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Multi-omics evidence reveals robust airborne-human resistome connectivity driven by high-risk ARGs and mediated by Staphylococcus.

Airborne microbiomes are considered an important source of human antimicrobial resistance (AMR) exposure, yet multi-omics evidence linking airborne and human nasal resistomes remains limited. Here, we integrated metagenomic sequencing and whole-genome sequencing of antibiotic-resistant Staphylococcus isolates to investigate the connectivity between air and human nasal resistomes in dairy farm environments. Metagenomic taxonomic profiling showed that Staphylococcus was prominent in total suspended particles (TSP) and consistently detected across all samples. Among environmental reservoirs, TSP resistomes exhibited the strongest similarity to human nasal resistomes. This connectivity was supported by multiple lines of evidence, including highly similar resistome profiles, extensive homologous antibiotic resistance gene (ARG) pairs, strain-level similarity of resistant Staphylococcus isolates, and conserved mobile ARG genetic contexts. Notably, this connectivity was primarily driven by high-risk ARGs, while Staphylococcus was frequently associated with mobile ARGs and represented the only shared pathogenic genomes carrying both ARGs and virulence factor genes between airborne and nasal samples. Although lower ARG diversity, nasal resistomes exhibited higher ARG burden, risk scores, antibiotic-resistant bacterial genome abundance, and prevalence of resistant Staphylococcus. Occupational exposure further increased total and high-risk ARG burdens among farm workers. Together, these findings indicate that TSP can serve as an important route of occupational AMR exposure, with high-risk ARGs and Staphylococcus contributing to connectivity between airborne and nasal resistomes. Incorporating the host microbiome may therefore provide a more complete assessment of human-associated AMR exposure within a One Health framework.

Airborneresistome

Metagenomic insights into biogeochemical functional potential and resistome dynamics of PM2.5 microbial communities.

Atmospheric particulate matter harbors diverse microorganisms, yet their functional potential in biogeochemical cycling and the associated risks of resistome remain poorly understood. Here, we performed metagenomic sequencing on PM2.5 samples collected across four months to unravel the microbial genetic repertoire involved in methane, nitrogen, phosphorus, and sulfur cycling, as well as the resistome, and pathogen composition. A broad range of functional genes was detected for each biogeochemical cycle, with more than 65% of gene subtypes shared across all months, indicating conserved functional signatures. In contrast, more than 80% of the resistome showed temporal variation in abundance, with the lowest richness observed in March. Temporal shifts were also observed in resistome composition, with several resistance determinants reaching higher abundances in April and May. Network analysis indicated frequent co-occurrence among several pathogenic and opportunistic taxa. Contig-based profiling identified 51 potential pathogenic taxa, including 32 human- or animal-associated taxa. In addition, both PM10 and PM2.5 concentrations were associated with pathogen abundance and functional gene richness (e.g., antibiotic resistance genes and virulence factors). Together, this metagenomic survey suggests contrasting temporal patterns between conserved biogeochemical functional potential and more variable resistome-related traits in PM2.5 microbial communities. While constrained by limited temporal coverage and sample size, this study provides preliminary insights into the ecological and potential public health relevance of airborne microbial communities in urban environments.

Particulate Matter

Investigating AHL-associated quorum sensing impact on antibiotic-driven resistome expansion in anaerobic fermentation microbiomes: Metagenomic insights.

Previous studies have demonstrated that quorum sensing (QS) can mitigate the impact of antibiotics on environmental microbial communities. Metagenomic analysis was used to examine AHL effects on the resistome in anaerobic fermentation microbiomes under antibiotic stress in this research. AHLs reduced ARGs, MGEs, and phage abundance compared to antibiotic-only samples following the addition of high concentrations (500 nmol/L) of AHLs. Phages and integrons played pivotal roles in shaping the resistome. Escherichia coli, Vibrio cholerae, and Pseudomonas aeruginosa were key targets affected by AHLs. Both the assembled environmental metagenomes and the complete genomes of isolated bacteria consistently support the broad potential of quorum-sensing systems in mediating the dissemination or regulation of resistome spreading. Quorum sensing systems are very likely to affect microbial community resistomes by regulating the phageome. These insights are valuable for refining fermentation and waste management processes, offering potential in environmental restoration and possibly curbing the spread of resistance genes.

Quorum Sensing

Maternal secretor status and human milk oligosaccharides influence the infant gut resistome.

The infant gut resistome is established early in life and is shaped by perinatal exposures, yet the mechanisms underlying its modulation remain unclear. We combined shotgun metagenomics of fecal samples from 57 one-month-old infants and paired milk samples from 50 mothers in the MAMI cohort to investigate the influence of maternal secretor status on early-life resistome development. Longitudinal follow-up at 6 and 12 months, and also further validation in the independent Lifelines NEXT (LLNEXT) cohort, support our findings. Cesarean section (C-section) was associated with increased antibiotic resistance gene (ARG) diversity, whereas exclusive breastfeeding reduced ARG abundance and diversity. Maternal secretor status further modified resistome composition among exclusively breastfed infants. Human milk oligosaccharide profiling identified specific glycans underlying these associations, with 2'-fucosyllactose and 6'-sialyllactose showing negative correlations with distinct ARG classes. These findings identify human milk composition as a key determinant of early-life resistome assembly and a potential target for modulating antimicrobial resistance.

Humans

The antimicrobial gut resistome of the Wayampi reveals a shared background of antibiotic and metal resistance genes with industrialized populations, underscoring the "robust-yet-fragile" architecture of human gut microbiomes.

BACKGROUND: Metagenomics enables detailed profiling of genes encoding antimicrobial resistance. However, most studies focus exclusively on antibiotic resistance genes (ARGs), excluding those associated with non-antibiotic antimicrobials (metals, biocides), and often rely on methods with low-sensitivity and low-specificity. Furthermore, they rarely examine populations exposed to minimal anthropogenic pollution. We analyzed fecal resistomes of 95 Wayampi individuals, an Indigenous community in remote French Guiana, using a targeted metagenomic capture platform covering 8667 genes, including ARGs, metal resistance genes (MRGs) and biocide resistance genes (BRGs) (PMID: 29335005). Resistome profiles were compared with those of Europeans to assess population-level differences. RESULTS: ARG richness was similar between groups (259 in Wayampi vs. 264 in Europeans, 159 shared), but MRGs&#x2009;+&#x2009;BRGs gene richness was significantly higher in Wayampi (11,930 vs. 7419). Most genes appeared in a minority of individuals (mean 5% for ARGs, 2% for MRGs&#x2009;+&#x2009;BRGs), but several ARGs for tetracyclines [tet(32), tet(40), tet(O), tet(Q), tet(W), tet(X), tetAB(P)], aminoglycosides (ant6'-I, aph3-III), macrolides (ermB, ermF, mefA), and sulfonamides (sul2) were present in all individuals. Tetracycline resistance genes predominated overall, while beta-lactam resistance genes were more common in Wayampi, and genes conferring resistance to aminoglycosides, amphenicols, and folate inhibitors were more frequent in Europeans. Among MRGs, copper and arsenic resistance genes prevailed in both groups, followed by those for zinc, iron, cobalt, and nickel. Up to 76% of Wayampiis carried acquired MRGs for copper (pcoABCDRS and tcrB), silver (silACFPRS), arsenic (ars), and mercury (mer) detoxification. Shannon diversity indices were similar for ARGs, MRGs, and BRGs, but composition and evenness differed significantly. UMAP and ADONIS analyses distinguished cohorts based on ARG profiles (p&#x2009;<&#x2009;0.001), but not on MRGs or BRGs. Correlation analysis revealed conserved gene-sharing networks and introgression of acquired ARGs and MRGs within both gut microbiomes. CONCLUSIONS: The diverse and balanced Wayampi resistome reflects a less perturbed microbiome compared to industrialized populations, and reveals a background of "core" and "shell" acquired ARGs and MRGs, consistent with the "robust-yet-fragile" architecture of scale-free networks. The patchy yet resilient gene distribution suggests varying levels of conserved gene sharing highways among populations, likely shaped by long-term microbial-human evolution, and supports a broader view on acquired antimicrobial resistance. Video Abstract.

Humans

Cerium dioxide nanoparticle exposure attenuates mobility-linked antibiotic resistome signatures across the soil-lettuce continuum.

Antibiotic resistance genes (ARGs) are contaminants of emerging concern in agricultural microbiomes. Their association with mobile genetic elements (MGEs) can enhance dissemination across soil-plant interfaces, creating potential environmental and food-chain exposure risks. However, how engineered nanoparticles modulate relative ARG abundance and mobility-linked resistome features in plant-associated microbiomes remains poorly understood. Here, we examined the effects of graded, experimentally elevated cerium dioxide nanoparticle (CeO2 NP) loadings in a soil-lettuce system by integrating compartment-resolved metagenomics, ARG-MGE co-occurrence analysis, putative host-reservoir profiling, transcriptomics, and functional assays. Metagenomic profiling identified 16 ARG types and 125 subtypes and revealed niche-dependent microbiome restructuring under CeO2 NP exposure. Rhizosphere relative ARG abundance showed a negative dose-associated trend, although overall inter-group differences were not significant, whereas leaf endophytes showed a weaker response. Relative MGE abundance decreased significantly in both compartments, and lower assembly-level ARG-MGE co-occurrence reflected fewer ARGs detected in MGE-associated genomic contexts, whereas fewer multi-ARG contigs suggested reduced ARG clustering and potential co-selection. Putative host-reservoir analysis associated key efflux determinants with bacterial families whose relative representation declined following CeO2 NP exposure. Transcriptomic profiling of representative putative ARG hosts revealed host-specific responses, including downregulation of genes involved in central metabolism and Sec-dependent trafficking. Complementary host assays showed reduced apparent envelope permeability and lower recovery of tetracycline-resistant recipient-identity colonies in the plasmid-associated host system. Together, under the tested elevated-loading conditions, CeO2 NP exposure was associated with lower relative ARG signals and weaker mobility-linked resistome features across the soil-lettuce continuum, providing mechanistic insight into nanoparticle-resistome interactions in soil-plant systems.

ARG dissemination

Microplastic aging drives convergence of the plastisphere microbiome and resistome toward agricultural soils.

The degree of microplastic (MP) aging varies substantially in agricultural soils; however, how this common aging gradient influences the plastisphere microbiome and resistome remains largely unknown. We therefore collected polyethylene MPs from long&#x2011;term mulched farmlands and classified them into low&#x2011;aged plastispheres (LAPs) and high&#x2011;aged plastispheres (HAPs). Bacterial community dissimilarity to soil decreased progressively from LAPs to HAPs, accompanied by broadening niche breadth, increasing bacterial diversity, and a shift toward more stochastic community assembly. The diversity and abundance of antibiotic resistance genes (ARGs) declined significantly along the aging gradient, with clinically relevant high-risk ARGs (e.g., vanR, ugd, and aac(6')-I) decreasing by 53.34-84.01%. Furthermore, the ARG hosts shifted from Actinomycetota in LAPs to Pseudomonadota in soils. Variance partitioning showed that the carbonyl index uniquely explained 57.03% of the variation in plastisphere ARG profile distance toward soil, identifying MP aging as the primary driver of resistome convergence. Collectively, these findings demonstrate that natural MP aging drives a progressive convergence of the plastisphere resistome toward that of the surrounding soil, indicating that aged MPs may pose a reduced risk of antibiotic resistance compared to newly formed MPs. This convergence underscores the need to incorporate plastic aging into future risk assessment frameworks for plastisphere-associated ARGs.

Soil Microbiology

Effects of commonly used antibiotics on children's developing gut microbiomes and resistomes in peri-urban Lima, Peru.

BACKGROUND: The effects of antibiotic use on children's gut microbiomes and resistomes are not well characterized in middle-income countries, where antibiotic consumption is exceptionally common. OBJECTIVES: We characterized the effects of antibiotics commonly used by Peruvian children (i.e. amoxicillin, azithromycin, cefalexin, trimethoprim/sulfamethoxazole) on the &#x3b1;-diversity, &#x3b2;-diversity and abundance of gut genera and antibiotic resistance genes (ARGs) from 3 to 16&#x2005;months. METHODS: This study included 54 children from a prospective cohort of enteric infections in peri-urban Lima, 2016-19. Stools collected at 3, 6, 7, 9, 12 and 16&#x2005;months underwent DNA extraction and short-read metagenomic sequencing. We profiled the taxonomy of stool metagenomes and assessed ARG abundance by aligning reads to the ResFinder database. We used daily surveillance data (40&#x200a;662 observations) to tabulate the number of antibiotic courses consumed in the 30&#x2005;days prior to stool sampling. Using linear mixed models, we examined associations of recent antibiotic use with richness, diversity and abundance of gut genera and ARGs over time. RESULTS: Each additional recent antibiotic course decreased Bifidobacterium and Dialister abundance and increased Veillonella abundance, although gut richness and diversity were not affected. Recent use of amoxicillin, azithromycin, cefalexin or trimethoprim/sulfamethoxazole, specifically, did not impact gut microbiome measures. Amoxicillin, azithromycin and trimethoprim/sulfamethoxazole significantly enriched multiple ARGs and amoxicillin use significantly increased total ARGs. CONCLUSIONS: Common antibiotics like amoxicillin and azithromycin appear to be key drivers of the paediatric gut resistome. Resistome perturbations appeared to be stronger, or persist for longer, than gut microbiome effects in this middle-income country setting.

Humans

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

Beyond borders: plasmids drive a shared antibiotic resistome in European urban water systems.

BACKGROUND: Urban wastewater systems (UWSs) act as reservoirs and conduits for the dissemination of antibiotic resistance genes (ARGs), with plasmids playing a central role in their spread. Despite their significance, the diversity and persistence of plasmids in UWSs remain underexplored. RESULTS: This study applies a multi-omics approach, including metagenomic and direct plasmidome sequencing, high-throughput qPCR array, and whole genome sequencing of plasmid isolates, to comprehensively profile the microbial plasmidome and resistome on 78 samples across UWSs in Denmark, Spain, and the UK. We successfully uncovered an extensive plasmid and ARG diversity that could not be fully captured by a single method, especially identified 78,574 plasmids, including 20,925 plasmids previously unreported. We also observed that plasmids carried a disproportionate share of clinically relevant ARGs, particularly beta-lactamase resistance genes; most importantly, they were preferentially located on transmissible plasmids. Furtherly, plasmids harbor ARG can enhance their persistence in wastewater ecosystems, especially harboring multiple types of ARGs. Moreover, Bacteroides emerged as a unique persistent ARG reservoir not only for harboring and disseminating diverse resistance genes especially in residential-relevant areas, but also emerged as a major driver of antimicrobial resistance dynamics across different wastewater treatment processes. CONCLUSIONS: Overall, this work provides the first attempt at a holistic description of the UWSs' resistome, its structure, dynamics, and mobility and significantly expands the current knowledge. Video Abstract.

Plasmids

Microbiome and resistome successions in pig carcasses and fresh pork meat throughout slaughtering, processing and shelf-life.

BACKGROUND: Slaughterhouses and meat cutting plants represent potential hotspots for the spread and transfer of spoilage and pathogenic, including antimicrobial resistant, bacteria to meat and meat products. Here, we characterise the progression of the microbiome and resistome of two pork cuts (loin and sirloin) at different stages of processing, from the slaughter line to the end of shelf-life. To this end, we analysed samples from facility surfaces, carcasses, and meat cuts using whole metagenome sequencing. RESULTS: The taxonomic and antimicrobial resistance gene (ARG) profiles of carcasses and meat cuts were significantly influenced by the point of sampling and the processing room. The facility surfaces were found to be the main source of some abundant genera, such as Anoxybacillus, Acinetobacter, Pseudomonas, and Brochothrix, in carcasses and meat cuts. A total of 1,291 metagenome-assembled genomes were reconstructed, corresponding to the most prevalent species identified in the taxonomic analysis at the read level. A reduction in bacterial and ARGs richness and diversity was observed for carcasses and meat cuts along the production chain, which suggests that processing procedures are effective in reducing bacterial and ARGs loads. Nonetheless, an increase in the ARGs load was observed at two sampling points: the carcass after evisceration and the sirloin at the end of its shelf-life (in this case linked to the increase of a single gene, tet(L)). The ARGs most frequently detected were those associated with resistance to tetracyclines, aminoglycosides, and lincosamides. Acinetobacter (in processing environments and carcass/meat samples) and Staphylococcus (in carcasses and meat) were identified as the main genera associated with the ARGs found. CONCLUSIONS: Overall, our results provide the most detailed metagenomics-based perspective on the microbial successions of pig carcasses and fresh meat cuts during slaughtering, processing, and commercialisation. The observations made suggest that selection pressures imposed by processing steps and contact with facility surfaces contribute to shaping the microbiome and resistome of the two pork products throughout their production line and shelf-life. Video Abstract.

Animals

Comparative genomics reveals genotype-phenotype concordance and cryptic resistomes in clinical Pseudomonas aeruginosa.

BACKGROUND: Pseudomonas aeruginosa (P. aeruginosa) is a major pathogen because of its adaptability. It shows rapid evolution of multidrug resistance (MDR). Phenotype-based diagnostics often fail to detect silent resistance determinants and early adaptive changes. This study integrates phenotypic profiling with whole-genome sequencing (WGS) to examine resistance architecture in clinical isolates from eastern India. METHODS: From 1295 culture-positive P. aeruginosa specimens collected at a tertiary care hospital in eastern India. Using predefined criteria, representative MDR and non-MDR isolates were selected, including distinct resistance phenotypes, specimen-source diversity, and hospital and community-acquired settings; multivariate analysis of resistance profiles illustrated phenotypic diversity. Antimicrobial susceptibility assessed using VITEK-2 and Kirby-Bauer disk diffusion, species identity confirmed by 16&#xa0;S rRNA sequencing, and genomic analysis processed through a reference-guided workflow. Antimicrobial Resistance (AMR) determinants were identified through CARD, and phylogenetic tree constructed from 454 publicly available P. aeruginosa genomes. RESULTS: MDR exhibited greater sequence divergence relative to PA14 (~&#x2009;69,000 variants) than the non-MDR isolate (~&#x2009;58,700 variants), with >&#x2009;92% coverage at &#x2265;&#x2009;30X depth. Strong genotype-phenotype concordance observed in MDR isolates across five antibiotic classes, associated with &#x3b2;-lactamase variants (PDC-67, OXA-396) and regulatory adaptations (ArmR, cprS). The non-MDR isolate harboured gyrA (T83I) resistance-associated mutations, PDC-1, and OXA-847 without phenotypic expression, indicating silent resistome. Phylogenetically, MDR isolates clustered tightly within the phylogeny, while the non-MDR isolate formed a distinct lineage. CONCLUSION: Observed genomic differences align with adaptation under antimicrobial selection, though confirmation requires larger collections. The non-MDR isolate retained a silent resistome. Findings highlight limitations of phenotype-only diagnostics, support genomic data integration, and emphasize transcriptomics for hidden resistance expression and regulatory dynamics.

Pseudomonas aeruginosa

Metagenomic insights into ecological risk of antibiotic resistome and mobilome in riverine plastisphere under impact of urbanization.

Microplastics (MPs) are of increasing concern due to their role as reservoirs for antibiotic resistance genes (ARGs) and pathogens. To date, few studies have explored the influence of anthropogenic activities on ARGs and mobile genetic elements (MGEs) within various riverine MPs, in comparison to their natural counterparts. Here an in-situ incubation was conducted along heavily anthropogenically-impacted Houxi River to characterize the geographical pattern of antibiotic resistome, mobilome and pathogens inhabiting MPs- and leaf-biofilms. The metagenomics result showed a clear urbanization-driven profile in the distribution of ARGs, MGEs and pathogens, with their abundances sharply increasing 4.77 to 19.90 times from sparsely to densely populated regions. The significant correlation between human fecal marker crAssphage and ARG (R2&#xa0;=&#xa0;0.67, P=0.003) indicated the influence of anthropogenic activity on ARG proliferation in plastisphere and natural leaf surfaces. And mantel tests and random forest analysis revealed the impact of 17 socio-environmental factors, e.g., population density, antibiotic concentrations, and pore volume of materials, on the dissemination of ARGs. Partial least squares-path modeling further unveiled that intensifying human activities not only directly boosted ARGs abundance but also exerted a comparable indirect impact on ARGs propagation. Furthermore, the polyvinylchloride plastisphere created a pathogen-friendly habitat, harboring higher abundances of ARGs and MGEs, while polylactic acid are not likely to serve as vectors for pathogens in river, with a lower resistome risk score than that in leaf-biofilms. This study highlights the diverse ecological risks associated with the dissemination of ARGs and pathogens in varied MPs, offering insights for the policymaking of usage and control of plastics within urbanization.

Urbanization

From regionalization to homogenization: Nationwide metagenomic assessment of priority pathogens and the resistome in Polish hospital wastewater.

Hospital wastewater (HWW) is a critical hotspot for the dissemination of antibiotic resistance genes (ARGs) and pathogens. This study provides the first comprehensive metagenomic characterization of HWW across Poland, analyzing 64 medical facilities across two seasons via Nanopore long-read sequencing (total of 128 HWW samples). The HWW microbiome was mostly dominated by Proteobacteria, Bacteroidota, and Firmicutes. Multivariate analysis confirmed a significant seasonal shift in the resistome. Winter samples exhibited geographic regionalization, with localized hotspots of specific ARGs, including vancomycin resistance (operon van) and carbapenemase genes (blaOXA, blaNDM). Conversely, summer samples showed a significant trend toward nationwide homogenization, characterized by a uniform distribution of ESBL genes (blaTEM, blaCTX-M) and multidrug resistance (MDR) determinants, alongside the persistence of localized clinical hotspots. Klebsiella pneumoniae emerged as a central network hub, particularly in summer, showing strong correlations with ESBLs. Quantitative genomic co-occurrence analysis revealed a functional division within dominant taxa: while environmental species like Acinetobacter johnsonii comprised the general background microbiome, clinical pathogens such as Acinetobacter baumannii served as primary vectors, showing frequent associations with high-risk ARGs. Environmental and opportunistic bacteria, such as Aeromonas spp. and Citrobacter spp., were identified as putative 'bridge hosts' associated with mobile resistance determinants and potentially contributing to HGT. The findings indicate that seasonal factors, such as increased temperature and sub-inhibitory antibiotic concentrations, may contribute to the transition from regionalized to homogenized resistance profiles, demonstrating that background resistome convergence can coexist with point-source clinical outbreaks. This seasonal "blurring" of regional boundaries positions HWW as an active vector for large-scale antimicrobial resistance (AMR) dissemination. These results underscore the urgent need for nationwide metagenomic surveillance and advanced wastewater treatment strategies within the "One Health" framework to mitigate the environmental spread of WHO priority pathogens.

Acinetobacter baumannii

Resistome and microbiome-immune interactions in an Eastern European population with high antibiotic use.

The gut microbiome influences host health, affecting gastrointestinal, metabolic, immune, cardiovascular, and neurological functions. A balanced microbiome is associated with favorable health outcomes. However, excessive antibiotic use and dietary habits can disrupt this ecosystem, leading to dysbiosis and affecting body homeostasis. This first comprehensive metagenomic analysis of the gut microbiome in a healthy Romanian cohort, a population underrepresented in microbiome studies and characterized by high antibiotic consumption, addresses a gap in current microbiome research. We report an enrichment of Enterobacteriaceae although overall composition is more comparable to other European than non-European cohorts. Community configurations align with established enterotype patterns, and our analysis provides insight into their relationship with within-phylum diversity. The analysis of antimicrobial resistance provides insight into the prevalence of resistance genes within this reservoir. We specifically report the presence of cfr(E), a Clostridioides difficile gene, and tet(X5), a variant from the ubiquitous tet family, genes not previously reported in healthy European populations. Integration with data from the European Centre for Disease Prevention and Control links the overall prevalence of resistance genes in this reservoir to antibiotic classes with higher community consumption in this population, notably beta-lactams and quinolones, highlighting potential targets for antibiotic stewardship programs. Finally, we investigate the relationship between the microbial profile and the systemic immune responses, inferred from correlations with in vitro cytokine production. Notably, we identify potential immune-priming roles for Collinsella, Flavonifractor, and Bifidobacterium species.IMPORTANCEThis first comprehensive study of the healthy gut microbiome in a Romanian cohort addresses a gap in current microbiome research, dominated by data sets from a limited number of regions. It sets a baseline for the microbiome and resistome composition of this population, and, while definitions of "healthy" microbiomes, or baseline resistomes, remain lacking, such study helps contextualize future studies and support the monitoring of dynamics. The Enterobacteriaceae abundance suggests a microbiome composition potentially influenced by antimicrobial consumption, a relevant pattern in a region with a high burden of nosocomial infections. In addition, the prevalence of antimicrobial resistance genes and the concordance with commonly used antibiotics in the community reinforce the need to address antibiotic use in public health strategies. Although gut microbiome-immunity relationships remain incompletely understood, our findings support a role for microbiome composition in immune-related traits and provide a valuable resource for future studies.

Humans

Divergent microbial preludes to necrotising enterocolitis defined by gut phages and bacterial resistomes.

BACKGROUND: Translating microbiome correlations into robust predictive features for complex gut disorders remains elusive, partly due to oversimplified models of pathogenesis and neglect of the virome, a key player in microbial ecosystems. Necrotising enterocolitis (NEC), a devastating disease of preterm infants with no reliable clinical predictors, exemplifies this challenge. OBJECTIVE: To determine the predictive potential of the gut prophageome and polymicrobial aetiologies for NEC. DESIGN: We applied integrated metagenomic and metatranscriptomic analyses and machine learning to 1825 longitudinal stool samples from 43 preterm infants who later developed NEC and 86 gestational age-matched and birthweight-matched controls across three US hospitals. We characterised gut prophageome acquisitions and their association with clinical exposures, including antibiotics, diet and pharmacotherapies. To predict NEC risk, we integrated pre-onset prophageome, antibacterial resistome and bacteriome profiles with neonatal pathology, stratifying the cohort by disease onset timing (early: &#x2264;40 days; late: >40&#x2009;days) for separate analysis. RESULTS: NEC cases exhibited distinct viral diversity trajectories before disease onset. Early-onset NEC was best predicted by phage-bacterial interaction signatures (75% accuracy, 81% sensitivity). Metatranscriptomics revealed increased phage DNA abundance with low gene expression, suggesting a lysogenic lifestyle that may stabilise pathobionts. These phages encode metabolic genes potentially enhancing pathobiont resilience. Late-onset NEC was best predicted by antibacterial resistome profiles (83% accuracy). CONCLUSION: The gut prophageome serves as both a source of pre-symptomatic predictive signals and an active modulator of NEC pathogenesis, with distinct microbial mechanisms driving early-onset and late-onset disease. These polymicrobial etiologies inform strategies for early detection, risk stratification and the development of microbiome-targeted preventive and therapeutic interventions.

BIOMARKERS

Portable metagenomics for preventive surveillance and outbreak control in livestock and poultry: Pathogen detection, resistome profiling, and antimicrobial stewardship.

Conventional diagnostics for livestock and poultry outbreaks commonly rely on culture or targeted PCR panels, which may be too slow or too narrow to guide early control decisions. Portable metagenomics, particularly real-time nanopore sequencing, offers a route to broad pathogen detection, antimicrobial-resistance gene profiling, and outbreak investigation within an integrated workflow. This implementation-focused review evaluates how near-point-of-care metagenomics may support preventive veterinary medicine through earlier detection, surveillance, cohorting, biosecurity decisions, and antimicrobial stewardship. We synthesize sample-to-answer workflows for enteric and respiratory disease in food-producing animals, including sampling, nucleic-acid extraction, host depletion or target enrichment, library preparation, sequencing, bioinformatics, quality control, and interpretation. Applications in calf diarrhea, bovine respiratory disease, poultry outbreaks, mastitis, and resistome monitoring are considered alongside the central limitation that detection alone does not establish causation. Pathogen and resistance-gene signals must therefore be interpreted with clinical signs, lesions, epidemiology, controls, and confirmatory testing. We also propose a minimum reporting checklist, intended as a practical framework rather than a validated consensus standard. Portable metagenomics is not a replacement for conventional diagnostics, but appropriately validated workflows can reduce uncertainty during time-sensitive outbreaks and support more judicious antimicrobial use.

Animals

Concurrence of antibiotic resistance genes in plasmid genomes shape environmental resistomes.

Horizontal transfer of plasmid-associated antibiotic resistance genes (ARGs) plays a pivotal role in environmental antibiotic resistance dissemination. Here, we characterized ARG concurrence patterns in plasmid genomes and examined plasmid-associated ARGs across 106 environmental metagenomes. Approximately half of known ARG subtypes (257) occurred in plasmid genomes, and nearly one-quarter of plasmids carried ARGs, including "super plasmids" harboring over 20 ARG subtypes spanning 10 antibiotic categories. Aminoglycoside resistance genes (AmRGs) exhibited the highest concurrence frequency (CF) with other ARGs in plasmid genomes, followed by beta-lactam and sulfonamide resistance genes. Many high-risk ARGs preferentially coexisted with AmRGs (45.6% of total AmRGs CF). Environmental metagenomes revealed distinct plasmid-associated ARG profiles between polluted and relatively pristine environments, with significantly greater diversity and abundance under anthropogenic pollution. Five widespread ARG subtypes occurred across all environmental media, whereas polluted environments contained more unique ARGs. Co-occurrence networks identified AmRGs as "hubs" linking multiple ARG subtypes in environmental resistomes. Plasmid-ARG interaction networks further showed more complex potential plasmid-mediated concurrent dissemination in polluted environments. Collectively, use of aminoglycosides is more likely to cause co-transmission of multiple plasmid-related ARGs than other antibiotics, and CF of ARGs is proposed as an important supplementary factor for evaluating ARG dissemination under anthropogenic antibiotic stress.

Antibiotic resistance genes (ARGs)