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Ultrasonic flow metering is one of flow measurement techniques applicable to low temperature environment. Unlike pipe provers or Coriolis mass flowmeters, ultrasonic flowmeters require waveguides in front of ultrasound sensors. The waveguides can prevent heat conduction from the ultrasound sensors to low temperature liquids, such as liquid nitrogen. The ultrasound sensors can maintain its piezoelectricity within the specified temperature ranges by thermal insulation of the waveguides. In this study, low temperature testing on a pair of ultrasound sensors was performed to see if ultrasound waves could be transmitted normally through liquid nitrogen. A flowmeter cell with diameter of 300 mm (equivalently, 12”) was used as a container for liquid nitrogen. Three pairs of ultrasound sensors were installed in the flowmeter cell. Fiber-optic sensors were also attached on its inner wall to measure the temperature of liquid nitrogen. As a result, ultrasound waves were successfully transmitted between a pair of ultrasound sensors by using a preamplifier. The fiber-optic sensors could measure the temperature of liquid nitrogen although the sensors were not calibrated by the reference temperature scale at KRISS.

In this paper, I have attempted to suggest possible meaning and function of the phrase, “γeννηθῇ ἄνωθeν” in the context of the Johannine community and in understanding Nicodemus. The Johannine community which was experiencing a crisis caused by the excommunication from the Jewish synagogue and inner conflicts among members tried to establish a new identity of “those who were born from above” and create a communal unity through the expression, “γeννηθῇ ἄνωθeν.” Although “γeννηθῇ ἄνωθeν” has a role of an “anti-language” and a rhetorical device of “misunderstanding,” it actually functions as an “invitational language” for Nicodemus in terms of being part of the vocabulary of Jesus-followers who accept a new identity of being “born from above” through water and the Spirit.

Red blood cell (RBC) alloimmunization varies across human populations and ethnic groups. We evaluated the characteristics of RBC alloimmunization and compared the risk of alloimmunization in Korean patients with myelodysplastic syndrome (MDS) and liver cirrhosis (LC), two representative diseases in which chronic transfusion is required. In total, 115 MDS patients and 202 LC patients transfused with RBCs between 2013 and 2015 were retrospectively included. Twenty patients (6.3%) were newly alloimmunized (five MDS patients, 4.3%; 15 LC patients, 7.4%). The median number of RBC units transfused in alloimmunized patients was nine (interquartile range, 4-15 units). As the number of transfused RBC units increased, the cumulative risk of alloimmunization was higher in LC than in MDS patients (P=0.001). The most common alloantibody detected in patients was anti-E (45%), followed by anti-c (17%), anti-e (10%), anti-C (7%), anti-Fyb (7%), and anti-Jka (7%). The present data indicate the need for matching of extended RBC antigens (Rh, Duffy, and Kidd systems) for chronically transfused patients with MDS and LC in Korea.

Cis-AB, a rare ABO variant, is caused by a gene mutation that results in a single glycosyltransferase enzyme with dual A and B glycosyltransferase activities. It is the most frequent ABO subgroup in Korea, and it occurs more frequently in the East Asian region than in the rest of the world. The typical phenotype of cis-AB is A2B3, but it can express various phenotypes when paired with an A or B allele, which can lead to misclassification in the ABO grouping and consequently to adverse hemolytic transfusion reactions. While cis-AB was first discovered as having an unusual inheritance pattern, it was later found that both A and B antigens are expressed from the same allele inherited from a single parent; hence, the name cis-AB. Earlier studies relied on serological and familial investigation of cis-AB subjects, but its detection has become much easier with the introduction of molecular methods. This review will summarize the serological variety, genetic basis and inheritance pattern, laboratory methods of investigation, clinical significance, and the blood type of choice for transfusion for the cis-AB blood group.

BACKGROUND/AIMS High-volume plasma exchange (HVPE), defined as an exchange of 8 to 12 L per day per procedure or 15% of the ideal body weight with fresh frozen plasma, has shown promising results in improving the survival of patients with acute liver failure (ALF). However, clinical evidence is limited. The aim of this study was to report our initial experience using HVPE as a bridge treatment in patients with ALF. METHODS We retrospectively reviewed 32 consecutive patients awaiting liver transplantation (LT) due to ALF between 2013 and 2020 at Samsung Medical Center in Korea. HVPE has been used for patients with ALF since May 2016 at our institution. RESULTS During the study period, 16 patients received HVPE. After HVPE, coagulopathies (INR, 4.46 [2.32-6.02] vs 1.48 [1.33-1.76], P

Petrochemical and electric power plants are using flow meters, of which capacity is larger than 1000 m3/h. They require the accuracy of flow meters better than ±0.3% if the flow meters are being used for custody transfer or allocation measurement. However, the number of national metrology institutes, which can handle this issue, is very limited, including PTB (Germany), NMIJ/AIST (Japan), MIKES (Finland), CEESI-NIST (USA), and TÜV-NEL (UK). Large-capacity flow measurement standards are also needed to make better quality control for process engineering in the Republic of Korea. This study aims at establishing the water flow measurement standards up to 2000 m3/h with uncertainty better than 0.06%. How to evaluate the measurement uncertainty is discussed for establishing the large-capacity water flow standards at KRISS.

Helical strake type thermowells are replacing standard thermowells according to ASME PTC 19.3 TW-2016 in various industrial sectors. It is because the helical strakes can suppress the flow-induced vibration by Kármán vortex street over a thermowell. However, the ASME PTC 19.3 TW-2016 does not regulate the helical strakes because their design rules are too complicated to be specified. This study attempts to characterize the effect of helical strakes on the thermowell vibrations by measuring pressure and strain signals at the same time. The pressure signal is expected to give information on the Kármán vortex street while the strain signal gives the flow-induced vibration on the thermowells. Relative vibration energy or relative vibration amplitude is defined to calculate the efficiency of suppressing the Kármán vortex street around the thermowells.

The correct identification of filamentous fungi is challenging. We evaluated the performance of the VITEK MS v3.0 system (bioMerieux, Marcy-l'Etoile, 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.

Main text A supplementary comparison, entitled as APMP.M.FF-S1, has been undertaken between KRISS and NMIJ, AIST under the supervision by the Technical Committee for Fluid Flow (TCFF) in the Asia Pacific Metrology Programme (APMP). The purpose of this supplementary comparison was to prove the measurement equivalence between NMIJ, AIST and KRISS for water flow measurement standards from 300 m3/h to 1 200 m3/h. This supplementary comparison was meaningful because there has not been an international comparison for water flows greater than 300 m3/h. Previous key comparisons have been performed only from 30 m3/h to 200 m3/h [1]. Therefore, this supplementary comparison became the first inter-laboratory comparison to cover the flow range for large-capacity water flow measurement standards. In fact, the inter-laboratory comparison between NMIJ, AIST and PTB (Berlin) has been already done for such flowrate range [2], however, this inter-laboratory comparison has not been supervised by APMP or EURAMET, such that the result of inter-laboratory comparison is published in a research journal, not in the BIPM KCDB for inter-laboratory comparisons. A turbine flow meter with the pipe diameter of 250 mm was chosen as a transfer standard in this supplementary comparison. A flow conditioner was used to define inflow conditions upstream of the turbine flow meter. The flow conditioner was a perforated plate with a well-known design. The turbine flow meter was calibrated in two ways: with or without the flow conditioner. The calibration of turbine flow meter with the flow conditioner was according to the revised test protocol for this supplementary comparison. The other calibration without the flow conditioner was performed to investigate the flow characteristics of the turbine flow meter. K-factor was the measurand to evaluate the measurement equivalence between NMIJ, AIST and KRISS. The K-factor was corrected by considering the temperature change between the water temperature and the reference temperature of 20 oC [3]. The measurement uncertainty of the K-factor included uncertainty factors such as repeatability, day-to-day reproducibility, re-installation effect, long-term stability, and the influence by temperature change. Inconclusiveness test was also performed to see whether the K-factor was suitable for evaluating the number of equivalence between NMIJ, AIST and KRISS. The number of equivalence was found to be less than 1. The number of equivalence became better in the case without the flow conditioner than the case with the flow conditioner. The number of equivalence was found to be conclusive because the inconclusiveness index was less than 2. Therefore, the measurement equivalence between NMIJ, AIST and KRISS has been proven by this supplementary comparison. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/. The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Background: The cis-AB phenotype, although rare, is the relatively most frequent of ABO subgroups in Koreans. To prevent ABO mistyping of cis-AB samples, our hospital has applied a combination of the manual tile method with automated devices. Herein, we report cases of ABO mistyping detected by the combination testing system. Methods: Cases that showed discrepant results by automated devices and the manual tile method were evaluated. These samples were also tested by the standard tube method. The automated devices used in this study were a QWALYS-3 and Galileo NEO. Exons 6 and 7 of the ABO gene were sequenced. Results: 13 cases that had the cis-AB allele showed results suggestive of the cis-AB subgroup by manual methods, but were interpreted as AB by either automated device. This happened in 87.5% of these cases by QWALYS-3 and 70.0% by Galileo NEO. Genotyping results showed that 12 cases were ABO*cis-AB01/ABO*O01 or ABO*cis-AB01/ABO*O02, and one case was ABO*cis-AB01/ ABO*A102. Conclusion: Cis-AB samples were mistyped as AB by the automated microplate technique in some cases. We suggest that the manual tile method can be a simple supplemental test for the detection of the cis-AB phenotype, especially in countries with relatively high cis-AB prevalence.

Master meter method is an efficient way to calibrate flow meters with less time and costs. The master meter method has simpler flow configuration than the gravimetric flow measurement method requires. Maintenance efforts of the master meter method are easier than the gravimetric method. However, the guidelines of master meter method have not been established completely. It is because the notion of relative deviations, which are used as a measure and for comparison calibration, is not clearly understood. On the other hand, the system uncertainty, which is typically used as the calibration and measurement capability of the gravimetric flow standards, are understood very well. In this study, a complete explanation on the master meter method is attempted. First, appropriate calibration conditions are assumed. Second, a suitable calibration procedure is suggested. Third, a mathematical model for the relative deviations is described. Fourth, uncertainty factors of the relative deviations are evaluated. Finally, two examples of the comparison calibration are explained in detail. The master meter method is compatible with the guide to the expression of uncertainty in measurement (GUM, ISO/IEC Guide 98-3:2008). In the examples, it is found that the master meter method can achieve the measurement uncertainty as low as 0.20%.

First-order partial derivatives of a mathematical model are an essential part of evaluating the measurement uncertainty of a liquid flow standard system according to the Guide to the expression of uncertainty in measurement (GUM). Although the GUM provides a straight-forward method to evaluate the measurement uncertainty of volume flow rate, the first-order partial derivatives can be complicated. The mathematical model of volume flow rate in a liquid flow standard system has a cross-correlation between liquid density and buoyancy correction factor. This cross-correlation can make derivation of the first-order partial derivatives difficult. Monte Carlo simulation can be used as an alternative method to circumvent the difficulty in partial derivation. However, the Monte Carlo simulation requires large computational resources for a correct simulation because it considers the completeness issue whether an ideal or a real operator conducts an experiment to evaluate the measurement uncertainty. Thus, the Monte Carlo simulation needs a large number of samples to ensure that the uncertainty evaluation is as close to the GUM as possible. Unscented transform can alleviate this problem because unscented transform can be regarded as a Monte Carlo simulation with an infinite number of samples. This idea means that unscented transform considers the uncertainty evaluation with respect to the ideal operator. Thus, unscented transform can evaluate the measurement uncertainty the same as the uncertainty that the GUM provides.

BackgroundTransfusion-associated graft-versus-host disease (TA-GvHD) is caused by leukocytes, specifically T cells within a transfused blood product. Currently, the prevention of transfusion-associated graft-versus-host disease is performed by irradiation of blood products. With a sufficient reduction of leukocytes, the risk for TA-GvHD can be decreased. With consistent advances in current state-of-the-art blood filters, we herein propose that double filtration can sufficiently reduce leukocytes to reduce the risk for TA-GvHD.MaterialsThirty RBC concentrates were filtered with leukocyte filters, followed by storage at 1-6 oC for 72 hours, and then a second filtration was performed. Residual leukocytes in the double-filtered RBC units (n = 30) were assessed with flow cytometric methods, and an additional assay with isolated peripheral blood mononuclear cells (PBMCs) (n = 6) was done by both flow cytometric methods and an automated hematology analyzer. Quality of the RBCs after filtration was evaluated by hematological and biochemical tests. In vitro T cell expansion was performed using anti-CD3/CD28-coated Dynabeads or anti-CD3 (OKT3). In vivo experiment for GvHD was performed by using NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice.ResultsDouble-filtered blood products showed residual leukocyte levels below detection limits, which calculated to be below 1200-2500 cells per blood unit. In vitro expansion rate of T cells showed that 6x103 and 1x103 cell-seeded specimens showed 60.8±10.6 fold and 10.2±9.7-fold expansion, respectively. Cell expansion was not sufficiently observed in wells planted with 1x102 or 10 cells. In vivo experiments showed that mice injected with 1x105 or more cells cause fatal GvHD. GvHD induced inflammation was observed in mice injected with 1x104 or more cells. No evidence of GvHD was found in mice injected with 103 cells.ConclusionsOur study suggests that additional removal of contaminating lymphocytes by a second leukodepletion step may further reduce the risk for TA-GvHD.

Background: Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. Although early diagnosis and treatment is the most successful strategy for improving patient survival, feasible and sensitive blood biomarkers for CRC screening remain elusive. Methods: Sixty-five CRC patients and thirty-three healthy individuals were enrolled. Peripheral blood (PB) and tumor tissues from CRC patients, and PB from healthy individuals were subjected to immunophenotyping and phospho-flow analysis of cytokine-induced phosphorylated STAT (CIPS). Logistic regression was used as a classifier that separates CRC patients from healthy individuals. Results: The proportion of regulatory T cells was increased in PB from CRC patients compared to PB from healthy individuals (p &lt, 0.05). Interestingly, peripheral T cells share several cytokine-induced phosphorylated STAT (CIPS) signatures with T cells from CRC tumor-sites. Additionally, a classifier was made using two signatures distinct between T cells from CRC patients and T cells from healthy individuals. The AUCs (area under curves) of the classifier were 0.88 in initial cohort and 0.94 in the additional validation cohort. Overall AUC was 0.94 with sensitivity of 91% and specificity of 88%. Conclusion: This study highlights that immune cell signatures in peripheral blood could offer a new type of biomarker for CRC screening.

A surface flow sensor is needed if turbulent drag force is to be measured over a vehicle, such as a car, a ship, and an airplane. In case of automobile industry, there are no automobile manufacturers which measure surface flow velocity over a car for wind tunnel testing. Instead, they rely on particle image velocimetry (PIV), pressure sensitive paint (PSP), laser Doppler anemometry (LDA), pitot tubes, and tufts to get information regarding the turbulent drag force. Surface flow sensors have not devised yet. This study aims at developing a surface flow sensor for measuring turbulent drag force over a rigid body in a wind tunnel. Two sensing schemes were designed for the fiber-optic distributed sensor and the thermal mass flow sensor. These concepts are introduced in this paper. As the first attempt, a thermal mass flow sensor has been fabricated. It was flush-mounted on the surface of a test section in the wind tunnel to measure the surface flow velocity. The thermal mass flow sensor was operated by either constant current or constant resistance modes. Resistance ratio was changed as the electric current was increased by the constant current mode, while power ratio was saturated as the resistance was increased by the constant resistance mode. Either the resistance ratio or the power ratio was changed with the flow velocity measured by a Pitot tube, located at the center of test section.

Clinical significance of isolates known for being a blood culture contaminant: a study on the pediatric population

Weak D types 1, 2, 3 and Asia type DEL (RHD 1227 G > A) can be treated as D-positive for purposes of Rho(D) immune globulin (RhIG) administration or selection of blood components for transfusion. To confirm these D variants, RHD genotyping can be used as a complementary to serologic tests. While ruling out weak D types 1,2,3 is useful in Caucasian populations, these are extremely rare in the Asian population, while Asia type DEL is relatively common. Distinguishing between true D-negative and Asia type DEL (RHD 1227 G > A) by genotyping has the same utility of distinguishing weak D types 1, 2, 3. The main difference between weak D and Asia type DEL is that the latter appears as D negative in conventional serologic methods, while the former will show positive in indirect anti-human immunoglobulin tests. RHD genotyping in apparent D-negative Asian patients has been established, yet the utility of genotyping in Asian patients with weakened D phenotypes require further investigation. We have observed cases of weak D patients with coexistence of a weak D allele and an Asia type DEL (RHD 1227 G > A) allele, we have found that antigen expression of D is as the weak D in indirect antiglobulin testing, yet all epitopes are detected with adsorption and elution assays. This is indicative of completeness of the D antigen epitope, and thus we suggest that all Asian patients with weakened D phenotypes can benefit from RHD genotyping.

Candida auris is an emerging worldwide fungal pathogen. Over the past 20 years, 61 patient isolates of C. auris (4 blood and 57 ear) have been obtained from 13 hospitals in Korea. Here, we reanalyzed those molecularly identified isolates using two matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) systems, including Biotyper and Vitek MS, followed by antifungal susceptibility testing, sequencing of the ERG11 gene, and genotyping. With a research-use-only (RUO) library, 83.6% and 93.4% of the isolates were correctly identified by Biotyper and Vitek MS, respectively. Using an in vitro diagnostic (IVD) library of Vitek MS, 96.7% of the isolates were correctly identified. Fluconazole-resistant isolates made up 62.3% of the isolates, while echinocandin- or multidrug-resistant isolates were not found. Excellent essential (within two dilutions, 96.7%) and categorical agreements (93.4%) between the Clinical and Laboratory Standards Institute (CLSI) and Vitek 2 (AST-YS07 card) methods were observed for fluconazole. Sequencing ERG11 for all 61 isolates revealed that only 3 fluconazole-resistant isolates showed the Erg11p amino acid substitution K143R. All 61 isolates showed identical multilocus sequence typing (MLST). Pulsed-field gel electrophoresis (PFGE) analyses revealed that both blood and ear isolates had the same or similar patterns. These results show that MALDI-TOF MS and Vitek 2 antifungal susceptibility systems can be reliable diagnostic tools for testing C. auris isolates from Korean hospitals. The Erg11p mutation was seldom found among Korean isolates of C. auris, and multidrug resistance was not found. Both MLST and PFGE analyses suggest that these isolates are genetically similar.

Background: Natural Killer (NK) cell-based immunotherapy used to treat cancer requires the adoptive transfer of a large number of activated NK cells. Here, we report a new effective method to expand human NK cells ex vivo using K562 cells genetically engineered (GE) to express OX40 ligand (K562-OX40L) in combination with a short exposure to soluble IL-21. In addition, we describe a possible mechanism of the NK cell expansion through the OX40 receptor-OX40 ligand axis which is dependent on NK cell homotypic interaction. Methods: K562-OX40L cells were generated by lentiviral transduction and were used as feeder cells to expand and activate NK cells from PBMCs in the presence of IL-2/IL-15. Soluble IL-21 was also added in various concentrations only once at the beginning of the culture. NK cells were expanded for 4-5 weeks, and the purity, expansion rate, phenotype and function (cytotoxicity, antibody-dependent cell-mediated cytotoxicity (ADCC), cytokine production, CD107a degranulation) of these expanded NK cells were compared to those generated by using K562 feeder cells. Results: The culture of NK cells with K562-OX40L cells in combination with the transient exposure to IL-21 highly enhanced NK cell expansion to approximately 2,000-fold after 4 weeks of culture, compared to a 303-fold expansion using the conventional K562 cells. Mechanistically, the OX40-OX40L axis between the feeder cells and NK cells as well as the homotypic interaction between NK cells through the OX40-OX40L axis were both necessary for NK cell expansion. The short exposure of NK cells to IL-21 had a synergistic effect with OX40 signaling for NK cell expansion. Apart from their enhanced expansion, NK cells grown with K562-OX40L feeder cells were similar to those grown with conventional K562 cells in regard to the surface expression of various receptors, cytotoxicity, ADCC, cytokine secretion, and CD107 degranulation. Conclusion: Our data suggest that OX40 ligand is a potent co-stimulant for the robust expansion of human NK cells and the homotypic NK cell interactions through the OX40-OX40L axis is a mechanism of NK cell expansion.

The objective of this study was to establish modified cutoff values of serum alpha-fetoprotein (AFP) according to hepatitis status. While AFP is used as a serum marker in the diagnosis or monitoring of hepatocellular carcinoma (HCC), its use as a screening method to the general population is controversial. We evaluated its screening performance in a hepatitis prevalent East Asian population, and suggest different cutoff values according to the individual's hepatitis status. We evaluated the performance of AFP as a screening test in 48,123 consecutive Koreans during the period from March, 2012 to August, 2013 who underwent routine health checks at a single institution. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated with fixed cutoff and with modified cutoffs according the individual's hepatitis status. A total of 24 out of 48,123 subject (0.05%) were newly diagnosed with HCC after screening. Among the 1,874 subject with positive hepatitis B virus surface antigen (HBsAg), 17 (0.91%) developed HCC, compared with two out of 393 (0.51%) individuals with hepatitis C virus antibody (anti-HCV). Five out of 45,855 (0.01%) subject with neither HBsAg nor anti-HCV developed HCC. Compared to the performance of a fixed cutoff, specificity, PPV, and NPV improved without sacrificing sensitivity when applying modified cutoff. In conclusion, our findings suggest that AFP with modified cutoffs according to the individual's hepatitis status might be a useful screening marker for HCC in hepatitis prevalent areas.

Background/aim γ-Irradiation has been proven to be the most effective method to inactivate K562 cells, but γ-irradiators are not available in some institutes. This study was designed to compare the effects of X-ray and γ-irradiation on K562 cells in natural killer (NK) cell expansion. Materials and methods To expand NK cells, isolated peripheral blood mononuclear cells (PBMCs) were co-cultured with γ-irradiated or X-ray-treated K562 cells plus IL-2 and IL-15. Characteristics of expanded NK cells were identified by flow cytometry. Results NK cell expansion rate tended be to lower in the X-ray-treated group (68.9±32.6) than the γ-irradiated group (78±28.7), but the difference was not significant (p=0.39). Furthermore, NK cell functions or receptor expression were similar in the two groups. Conclusion Our results suggest that X-ray treatment can be used as an alternative to γ-irradiation for K562 cells inactivation in human NK cell expansion.

Background Chimeras are composed of two or more different populations that originated from different zygotes. Blood chimerism arising from twins have been reported in the literature. Herein, we report the first blood group chimerism in triplets. Methods ABO blood grouping was carried out by manual tile methods (Merck Millipore, UK) and micro-column agglutination method (Bio-Rad, Cressier sur Morat, Switzerland). Flow cytometric analysis was performed with Anti-A-PE conjugated monoclonal antibodies (BD Biosciences, San Jose, CA, USA) and FACS Canto II (BD Biosciences). Molecular analysis was performed with allele-specific polymerase chain reaction (AS-PCR) and direct sequencing of the exons 6 and 7. Results Mixed-field agglutination and weak agglutination against anti-A were revealed by ABO blood grouping. Flow cytometric analysis revealed the presence of both A cells and O cells. AS-PCR and sequencing showed two neonates with chimerism, with each neonate`s genotype being A102/O01/O02. Conclusion This is the first recorded case of blood chimera from a triplet in Korea. We recommend full investigation of blood group chimerism in neonates with ABO discrepancy, as blood chimerism is subject to certain caution in the clinical environment.

BACKGROUND Although testing to detect weak D antigens using the antihuman globulin reagent is not required for D- patients in many countries, it is routinely performed in Korea. However, weak D testing can be omitted in D- patients with a C-E- phenotype as this indicates complete deletion of the RHD gene, except in rare cases. We designed a new algorithm for weak D testing, which consisted of RhCE phenotyping followed by weak D testing in C+ or E+ samples, and compared it with the current algorithm with respect to time and cost-effectiveness. METHODS In this retrospective study, 74,889 test results from January to July 2017 in a tertiary hospital in Korea were analyzed. Agreement between the current and proposed algorithms was evaluated, and total number of tests, time required for testing, and test costs were compared. With both algorithms, RHD genotyping was conducted for samples that were C+ or E+ and negative for weak D testing. RESULTS The algorithms showed perfect agreement (agreement=100%; κ=1.00). By applying the proposed algorithm, 29.56% (115/389 tests/yr) of tests could be omitted, time required for testing could be reduced by 36% (8,672/24,084 min/yr), and the test cost could be reduced by 16.53% (536.11/3,241.08 USD/yr). CONCLUSIONS Our algorithm omitting weak D testing in D- patients with C-E- phenotype may be a cost-effective testing strategy in Korea.

Background Viridans group streptococci (VGS) are both commensal microbes and potential pathogens. Increasing resistance to penicillin in VGS is an ongoing issue in the clinical environment. We investigated the difference in susceptibility and resistance to penicillin among various VGS species. Methods In total 1,448 VGS isolated from various clinical specimens were analyzed over a two-yr period. Identification and antimicrobial susceptibility test was performed by the automated VITEK 2 system (bioMerieux, France) or the MicroScan MICroSTREP system (Siemens, Germany). Results Among the 1,448 isolates, 412 were isolated from blood (28.4%). Streptococcus mitis group was the most frequently isolated (589 isolates, 40.7%), followed by the S. anginosus group (290 isolates, 20.0%), S. sanguinis group (179 isolates, 12.4%) and S. salivarius group (57 isolates, 3.9%). In total, 314 isolates could not be identified up to the species level. The overall non-susceptibility to penicillin was observed to be 40.0% (resistant, 11.2% and intermediately resistant, 28.8%) with uneven distribution among groups; 40.2% in S. sanguinis group (resistant, 5.0% and intermediately resistant, 35.2%), 60.3% in S. mitis group (resistant, 20.9% and intermediately resistant, 39.4%), 78.9% in S. salivarius group (resistant, 8.8% and intermediately resistant, 70.1%), and 6.2% in S. anginosus group (resistant, 1.7% and intermediately resistant, 4.5%). Conclusions Antimicrobial resistance patterns towards penicillin show differences among various VGS; this should be considered while devising an effective antimicrobial treatment against VGS.