Publications by authors named "Hae Sun Chung"

In this study, we investigated the antimicrobial susceptibility and molecular characteristics of antimicrobial resistance of strains isolated from the bloodstream using whole-genome sequencing. Clinical isolates identified as and showing colistin resistance at the time of detection were collected. Antimicrobial susceptibility was determined using the VITEK2 system (bioMérieux) and Sensititre system (Thermo Fisher Scientific).

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This study aimed to analyze the genetic characteristics of Staphylococcus aureus with reduced vancomycin susceptibility (RVS-SA). Whole-genome sequencing was performed on 27 RVS-SA clinical isolates, and comparative genomic analysis was performed using S. aureus reference strains.

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Article Synopsis
  • Monitoring cytomegalovirus (CMV) viral load is essential for treatment decisions in immunocompromised patients to prevent severe health issues.
  • The Alinity m CMV assay was evaluated for its analytical and clinical performance against established tests at three hospitals, showing strong precision and excellent correlation with existing assays.
  • The Alinity m CMV assay demonstrated a quick turnaround time of under 3 hours, potentially speeding up treatment initiation for patients.
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The prompt implementation of optimal antibacterial therapy through the rapid identification of the causative organisms is essential for improving outcomes for critically ill patients with bloodstream infections. We evaluated the clinical performance of the FilmArray blood culture identification (BCID) panel for rapidly identifying causative pathogens in the bloodstream using large-scale clinical samples. We analyzed the results of identification using a BCID panel performed on 2005 positive blood culture bottles from September 2019 to June 2022.

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Eighty-five Korean kidney transplant recipients who received three doses of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine were tested with anti-receptor binding domain (RBD) antibody and neutralizing antibody. High anti-RBD antibody (≥ 100 U/mL) and neutralizing antibody responses (≥ 30%) were detected in 51/85 (60.0%) patients.

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This study aimed to investigate the efficacy of different COVID-19 booster vaccines by measuring the serum antibody titer. SARS-CoV-2 anti-nucleocapsid protein antibody (N-Ab), anti-spike protein antibody (S-Ab), and neutralizing antibody (Neut.Ab) were measured before and 4-6 weeks after booster vaccinations in healthcare personnel with a previous vaccination within 3-6 months.

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Article Synopsis
  • - The Xpert Xpress SARS-CoV-2 (Xpert) assay is being increasingly used for rapid COVID-19 screening in emergency rooms, and it was evaluated against qRT-PCR tests for accuracy during the pandemic.
  • - The study found a strong agreement of 91.9% between Xpert and qRT-PCR, with a high true-positive rate of 95.4% for the Xpert test, indicating it effectively identifies infections.
  • - Caution is advised when interpreting Xpert results, especially in cases showing only N2 signals with high Ct values, as some results were determined to be false positives; retesting over time is recommended.
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  • The study evaluates the performance of two antimicrobial susceptibility testing systems, VITEK2 and Sensititre, in detecting colistin resistance in clinical isolates.
  • A total of 213 clinical isolates were tested, revealing that Sensititre showed better agreement with manual reference methods (99.1%) compared to VITEK2 (95.3%), which had a high rate of very major errors (9.9%).
  • Overall, both automated systems performed adequately for detecting colistin resistance, but challenges remain, especially with VITEK2's error rate and Sensititre's inconsistent minimum inhibitory concentration (MIC) results.*
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The methods and results obtained using commercialized automation systems used for antimicrobial susceptibility testing are not entirely consistent. Therefore, we evaluated different antimicrobial susceptibility testing methods to determine vancomycin susceptibility and minimum inhibitory concentration (MIC) for Staphylococcus aureus with reduced vancomycin susceptibility (SA-RVS). A total of 128 clinical isolates of S.

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Background: Multidrug-resistant Acinetobacter baumannii is an important causal pathogen of healthcare-associated infections, and colistin-resistant strains have recently emerged owing to the increased use of colistin. Using next-generation sequencing (NGS), a single whole-genome sequencing (WGS) protocol can identify and type pathogens, analyze genetic relationships among different pathogens, predict pathogenic transmissions, and detect antibiotic resistance genes. However, only a few studies have applied NGS in studying the resistance mechanism and epidemiology of colistin-resistant A.

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Background: The interest in infection (CDI) has increased, and the choice of assays became wider since the first national survey in Korea on CDI diagnosis in 2015. We conducted a survey of the domestic CDI assays with more varied questions to understand the current situation in Korea.

Methods: In April 2018, about 50 questions on the current status of CDI assays and details on implementation and perceptions were written, and a survey questionnaire was administered to laboratory medicine specialists in 200 institutions.

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Background: Deficiency in DNA damage response (DDR) pathway and accumulation of DNA damage increases mutation rates resulting in genomic instability and eventually increases the risk of cancer. The aim of our study was to investigate expressions of DNA repair genes as new prognostic biomarkers in acute myeloid leukemia (AML).

Methods: We utilized The Cancer Genome Atlas AML project (TCGA-LAML cohort, 15 acute promyelocytic leukemia (APL) and 155 non-APL AML) for the expression data of DNA repair genes.

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Article Synopsis
  • The spread of delta variants of SARS-CoV-2 is a significant global health threat, and confirming infections typically involves multiplex real-time PCR tests.
  • Whole genomic sequencing is needed to identify viral mutations but is often impractical due to time and cost constraints.
  • The study found that specific patterns in the amplification curves during PCR testing can predict the presence of delta and alpha variants with 100% sensitivity and specificity, allowing for quicker and more cost-effective variant identification in clinical settings.
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We aimed to identify the presence of the measles IgG antibody (mIgG-Ab) in healthcare personnel and finding out who needs the measles vaccination. The history of measles vaccination was obtained from the national vaccine registry. A baseline mIgG-Ab test was performed, and the measles vaccine was administered to participants who tested negative or equivocal for mIgG-Abs.

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Background: Various methods are used for the diagnosis of infection (CDI). We systematically analyzed and investigated the performance of current laboratory diagnostic methods for CDI.

Methods: We performed systematic review and meta-analysis of studies in PubMed, Web of Science, Cochrane Library, and KoreaMed.

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In May 2015, we conducted a voluntary online survey on laboratory diagnostic assays for infection (CDI) across clinical microbiology laboratories in Korea. Responses were obtained from 66 laboratories, including 61 hospitals and five commercial laboratories. Among them, nine laboratories reported having not conducted CDI assays.

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  • The study explored the link between HLA genotypes and inhibitor development in 100 Korean patients with severe hemophilia A, including 27 with inhibitors.
  • HLA class I alleles showed no correlation with inhibitor status, while certain class II alleles (DRB1*15 and DPB1*05:01) were negatively associated with inhibitors, suggesting protective effects.
  • Conversely, a specific allele (C*07:02) was positively associated with inhibitor development in patients with intron 22 inversion, and different associations were observed in patients without this inversion.
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Nowadays, is described as a causative organism for antibiotic-associated hemorrhagic colitis (AAHC). Here we report two cases of pediatric AAHC, from which was cultured after starting amoxicillin-clavulanate or amoxicillin treatment. The patients developed severe abdominal pain and a large amount of bloody diarrhea.

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Rapid and accurate diagnosis of Clostridium difficile infection (CDI) is crucial for patient care, infection control, and efficient surveillance. We evaluated C. DIFF QUIK CHEK COMPLETE (QCC; TechLab), which detects glutamate dehydrogenase (GDH) antigen (QCC-Ag) and toxin A/B (QCC-Tox) simultaneously, and compared it to the laboratory diagnostics for CDI currently in use in a tertiary hospital setting with a high prevalence of CDI.

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Trimethoprim-sulfamethoxazole is the first-line antimicrobial combination for Stenotrophomonas maltophilia infections. However, allergy or intolerance and increasing resistance limit the use of trimethoprim-sulfamethoxazole. Quinolones can be used as an alternative therapeutic option, but resistance can emerge rapidly during therapy.

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Background: Glycated albumin (GA) is a better marker of short-term glycemic control than glycated hemoglobin (A1c). Dyslipidemia is the main cause of cardiovascular complications in diabetes mellitus (DM). Studies on the correlation of GA with lipid indices are sparse.

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The aim of this study was to investigate the molecular mechanisms of ertapenem resistance among Enterobacteriaceae isolates in a clinical microbiology laboratory at a tertiary university hospital. A total of 40 clinical isolates including 20 resistant and 20 intermediate isolates were collected from August 2012 to July 2013. Ertapenem susceptibility was confirmed by the broth microdilution method.

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Calreticulin, encoded by CALR, is a multifunctional protein with roles in calcium homeostasis and chaperoning molecular processes. This study aimed to evaluate calreticulin mRNA expression levels in acute myeloid leukemia (AML) compared with other hematologic malignancies, and to investigate the clinicopathological characteristics associated with expression in AML patients. The study group included 43 patients diagnosed with AML, 57 with other hematologic malignancies, and 21 benign hematologic conditions.

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Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy characterized by CD4 and CD56 coexpression without apparent lineage commitment. The molecular pathogenesis of BPDCN has been studied in only a limited number of cases, and specific chromosomal aberrations are lacking thus far. KMT2A (MLL) rearrangements are observed in various types of pediatric and adult leukemia, but only one adult case report has so far showed KMT2A (MLL)-MLLT1 gene rearrangements in BPDCN.

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