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At least 19 recordsLinked to original sources
PubMed2024

Gene transfer agents: The ambiguous role of selfless viruses in genetic exchange and bacterial evolution.

Gene transfer agents (GTAs) are genetic elements derived from ancestral bacteriophages that have become domesticated by the host. GTAs are present in diverse prokaryotic organisms, where they can facilitate horizontal gene transfer under certain conditions. Unlike typical bacteriophages, GTAs do not exhibit any preference for the replication or transfer of the genes encoding them; instead, they exhibit a remarkable capacity to package chromosomal, and sometimes extrachromosomal, DNA into virus-like capsids and disseminate it to neighboring cells. Because GTAs resemble defective prophages, identification of novel GTAs is not trivial. The detection of candidates relies on the genetic similarity to known GTAs, which has been fruitful in α-proteobacterial lineages but challenging in more distant bacteria. Here we consider several fundamental questions: What is the true prevalence of GTAs in prokaryote genomes? Given there are high costs for GTA production, what advantage do GTAs provide to the bacterial host to justify their maintenance? How is the bacterial chromosome recognized and processed for inclusion in GTA particles? This article highlights the challenges in comprehensively understanding GTAs' prevalence, function and DNA packaging method. Going forward, broad study of atypical GTAs and use of ecologically relevant conditions are required to uncover their true impact on bacterial chromosome evolution.

Gene Transfer, Horizontal↗
PubMed2025

Mobile genetic elements in Klebsiella pneumoniae.

Klebsiella pneumoniae is a clinically important pathogenic bacteria that poses a serious threat to human health. In particular, the emergence of hypervirulent and multidrug-resistant K. pneumoniae has posed great challenges in clinical anti-infective therapy. In the K. pneumoniae genome, mobile genetic elements (MGEs), such as plasmids, prophages, transposons, and insertion sequences, enhance bacterial viability and adaptation by mediating the horizontal transfer of virulence genes, antibiotic resistance genes, and other adaptive genes. This paper reviews the types and characteristics of the main MGEs in K. pneumoniae, focusing on their effects on bacterial virulence and antibiotic resistance, with the aim of providing clues for developing infection control measures and new antibacterial drugs.

Klebsiella pneumoniae↗
PubMed2026

From commensal to pathobiont: The emergence of virulence-enhanced Escherichia coli in China's food-animal systems - insights with future implications.

A fundamental shift in Escherichia coli epidemiology is being driven by convergence of virulence determinants and antimicrobial resistance within linked human-animal-environment systems. In China, the rapid growth of food-animal production, extensive antimicrobial use, and complex food networks are accelerating the emergence and dissemination of virulence-enhanced E. coli pathobionts. This review synthesizes recent epidemiological, genomics, and outbreak data to characterize China's evolving landscape of food-animal-associated E. coli. We highlight a significant shift from classical pathotypes to hybrid lineages that simultaneously carry virulence factors and last-resort antibiotic resistance determinants, including mcr-1, tet(X4), and blaNDM. These traits disseminate rapidly via plasmid-mediated horizontal gene transfer, facilitating rapid adaptation and enabling cross-sectoral One Health transmission. National surveillance, foodborne outbreak investigations, and whole-genome sequencing data show that food-animal reservoirs are active evolutionary niches that drive pathogen diversity and fitness, rather than serving merely as contamination sources. Whole-genome sequencing also pinpoints high-risk clones (e.g., ST394) and plasmid-mediated co-selection of virulence and AMR. The emergence of hybrid pathotypes (e.g., STEC/ETEC) and AMR-virulence co-selection challenges traditional classification and limits the effectiveness of conventional surveillance approaches. The 2017 colistin ban reduced mcr-1, yet ongoing resistance and emerging tet(X4) demand integrated surveillance. Collectively, these findings call for reconceptualizing E. coli as a dynamic genomic entity embedded within a unified ecological network. Addressing this threat requires an integrated One Health strategy including genomic surveillance, agricultural antimicrobial stewardship, and coordinated food-environment-clinical monitoring to prevent high-risk clone emergence and global spread.

Animals↗
PubMed2026

Fate of antibiotic resistance genes during rural domestic wastewater treatment: Anaerobic unit as enrichment hotspot versus aerobic unit as attenuation zone.

Rural domestic wastewater treatment systems are important but understudied reservoirs for antibiotic resistance genes (ARGs), whose full-process migration mechanisms remain unclear. Herein, the contribution of each treatment unit of ARGs was investigated using metagenomic methods across two seasons in typical rural domestic wastewater treatment systems. Although a removal efficiency (69 % in winter and 22 % in summer) was observed for ARGs, higher antibiotic residues and temperature dramatically induced ARG occurrence in wastewater and horizontal gene transfer (HGT) risk during wastewater treatment. The ARG abundances in the anaerobic unit increased by 1.6-2.1 fold compared to the regulating pool, primarily driven by elevated mobile genetic element (MGE) activity. In sharp contrast, ARG reduction was achieved through ARG host removal and suppressed HGT potential in the aerobic unit. Notably, mobile ARGs were dominated by tetracycline resistance genes in winter and co-dominated by tetracycline and sulfonamide genes in summer, with most flanked by transposases. Key pathogenic hosts, including Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa carrying ARG-MGE complexes, were primarily concentrated in the regulating pool and the influent, forming high-risk upstream sources of dissemination. Partial least-squares path model highlighted MGEs as the primary drivers, and variance partitioning analysis indicated that MGEs account for 31 % of the explained variation in ARGs during wastewater treatment. In summary, the anaerobic unit was an ARG enrichment hotspot, while the aerobic unit as ARG attenuation zone during wastewater treatment. These findings provide crucial evidence to optimize rural wastewater treatment processes and to target the control of antibiotic resistance.

Wastewater↗
PubMed2025

Comprehensive genomic analysis of antibiotic resistance plasmids in animal-associated Staphylococcus aureus in France.

UNLABELLED: In Staphylococcus aureus, an animal pathogen and zoonotic agent, plasmids play a pivotal role in the acquisition and spread of antibiotic resistance genes (ARGs). This study investigated the plasmid content of 329 S. aureus isolates from livestock and companion animals collected in France between 2010 and 2021. Plasmids (n = 211) were identified from 139 isolates. The major families identified-rep7a, rep20, and rep10-were associated with specific resistance genes (str, cat, blaZ, erm(C)) and exhibited widespread horizontal transfer across different S. aureus sequence types (STs) and animal hosts. In temporal analysis, the rep7a/str and rep7a/cat plasmids circulating in horses were progressively replaced by a rep7a plasmid carrying both str and cat genes. The study also highlighted the presence of mosaic plasmids, which combined elements from different bacterial species/genera, confirming the broad host range of S. aureus plasmids and their ability to acquire ARGs from diverse sources. Moreover, the occurrence of hybrid plasmids (carrying multiple rep genes) underscores the plasticity of these vectors of ARGs. This study emphasizes the need to investigate the mechanisms driving the spread and persistence of antibiotic-resistant plasmids in S. aureus, with a view to developing strategies aimed at combating antibiotic resistance. IMPORTANCE: The spread of antibiotic resistance in Staphylococcus aureus is a growing concern, particularly in animals that can serve as reservoirs for resistant strains. This study highlights the crucial role of plasmids in transmitting resistance genes among different animal hosts and S. aureus lineages. The characterization of 329 isolates collected over 10 years revealed how certain plasmid families are associated with specific resistance genes and how they evolve over time. The occurrence of mosaic and hybrid plasmids further underscores the ability of S. aureus to acquire resistance from diverse bacterial sources. These findings provide key insights into the mechanisms shaping antibiotic resistance in this pathogen and emphasize the fact that understanding plasmid-driven resistance is essential for developing effective interventions to limit the spread of multidrug-resistant S. aureus in both veterinary and human medicine.

Animals↗
PubMed2026

Eco-evolutionary dynamics sustain a potent yet rare antibiotic gene cluster in Streptomyces.

Microbial secondary metabolites have been recognized and utilized for nearly a century. Nevertheless, the eco-evolutionary mechanisms governing their distribution among microorganisms remain largely unresolved. In this study, we examined intraspecific interactions within Streptomyces albidoflavus and identified a strain exhibiting potent antagonistic activity against conspecifics. This "killer" phenotype was attributed to the production of kosinostatin, a hybrid aromatic polyketide antibiotic. Evolutionary genomic analyses provided strong evidence that the kosinostatin biosynthetic gene cluster was horizontally acquired in S. albidoflavus over a relatively short evolutionary timescale, a finding consistent with its sparse distribution within this species, across the genus Streptomyces, and even throughout the phylum Actinomycetota. Using microcosm assays, we demonstrated that the kosinostatin producer outcompeted sensitive conspecifics in liquid culture but not in soil, indicating that environmental context plays a key role in altering the fitness benefits of this cluster. Moreover, the competitive advantage was observed only in the presence of sensitive strains, revealing a trade-off between fitness benefits and metabolic costs. These results highlight the role of context-dependent selection in shaping the evolutionary persistence of the kosinostatin cluster. The current distribution pattern of this cluster in S. albidoflavus likely results from a dynamic interplay of intraspecific horizontal gene transfer, vertical inheritance, and recurrent gene loss. Overall, our findings establish an eco-evolutionary framework that explains the rarity of a potent antibiotic gene cluster in Streptomyces, illustrating how environmental constraints, fitness trade-offs, and gene flux collectively orchestrate the biosynthetic architecture of Streptomyces species.

Streptomyces↗
PubMed2026

Suppression of AAV-Delivered Transgene Expression Using Artificial MicroRNAs Delivered by an Alternative AAV Serotype.

Adeno-associated virus (AAV) gene transfer vectors mediate long-term expression in nondividing cells, an advantage for treating chronic disorders. However, current platforms lack a way to selectively shut down transgene expression if adverse effects arise. To create an "off switch," we hypothesized that incorporating unique artificial microRNA (amiRNA) target sequences into an AAV expression cassette would allow subsequent suppression of transgene expression using a second AAV vector encoding the cognate amiRNA. We introduced 22-nt sequences absent from human and mouse transcriptomes into the 3' untranslated region (UTR) of a therapeutic AAV cassette. To identify optimal amiRNAs, two tandem copies of each amiRNA were cloned into the 3'UTR of an mCherry reporter gene. In vitro assessment of six amiRNA/target pairs using a dual luciferase assay identified four amiRNAs that efficiently suppressed reporter expression. Cells cotransfected with target site 3 (TS3) and amiRNA-T3B showed the greatest reduction in luciferase activity (80%, p < 0.0001) and were selected for further study. The "off-switch" system was then evaluated using an AAV5 therapeutic vector expressing a recombinant humanized anti-IgE monoclonal antibody (AAV5-TBG-anti-IgE-TS3), designed for long-term suppression of allergen-induced reactions. Co-transfection of HEK293T cells with anti-IgE-TS3 and amiRNA-T3B significantly reduced anti-IgE mRNA and protein levels relative to a control amiRNA (p < 0.0001). In vivo testing in Balb/c mice (n = 5) involved intravenous administration of AAV5-anti-IgE-TS3 (3.2 &#xd7; 1010 gc), followed 4 weeks later by an AAVrh.10 amiRNA vector (AAVrh.10-TBG-amiRNA-T3B; 1 &#xd7; 1011 gc). Control mice receiving only the therapeutic vector expressed 18.4 &#xb1; 13.8 &#xb5;g/mL serum anti-IgE at 10 weeks. In contrast, mice receiving the amiRNA "off" vector showed marked suppression of anti-IgE (0.3 &#xb1; 0.15 &#xb5;g/mL, p < 0.0001). These findings provide proof-of-concept that AAV-delivered amiRNAs can selectively switch off transgene expression, offering a strategy to improve the safety of AAV-mediated gene therapies.

Dependovirus↗
PubMed2026

Interindividual variability in immune response to AAV ocular gene delivery across species impedes immunomonitoring.

Adeno-associated viruses (AAVs) have been used in gene therapy, especially for inherited retinal diseases. Despite their effectiveness in gene transduction, immune responses to the AAV capsid and transgene products have been reported, which can compromise both the efficacy and the safety of AAV-mediated therapies. The eye is regarded as an immune-privileged organ where immune activity is constitutively suppressed. Here, we highlight that immunomonitoring in an ocular gene transfer reveals variable immune responses, whatever the species (human clinical trial, nonhuman primates, mice), the site of injection, the cassette, and the dose. We further explored factors contributing to this variability, investigating the potential correlation among immune parameters in a controlled experimental setting. In a syngeneic murine model after a subretinal injection of AAV, our results highlight an interindividual variability of immune parameters, emphasizing the importance of considering inherent variability among individuals when designing personalized therapies.

Animals↗
PubMed2026

A Tripartite AAV System with Engineered Lox Sites Enables Efficient Delivery of the EYS Gene for Retinal Gene Therapy.

Mutations in the Eyes Shut Homolog (EYS) gene are one of the leading causes of autosomal recessive retinitis pigmentosa, a progressive retinal degenerative disease for which no effective treatment currently exists. However, the large size of the EYS coding sequence (&#x223c;9.4 kb) exceeds the packaging limit of adeno-associated virus (AAV) vectors, posing a major barrier to gene replacement therapy. To address this challenge, we developed a tripartite AAV vector system that enables delivery and reconstitution of the full-length EYS gene using a Cre-lox-based unidirectional DNA recombination strategy, Uni-directional and Site-specific Transgene Assembly by Recombination (Uni-STAR). The system consists of three AAV constructs carrying discrete EYS segments flanked by engineered, noncompatible lox sites that drive ordered and unidirectional recombination in target cells. We validated this system in vitro by demonstrating successful reconstitution and expression of full-length EYS protein in HEK293T cells. In vivo, subretinal co-injection of the three AAV vectors into mouse eyes led to precise reconstitution and expression of full-length EYS protein in the retina. These findings establish the feasibility of using a tripartite AAV system to deliver the complete EYS gene and provide a foundation for future therapeutic development targeting EYS-associated retinal degenerations.

Dependovirus↗
PubMed2024

Horizontal plasmid transfer promotes antibiotic resistance in selected bacteria in Chinese frog farms.

The emergence and dissemination of antibiotic resistance genes (ARGs) in the ecosystem are global public health concerns. One Health emphasizes the interconnectivity between different habitats and seeks to optimize animal, human, and environmental health. However, information on the dissemination of antibiotic resistance genes (ARGs) within complex microbiomes in natural habitats is scarce. We investigated the prevalence of antibiotic resistant bacteria (ARB) and the spread of ARGs in intensive bullfrog (Rana catesbeiana) farms in the Shantou area of China. Antibiotic susceptibilities of 361 strains, combined with microbiome analyses, revealed Escherichia coli, Edwardsiella tarda, Citrobacter and Klebsiella sp. as prevalent multidrug resistant bacteria on these farms. Whole genome sequencing of 95 ARB identified 250 large plasmids that harbored a wide range of ARGs. Plasmid sequences and sediment metagenomes revealed an abundance of tetA, sul1, and aph(3&#x2033;)-Ib ARGs. Notably, antibiotic resistance (against 15 antibiotics) highly correlated with plasmid-borne rather than chromosome-borne ARGs. Based on sequence similarities, most plasmids (62%) fell into 32 distinct groups, indicating a potential for horizontal plasmid transfer (HPT) within the frog farm microbiome. HPT was confirmed in inter- and intra-species conjugation experiments. Furthermore, identical mobile ARGs, flanked by mobile genetic elements (MGEs), were found in different locations on the same plasmid, or on different plasmids residing in the same or different hosts. Our results suggest a synergy between MGEs and HPT to facilitate ARGs dissemination in frog farms. Mining public databases retrieved similar plasmids from different bacterial species found in other environmental niches globally. Our findings underscore the importance of HPT in mediating the spread of ARGs in frog farms and other microbiomes of the ecosystem.

Animals↗
PubMed1979

Antibiotic-resistance transfer in Yersinia enterocolitica.

Most clinical isolates of Yersinia enterocolitica have been reported to be inhibited by a wide variety of antimicrobial agents. This finding indicates that Y. enterocolitica infrequently acquires resistance by gene transfer from other bacteria in nature. In the present study the authors examined whether Y. enterocolitica has the potential for acquiring antibiotic resistance from another organism in vitro. Mixed cultures of multiple-antibiotic-resistant Escherichia coli and a sensitive Y. enterocolitica yielded resistant Y. enterocolitica. Resistance to at least four drugs was transferred at a frequency of approximately 10(-7) transconjugants per donor. The newly resistant Y. enterocolitica transferred resistance to a sensitive E. coli at a slightly higher frequency. Resistance to at least one antibiotic was transferred to all five strains of Y. enterocolitica tested.

Drug Resistance, Microbial↗
PubMed2026

Adenoviral Vectors in Gene Therapy: A Detailed Overview.

Adenoviral vectors (AdVs) represent one of the most extensively researched platforms in the realm of gene therapy, providing advantages such as high transduction efficiency, large transgene capacity, and broad tropism. This review provides a detailed and structured overview of AdVs, highlighting their biology, gene delivery mechanisms, clinical applications, and challenges limiting their broader therapeutic applicability. The study also explores recent progress in vector engineering, such as rare serotypes, capsid modifications, third-generation vectors, as well as strategies for immune modulation and toxicity reduction. AdVs are used in therapies for genetic disorders, oncology, and vaccinology, alongside innovations such as CRISPR-Cas9, nanotechnology, and artificial intelligence design. Nevertheless, persistent hurdles, including vector immunogenicity, hepatotoxicity, scalability, and the lack of durable expression, prevent widespread clinical use. This review consolidates current knowledge and presents a future perspective on how AdVs may evolve as powerful, adaptable, and precise tools in modern gene therapy. By contextualizing strengths and unresolved challenges, this work aims to give researchers and clinicians a balanced foundation for evaluating their future roles in translational medicine.

Humans↗
PubMed2020

Chromosomal toxin-antitoxin systems in Pseudomonas putida are rather selfish than beneficial.

Chromosomal toxin-antitoxin (TA) systems are widespread genetic elements among bacteria, yet, despite extensive studies in the last decade, their biological importance remains ambivalent. The ability of TA-encoded toxins to affect stress tolerance when overexpressed supports the hypothesis of TA systems being associated with stress adaptation. However, the deletion of TA genes has usually no effects on stress tolerance, supporting the selfish elements hypothesis. Here, we aimed to evaluate the cost and benefits of chromosomal TA systems to Pseudomonas putida. We show that multiple TA systems do not confer fitness benefits to this bacterium as deletion of 13 TA loci does not influence stress tolerance, persistence or biofilm formation. Our results instead show that TA loci are costly and decrease the competitive fitness of P. putida. Still, the cost of multiple TA systems is low and detectable in certain conditions only. Construction of antitoxin deletion strains showed that only five TA systems code for toxic proteins, while other TA loci have evolved towards reduced toxicity and encode non-toxic or moderately potent proteins. Analysis of P. putida TA systems' homologs among fully sequenced Pseudomonads suggests that the TA loci have been subjected to purifying selection and that TA systems spread among bacteria by horizontal gene transfer.

Anti-Bacterial Agents↗
PubMed2026

Hurdles to horizontal gene transfer: species-specific effects of synonymous variation and plasmid copy number determine antibiotic resistance phenotype.

Could codon composition condition the immediate success and the orientation of horizontal gene transfer? Horizontal gene transfer represents a change in the genome of expression of the transferred gene, and experimental evidence has accumulated indicating that the codon composition of a sequence is an important determinant of its compatibility with the translation machinery of the genome in which it is expressed. This suggests that codon composition influences the phenotype and the fitness conferred by a transferred gene and thus the immediate success of the transfer. To directly test this hypothesis, we characterized the resistance conferred by synonymous variants of a gentamicin resistance gene in three bacterial species: Escherichia coli, Acinetobacter baylyi and Pseudomonas aeruginosa. The strongest determinant of the resistance level conferred was the species in which the resistance gene was transferred, very likely because of important differences in the copy number of the plasmid carrying the gene. Significant differences in resistance were also found between synonymous variants within each of the three species, but more importantly, there was a strong interaction between species and variant: variants conferring high resistance in one species confer low resistance in another. However, the similarity in codon usage between the synonymous variants and the host genome only explained part of the phenotypic differences between variants in one species, P. aeruginosa. Further investigation of alternative explanations did not reveal common universal mechanisms across our three bacterial species. We conclude that codon composition can be a determinant of post-horizontal gene transfer success. However, there are multiple paths leading from synonymous sequence to phenotype, and sensitivity to these different paths is species-specific.

Gene Transfer, Horizontal↗
PubMed2026

Gene transfer from NDM-5-producing and OXA-48-producing Enterobacter hormaechei ST79 on contaminated dicloxacillin capsules to other Enterobacterales in Europe, 2020-23: a retrospective, observational, molecular epidemiological study.

BACKGROUND: In February, 2023, an outbreak of Enterobacter hormaechei ST79 carrying blaNDM-5 and blaOXA-48 was linked to contaminated dicloxacillin capsules administered to approximately 79&#x2009;000 individuals in Denmark. Initial clonal outbreak investigations identified 11 patients with the E hormaechei ST79 outbreak strain, which carried blaNDM-5 on a distinct IncX3 plasmid, and in nine cases, blaOXA-48 was on a distinct IncL plasmid. Interspecies plasmid transfer was observed in one patient, suggesting a potential plasmid-mediated outbreak involving other Enterobacterales. However, no studies have characterised the progression of a clonal outbreak originating from a contaminated medicine into plasmid-mediated dissemination of carbapenemase genes. Hence, we aimed to characterise the clonal and plasmid-mediated spread of carbapenemase genes in this outbreak. METHODS: We conducted a retrospective genomic and epidemiological investigation using existing short-read whole-genome sequencing data from all carbapenemase-producing Enterobacterales (CPE) from the Danish national surveillance, collected between Jan 1, 2014, and Oct 1, 2023. All confirmed CPE isolates were eligible for inclusion. Using in-silico screening for unique fragments of the two outbreak plasmids, we selected 160 isolates for long-read sequencing to obtain complete plasmid sequences for outbreak investigation. Analyses were descriptive and included comparison of sequence identity and coverage to define outbreak-associated plasmids and summary statistics of patient characteristics. FINDINGS: Data from 1829 isolates were obtained. We detected 16 of 53 isolates involved in the outbreak using conventional outbreak detection methods. The remaining 37 isolates were detected using plasmid-specific screening and long-read sequencing. 15 patients carried the outbreak E hormaechei strain, including the 11 patients previously reported. Three of the 15 patients presented with at least one additional bacterial species carrying one or both outbreak plasmids (pDcap_OXA-48 and pDcap_NDM-5). A further 24 patients, sampled between July 1, 2020, and Oct 1, 2023, presented with other Enterobacterales carrying one or both outbreak-associated plasmids but not the original E hormaechei ST79 strain. In four cases, outbreak-associated plasmids differed structurally from the original outbreak plasmid. INTERPRETATION: This study describes how a clonal CPE outbreak caused by a contaminated medicine evolved into a complex plasmid-mediated outbreak involving multiple Enterobacterales species. Most patients related to the outbreak did not present with the original E hormaechei ST79 outbreak strain and were therefore not identified using standard outbreak detection methods. These findings highlight the importance of using plasmid-focused approaches in outbreak investigations. FUNDING: The Danish Ministry of Health, SSI-Seq (cofunded by EU4Health).

Humans↗
PubMed2026

Mobile genetic elements-driven partitions of mega-plasmids resistome in Salmonella Infantis.

Salmonella enterica serovar Infantis (S. Infantis) becomes the primary pathogen among the top Salmonella serotypes, contributing to numerous cases of foodborne illness annually in the United States. S. Infantis infection has spread rapidly worldwide, especially the clones with pESI-like plasmids. However, the underlying mechanisms regarding the transmission of S. Infantis, particularly mobile genetic elements (MGEs), mediated horizontal gene transfer, are limited. The objective of this study was to evaluate the relationship, if any, among MGEs, antibiotic-resistant genes (ARGs), and virulence factors (VFs) within S. Infantis via genomic analysis. A total of 91 S. Infantis complete genomes with high sequencing quality were selected for downstream bioinformatic analysis. The results showed that the majority of VFs were located in the bacterial chromosomes, while most ARGs were carried by S. Infantis mega-plasmids in an MGE-favored manner. Integrons and transposons were closely associated with certain ARGs, but prophages within mega-plasmids displayed a diverse ARG profile. Collectively, MGE-mediated horizontal gene transfer might lead to ARG acquisition by mega-plasmids, subsequently contributing to the resistome of S. Infantis. Our findings provide insights into the development of MGE-associated resistome in S. Infantis that could inform more effective prevention and intervention strategies to control this pathogen, further ensuring public health and safety.IMPORTANCEThe rapid emergence and transmission of antibiotic-resistant foodborne pathogens pose a significant risk to public health, necessitating the discovery of underlying mechanisms to control multidrug-resistant pathogens. Salmonella enterica serovar Infantis (S. Infantis) has become a pathogen of clinical and epidemiological relevance in recent years, ranking as the top prevalent serovar associated with foodborne illnesses and exhibiting resistance to several antibiotics. The current investigation of multidrug resistance (MDR) S. Infantis strains primarily emphasized the presence of mega-plasmids. However, the question of how mega-plasmids contribute to the transmission of antibiotic-resistant genes (ARG) is unaddressed. Utilizing the genomic characterization of S. Infantis complete genomes with high quality, our study revealed that the resistome of S. Infantis mega-plasmids-the primary ARG reservoirs of S. Infantis-followed a specific pattern of mobile genetic elements (MGEs). Monitoring the spread of MGE-carried ARGs within mega-plasmids should be considered in future surveillance.

Interspersed Repetitive Sequences↗