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We analyzed whole-genome sequences of Salmonella enterica serovar Enteritidis isolates in South Korea that had the SEGX01.049 pulsed-field gel electrophoresis pattern. That lineage has emerged and circulated in South Korea since 2020, leading to 2 fatal infection cases. We investigated the genomic characteristics and identified potential sources of that lineage. Isolates from outbreaks during 2020-2023 clustered in the Global IIa clade, along with other Salmonella Enteritidis strains from chicken farms in South Korea and human isolates from the United Kingdom. Bayesian molecular clock analysis estimated the time to the most recent common ancestor of our isolates in the Global IIa clade was 2017.57. Moreover, phylogeographic analysis supported substantial statistical evidence (Bayes factor 111.415; posterior probability 0.97) for the introduction of this lineage into South Korea from the United Kingdom. Continued genomic surveillance will be needed to monitor the spread of foodborne pathogens such as Salmonella Enteritidis and improve prevention strategies.

The global rise of multidrug-resistant (MDR) Streptococcus pneumoniae serotype 19A despite widespread pneumococcal conjugate vaccine (PCV) use poses an emerging challenge for pediatric infectious disease control. In South Korea, the detection of serotype 19A initially declined following PCV13 implementation, but it has recently re-emerged, raising concerns over the evolution and persistence of high-risk clones. We investigated invasive serotype 19A isolates recovered from children under five years of age between 2018 and 2024. Antimicrobial susceptibility testing and whole-genome sequencing (WGS) were conducted to characterize resistance mechanisms, clonal structure, and phylogenetic relationships. Among the 104 invasive pneumococcal isolates, 11 (10.6%) were identified as serotype 19A. All of these belonged to GPSC1/CC320 and were classified as ST320 or ST6400. These isolates exhibited resistance to meropenem but retained susceptibility to cefotaxime, carrying a conserved pbp1a-13, pbp2b-11, and pbp2x-16 combination. Phylogenetic analysis revealed four distinct subclades among the South Korean isolates, each showing high similarity to international strains. To our knowledge, this is the first genomic study of meropenem-resistant 19A in children from South Korea. Our findings suggest that the resurgence of 19A is driven by stable, high-risk MDR. These results underscore the need for clone-level genomic surveillance to preempt emerging threats and inform next-generation vaccine and antibiotic strategies.

Background The emergence of carbapenem-resistant Enterobacterales (CRE) infections is rapidly increasing and represents a serious public threat. In 2020, a total of 16,883 carbapenemase-producing Enterobacterales strains were collected; among these isolates, 21 strains were repeatedly isolated in a local tertiary care hospital. Methods Antimicrobial susceptibility testing was performed using the broth microdilution method. All 21 strains of CRKP were analyzed by PFGE after Xba I digestion. The 21 CRKP strains were sequenced on the Illumina Miseq and Oxford Nanopore GridION platforms. Results These 21 CRKP isolates showed an identical antimicrobial resistance profile, including resistance to ampicillin, carbapenems, cephems, chloramphenicol, fluoroquinolone, macrolides and trimethoprim/sulfamethoxazole. Based on whole-genome analysis, these 21 CRKP isolates shared a common genetic structure ( ISAba125 - IS630 - bla NDM−1 - ble MBL ) and harbored additional resistance determinants ( bla OXA−1 , bla CTX−M−15 , bla SHV−11 , bla SHV−67 , aac(6’)-Ib-cr , qnrS1 , OqxA , OqxB , catB3 , mph(A) , sul1 , and dfrA12 ) and mutations in the quinolone resistance-determining regions of gyrA (S83I) and parC (S80I). These isolates belonged to the ST147 and KL64 capsular types, which were carried on IncFIB replicon plasmids. The 21 CRKP strains collected from one hospital were divided into five PFGE patterns, and they were closely related with a minimum similarity value of 95.2%. These isolates were found to be highly related based on the presence of between 2 and 27 SNPs. Conclusions These findings indicate that NDM-1-producing K. pneumoniae ST147 may have been introduced via a common source, implying nosocomial transmission; furthermore, continuous monitoring is necessary to prevent endemic transmission.

ESBL-producing E. coli is a public health concern in healthcare settings and the community. Between 2009 and 2018, a total of 187 ESBL-producing pathogenic E. coli isolates were identified, and clonal complex (CC) 10 was the predominant clone (n = 57). This study aimed to characterize the ESBL-producing pathogenic E. coli CC10 strains obtained from patients with diarrhea to improve our understanding of CC10 distribution in the Republic of Korea. A total of 57 CC10 strains were selected for comprehensive molecular characterization, including serotype identification, the analysis of antibiotic resistance genes, the investigation of genetic environments, the determination of plasmid profiles, and the assessment of genetic correlations among CC10 strains. Among the CC10 isolates, the most prevalent serotype was O25:H16 (n = 21, 38.9%), followed by O6:H16 (10, 19.6%). The most dominant ESBL genes were blaCTX-M-15 (n = 31, 55%) and blaCTX-M-14 (n = 15, 27%). Most blaCTXM genes (n = 45, 82.5%) were located on plasmids, and these incompatibility groups were confirmed as IncB/O/K/Z, IncF, IncI1, and IncX1. The mobile elements located upstream and downstream mainly included ISEcp1 (complete or incomplete) and IS903 or orf477. Phylogenetic analysis showed that the CC10 strains were genetically diverse and spread among several distinct lineages. The results of this study show that ESBL-producing pathogenic E. coli CC10 has been consistently isolated, with CTX-M-15-producing E. coli O25:H16 isolates being the major type associated with the distribution of CC10 clones over the past decade. The identification of ESBL-producing pathogenic E. coli CC10 isolates underscores the possible emergence of resistant isolates with epidemic potential within this CC. As a result, continuous monitoring is essential to prevent the further dissemination of resistant ESBL-producing E. coli CC10 strains.

Objectives We investigated the epidemiological patterns of carbapenem-resistant, blaKPC-2 harbouring Klebsiella pneumoniae (K. pneumoniae) ST 307 isolates in a tertiary hospital in South Korea between 2019 and 2021 and compared them to isolates collected from 25 hospitals through a nationwide survey, using whole genome sequencing and phylogenetic analysis. Methods Whole genome sequences of 25 isolates from hospital GB2 and 45 isolates from 25 other hospitals were analysed for antibiotic resistance gene profiles, virulence gene profiles, plasmid replicons, and phylogenetic relationships. Results Core genome single nucleotide polymorphism (cgSNP)-based phylogenetic analysis categorized the 70 isolates into three distinct groups and 13 subgroups, supported by high bootstrap values and low SNP differences. Subgroup 1 comprised the 18 isolates from GB2 collected over 3 years, suggesting long-term persistence and repeated outbreaks within GB2. Region-specific dissemination was indicated by several subgroups containing isolates from different hospitals within the same province. Subgroup 7 comprised isolates from multiple provinces and years, suggesting potential long-distance transmission via patient transfers or community reservoirs. All isolates carried multiple β-lactam resistance genes; blaCTX-M-15 was observed in 67 isolates (89.3%) and the OXA variants in 70 isolates (93.3%). None of the isolates carried the rmpA/rmpA2 or magA genes, while 58 of the 70 (82.9%) harboured yersiniabactin-encoding genes. Conclusions Our findings reveal both clonal persistence within a tertiary hospital and region-specific dissemination of blaKPC-2 producing K. pneumoniae ST307 across South Korea. These results highlight the importance of continuous nationwide surveillance and genomic analysis to implement effective infection control measures to mitigate further dissemination.

We investigated the epidemiological patterns of carbapenem-resistant, harbouring ( ) ST 307 isolates in a tertiary hospital in South Korea between 2019 and 2021 and compared them to isolates collected from 25 hospitals through a nationwide survey, using whole genome sequencing and phylogenetic analysis. Whole genome sequences of 25 isolates from hospital GB2 and 45 isolates from 25 other hospitals were analysed for antibiotic resistance gene profiles, virulence gene profiles, plasmid replicons, and phylogenetic relationships. Core genome single nucleotide polymorphism (cgSNP)-based phylogenetic analysis categorized the 70 isolates into three distinct groups and 13 subgroups, supported by high bootstrap values and low SNP differences. Subgroup 1 comprised the 18 isolates from GB2 collected over 3 years, suggesting long-term persistence and repeated outbreaks within GB2. Region-specific dissemination was indicated by several subgroups containing isolates from different hospitals within the same province. Subgroup 7 comprised isolates from multiple provinces and years, suggesting potential long-distance transmission via patient transfers or community reservoirs. All isolates carried multiple β-lactam resistance genes; was observed in 67 isolates (89.3%) and the OXA variants in 70 isolates (93.3%). None of the isolates carried the or genes, while 58 of the 70 (82.9%) harboured yersiniabactin-encoding genes. Our findings reveal both clonal persistence within a tertiary hospital and region-specific dissemination of producing ST307 across South Korea. These results highlight the importance of continuous nationwide surveillance and genomic analysis to implement effective infection control measures to mitigate further dissemination.

ESBL-producing E. coli is a public health concern in healthcare settings and the community. Between 2009 and 2018, a total of 187 ESBL-producing pathogenic E. coli isolates were identified, and clonal complex (CC) 10 was the predominant clone (n = 57). This study aimed to characterize the ESBL-producing pathogenic E. coli CC10 strains obtained from patients with diarrhea to improve our understanding of CC10 distribution in the Republic of Korea. A total of 57 CC10 strains were selected for comprehensive molecular characterization, including serotype identification, the analysis of antibiotic resistance genes, the investigation of genetic environments, the determination of plasmid profiles, and the assessment of genetic correlations among CC10 strains. Among the CC10 isolates, the most prevalent serotype was O25:H16 (n = 21, 38.9%), followed by O6:H16 (10, 19.6%). The most dominant ESBL genes were bla[sub.CTX-M-15] (n = 31, 55%) and bla[sub.CTX-M-14] (n = 15, 27%). Most bla[sub.CTXM] genes (n = 45, 82.5%) were located on plasmids, and these incompatibility groups were confirmed as IncB/O/K/Z, IncF, IncI1, and IncX1. The mobile elements located upstream and downstream mainly included ISEcp1 (complete or incomplete) and IS903 or orf477. Phylogenetic analysis showed that the CC10 strains were genetically diverse and spread among several distinct lineages. The results of this study show that ESBL-producing pathogenic E. coli CC10 has been consistently isolated, with CTX-M-15-producing E. coli O25:H16 isolates being the major type associated with the distribution of CC10 clones over the past decade. The identification of ESBL-producing pathogenic E. coli CC10 isolates underscores the possible emergence of resistant isolates with epidemic potential within this CC. As a result, continuous monitoring is essential to prevent the further dissemination of resistant ESBL-producing E. coli CC10 strains.

Agriculture is a major global source of methane (CH4), and accurate emission estimates are essential for refining national greenhouse gas inventories and supporting climate-resilient policies. This study develops a high-resolution estimation framework for CH4 emissions from Korean rice paddies by integrating multi-source datasets, including Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices, European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis Version 5 (ERA5)-Land meteorological variables, and Harmonized World Soil Database (HWSD) soil properties. Using CH4 flux observations from four global rice ecosystems (Italy, Japan, South Korea, and USA), we constructed parallel daily and hourly machine learning models using an automated machine learning (AutoML) framework to compare their performance and process-level interpretability. The daily model demonstrated high predictive accuracy with correlation coefficients (CC) of 0.897 in 5-fold cross-validation and 0.819 in Leave-One-Year-Out (LOYO) cross-validation. Shapley Additive Explanations (SHAP) analysis revealed that while soil temperature is the dominant predictor for daily emissions (explaining ~50% of the variance), variable importance shifts significantly at finer resolutions. The hourly model exhibited a more complex multivariate structure. In this high-resolution context, although Normalized Difference Vegetation Index (NDVI) remains constant diurnally, its importance strengthens as a critical regulator of emission sensitivity, interacting with hourly meteorological fluctuations to capture short-term dynamics. The resulting 500 m daily gridded maps provide a robust foundation for national inventory refinement and spatially targeted mitigation planning. Our findings suggest that while the daily model offers optimal computational efficiency for long-term monitoring, the hourly model is superior for mechanistic understanding and detecting episodic emission events. This multi-resolution framework establishes an empirical basis for selecting appropriate temporal scales in operational greenhouse gas monitoring systems.

We propose an unsupervised network with adversarial learning, the Raindrop-aware GAN, which enhances the quality of coastal video images contaminated by raindrops. Raindrop removal from coastal videos faces two main difficulties: converting the degraded image into a clean one by visually removing the raindrops, and restoring the background coastal wave information in the raindrop regions. The components of the proposed network—a generator and a discriminator for adversarial learning—are trained on unpaired images degraded by raindrops and clean images free from raindrops. By creating raindrop masks and background-restored images, the generator restores the background information in the raindrop regions alone, preserving the input as much as possible. The proposed network was trained and tested on an open-access dataset and directly collected dataset from the coastal area. It was then evaluated by three metrics: the peak signal-to-noise ratio, structural similarity, and a naturalness-quality evaluator. The indices of metrics are 8.2% (+2.012), 0.2% (+0.002), and 1.6% (−0.196) better than the state-of-the-art method, respectively. In the visual assessment of the enhanced video image quality, our method better restored the image patterns of steep wave crests and breaking than the other methods. In both quantitative and qualitative experiments, the proposed method more effectively removed the raindrops in coastal video and recovered the damaged background wave information than state-of-the-art methods.

An attempt was made to predict the macroscopic plastic flow of a high-performance pipeline steel, consisting of dual constituent phases (soft ferrite and hard bainite), by performing nanoindentation experiments on each microphase with two spherical indenters that have different radii (550 nm and 3.3 μm). The procedure is based on the well known concepts of indentation stress-strain and constraint factor, which make it possible to relate indentation hardness to the plastic flow of the phases. Additional consideration of the indentation size effect for sphere and application of a simple “rule-of-mixture” led us to a reasonably successful estimation of the macroscopic plastic flow of the steel from the microphases properties, which was verified by comparing the predicted stress-strain curve with that directly measured from the conventional tensile test of a bulky sample.