Letter to the Editor2021-09-01
Diagnostic Hematology
Kuenyoul Park 
, M.D., Hyeri Kim , M.D., Ph.D., Kyung-Nam Koh , M.D., Ph.D., Ho Joon Im , M.D., Ph.D., Young-Uk Cho , M.D., Ph.D., Seongsoo Jang , M.D., Ph.D., Eul-Ju Seo , M.D., Ph.D., Chan-Jeoung Park , M.D., Ph.D.
Letter to the Editor2021-07-01
Diagnostic Genetics
Ha Jin Lim , M.D., Jun Hyung Lee , M.D., Young Eun Lee , M.S., Hee-Jo Baek , M.D., Hoon Kook , M.D., Ju Heon Park , M.D., Seung Yeob Lee , M.D., Hyun-Woo Choi , M.D., Hyun-Jung Choi , M.D., Seung-Jung Kee , M.D., Jong Hee Shin , M.D., and Myung Geun Shin , M.D.
Original Article2021-01-01
Clinical Microbiology
Miyoung Lee , M.S. and Tae-Jin Choi , Ph.D.
Abstract : Background: A lineage of Klebsiella pneumoniae that produces carbapenemase-2 (KPC-2), sequence type (ST) 307, emerged in 2017. We analyzed the complete sequences of plasmids from KPC-2-producing K. pneumoniae (KPC-Kp) ST307, investigated the antimicrobial resistance conferred by this strain, and confirmed the horizontal interspecies transmission of KPC- carbapenemase-producing Enterobacteriaceae (CPE) characteristics among Enterobacteriaceae. Methods: We performed antimicrobial susceptibility testing, PCR analysis, multilocus sequence typing, curing tests, and whole-genome sequencing to characterize plasmid-derived KPC-2-producing Enterobacteriaceae clinical isolates. Results: Sequence analysis of KPC-Kp strain ST307 revealed novel plasmid-located virulence factors, including a gene cluster for glycogen synthesis. Three Enterobacteriaceae strains were identified in one patient: K. pneumoniae (CPKp1825), Klebsiella aerogenes (CPEa1826), and Escherichia coli (CPEc1827). The blaKPC-2 gene from K. pneumoniae ST307 was horizontally transmitted between these strains. The plasmids could be transferred through conjugation, because all three strains of bacteria contained the type IV secretion system, pilus genes, and tra genes for conjugal transfer. The blaKPC-2 gene was located on a truncated Tn4401 transposon. Plasmids containing the blaKPC-2 gene could not be artificially removed; thus, the three strains could not be cured. Conclusions: The ease of horizontal transfer of KPC-Kp ST307 carbapenem resistance has serious public health and epidemiological implications. This study provides a better understanding of the genetic characteristics that can contribute to the growth and spread of KPC-Kp ST307, and their association with antimicrobial resistance genes.
Brief Communication2021-03-01
Ju Hyeon Shin , M.D., Soo Hyun Kim , M.D., Dain Lee , M.S., Seung Yeob Lee , M.D., Sejong Chun , M.D., Jun Hyung Lee , M.D., Eun Jeong Won , M.D., Hyun Jung Choi , M.D., Hyun Woo Choi , M.D., Seung Jung Kee , M.D., Myung Geun Shin , M.D., and Jong Hee Shin , M.D.
Abstract : The correct identification of filamentous fungi is challenging. We evaluated the performance of the VITEK MS v3.0 system (bioMérieux, Marcy-l’Étoile, France) for the identification of a wide spectrum of clinically relevant filamentous fungi using a Korean collection. Strains that were added to the upgraded v3.2 database were additionally identified by the VITEK MS v3.2 system. Of the 105 tested isolates, including 37 Aspergillus (nine species), 41 dermatophytes (seven species), and 27 other molds (17 species), 43 (41.0%) showed “no identification” or “multiple species identification” results at the initial VITEK MS testing; these isolates were retested using the same method. Compared with sequence-based identification, the correct identification rate using VITEK MS for Aspergillus, dermatophytes, other molds, and total mold isolates was 67.6%, 56.1%, 48.1%, and 58.1% at the initial testing and 94.6%, 78.0%, 55.6%, and 78.1% with retesting, respectively. Following retesting, 19 (18.1%) and two (1.9%) isolates showed “no identification” and “misidentification” results, respectively. VITEK MS reliably identified various filamentous fungi recovered in Korea, with a very low rate of misidentification.
Original Article2022-03-01
Clinical Chemistry
Fernando Marques-Garcia , Ph.D., David Hansoe Heredero Jung , M.D., and Sandra Elena Pérez, B.D.
Abstract : Background: Hemolysis is the most common type of preanalytical interference. Cut-offs based on the hemolysis index level can be established using different approaches. The Working Group for Preanalytical Phase of the European Federation of Laboratory Medicine has developed a protocol for hemolysis management based on cut-offs estimated from biological variation (BV) and the use of interpretative comments. We developed and assessed the implementation of the protocol in our laboratory. Methods: Hemolysates from whole blood were prepared following the Meites method, and pooled serum samples with known Hb concentrations were prepared. For each analyte (42 ), interferograms were generated and used to establish cut-offs: desirable analytical quality specification and reference change value. This protocol was assessed, both pre- and post-implementation, according to expert rules in the Laboratory Information System. Results: Among the analytes evaluated, we selected those that showed the highest degree of hemolysis interference: lactate dehydrogenase (LDH), aspartate aminotransferase, direct bilirubin, potassium, and folic acid. The cut-offs for LDH and direct bilirubin were the lowest. Only 28.16% of all LDH values were adequately reported in the pre-implantation retrospective study, but this percentage improved in the post-implementation stage. Conclusions: The development and implementation of a harmonized protocol for hemolysis management based on BV cut-offs and result reporting significantly improve hemolysis detection and lead to a decrease in the number of hemolyzed samples over time.
Brief Communication2021-03-01
Sollip Kim , M.D., Ph.D., Kyunghoon Lee , M.D., Ph.D., Hyung-Doo Park , M.D., Ph.D., Yong-Wha Lee , M.D., Ph.D., Sail Chun , M.D., Ph.D., and Won-Ki Min , M.D., Ph.D.
Abstract : External quality assessment (EQA) is important for evaluating clinical laboratories and enhancing their testing quality. EQA schemes are variable; thus, it is crucial that the EQA organizers share their experiences to continuously improve the EQA scheme. The Korean Association of External Quality Assessment Service (KEQAS) has been the leading, authorized EQA institute for the standardization and quality management of laboratory testing in Korean medical institutions since 1976. The EQA scheme underwent a major change in 2016, and the number of EQA programs increased significantly since then. The key changes implemented in EQA scheme include a fully computerized assessment to accelerate feedback and unification of the testing and reporting methods. We provide an overview of the EQA schemes and performance evaluation criteria of the KEQAS and suggest directions for achieving the global harmonization of EQA.
Brief Communication2021-07-01
Clinical Chemistry
Jake TB Collie , B.ASc., Elizabeth P Hudson , M.D., Adam M Deane , Ph.D., Rinaldo Bellomo , Ph.D., and Ronda F Greaves , Ph.D.
Abstract : The commonly used Chromsystems vitamin C (ascorbate) assay (Munich, Germany) has a sample storage life of five days at -20°C. Stabilizing agents have been successfully used to increase longevity; however, their suitability with this commercial assay is unclear. We investigated the compatibility of a stabilizing agent, perchloric acid/diethylenetriaminepentaacetic acid (PCA/DTPA), with the Chromsystems assay. Plasma was stored at -80°C, with or without PCA/DTPA. Storage up to six months was assessed through baseline and repeat analyses, stability was assessed by comparing paired non-stabilized and PCA/DTPA-stabilized plasma, and performance was assessed using allowable performance specifications of an external quality assurance program. Ascorbate concentration was significantly lower in non-stabilized plasma than in paired PCA/DTPA-stabilized plasma, with a proportional difference of 11% (P=0.01). All storage analysis results were within the allowable performance specifications. Storage at -80°C prevented plasma ascorbate oxidation; however, substantial oxidation occurred during sample processing. In conclusion, PCA/DTPA significantly reduces ascorbate oxidation, and PCA/DTPA-stabilized ascorbate plasma is compatible with the Chromsystems assay and stable for up to six months, when stored at -80°C.
Letter to the Editor2022-01-01
Diagnostic Immunology
Danilo Villalta , M.D., Anna Moratto , Ph.D., Valeria Salgarolo , Ph.D., Mirella Da Re , Ph.D., Roberto Giacomello , Ph.D., and Giacomo Malipiero , M.D.
Original Article2022-03-01
Clinical Chemistry
Hanwool Cho , M.D., Jaeeun Yoo , M.D., Hyunjung Kim , M.D., Hyunsik Jang , M.T., Yonggoo Kim , M.D., and Hyojin Chae , M.D.
Abstract : Background: Automated urine sediment analysis has been developed to address the limitations of microscopic examination of dysmorphic red blood cells (RBCs). We evaluated the urinary RBC distribution (URD) parameter of a recently launched automated urinary flow cytometry analyzer, UF-5000 (Sysmex, Kobe, Japan), to differentiate glomerular hematuria (GH) from non-GH (NGH). Methods: Samples submitted for urine sediment analysis from patients with hematuria (>20 RBCs/μL) were divided into derivation (N=156; 101 GH, 55 NGH) and validation cohorts (N=107; 60 GH, 47 NGH). The clinical diagnosis of GH or NGH was established based on clinical data review. Differences in UF-5000 parameters (URD, small RBC, lysed RBC, RBC-P70FSC, RBC-SF-FSC-W, mean forward-scattered light, and mean side-scattered light) between GH and NGH, and areas under the ROC curves (AUC) were analyzed in the derivation cohort. The derived ideal cut-off value was evaluated in the validation cohort. We applied the Kitasato criteria to compare the diagnostic performance. Results: URD (%), differed significantly between GH and NGH (P20.1%, the sensitivity was 99.0%/89.4% and the specificity was 50.9%/63.3% in the derivation/validation cohort. When the Kitasato criteria were applied, the sensitivity and specificity were 80.2% and 52.7%, respectively. Conclusions: URD is a rapid, objective, and quantitative measure that can be used to differentiate GH and NGH.
Original Article2021-07-01
Clinical Chemistry
Young Ahn Yoon , M.D., Yong-Wha Lee , M.D., Ph.D., Sollip Kim , M.D., Ph.D., Kyunghoon Lee , M.D., Ph.D., Hyung-Doo Park , M.D., Ph.D., Sail Chun , M.D., Ph.D., and Won-Ki Min , M.D., Ph.D.
Abstract : Background: Total cholesterol concentration measurement is important in the diagnosis of dyslipidemia and evaluation of cardiovascular disease risk factors. Measurement reliability for obtaining an accurate total cholesterol concentration requires procedure standardization. We evaluated the standardization status for total cholesterol concentration measurement through Korean external quality assessment (EQA) data analysis. Methods: This study involved 1,670 laboratories that participated in the EQA of total cholesterol concentration measurements in 2019 for 32 products from different manufacturers. The target concentrations of three quality control (QC) materials (samples A, B, and C) were measured using the reference method and compared with EQA data. The performance criteria for total cholesterol concentration measurement were based on the National Cholesterol Education Program guidelines, with ±3% inaccuracy. Results: The target values and inaccuracies of the QC material based on the reference method measurements were 254.65±7.64, 108.30±3.25, and 256.29±7.69 mg/dL (6.59±0.20, 2.80±0.08, and 6.63±0.20 mmol/L) for samples A, B, and C, respectively. The performance criteria were not met in 42.7% laboratories for sample A, 68.4% of laboratories for sample B, and 38.0% laboratories for sample C. Conclusions: Despite significant efforts to accurately measure total cholesterol concentrations, further actions are needed for measurement standardization. Manufacturers reporting values that differ from target values should check calibrator traceability; additional efforts to accurately measure total cholesterol concentrations are required for laboratories that use products from these manufacturers.
Full Text
PDF
Pubmed
PMC
