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PubMed2026

Dynamics of antibiotic resistance genes co-occurrence with pathogenic and non-pathogenic bacteria throughout wastewater treatment processes.

Wastewater treatment plants (WWTPs) are recognized hotspots for antibiotic resistance genes (ARGs) and pathogenic bacteria. Despite advancements in treatment technologies, the persistence of ARGs and pathogenic bacteria remains a concern. In this study, we analyzed the dynamic changes in ARGs and bacterial communities throughout the treatment processes within an anaerobic-anoxic-oxic (AAO) WWTP over one week by using HT-qPCR coupled with 16S rRNA gene amplicon sequencing. The connectedness index, based on network analysis, showed that the dynamics of ARGs and mobile genetic elements (MGEs) were more strongly associated with potentially pathogenic bacteria than with non-pathogenic bacteria, suggesting that ARG immigration and dissemination in the WWTP were likely driven by potentially pathogenic taxa. The AAO treatment significantly reduced ARGs in final effluent (EF) (∼64 %) and residual sludge (RS) (∼81 %); however, potential hosts of ARGs such as Comamonas testosteroni and Clostridioides difficile persisted with minimal changes in relative abundance and remained detectable in EF and RS. Notably, the abundance of ARGs was lower in RS than in EF, and source tracking analysis identified influent as the primary source of ARGs and potentially pathogenic taxa in EF, underscoring the greater health risks associated with effluent discharge.

Wastewater↗

PubMed2026

Discarding Bedside Cart Paper-Packaged Supplies Between Patients: What Evidence Is Required?

BACKGROUND: Discarding paper-packaged sterile supplies from bedside supply carts between patients in pediatric intensive care units (PICUs) is a potential practice to target for environmental stewardship. OBJECTIVES: To determine opinions about this practice, including what evidence should be required to implement and what evidence would be adequate to abandon it. METHODS: A survey was distributed to all pediatric intensivists engaged in multicenter research in Canada and to all PICU nurses at one institution in Canada. RESULTS: The response rate was 75 of 254 (30%). The practice occurred in 54 (72%) of the respondents' units. Ten respondents (13%) agreed the practice was effective in preventing nosocomial infections. Most respondents agreed the practice should be based on empirical evidence, including a combination of improved patient outcomes (n = 57, 76%), rate of contamination of supplies within the supply carts (n = 55, 73%), and survivability of pathogens inoculated onto paper (n = 56, 75%). Most respondents agreed they would be comfortable with a randomized controlled trial (n = 52, 69%) and would support action based on the results (n = 54, 72%). The potential trial outcome most highly ranked was next-patient nosocomial infection with pathogen from the previous patient (n = 23, 31%); this was ranked more often by intensivists (P = .005). Other outcomes highly ranked included next-patient colonization with pathogen from the previous patient (n = 44, 59%) and pathogen detection on supplies within the supply cart (n = 43, 57%). CONCLUSIONS: Most respondents agreed that the practice was not based on empirical evidence, agreed the practice should be based on empirical evidence, and would agree to a randomized trial with patient-important outcomes.

Humans↗

PubMed2026

Emergence of an optrA-positive Enterococcus faecalis ST699 lineage in animal-derived foods in Beijing, China.

Enterococci from animal-derived foods are key reservoirs for antimicrobial resistance (AMR) in the food chain. However, comparative genomic studies investigating the distribution of the oxazolidinone resistance gene optrA among food- and human-derived Enterococci remain limited. This study assessed linezolid-resistant Enterococci from retail meat and healthy humans in Beijing, China (2023-2024). Among 87 isolates, E. faecalis and E. faecium predominated. Food-derived isolates showed broader resistance profiles than human isolates. Fourteen optrA-positive strains were identified, accounting for 92.9% of food isolates. optrA frequently co-localized with erm(A), ant(9)-Ia, and fexA on Tn554-family transposons, suggesting a potentially transferable multidrug resistance module. Notably, an optrA-positive E. faecalis ST699 clone was identified for the first time in Chinese retail meat. This clone formed a distinct lineage and carried a complete Tn554-optrA island. A representative ST699 isolate exhibited enhanced fitness and virulence potential in the Galleria mellonella model. These findings highlight animal-derived foods as important reservoirs of linezolid-resistant Enterococci and provide genomic evidence consistent with their role as potential sources of optrA-mediated resistance. The emergence of a multidrug-resistant E. faecalis ST699 clone with enhanced fitness characteristics underscores the need for continued surveillance of foodborne antimicrobial resistance within the One Health framework.

Enterococcus faecalis↗

PubMed2026

In Vitro comparison of herbal and conventional antifungals against Candida strains in Oral candidiasis: A systematic review and meta-analysis.

OBJECTIVE: This study aimed to systematically review and meta-analyze the in vitro antifungal activity of herbal and conventional antifungals against Candida strains. DESIGN: In vitro studies were identified through PubMed, Embase, Scopus, and Web of Science up until May 2026. This review is registered with Prospero (CRD420251128404). Eligibility was determined using the Population, Intervention, Comparison, and Outcome (PICO) framework, with specific inclusion and exclusion criteria focused on in vitro antifungal investigations comparing herbal antifungals with conventional antifungals. The risk of bias was assessed using the modified Quality Assessment Tool for In Vitro Studies (QUIN Tool). A meta-analysis was performed, with the primary outcome measure being the ratio of means (RoM). RESULTS: The systematic review included twenty-five articles. Most studies showed different results in inhibition zones or minimum inhibitory concentrations between herbal and conventional agents. The meta-analysis indicates that certain herbal antifungals are equally effective as or more effective than conventional antifungals against Candida dubliniensis, Candida lusitaniae, and Candida tropicalis. While the efficacy of herbal antifungals for Candida albicans and Candida glabrata was modest, Piper betle L. demonstrated significant inhibitory potential. In contrast, conventional antifungals outperformed herbal antifungals against Candida krusei and Candida parapsilosis. CONCLUSIONS: This systematic review and meta-analysis highlight herbal medicine as a potential antifungal therapy for oral candidiasis, emphasizing the need for new strategies due to resistance to conventional antifungals.

Humans↗

PubMed2026

A mechanism-guided framework for prioritizing membrane-interaction anti-Vibrio peptides from peptidomics data.

A mechanism-guided framework for prioritizing membrane-interaction antimicrobial peptide candidates from proteomics-derived peptide mixtures is presented. The framework integrates conservative machine-learning-based antimicrobial peptide (AMP) screening with a literature-derived membrane-interaction plausibility (MAP) assessment and a data-driven membrane-interaction ranking function (AIPx), followed by structural visualization for interpretability. MAP encodes physicochemical characteristics commonly associated with peptide-membrane interaction and provides a graded plausibility assessment. Building upon this physicochemically interpretable framework, AIPx ranks peptides using feature weights calibrated from experimentally characterized anti-Vibrio peptides, where minimum inhibitory concentration (MIC) values are used as a coarse-grained ranking reference rather than a direct prediction target. In a peptidomics-based peptide fractionation study targeting Vibrio spp., AIPx exhibited a consistent relationship with experimentally observed antibacterial activity. Distributional analysis revealed that peptide fractions exhibiting high anti-Vibrio activity are characterized by enrichment of high-ranking peptides rather than by AMP abundance alone. By structuring AMP identification and prioritization as sequential stages, the MAP + AIPx framework enables interpretable and experimentally actionable candidate selection by reducing biologically implausible candidates. The framework facilitates species-oriented prioritization of AMP candidates, addressing a key challenge in antimicrobial peptide discovery where activity may depend on target-specific membrane characteristics. Moreover, the approach is extensible through species-specific calibration and supports interpretable, mechanism-informed prioritization in antimicrobial peptide discovery.

Proteomics↗

PubMed2026

Tigecycline-resistant Staphylococcus in waiting pens of a pig slaughterhouse: genomic insights into a food safety alert.

BACKGROUND: The waiting pens of slaughterhouses represent a critical control point in the 'farm-to-fork' continuum, yet their role in the emergence and dissemination of antimicrobial resistance remains understudied. This study investigated tigecycline-resistant Staphylococcus (TRS) in these high-risk zones to assess their prevalence, resistance mechanisms, and transmission dynamics. METHODS: 400 samples were collected from the waiting pens of a pig slaughterhouse in Guangzhou, China. Antimicrobial susceptibility testing, whole-genome sequencing, phylogenetic analysis, and molecular cloning were employed to characterize resistance mechanisms and transmission patterns. RESULTS: 78 TRS strains were isolated and classified into three species, including S. borealis, S. ureilyticus, and S. pasteuri. These isolates exhibited multidrug-resistant phenotypes and carried new mutations in rpsJ and tet(M), which were functionally confirmed to reduce tigecycline susceptibility. Phylogenetic evidence demonstrated clonal transmission between pig farms and the slaughterhouse. The tet(M) gene was located within Staphylococcal cassette chromosome mec elements mediated by IS257, while tet(L) was carried by plasmids formed through IS256/IS257-mediated recombination. CONCLUSIONS: Waiting pens serve as crucial reservoirs for the amplification and dissemination of antimicrobial resistance. Our findings underscore the urgent need for enhanced biosecurity measures, improved waste management, and routine molecular surveillance in these high-risk zones to mitigate the spread of resistance along the food production chain.

Animals↗

PubMed2026

Efficacy of the NMIC-150 system in identifying extended-spectrum beta-lactamases in clinical isolates.

Extended-spectrum beta-lactamases (ESBLs) are significant contributors to the growing global crisis of antimicrobial resistance. This study evaluated the performance of the NMIC-150 System for susceptibility testing of third-generation cephalosporins (3GCs) and assessed whether ceftazidime-avibactam and aztreonam-avibactam could identify ESBL-producing carbapenem-resistant Enterobacterales (CREs). A total of 278 non-duplicate clinical isolates (Klebsiella pneumoniae, E. coli, and Proteus mirabilis) were analyzed. Antimicrobial susceptibility was determined using reference broth microdilution (BMD) and the NMIC-150 System. ESBL production was defined as an ≥eight-fold reduction in the minimum inhibitory concentration (MIC) of 3GCs in the presence of clavulanic acid, according to CLSI criteria. Whole-genome sequencing was performed to characterize ESBL and carbapenemase genes among 3GC-resistant isolates. A Random Forest model was used to predict ESBL-producing isolates based on MIC values. The NMIC-150 System demonstrated over 90% categorical and essential agreement with BMD for ceftazidime and ceftriaxone, along with robust predictive performance via Random Forest analysis. These findings suggest that the NMIC-150 System is a reliable platform for 3GC susceptibility testing and that an ≥eight-fold MIC reduction with ceftazidime-avibactam or aztreonam-avibactam may serve as a phenotypic indicator of ESBL production in CRE isolates. In conclusion, the NMIC-150 System shows potential for routine antimicrobial resistance surveillance and may facilitate the rapid identification of ESBL-producing CREs in clinical settings.

Microbial Sensitivity Tests↗

PubMed2026

Systematic modular engineering of genome-integrated Escherichia coli MG1655 for high-level 2'-fucosyllactose production.

2'-Fucosyllactose (2'-FL), the most abundant human milk oligosaccharide (HMO), has attracted considerable interest for its prebiotic and immunomodulatory functions, with broad applications in infant nutrition. In this study, we report the development of a high-yield, genome-integrated 2'-FL-producing strain based on Escherichia coli MG1655 through systematic modular optimization. Starting from a single-copy BKHT strain (MGC06), we first optimized the copy number of the α-1,2-fucosyltransferase (α-1,2-FT) gene BKHT. Subsequently, the GDP-L-fucose supply was enhanced through coordinated genomic integration of the gene clusters cpsG-cpsB and gmd-fcl, while the multidrug efflux transporter gene mdfA was integrated to improve product export and strain robustness. BKHT copy number was then re-evaluated in the optimized background, with four copies yielding the highest production. The final engineered strain, harboring all genetic modifications stably integrated into the chromosome, produced 17.18 g/L 2'-FL in shake-flask culture. In fed-batch fermentation using a 5-L bioreactor, this strain achieved a titer of 154.12 g/L after 60 h, with a productivity of 2.57 g/L/h. Notably, throughout the entire fermentation process, no antibiotics or inducers were supplemented, underscoring the genetic stability and regulatory compliance of this plasmid-free system. To our knowledge, this represents the highest 2'-FL titer reported to date, positioning our engineered strain as a promising candidate for commercial 2'-FL production.

Escherichia coli↗

PubMed2025

Coupling of spectroscopy and nitrogen-oxygen isotopes unveils the mechanisms of dissolved organic matter and nitrate pollution in lakes within the agro-pastoral transition zone.

Lakes in arid and semi-arid regions are subjected to severe ecological stress, such as organic pollution, eutrophication, and salinization, due to climate change and human activities. This study investigates Chagannur Lake, a typical arid-region lake that is representative and ecologically sensitive in Northern China's agro-pastoral ecotone, to uncover its pollution characteristics and mechanisms. We employed fluorescence spectroscopy and stable isotope analysis to trace dissolved organic matter (DOM) and nitrate sources. The DOM composition was dominated by microbial metabolic byproducts and protein-like substances, suggesting that microbial processes are key to organic matter transformation. Source apportionment revealed that pollutants primarily originated from livestock and poultry manure (37.6 %), agricultural fertilizers (35.6 %), and soil erosion (24.7 %), with agricultural fertilizers contributing most significantly in the Gogstai River (63.3 %). A structural equation model (SEM) coupling spectral and mass spectrometric data revealed that microbial transformation significantly impairs the lake's self-purification capacity, thereby promoting pollutant accumulation (path coefficient = 0.91,*p < 0.05). Moreover, microbial processes link endogenous and exogenous pollution, a mechanism effectively traced by isotopic and fluorescence indices (path coefficient = 0.55, ⁎⁎p < 0.01). These findings enhance the understanding of pollution sources and transformation mechanisms in arid-region lakes and offer foundational theoretical support for policymakers engaged in pollution control strategies.

Lakes↗

PubMed2026

Development and protective efficacy of a live attenuated vaccine candidate against goose astrovirus.

Goose astrovirus (GAstV) is a significant pathogen affecting goslings by inducing visceral gout, yet no commercial vaccine is currently available. This study involved the serial passaging of the GAstV-GXNN strain in LMH cells to investigate alterations in viral replication, genomic stability, and pathogenicity, as well as to assess the potential of a vaccine candidate. The findings indicated that the viral titer increased progressively with each passage, reaching 107.35 TCID50/mL by the 120th passage (GAstV-GXNNP120). Whole-genome sequencing revealed the presence of 6, 19, 26, and 28 nucleotide mutations at the 30th, 60th, 90th, and 120th passages, respectively. Pathogenicity assays demonstrated a reduction in virulence with successive passages, culminating in the complete attenuation of GAstV-GXNNP120, which did not induce clinical signs or lesions in one-day-old goslings. Following five successive passages in goslings, the attenuated strain exhibited stable genetic characteristics without any reversion to virulence. Goslings aged one day, inoculated with GAstV-GXNNP120 at dosages ranging from 102.0 to 105.0 TCID50, developed neutralizing antibodies by the third day post-vaccination. Antibody levels increased in a dose-dependent manner, peaking at day 21 and remaining elevated through day 42. Challenge experiments utilizing the virulent GAstV-GXNN strain revealed that groups vaccinated with doses of 103.0 TCID50 and above achieved complete protection. These groups exhibited no clinical symptoms or pathological damage post-challenge, and both tissue viral loads and virus shedding levels were significantly reduced compared to the control group. Consequently, the minimum effective vaccination dose was established at 103.0 TCID50. These results provide a crucial foundation for the development of a live attenuated GAstV vaccine.

Animals↗

PubMed2025

UV-based homogeneous disinfection process for removal of antibiotic resistance genes: Efficiency, mechanisms and influencing factors.

The proliferation and dissemination of antibiotic resistance genes (ARGs) in aquatic environments pose a serious threat to global public health. Ultraviolet-driven homogeneous advanced oxidation processes (UV-AOPs) represent a prospective suite of technologies for the efficient removal of ARGs. This review critically assesses recent advances in the application of UV-AOPs, specifically UV/hydrogen peroxide (UV/H2O2), UV/peracetic acid (UV/PAA), UV/persulfate (UV/PS), and UV/chlorine (UV/Cl), for the elimination of extracellular ARGs and intracellular ARGs. The underlying mechanisms involve direct ultraviolet-induced DNA damage, including pyrimidine dimer formation and strand breakage, as well as oxidation mediated by radicals such as hydroxyl radicals, sulfate radicals, carbon-centered radicals, and reactive chlorine species. The relative contribution of radical and non-radical pathways is strongly influenced by water chemistry and process conditions. We further expound on the critical operational and environmental factors governing ARG removal kinetics, including UV wavelength and fluence, oxidant type and dosage, ARG sequence characteristics, pH, ubiquitous anions, and dissolved organic matter, which collectively affect radical generation, quenching, and reaction microenvironments. Notably, for i-ARGs, UV-AOPs facilitate degradation not only through direct radical attack but also by disrupting cellular integrity and permeabilizing membranes, thereby enhancing the exposure of genetic materials to oxidative and photolytic damage. This review synthesizes current understanding to provide a mechanistic basis for the design and optimization of UV-AOP systems, highlighting their potential as effective barriers against the dissemination of antibiotic resistance in water reuse and purification scenarios.

Disinfection↗

PubMed2026

Quantifying the aromatic amino acid metabolome: UPLC-MS/MS analysis of aromatic amino acids and their host and co-metabolites in plasma.

Aromatic amino acids (AAAs), tryptophan, phenylalanine, and tyrosine along with their pathway metabolites have been implicated in the pathogenesis of diseases ranging from cardiovascular, neurological, inflammatory, and cancer diseases, among others. As such, the measurement of the primary AAAs, their host pathway metabolites, and microbiome derived co-metabolites in blood can provide a sensitive reflection of systemic health. The aim of the study was to develop a method for the quantification of 17 metabolites, the three AAAs and various of their metabolites in plasma using a high-throughput ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method. The method demonstrated a dynamic range (1 to 16,700 ng/mL), with detection limits (LOD) as low as 0.05 ng/mL. Quantification limits ranged from 3 to 5019 ng/mL (LLOQ) and up to 16,700 ng/mL (ULOQ). Recovery at LQC, MQC, and HQC was satisfactory and consistent across most metabolites, with significant matrix effects observed only for 4-ethylphenol sulfate. Furthermore, intra and inter-day accuracy and precision met all acceptance criteria at all quality control concentrations for most of the metabolites. Measurement of NIST SRM 1950 showcased the method's accuracy for most of the metabolites. Finally, the method was applied on the analysis of plasma samples from 55 individuals (13 males and 42 females) providing information on AAAs and their pathway metabolites relevant concentrations in human plasma.

Amino Acids, Aromatic↗

PubMed2026

Genomic epidemiology of clinically critical antibiotic resistance in Salmonella enterica causing bloodstream infections across six Chinese provinces, 1994-2023.

Clinically critical antibiotic-resistant Salmonella enterica (S. enterica) causing bloodstream infections remains a public health challenge. Here, we aim to reveal the emergence and trends of clinically important antibiotic resistance in S. enterica causing bloodstream infections using 833 isolates from six Chinese provincial-level administrative areas during 1994-2023. We identified 48 serovars and 64 sequence types (STs). Overall, 8.52% of 833 isolates were resistant or had decreased susceptibility to ciprofloxacin, 4.32% and 6.84% reported resistance or decreased susceptibility to third- and fourth-generation cephalosporins (3GCs and 4GCs), 1.80% reported resistance to fosfomycin, and 2.16% reported resistance to azithromycin. Across these six regions, azithromycin and fosfomycin resistance is increasing, as is decreased susceptibility or resistance to ciprofloxacin, 3GCs, and 4GCs, especially among younger children and elderly people. Clinically prioritized antibiotic resistance also varies by region, serovar, and age group. S. Paratyphi A genotype 2.3.3 strains are mainly divided into 2 lineages distributed in Guangxi and Shanghai. Within the scope of this passive surveillance dataset, S. Typhi genotype 4.3.1.2.1 was identified as the earliest documented case among the collected isolates. Our retrospective and longitudinal genomic epidemiology study provides critical data for the formulation of treatment guidelines and policies for bloodstream infections and for the monitoring and control of antimicrobial resistance.

Humans↗

PubMed2026

Herbicolin A, an antifungal lipopeptide produced by Pantoea agglomerans APC 4211 is a promising biocontrol agent against food spoilage fungi.

Fungal contamination of food with yeast and molds is associated with major economic losses due to spoilage and also poses health risks in the form of mycotoxin production. The strain Pantoea agglomerans APC 4211 isolated from leaves of Ilex aquifolium (holly tree) has broad spectrum antifungal activity against a variety of food spoilage fungi. Genomic analysis of the strain confirmed the presence of biosynthetic gene clusters potentially encoding for the enzymatic machinery required for the production of the antifungal lipopeptide herbicolin A. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis of the cell-free supernatant (CFS) confirmed the presence of molecular masses corresponding to herbicolin A (1300.8 Da), and herbicolin B (1138 Da). Purified herbicolin A has desirable properties for biotechnological applications, including potent antifungal activity against a range of spoilage fungi, thermal stability and resistance to proteases. The lipopeptide has low cytotoxicity against epithelial cell lines and has minimum inhibitory concentrations (MICs) lower than those of some commercial antifungal drugs (0.2-2.5 mg/L). In a model dairy system (10% skim milk), herbicolin A demonstrated excellent solubility and stability, effectively eliminating Aspergillus niger and Penicillium notatum at a concentration of 5 mg/L. Overall, the study determines herbicolin's A spectrum against food spoilage organisms and examines potential applications in food. In conclusion, herbicolin A is a potent, naturally occurring antifungal agent with the potential to be applied as a biopreservative in food systems, providing a safe, clean-label, and efficient compound for synthetic preservatives replacement.

Pantoea↗

PubMed2026

Contribution of the Arg-33-His replacement in the histidine kinase CpxA to carbapenem and cefiderocol resistance in Serratia marcescens.

OBJECTIVE: The Serratia marcescens ROT_R clinical isolate, which was resistant to almost all β-lactams, including cefiderocol (4 mg/L), was recovered from a neonate 2 months after the isolation of the S. marcescens ROT_S strain that was susceptible to extended-spectrum cephalosporins (ESCs). In this study, we attempted to decipher the mechanism of resistance displayed by the ROT_R isolate. METHODS: The genomes of ROT_S and ROT_R were sequenced using the Illumina and the Oxford Nanopore Technologies. Long and short reads were assembled together, giving rise to a circularized hybrid genome. RESULTS: Genomic comparison between ROT_S and ROT_R disclosed only one mutation (G98A) in the cpxA gene of ROT_R, which led to the Arg-33-His substitution in the histidine kinase of the two-component system CpxA/CpxR. The cpxA alleles of ROT_S and ROT_R were amplified and cloned, thus giving rise to the pCpxA_WT and pCpxA_R33H recombinant plasmids, respectively, which were subsequently introduced into the S. marcescens HatR recipient strain, which lacks functional CpxA. The S. marcescens HatR (pCpxA_R33H) recombinant clone, which produced the altered CpxA_R33H variant, differed from the S. marcescens HatR (pCpxA_WT) recombinant clone, which produced the wild-type CpxA, by enhanced MICs of carbapenems and ESCs, including cefiderocol (1 mg/L). CONCLUSIONS: This study demonstrates that CpxA alteration, such as Arg-33-His substitution, can contribute to cefiderocol resistance. Although it increases slightly the MIC of cefiderocol without resulting per se in clinical resistance, it can contribute, in combination with other additional mechanisms, to achieve a high level of resistance to this siderophore cephalosporin.

Cefiderocol↗

PubMed2026

Herd-level heterogeneity of antimicrobial resistance in commensal Escherichia coli: A nationwide high-throughput survey of Australian pig herds.

Antimicrobial resistance in commensal Escherichia coli provides a useful indicator for overall antimicrobial resistance burden. We applied this approach to assess antimicrobial resistance within and between commercial pig herds across Australia. A high-throughput robotic workflow was used to isolate 2730 E. coli colonies from rectal contents collected in 2022 from healthy slaughter pigs (n = 300) representing 30 herds (∼70% of national production). Up to 94 isolates per herd underwent antimicrobial susceptibility testing using the Robotic Antimicrobial Susceptibility Platform. Isolate- and herd-level antimicrobial resistance indices were calculated, weighting antimicrobials by their human health importance. Resistance to first-line agents was widespread: ampicillin 77% and tetracycline 79%. By contrast, resistance to critically important antimicrobials was rare (ciprofloxacin 0.11%; extended-spectrum cephalosporins 0.04%), and no clinical resistance to carbapenems or colistin was detected. Overall, 56.9% of isolates were multi-class resistant. Herd-level antimicrobial resistance within indices ranged from 1.51 to 5.76, revealing substantial between-herd heterogeneity. Three herds carried critically important antimicrobials-resistant isolates that would likely have been missed using conventional, lower-density sampling approaches. Whole-genome sequencing identified fluoroquinolone-resistant isolates belonging to ST10 and ST69 (both qnrS1), and ST744 (Quinolone Resistance Determining Region mutations plus blaCTX-M-27). By testing approximately tenfold more isolates than conventional surveys, we uncovered considerable antimicrobial resistance with heterogeneity within and between animals and herds, including farm-specific variability. This expanded sampling also enabled detection of critically important antimicrobial resistance at very low prevalence. In conclusion, high-throughput, high-density testing offers a practical early-warning system and herd-level benchmark to inform surveillance and targeted interventions.

Animals↗

PubMed2026

Diverse structures of mcr-10-bearing plasmids and high colistin resistance in Enterobacter cloacae complex clinical isolates from South Korea.

BACKGROUND: The emergence of mcr-mediated colistin resistance in Enterobacter cloacae complex (ECC) poses a significant threat to antimicrobial therapy. Among mcr variants, mcr-10 has been identified in various environments, but its genetic diversity, structural context, and functional role in colistin resistance remain unclear. METHODS: We investigated 183 ECC isolates and identified 60 colistin-resistant strains through minimum inhibitory concentration (MIC) testing. The presence of mcr-10 was screened using reference genomes from NCBI, and whole plasmid sequencing was conducted on mcr-10-positive isolates. The genetic environment of mcr-10 was analyzed via synteny and structural annotation. RESULTS: Whole-plasmid sequencing of eight mcr-10-positive ECC isolates identified three replicon types among the mcr-10-harboring plasmids: IncFIB (n=3), IncFII (n=3), and IncFII/IncFIB (n=2). Although all plasmids shared the xerC-mcr-10 cassette, they lacked a conserved backbone and showed diverse genetic contexts with variable insertion sequences near mcr-10, indicating marked structural heterogeneity. No additional antimicrobial resistance genes were detected on these plasmids. When introduced into E. coli DH5α, the plasmids increased colistin MICs only modestly, whereas representative plasmids transferred into colistin-susceptible E. roggenkampii and E. kobei conferred high-level resistance comparable to that of the parental mcr-10-positive isolates. Consistently, qRT-PCR showed higher mcr-10 expression in ECC transformants than in E. coli under colistin exposure, supporting a hostdependent effect on mcr-10-mediated colistin resistance. CONCLUSION: These findings highlight the diversity of mcr-10-carrying plasmids and suggest that mcr-10-mediated colistin resistance is shaped by the host genetic background. Further studies are needed to clarify the mechanisms underlying mcr-10 expression.

Colistin↗

PubMed2026

Interface-dependent V. parahaemolyticus biofilm under varying temperatures, media, and oxygen conditions: implications for seafood safety.

Vibrio parahaemolyticus biofilms play a critical role in pathogen persistence in marine and seafood-processing environments, where oxygen availability, temperature, and surface interfaces vary widely. This study investigated biofilm development by three strains on partially submerged stainless-steel coupons under gas-liquid-wall (GLW) and fully submerged (SM) interfaces. Viable cell counts (log₁₀CFU/cm2) along with normalized protein concentration per viable cell (nProt) and normalized polysaccharide concentration per viable cell (nPol) were measured, under aerobic and anaerobic conditions across a temperature range of 15-30 °C, using tryptic soy broth with 3% NaCl (TSB) and seawater-based medium (SW). GLW biofilms consistently exhibited higher cell counts (6.4-7.3 log₁₀CFU/cm2) compared to SM biofilms (5.9-6.3 log₁₀CFU/cm2), suggesting that enhanced oxygen diffusion promotes bacterial proliferation. Conversely, SM biofilms exhibited significantly higher nProt and nPol levels (p < 0.001), indicating increased production of the extracellular polymeric substance (EPS) matrix under low-oxygen, high-nutrient conditions. Microscopy and three-dimensional surface plot analyses revealed relatively uniform biofilm layers at the GLW interface, whereas SM biofilms formed heterogeneous, tower-like structures. EPS production was further influenced by medium composition, oxygen, and temperature. SM biofilms grown in SW exhibited significantly higher nProt and nPol than those in TSB under aerobic conditions (p < 0.001), indicating enhanced matrix stabilization. Under anaerobic conditions at 15 °C, nProt and nPol were higher, whereas under aerobic conditions, peak nProt and nPol occurred at elevated temperatures. These findings highlight a trade-off between bacterial growth and matrix production and provide insight into biofilm adaptation and persistence in seafood-processing environments. These insights may help develop improved biofilm control and seafood safety management.

Biofilms↗