Showing papers in "Annals of laboratory medicine in 2022"

Hormone Immunoassay Interference: A 2021 Update

Abstract: Immunoassays are powerful qualitative and quantitative analytical techniques. Since the first description of an immunoassay method in 1959, advances have been made in assay designs and analytical characteristics, opening the door for their widespread implementation in clinical laboratories. Clinical endocrinology is closely linked to laboratory medicine because hormone quantification is important for the diagnosis, treatment, and prognosis of endocrine disorders. Several interferences in immunoassays have been identified through the years; although some are no longer encountered in daily practice, cross-reaction, heterophile antibodies, biotin, and anti-analyte antibodies still cause problems. Newer interferences are also emerging with the development of new therapies. The interfering substance may be exogenous (e.g., a drug or substance absorbed by the patient) or endogenous (e.g., antibodies produced by the patient), and the bias caused by interference can be positive or negative. The consequences of interference can be deleterious when clinicians consider erroneous results to establish a diagnosis, leading to unnecessary explorations or inappropriate treatments. Clinical laboratories and manufacturers continue to investigate methods for the detection, elimination, and prevention of interferences. However, no system is completely devoid of such incidents. In this review, we focus on the analytical interferences encountered in daily practice and possible solutions for their detection or elimination.

Prognostic Utility of Procalcitonin, Presepsin, and the VACO Index for Predicting 30-day Mortality in Hospitalized COVID-19 Patients

Abstract: Background Biomarkers and clinical indices have been investigated for predicting mortality in patients with coronavirus disease (COVID-19). We explored the prognostic utility of procalcitonin (PCT), presepsin, and the Veterans Health Administration COVID-19 (VACO) index for predicting 30-day-mortality in COVID-19 patients. Methods In total, 54 hospitalized COVID-19 patients were enrolled. PCT and presepsin levels were measured using the Elecsys BRAHMS PCT assay (Roche Diagnostics GmbH, Mannheim, Germany) and HISCL Presepsin assay (Sysmex, Kobe, Japan), respectively. The VACO index was calculated based on age, sex, and comorbidities. PCT and presepsin levels and the VACO index were compared using ROC curve, Kaplan–Meier method, and reclassification analysis for the 30-day mortality. Results ROC curve analysis was used to measure PCT and presepsin levels and the VACO index to predict 30-day mortality; the optimal cut-off values were 0.138 ng/mL for PCT, 717 pg/mL for presepsin, and 12.1% for the VACO index. On Kaplan–Meier survival analysis, hazard ratios (95% confidence interval) were 15.9 (4.1-61.3) for PCT, 26.3 (6.4-108.0) for presepsin, and 6.0 (1.7-21.1) for the VACO index. On reclassification analysis, PCT and presepsin in addition to the VACO index significantly improved the prognostic value of the index. Conclusions This study demonstrated the prognostic utility of measuring PCT and presepsin levels and the VACO index in COVID-19 patients. The biomarkers in addition to the clinical index were more useful than the index alone for predicting clinical outcomes in COVID-19 patients.

Review of the Use of Liquid Chromatography-Tandem Mass Spectrometry in Clinical Laboratories: Part I-Development

Abstract: The process of method development for a diagnostic assay based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) involves several disparate technologies and specialties. Additionally, method development details are typically not disclosed in journal publications. Method developers may need to search widely for pertinent information on their assay(s). This review summarizes the current practices and procedures in method development. Additionally, it probes aspects of method development that are generally not discussed, such as how exactly to calibrate an assay or where to place quality controls, using examples from the literature. This review intends to provide a comprehensive resource and induce critical thinking around the experiments for and execution of developing a clinically meaningful LC-MS/MS assay.

Clinical Evaluation of the Rapid STANDARD Q COVID-19 Ag Test for the Screening of Severe Acute Respiratory Syndrome Coronavirus 2

Abstract: Standard tests for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detect the presence of viral RNA using real-time reverse transcription (rRT)-PCR. Recently, convenient, rapid, and relatively inexpensive SARS-CoV-2 antigen (Ag) detection methods have been developed. The STANDARD Q COVID-19 Ag test (SD Biosensor, Inc., Suwon, Korea) is a rapid immunochromatography test that qualitatively detects the nucleocapsid protein of SARS-CoV-2 using gold conjugated antibodies. We evaluated its performance in comparison with that of Allplex 2019-nCoV Assay (Seegene, Seoul, Korea) in a retrospective case-control study using residual samples. The sensitivity and specificity of the STANDARD Q COVID-19 Ag test were 89.2% (58/65) and 96.0% (96/100), respectively. Cycle threshold (Ct) values for the three target SARS-CoV-2 genes (envelope, RNA-dependent RNA polymerase, and nucleocapsid genes) included in Allplex 2019-nCoV Assay were significantly lower in Ag test-positive patients than in Ag test-negative patients (P<0.001). The Ag test sensitivity was higher in samples with Ct≤30 and those collected one to five days post symptom onset. In conclusion, the STANDARD Q COVID-19 Ag test can serve as an alternative in high-prevalence settings, when the low sensitivity is compensated or when rRT-PCR tests are limited.

Update of Guidelines for Laboratory Diagnosis of COVID-19 in Korea

Abstract: Korean Society for Laboratory Medicine and the Korea Disease Prevention and Control Agency have announced guidelines for diagnosing coronavirus disease (COVID-19) in clinical laboratories in Korea. With the ongoing pandemic, we propose an update of the previous guidelines based on new scientific data. This update includes recommendations for tests that were not included in the previous guidelines, including the rapid molecular test, antigen test, antibody test, and self-collected specimens, and a revision of the previous recommendations. This update will aid clinical laboratories in performing laboratory tests for diagnosing COVID-19.

Unreliable Automated Complete Blood Count Results: Causes, Recognition, and Resolution

Abstract: Automated hematology analyzers generate accurate complete blood counts (CBC) results on nearly all specimens. However, every laboratory encounters, at times, some specimens that yield no or inaccurate result(s) for one or more CBC parameters even when the analyzer is functioning properly and the manufacturer’s instructions are followed to the letter. Inaccurate results, which may adversely affect patient care, are clinically unreliable and require the attention of laboratory professionals. Laboratory professionals must recognize unreliable results, determine the possible cause(s), and be acquainted with the ways to obtain reliable results on such specimens. We present a concise overview of the known causes of unreliable automated CBC results, ways to recognize them, and means commonly utilized to obtain reliable results. Some examples of unreliable automated CBC results are also illustrated. Pertinent analyzer-specific information can be found in the manufacturers’ operating manuals.

Myelodysplastic Syndromes with Bone Marrow Fibrosis: An Update

Abstract: Myelodysplastic syndrome (MDS) is a diverse hematological malignancy with a wide spectrum of presentations and implications. Treatment strategies for patients with MDS heavily rely on prognostic scoring systems, such as the revised international prognostic scoring system (IPSS-R). Bone marrow fibrosis (BMF) has been identified as an independent risk factor for poor survival in patients with MDS, irrespective of the IPSS-R risk category. However, BMF is not widely included in scoring systems and is not always considered by clinicians when making treatment decisions for patients. In this review, we discuss the available literature about the presentation and prognosis of patients with MDS and concurrent BMF. The prognostic impact of BMF should be factored in when deciding on transplant candidacy, especially for intermediate-risk patients.

Comprehensive Laboratory Data Analysis to Predict the Clinical Severity of Coronavirus Disease 2019 in 1,952 Patients in Daegu, Korea

Abstract: Laboratory parameter abnormalities are commonly observed in COVID-19 patients; however, their clinical significance remains controversial. We assessed the prevalence, characteristics, and clinical impact of laboratory parameters in COVID-19 patients hospitalized in Daegu, Korea.We investigated the clinical and laboratory parameters of 1,952 COVID-19 patients on admission in nine hospitals in Daegu, Korea. The average patient age was 58.1 years, and 700 (35.9%) patients were men. The patients were classified into mild (N=1,612), moderate (N=294), and severe (N=46) disease groups based on clinical severity scores. We used chi-square test, multiple comparison analysis, and multinomial logistic regression to evaluate the correlation between laboratory parameters and disease severity.Laboratory parameters on admission in the three disease groups were significantly different in terms of hematologic (Hb, Hct, white blood cell count, lymphocyte%, and platelet count), coagulation (prothrombin time and activated partial thromboplastin time), biochemical (albumin, aspartate aminotransferase, alanine aminotransferase, lactate, blood urea nitrogen, creatinine, and electrolytes), inflammatory (C-reactive protein and procalcitonin), cardiac (creatinine kinase MB isoenzyme and troponin I), and molecular virologic (Ct value of SARS-CoV-2 RdRP gene) parameters. Relative lymphopenia, prothrombin time prolongation, and hypoalbuminemia were significant indicators of COVID-19 severity. Patients with both hypoalbuminemia and lymphopenia had a higher risk of severe COVID-19.Laboratory parameter abnormalities on admission are common, are significantly associated with clinical severity, and can serve as independent predictors of COVID-19 severity. Monitoring the laboratory parameters, including albumin and lymphocyte count, is crucial for timely treatment of COVID-19.

Prevalence of a Single-Nucleotide Variant of SARS-CoV-2 in Korea and Its Impact on the Diagnostic Sensitivity of the Xpert Xpress SARS-CoV-2 Assay

Abstract: The sensitivity of molecular diagnostics could be affected by nucleotide variants in pathogen genes, and the sites affected by such variants should be monitored. We report a single-nucleotide variant (SNV) in the nucleocapsid (N) gene of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), i.e., G29179T, which impairs the diagnostic sensitivity of the Xpert Xpress SARS-CoV-2 assay (Cepheid, Sunnyvale, CA, USA). We observed significant differences between the threshold cycle (Ct) values for envelope (E) and N genes and confirmed the SNV as the cause of the differences using Sanger sequencing. This SNV, G29179T, is the most prevalent in Korea and is associated with the B.1.497 virus lineage, which is dominant in Korea. Clinical laboratories should be aware of the various SNVs in the SARS-CoV-2 genome and consider their potential effects on the diagnosis of coronavirus disease 2019.

Clinical Practice Guidelines for Pre-Analytical Procedures of Plasma Epidermal Growth Factor Receptor Variant Testing

Abstract: Standardization of cell-free DNA (cfDNA) testing processes is necessary to obtain clinically reliable results. The pre-analytical phase of cfDNA testing greatly influences the results because of the low proportion and stability of circulating tumor DNA (ctDNA). In this review, we provide evidence-based clinical practice guidelines for pre-analytical phase procedures of plasma epidermal growth factor receptor gene (EGFR) variant testing. Specific recommendations for pre-analytical procedures were proposed based on evidence from the literature and our experimental data. Standardization of pre-analytical procedures can improve the analytical performance of cfDNA testing.

Review of the Use of Liquid Chromatography-Tandem Mass Spectrometry in Clinical Laboratories: Part II–Operations

Abstract: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is increasingly utilized in clinical laboratories because it has advantages in terms of specificity and sensitivity over other analytical technologies. These advantages come with additional responsibilities and challenges given that many assays and platforms are not provided to laboratories as a single kit or device. The skills, staff, and assays used in LC-MS/MS are internally developed by the laboratory, with relatively few exceptions. Hence, a laboratory that deploys LC-MS/MS assays must be conscientious of the practices and procedures adopted to overcome the challenges associated with the technology. This review discusses the post-development landscape of LC-MS/MS assays, including validation, quality assurance, operations, and troubleshooting. The content knowledge of LC-MS/MS users is quite broad and deep and spans multiple scientific fields, including biology, clinical chemistry, chromatography, engineering, and MS. However, there are no formal academic programs or specific literature to train laboratory staff on the fundamentals of LC-MS/MS beyond the reports on method development. Therefore, depending on their experience level, some readers may be familiar with aspects of the laboratory practices described herein, while others may be not. This review endeavors to assemble aspects of LC-MS/MS operations in the clinical laboratory to provide a framework for the thoughtful development and execution of LC-MS/MS applications.

Serotype Distribution and Antimicrobial Resistance of Streptococcus pneumoniae Causing Invasive Pneumococcal Disease in Korea Between 2017 and 2019 After Introduction of the 13-Valent Pneumococcal Conjugate Vaccine

Abstract: Background Streptococcus pneumoniae is a serious pathogen causing various infections in humans. We evaluated the serotype distribution and antimicrobial resistance of S. pneumoniae causing invasive pneumococcal disease (IPD) after introduction of pneumococcal conjugate vaccine (PCV)13 in Korea and investigated the epidemiological characteristics of multidrug-resistant (MDR) isolates. Methods S. pneumoniae isolates causing IPD were collected from 16 hospitals in Korea between 2017 and 2019. Serotyping was performed using modified sequential multiplex PCR and the Quellung reaction. Antimicrobial susceptibility tests were performed using the broth microdilution method. Multilocus sequence typing was performed on MDR isolates for epidemiological investigations. Results Among the 411 S. pneumoniae isolates analyzed, the most prevalent serotype was 3 (12.2%), followed by 10A (9.5%), 34 (7.3%), 19A (6.8%), 23A (6.3%), 22F (6.1%), 35B (5.8%), 11A (5.1%), and others (40.9%). The coverage rates of PCV7, PCV10, PCV13, and pneumococcal polysaccharide vaccine (PPSV)23 were 7.8%, 7.8%, 28.7%, and 59.4%, respectively. Resistance rates to penicillin, ceftriaxone, erythromycin, and levofloxacin were 13.1%, 9.2%, 80.3%, and 4.1%, respectively. MDR isolates accounted for 23.4% of all isolates. Serotypes 23A, 11A, 19A, and 15B accounted for the highest proportions of total isolates at 18.8%, 16.7%, 14.6%, and 8.3%, respectively. Sequence type (ST)166 (43.8%) and ST320 (12.5%) were common among MDR isolates. Conclusions Non-PCV13 serotypes are increasing among invasive S. pneumoniae strains causing IPD. Differences in antimicrobial resistance were found according to the specific serotype. Continuous monitoring of serotypes and antimicrobial resistance is necessary for the appropriate management of S. pneumoniae infections.

Current State of Blood Management Services in Korea

Abstract: Blood is lifesaving; however, it can neither be limitlessly acquired nor artificially produced. The supply and use of blood, as an invaluable biological commodity, necessitate systematic and rational management under governmental guidance to ensure safe and reliable transfusions. Despite Korea’s blood donation rate of 5.04%, which is higher than the 3.15% in high-income countries as reported by the WHO, the demand for blood exceeds the availability. This is due to the birthrate decline, dearth of young donors, and growing and aging recipient population. This review outlines the Korean blood management system, with a focus on blood service data from 2020, with the aim to delineate the current state of Korea’s blood management system and the policies established to address the imminent blood shortage. Each policy is described in detail to provide helpful information for blood management services in other countries.

Clinical Differences in Patients Infected with<i>Fusobacterium</i>and Antimicrobial Susceptibility of<i>Fusobacterium</i>Isolates Recovered at a Tertiary-Care Hospital in Korea

Abstract: Fusobacterium species are obligately anaerobic, gram-negative bacilli. Especially, F. nucleatum and F. necrophorum are highly relevant human pathogens. We investigated clinical differences in patients infected with Fusobacterium spp. and determined the antimicrobial susceptibility of Fusobacterium isolates.We collected clinical data of 86 patients from whom Fusobacterium spp. were isolated from clinical specimens at a tertiary-care hospital in Korea between 2003 and 2020. In total, 76 non-duplicated Fusobacterium isolates were selected for antimicrobial susceptibility testing by the agar dilution method, according to the Clinical and Laboratory Standards Institute guidelines (M11-A9).F. nucleatum was most frequently isolated from blood cultures and was associated with hematologic malignancy, whereas F. necrophorum was mostly prevalent in head and neck infections. Anti-anaerobic agents were more commonly used to treat F. nucleatum and F. varium infections than to treat F. necrophorum infections. We observed no significant difference in mortality between patients infected with these species. All F. nucleatum and F. necrophorum isolates were susceptible to the antimicrobial agents tested. F. varium was resistant to clindamycin (48%) and moxifloxacin (24%), and F. mortiferum was resistant to penicillin G (22%) and ceftriaxone (67%). β-Lactamase activity was not detected.Despite the clinical differences among patients with clinically important Fusobacterium infections, there was no significant difference in the mortality rates. Some Fusobacterium spp. were resistant to penicillin G, ceftriaxone, clindamycin, or moxifloxacin. This study may provide clinically relevant data for implementing empirical treatment against Fusobacterium infections.

Sex-Specific U-Shaped Relationships Between High-Density Lipoprotein Cholesterol Levels and 10-year Major Adverse Cardiovascular Events: A Nationwide Cohort Study of 5.7 Million South Koreans

Abstract: Background High-density lipoprotein cholesterol (HDL-C) is a well-known predictor of atherosclerotic cardiovascular diseases (ASCVD). We explored the relationships between HDL-C levels and 10-year major adverse cardiovascular events (MACE) and provided sex-specific upper reference limits for HDL-C levels. Methods Based on the Korean National Health Insurance Sharing Service, we identified 5,703,897 subjects (women, 48%) with age ≥40 years, eligible HDL-C results, and no prior ASCVD in 2009. We investigated the distribution of 10-year MACE according to HDL-C levels in 10 mg/dL (0.26 mmol/L) intervals and in three HDL-C groups (low men <40 mg/dL [1.03 mmol/L], women <50 mg/dL [1.29 mmol/L]; high between low and extremely high levels; and extremely high >90 mg/dL [2.33 mmol/L]). Results There were U-shaped relationships between HDL-C levels and 10-year MACE with later inflection in women than in men (nadir 80-99 mg/dL [2.07-2.56 mmol/L] and 50-59 mg/dL [1.29-1.53 mmol/L], respectively). In men, the extremely high HDL-C group showed significantly higher 10-year MACE than the high group (28.1% vs. 24.6%, P<0.0001). In women, the extremely high group showed the lowest 10-year MACE; if the extremely high starting point was raised to 130 mg/dL, it became similar to that in men and showed higher 10-year MACE than the high group (25.6% vs. 20.1%, P<0.0001). Conclusions The 10-year MACE showed U-shaped relationships with HDL-C levels, and extremely high HDL-C level at 90 mg/dL (2.33 mmol/L) in men was corresponding in risk to 130 mg/dL (3.36 mmol/L) in women.

Performance Comparison of Five SARS-CoV-2 Antibody Assays for Seroprevalence Studies

Abstract: Seroprevalence studies of coronavirus disease 2019 (COVID-19) cases, including asymptomatic and past infections, are important to estimate the scale of the disease outbreak and to establish quarantine measures. We evaluated the clinical performance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody assays available in Korea for use in seroprevalence studies.The sensitivity, specificity, cross-reactivity, and interference of five SARS-CoV-2 antibody assays were evaluated using the following: 398 serum samples from confirmed COVID-19 patients, 510 negative control samples from before 2018 (pre-pandemic), 163 serum samples from patients with SARS, Middle East respiratory syndrome (MERS), and other viral infections, and five samples for the interference study.The sensitivities of the five assays ranged from 92.2% to 98%, and their specificities, including cross-reactivity and interference, ranged from 97.5% to 100%. The agreement rates were excellent (kappa >0.9). Adjustment of the cutoff values could be considered through ROC curve analysis. The positive predictive values of the individual assays varied from 3.5% to 100% at a 0.1% prevalence but were as high as ≥95% when two assays were combined.The prevalence of COVID-19 in Korea is considered to be exceptionally low at present; thus, we recommend using a combination of two or more SARS-CoV-2 antibody assays rather than a single assay. These results could help select SARS-CoV-2 antibody assays for COVID-19 seroprevalence studies in Korea.

Current Status of Serum Insulin and C-Peptide Measurement in Clinical Laboratories: Experience from 94 Laboratories in China

Abstract: Background Accurate measurements of serum insulin and C-peptide are needed for the therapy and classification of diabetes. This study investigated the status of serum insulin and C-peptide measurements in China by analyzing the results of five pooled serum samples measured in 94 laboratories. Methods Patient serum samples were pooled into five groups according to insulin and C-peptide concentrations and measured in 94 laboratories using different measurement systems. The inter- and intra-laboratory %CV as well as inter- and intra-measurement system %CV were calculated to assess the status of insulin and C-peptide measurements. To verify whether the disagreement between laboratories was due to different calibrators, as reported in previous studies, one low-level and one high-level sample extracted from the five pooled serum samples were used to recalibrate clinical measurement systems. Results The mean intra-laboratory, intra-measurement system, inter-laboratory, and inter-measurement system %CVs were 2.7%, 4.8%, 21.8%, and 22.4%, respectively, for insulin and 2.3%, 6.7%, 16.4%, and 24.5%, respectively, for C-peptide. The inter- and intra-laboratory %CVs for insulin decreased with increasing concentration. After recalibration with low- and high-level samples, the mean inter-measurement %CV decreased from 22.4% to 17.2% for insulin and from 24.5% to 5.7% for C-peptide. Conclusions The intra-laboratory and intra-measurement system imprecision values are satisfactory for serum insulin and C-peptide measurements. However, the results from laboratories using different measurement systems were not comparable, and there is still much work needed to achieve the standardization or harmonization of serum insulin and C-peptide measurements.

Digital Morphology Analyzer Sysmex DI-60 vs. Manual Counting for White Blood Cell Differentials in Leukopenic Samples: A Comparative Assessment of Risk and Turnaround Time

Abstract: Background Digital morphology (DM) analyzers are increasingly being used for white blood cell (WBC) differentials. We assessed the laboratory efficiency of the Sysmex DI-60 system (DI-60; Sysmex, Kobe, Japan) in comparison with manual counting in leukopenic samples. Methods In total, 40 peripheral blood smear samples were divided into normal, mild leukopenia, moderate leukopenia, and severe leukopenia groups based on WBC count. In each group, the risk and turnaround time (TAT) were compared between DI-60 and manual counting. Risk was determined by failure mode and effect analysis using the risk priority number (RPN) score, and TAT was recorded for the analytical phase. Results Overall, DI-60 showed a five-fold lower risk (70 vs. 350 RPN) and longer TAT than manual counting. In severe leukopenic samples, DI-60 showed a shorter TAT/slide and a remarkably lower cell count/slide than manual counting. In all samples, the TAT/cell for DI-60 was substantially longer than that for manual counting (DI-60 vs. manual total, 1.8 vs. 1.0 sec; normal, 1.5 vs. 0.7 sec; mild leukopenia, 1.9 vs. 0.9 sec; moderate leukopenia, 1.8 vs. 1.0 sec; severe leukopenia, 28.8 vs. 19.0 sec). Conclusions This is the first comparative assessment of risk and TAT between DI-60 and manual counting in leukopenic samples. DI-60 decreases the laboratory risk and improves patient safety, but requires more time to count fewer cells, especially in severe leukopenic samples. DM analyzers should be applied selectively depending on the WBC count to optimize laboratory efficiency.

Immunogenicity of Third-dose BNT162b2 mRNA Vaccine Following Two Doses of ChAdOx1 in Health Care Workers: A Prospective Longitudinal Study

Abstract: Following the original severe acute respiratory syndrome coronavirus 2 strain (Wuhan-Hu-1) in December 2019, the Delta variant in May 2021 and the Omicron variant in December 2021 were classified as variants of concern. The pandemic has been ongoing for more than two years, and the three-dose vaccination rate has reached approximately 50% in Korea. We analyzed anti-S antibodies (Abs) and neutralizing Abs (NAbs) in 32 healthcare workers at a university hospital, focusing on the first to third doses of ChAdOx1-ChAdOx1-BNT162b2, which is the most common vaccination regimen in Korea. Antibodies were analyzed at eight time points according to the vaccine regimen. The first to third doses of ChAdOx1-ChAdOx1-BNT162b2 produced high Ab concentrations; NAb concentrations after the third dose were predicted to remain high for a longer period than those after the first and second doses. The effectiveness of a second dose of ChAdOx1 in the real world was demonstrated by analyzing samples collected during an outbreak that occurred in the study period, 4–5 months after the second dose. The relative risk ratio was 88.0%, and the efficacy of the second ChAdOx1 dose was 12.0% (P<0.05). Therefore, maintaining appropriate Ab concentrations through regular vaccination will help protect against coronavirus disease-19.

Erythroid Differentiation of Induced Pluripotent Stem Cells Co-cultured with OP9 Cells for Diagnostic Purposes

Abstract: Background Reagent red blood cells (RBCs) are prepared from donated whole blood, resulting in various combinations of blood group antigens. This inconsistency can be resolved by producing RBCs with uniform antigen expression. Induced pluripotent stem cells (iPSCs) generated directly from mature cells constitute an unlimited source for RBC production. We aimed to produce erythroid cells from iPSCs for diagnostic purposes. We hypothesized that cultured erythroid cells express surface antigens that can be recognized by blood group antibodies. Methods iPSCs were co-cultured with OP9 stromal cells to stimulate differentiation into the erythroid lineage. Cell differentiation was examined using microscopy and flow cytometry. Hemoglobin electrophoresis and oxygen-binding capacity testing were performed to verify that the cultured erythroid cells functioned normally. The agglutination reactions of the cultured erythroid cells to antibodies were investigated to confirm that the cells expressed blood group antigens. Results The generated iPSCs showed stemness characteristics and could differentiate into the erythroid lineage. As differentiation progressed, the proportion of nucleated RBCs increased. Hemoglobin electrophoresis revealed a sharp peak in the hemoglobin F region. The oxygen-binding capacity test results were similar between normal RBCs and cultured nucleated RBCs. ABO and Rh-Hr blood grouping confirmed similar antigen expression between the donor RBCs and cultured nucleated RBCs. Conclusions We generated blood group antigen-expressing nucleated RBCs from iPSCs co-cultured with OP9 cells that can be used for diagnostic purposes. iPSCs from rare blood group donors could serve as an unlimited source for reagent production.

Rates of Coinfection Between SARS-CoV-2 and Other Respiratory Viruses in Korea

Abstract: Young-gon Kim, M.D., Hyunwoong Park, M.D., Ph.D., So Yeon Kim, M.D., Ph.D., Ki Ho Hong, M.D., Ph.D., Man Jin Kim, M.D., Jee-Soo Lee, M.D., Sung-Sup Park, M.D., Ph.D., and Moon-Woo Seong, M.D., Ph.D.. Ann Lab Med 2022;42:110-2. https://doi.org/10.3343/alm.2022.42.1.110

Natural Killer Cell Expansion and Cytotoxicity Differ Depending on the Culture Medium Used

Abstract: Background Adoptive cell therapy using umbilical cord blood (UCB)-derived allogeneic natural killer (NK) cells has shown encouraging results. However, because of the insufficient availability of NK cells and limited UCB volume, more effective culture methods are required. NK cell expansion and functionality are largely affected by the culture medium. While human serum is a major affecting component in culture media, the way it regulates NK cell functionality remains elusive. We elucidated the effects of different culture media and human serum supplementation on UCB NK cell expansion and functionality. Methods UCB NK cells were cultured under stimulation with K562-OX40L-mbIL-18/21 feeder cells and IL-2 and IL-15 in serum-containing and serum-free culture media. The effects of the culture media and human serum supplementation on NK cell expansion and cytotoxicity were evaluated by analyzing the expansion rate, activating and inhibitory receptor levels, and the cytotoxicity of the UCB NK cells. Results The optimal medium for NK cell expansion was Dulbecco’s modified Eagle’s medium/Ham’s F12 with supplements and that for cytotoxicity was AIM V supplemented with Immune Cell Serum Replacement. Shifting media is an advantageous strategy for obtaining several highly functional UCB NK cells. Live cell imaging and killing time measurement revealed that human serum enhanced NK cell proliferation but delayed target recognition, resulting in reduced cytotoxicity. Conclusions Culture medium supplementation with human serum strongly affects UCB NK cell expansion and functionality. Thus, culture media should be carefully selected to ensure both NK cell quantity and quality for adoptive cell therapy.

Calibration Practices in Clinical Mass Spectrometry: Review and Recommendations

Abstract: Background Calibration is a critical component for the reliability, accuracy, and precision of mass spectrometry measurements. Optimal practice in the construction, evaluation, and implementation of a new calibration curve is often underappreciated. This systematic review examined how calibration practices are applied to liquid chromatography-tandem mass spectrometry measurement procedures. Methods The electronic database PubMed was searched from the date of database inception to April 1, 2022. The search terms used were “calibration,” “mass spectrometry,” and “regression.” Twenty-one articles were identified and included in this review, following evaluation of the titles, abstracts, full text, and reference lists of the search results. Results The use of matrix-matched calibrators and stable isotope-labeled internal standards helps to mitigate the impact of matrix effects. A higher number of calibration standards or replicate measurements improves the mapping of the detector response and hence the accuracy and precision of the regression model. Constructing a calibration curve with each analytical batch recharacterizes the instrument detector but does not reduce the actual variability. The analytical response and measurand concentrations should be considered when constructing a calibration curve, along with subsequent use of quality controls to confirm assay performance. It is important to assess the linearity of the calibration curve by using actual experimental data and appropriate statistics. The heteroscedasticity of the calibration data should be investigated, and appropriate weighting should be applied during regression modeling. Conclusions This review provides an outline and guidance for optimal calibration practices in clinical mass spectrometry laboratories.

Serotype Distribution and Antimicrobial Resistance of <i>Salmonella</i> Isolates in Korea between 2016 and 2017

Abstract: Salmonella is one of the major causes of food-borne infections. We investigated the serotype distribution and antimicrobial resistance of Salmonella isolates collected in Korea between January 2016 and December 2017. In total, 669 Salmonella isolates were collected from clinical specimens at 19 university hospitals. Serotyping was performed according to the Kauffmann-White scheme, and antimicrobial susceptibility was tested using Sensititre EUVSEC plates or disk diffusion. Among the strains, C (39.8%) and B (36.6%) were the most prevalent serogroups. In total, 51 serotypes were identified, and common serotypes were S. enterica serovar I 4,[5],12:i:- (16.7%), S. Enteritidis (16.1%), S. Bareilly (14.6%), S. Typhimurium (9.9%), and S. Infantis (6.9%). The resistance rates to ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole were 32.6%, 12.1%, and 8.4%, respectively. The resistance rates to cefotaxime and ciprofloxacin were 8.1% and 3.0%, respectively, while 5.4% were multidrug-resistant. S. enterica serovar I 4,[5],12:i:- and S. Enteritidis were highly prevalent, and there was an increase in rare serotypes. Multidrug resistance and ciprofloxacin resistance were highly prevalent. Periodic investigations of Salmonella serotypes and antimicrobial resistance are needed.

Impact of Individualized Hemolysis Management Based on Biological Variation Cut-offs in a Clinical Laboratory

Abstract: 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.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.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.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.

Active Surveillance for Carbapenem-resistant Enterobacteriaceae at a Single Center for Four Years

Abstract: The main resistance mechanism of carbapenem-resistant Enterobacteriaceae (CRE) is through acquired carbapenemases [1]. Carbapenemase-producing Enterobacteriaceae (CPE) har-boring plasmid-encoded resistance genes easily spread the genes to different species [2]. A screening test for CPE should be performed for infection control and prevention [3]. The Korea Dis-ease Control and Prevention Agency conducted a surveillance beginning in June 2017 [4]. A European study suggests that within-hospital transmission and inter-hospital spread of CPE is more frequent within countries rather than between countries [5]. Therefore, both hospital and national surveillance are im-portant to help prevent the CPE spread . We retrospectively analyzed active surveillance data for CRE at Hanyang University Seoul Hospital, from July 2017 to December 2020. The candidates for CRE surveillance were patients who were transferred from long-term care facilities in the previous three months, those admitted to the intensive care unit, and those who had positive results for CRE isolates in the previous six months. Stool or rectal swab samples were in-oculated onto chromID CARBA medium (bioMérieux, Marcy l’Etoile, France) and incubated at 35°C for 24 hours. Bacterial species were identified using matrix-assisted laser desorption/ ionization-time of flight mass spectrometry (MALDI-TOF MS)

Comparison of the Clinical Performance of the Point-of-care STANDARD M10 SARS-CoV-2 and Xpert Xpress SARS-CoV-2 Assays

Abstract: Ki Ho Hong , M.D., Jaehyeon Lee , M.D., So Yeon Kim , M.D., Yeseul Oh , M.T., Hae Weon Cho , M.D., and Hyukmin Lee , M.D. Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, Korea; Department of Laboratory Medicine, Jeonbuk National University Medical School and Hospital, Jeonju, Korea; Department of Laboratory Medicine, National Medical Center, Seoul, Korea; Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, Korea

Comparison of the Automated Fluorescent Immunoassay System With Roche Elecsys and Beckman Coulter Access 2 Assays for Anti-Müllerian Hormone Measurement

Abstract: Since 2017, automated assays have been used in most clinical laboratories for anti-Müllerian hormone (AMH) level measurement. We evaluated the analytical performance of the newly developed automated fluorescent immunoassay system (AFIAS) AMH assay (Boditech Med, Gangwon-do, Korea) in comparison with the Roche Elecsys and Beckman Coulter Access 2 AMH assays.Analytical performance of the AFIAS AMH assay was assessed in terms of linearity, repeatability, and within-laboratory precision (CV%) using human recombinant AMH samples according to the Clinical and Laboratory Standards Institute (CLSI) guidelines EP05 and EP06. Using 293 serum samples collected from an infertility clinic, the AMH levels were compared across AFIAS, Elecsys, and Access 2 AMH assays according to the CLSI EP09 guidelines.The AFIAS AMH assay results were linear across the measurement range of 0.420-72.386 pmol/L AMH, with repeatability of 6.341%. CV% of the AFIAS AMH assay for three levels of control, 1.786, 7.143, and 56.857 pmol/L, were 5.801%, 5.714%, and 6.228%, respectively. The results of the three AMH assays showed strong correlation: AFIAS and Elecsys [slope, 1.055 (95% confidence interval (CI), 1.022-1.088) and Spearman's rho, 0.978 (95% CI, 0.973-0.983)], Elecsys and Access 2 [slope, 0.813 (95% CI, 0.791-0.834) and Spearman's rho, 0.986 (95% CI, 0.983-0.989)], and AFIAS and Access 2 [slope, 0.836 (95% CI, 0.821-0.853) and Spearman's rho, 0.984 (95% CI, 0.980-0.988)].The AFIAS AMH assay may be an alternative to the Roche Elecsys and Beckman Coulter Access 2 AMH assays.

Guidelines for the Laboratory Diagnosis of Monkeypox in Korea

Abstract: While the coronavirus disease 2019 pandemic is ongoing, monkeypox has been rapidly spreading in non-endemic countries since May 2022. Accurate and rapid laboratory tests are essential for identifying and controlling monkeypox. Korean Society for Laboratory Medicine and the Korea Disease Prevention and Control Agency have proposed guidelines for diagnosing monkeypox in clinical laboratories in Korea. These guidelines cover the type of tests, selection of specimens, collection of specimens, diagnostic methods, interpretation of test results, and biosafety. Molecular tests are recommended as confirmatory tests. Skin lesion specimens are recommended for testing in the symptomatic stage, and the collection of both blood and oropharyngeal swabs is recommended in the presymptomatic or prodromal stage.

Guidelines for Mobile Laboratories for Molecular Diagnostic Testing of COVID-19

Abstract: With the rapid spread of the coronavirus disease (COVID-19), the need for rapid testing and diagnosis and consequently, the demand for mobile laboratories have increased. Despite this need, there are no clear guidelines for the operation, maintenance, or quality control of mobile laboratories. We provide guidelines for the operation, management, and quality control of mobile laboratories, and specifically for the implementation and execution of COVID-19 molecular diagnostic testing. These practical guidelines are primarily based on expert opinions and a laboratory accreditation inspection checklist. The scope of these guidelines includes the facility, preoperative evaluation, PCR testing, internal and external quality control, sample handling, reporting, laboratory personnel, biosafety level, and laboratory safety management. These guidelines are useful for the maintenance and operation of mobile laboratories not only in normal circumstances but also during public health crises and emergencies.