underscore the importance of genomic surveillance to track high-risk P. aeruginosa clones at the clinical–environmental interface. Full article

The aim of the study was to investigate the early response of apple fruit infected with Penicillium expansum (P. expansum) to blue light-emitting diode (LED) light (BLL) irradiation. To focus our study on the interaction between apple fruit, the pathogen, and BLL, the effect of BLL was also studied on apples without P. expansum and P. expansum grown on malt extract agar (MEA). Transcriptome analysis revealed that the most pronounced responses among biological processes were observed in inoculated apples under BLL. The upregulated processes included water transport, response to heat, and response to high light intensity. The defence response of apples was enhanced by the upregulation of thaumatin-like proteins and caffeic acid 3-O-methyltransferase, while the cellular response to phosphate deficiency and the regulation of multicellular organism development were downregulated. In P. expansum grown on apples under BLL, transcriptome analysis revealed downregulation of genes related to signalling, response to organic compounds, and regulation of metabolic and biosynthetic processes, while genes involved in the biosynthesis of secondary metabolites were upregulated. In addition, the expression of patulin cluster genes was predominantly downregulated in P. expansum. The significant upregulation of genes related to cryptochrome inhibition, defence response, and caffeic acid metabolism in apples under BLL, together with the reduced virulence of P. expansum, contributes to the inhibition of fungal growth. 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

(1) Background: Listeria monocytogenes (Lm) is recognized by the World Health Organization (WHO) as one of the four principal foodborne pathogens. This study aimed to investigate the molecular characteristics of Lm isolates from Jiaxing, China, using whole-genome sequencing (WGS) to enhance our understanding of their molecular epidemiology. (2) Methods: A total of 39 foodborne Lm isolates and 7 clinical Lm isolates were analyzed via WGS to identify resistance genes, virulence factors, lineage, sequence type (ST), and clonal complex (CC). Antibiotic susceptibility was assessed using Minimum Inhibitory Concentration (MIC) testing, and serotypes were confirmed via multiplex PCR. (3) Results: We found that 39 food isolates were mainly lineage II (66.67%), with 13 STs; ST8 was the dominant ST, and 2 new types, ST3210 and ST3405, were found. Among the seven clinical isolates, lineage I was dominant (57.14%), and ST87 was the dominant ST. Serotype 1/2a was dominant, accounting for 54.35%, followed by 1/2b, which accounted for 36.96%. The overall antimicrobial resistance rate was 13.04%, with a multidrug resistance rate of 2.17%. All strains harbored LIPI-1 and LIPI-2, and five strains carried LIPI-3 genes: one strain belonged to ST619 of lineage I, two strains belonged to ST224 of lineage I, and two strains belonged to ST11 of lineage II. (4) Conclusions: This study clarified the genotype and serotype characteristics of Listeria monocytogenes in Jiaxing, as well as their molecular characteristics relating to drug resistance and virulence, thus providing a technical basis for improving exposure risk assessment of Listeria monocytogenes. Continuous monitoring, prevention, and control are recommended to further improve regional public health and safety. Full article

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen in both healthcare-associated (HA-MRSA) and community-associated (CA-MRSA) infections, posing major challenges due to its evolving antimicrobial resistance (AMR) and genetic diversity. This study investigates the prevalence, antimicrobial resistance patterns, and molecular characteristics of HA-MRSA and CA-MRSA isolates in Saudi Arabia. A retrospective analysis was conducted on 178 MRSA isolates obtained from clinical samples. MRSA identification was performed using cefoxitin disk diffusion, and antimicrobial susceptibility testing for vancomycin, linezolid, and ciprofloxacin was conducted using the BD Phoenix M50 system. Molecular characterization included SCCmec typing, spa typing, and PCR-based detection of virulence genes (pvl, tst, eta, etb, lukS, lukF). Statistical analysis was carried out using SPSS, with a significance threshold of p < 0.05. Among 1496 S. aureus isolates, 178 (11.9%) were confirmed as MRSA, with HA-MRSA (61.8%) being more prevalent than CA-MRSA (38.2%). Notably, 7.8% of HA-MRSA isolates exhibited heteroresistant vancomycin-intermediate S. aureus (hVISA). Ciprofloxacin resistance was significantly higher in HA-MRSA (85.0%) compared to CA-MRSA (38.9%). SCCmec type V was the predominant genotype (87.1%), suggesting increased infiltration of CA-MRSA strains into hospital settings. Spa typing revealed high genetic diversity, with t037 being the most common (27%). Virulence genes were detected in 6% of isolates, indicating limited dissemination of these factors. The findings highlight the increasing prevalence of MRSA, the emergence of hVISA, and shifts in clonal distribution, underscoring the need for ongoing molecular surveillance and stringent antimicrobial stewardship programs to control MRSA spread in both healthcare and community environments. Full article

‘Candidatus Phytoplasma solani’ of the 16SrXII group is an emerging vector-borne pathogen in European crop production. The cixiid planthopper Hyalesthes obsoletus transmits 16SrXII-A stolbur phytoplasmas that are associated with diseases in grapevine, potato, and various weeds. While 16SrXII-P genomes transmitted by Pentastiridius leporinus are available, no genome of an H. obsoletus-transmissible 16SrXII-A phytoplasma has been reported from Germany. Here, we present insights into the phylogenetic position and pathogen–host interactions through the functional reconstruction of the complete 832,614 bp genome of the H. obsoletus transmissible ‘Ca. P. solani’ 16SrXII-A strain POT from a potato field. Phylogenetic analyses highlight the heterogeneity within the stolbur group using whole-genome alignment and a BUSCO-based core gene analysis approach. The POT chromosome shares highest average nucleotide identity with Italian bindweed-associated genomes and displays strong synteny with the c5 strain. Consistent with the typical phytoplasma architecture, the POT genome combines mobile-element-driven instability with a conserved core metabolism. Virulence factors include transposon-linked effectors but lack pathogenicity island organisation. POT further differs from other 16SrXII-group phytoplasmas through unique collagen-like proteins that could contribute to virulence. These findings provide a robust genomic framework that improves diagnostics, enables strain-level resolution and supports the assessment of breeding materials under stolbur phytoplasma pressure, thereby refining our understanding of stolbur phytoplasma diversity and highlighting the evolutionary divergence within the 16SrXII subgroup. Full article

Background/Objectives: Staphylococcus aureus is a multifaceted pathogen responsible for diseases in humans and in several animal species, including dairy cows. This study aimed to characterize and compare the genetic diversity, lineage distribution, and antimicrobial resistance profiles of S. aureus isolates from bovine milk with human-derived reference genomes to investigate host adaptation and inter-species transmission. Methods: Genomic analyses were performed on S. aureus isolates from quarter milk samples of dairy cows together with human-derived sequences from public databases. Whole-genome sequencing and multi-locus sequence typing (MLST) were used to determine sequence type (ST) distribution, and the presence of key antibiotic resistance genes and mobile genetic elements (MGEs) was assessed. Comparative genomics was applied to evaluate gene content, phylogenetic relationships, and lineage–host associations. Results: The dataset encompassed bovine-adapted lineages (CC97, CC133, CC151) and human-associated lineages (CC1, CC5, CC8, CC30, CC45), as well as livestock-associated ST398 in bovine samples and human-adapted ST5 and ST6 in animals. ST8 was the only ST shared between animal and human isolates and showed differing resistance profiles, with animal ST8 carrying resistance determinants absent from human ST8. Bovine-adapted strains were characterized by recurrent loss of human-associated virulence genes and acquisition of bovine-associated mobile genetic elements, and blaZ and mecA were rarely detected in bovine-adapted CC97 but were frequently present in human CC5 and CC8. Overall, animal isolates carried fewer resistance genes than human isolates. Conclusions: S. aureus from dairy cows and humans displayed substantial genetic diversity, with evidence of host-associated lineages and dynamic changes in gene and mobile element content. These findings support the need for integrated One Health surveillance to track shared and host-adapted lineages and their antibiotic resistance determinants. Full article

A novel lytic bacteriophage, XAN_XB1, was isolated from hospital wastewater through host bacterial enrichment and evaluated for its potential in controlling multidrug-resistant Stenotrophomonas maltophilia infections. Transmission electron microscopy revealed that XAN_XB1 has a long tail, possessing an icosahedral head of ~80 nm in diameter and a tail measuring ~150 nm in length. It produced clear plaques of 0.5–1 mm on host bacterial lawns. Host range analysis demonstrated its ability to infect multiple multidrug-resistant S. maltophilia isolates. Biological characterization showed that the phage is chloroform-insensitive, retains strong lytic activity across a wide temperature (4–60 °C) and pH (3.0–10.0) range, and achieves more rapid host suppression under higher multiplicity of infection (MOI). Whole-genome sequencing determined a ~47 kb double-stranded DNA genome encoding 71 predicted open reading frames, with no known virulence or antibiotic resistance genes. Phylogenetic analysis of MCP and terminase large subunit sequences placed XAN_XB1 in a unique Caudoviricetes, with ANI values below the 95% ICTV threshold verifying its status as a novel phage species. The XAN_XB1 therapy significantly alleviates S. maltophilia infection-induced severe pulmonary inflammatory lesions, high mortality, elevated serum inflammatory factors and massive pulmonary bacterial colonization in male BALB/c mice, confirming its favorable therapeutic effect on such infections. Collectively, these results reveal that is an efficacious candidate for therapeutic development against S. maltophilia infections. Full article

Macroalgae plays a significant role in the formulation of innovative and environmentally sustainable approaches to address food challenges. Specifically, green macroalgae serve as dietary supplements aimed at improving the health, growth, and feeding efficiency of various species of marine and freshwater fishes, as well as mollusks. The effects of Chaetomorpha linum extract (CLE) on growth performance, physiological responses, and disease resistance are studied in Bellamya bengalensis against Aeromonas hydrophila. In this experiment, adult B. bengalensis (4412 ± 165.25 mg) were randomly divided into 15 rectangular glass aquariums (35 snail/aquaria; 45 L capacity) and their basal diet was supplemented with different levels of CLE, including 0 (CLE0), 1 (CLE1), 2 (CLE2), 3 (CLE3), and 4 (CLE4) g/kg for 60 days. The growth performance in the CLE3 dietary group was significantly higher that of the CLE0 group, exhibiting both linear and quadratic trends in relation to dietary CLE levels (p < 0.05). The activities of pepsin, amylase, and lipase were found to be highest in CLE3 and lowest in CLE0. Both linear and quadratic responses to dietary CLE levels in digestive enzymes were observed (p < 0.05). The activities of superoxide dismutase and catalase in the hepatopancreas were found to be elevated in snails due to the synergistic effect of the supplemented CLE diet. Among different levels of diet given, CLE2-supplemented snails showed an increase in their enzyme activity (p < 0.05). Interestingly, all the CLE-treated snails expressed elevated levels of mucus lysozyme and mucus protein when compared to control (p < 0.05). Additionally, hepatopancreatic acid phosphatase and alkaline phosphatase activity were elevated in snails consuming CLE3 (p < 0.05). The transcription levels of immune-related genes, including mucin-5ac and cytochrome, were significantly elevated in snails that were fed a diet supplemented with 2–4 g of CLE/kg. Furthermore, the transcription level of the acid phosphatase-like 7 protein gene also increased in snails receiving CLE-supplemented diets. After a 14-day period of infection, snails that consumed a diet supplemented with 3–4 g/kg of CLE exhibited a notable increase in survival rates against virulent A. hydrophila. Based on the above findings, it is suggested that a diet supplemented with 3 g/kg of CLE may enhance growth, antioxidant and immune defense, and disease resistance in the freshwater snail B. bengalensis. Full article

Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen of public health concern, requiring a One Health approach to clarify its transmission and distribution. However, its prevalence and genomic characteristics in livestock and companion animals remain underexplored in low-income countries. We investigated prevalence and genomic features of STEC in animals in western Ghana, representing the first genomic report of STEC in Ghana. Fecal samples (97) were collected from goats (n = 33), sheep (n = 33), dogs (n = 30), and a cat (n = 1), with STEC detected in 12.1% of goats and sheep samples. Whole-genome sequencing identified serotypes O38:H26, O43:H2, and O157:H7. stx1c and stx2b genes were detected in O38:H26 and O43:H2, whereas stx2c and key virulence genes (chuA, eae, esp, nle, tir, and toxB) were exclusively found in O157:H7. Phylogenetic analysis revealed that O38:H26 isolates form a cluster closely related to clinical strains from the UK. O43:H2 isolates exhibited diverse stx profiles, linking animal, environmental, and clinical strains from North America and the UK. O157:H7 isolates were genetically similar to European clinical and food-derived strains, suggesting that goats and sheep are important STEC reservoirs in Ghana, offering data for public health risk assessment and effective One Health-based control strategies. 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

Streptococcus uberis is a bovine mastitis pathogen with a demonstrated ability to form biofilms. However, the dynamics of this process remain poorly characterized. This study aimed to comprehensively characterize biofilm formation in four S. uberis strains that differed in their biofilm-forming capacity, from weak to strong producers, and in the presence of key virulence-associated genes, such as sua, hasA and hasC. To achieve this, we integrated structural, biochemical, physiological and transcriptional analyses using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), spectral flow cytometry and qRT-PCR. The multi-faceted analysis revealed a coordinated maturation peak at 48 h, characterized by a structured architecture with water channels, a distinct biochemical signature rich in polysaccharides and proteins, and a predominantly viable bacterial population. This peak coincided with a marked upregulation of key virulence-associated genes, with sua expression increasing 2.5-fold and hasA increasing 3-fold at 48 h. This mature biofilm conferred high tolerance to antibiotics, with eradication concentrations (>256 µg/mL) exceeding planktonic MICs, although tetracycline was notably effective. At 72 h, the biofilm entered a dispersion phase characterized by structural collapse and reduced viability. These findings establish S. uberis biofilm maturation as a highly coordinated process, providing new insights into the biofilm lifecycle of this important pathogen and identifying key temporal and molecular targets for future interventions. Full article