Yeongsic Kim

Direct identification of urinary tract pathogens from urine samples using the Vitek MS system based on matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Background We evaluated the coincidence rate between Vitek MS system (bioMérieux, France) and Vitek 2 in identifying uropathogens directly from urine specimens. Methods Urine specimens submitted to our microbiology laboratory between July and September 2013 for Gram staining and bacterial culture were analyzed. Bacterial identification was performed by using the conventional method. Urine specimens showing a single morphotype by Gram staining were processed by culturing and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Of 2,370 urine specimens, 251 showed a single morphotype on Gram staining, and among them, 202 were available for MALDI-TOF MS. Results In these 202 specimens, colony growth was observed in 189 specimens, and 145 specimens had significant growth of single-colony morphotype in culture. One hundred and ten (75.9%) of them had colony counts of ≥105 colony-forming units (CFU)/mL and included 71 enteric gram-negative bacteria (GNB), 5 glucose-non-fermenting GNB, 9 gram-positive cocci (GPC), and 25 yeasts. Furthermore, 70 (98.6%), 3 (60.0%), 4 (44.4%), and 5 (20.0%), respectively, of these were correctly identified by Vitek MS. Thirty-one specimens (21.4%; 11 GNB, 7 GPC, 12 yeasts, and 1 gram-positive bacillus) had colony counts of 104-105 CFU/mL. Four specimens (2.8%) yielded colony counts of 103-104 CFU/mL. Conclusions Vitek MS showed high rate of accuracy for the identification of GNB in urine specimens (≥105 CFU/mL). This could become a rapid and accurate diagnostic method for urinary tract infection caused by GNB. However, for the identification of GPC and yeasts, further studies on appropriate pre-treatment are warranted.

Automated Heart-Type Fatty Acid–Binding Protein Assay for the Early Diagnosis of Acute Myocardial Infarction

We compared an automated quantitative heart-type fatty acid-binding protein (H-FABP) assay with other cardiac-marker assays to examine its usefulness as an early diagnostic marker of acute myocardial infarction (AMI). Serum samples for cardiac troponin T (cTnT), creatine kinase-MB isozyme (CK-MB), myoglobin, and H-FABP were obtained from 64 patients with AMI and 53 patients with other conditions (control group). H-FABP was measured by using 2 immunoassays, the H-FABP enzyme-linked immunosorbent assay (ELISA; Biocheck, Foster City, CA) and the H-FABP latex turbidimetric immunoassay (LTIA; HBI, Anyang, Korea). Sensitivities of assays for cTnT, CK-MB, myoglobin, H-FABP (by ELISA), H-FABP (by LTIA), and electrocardiogram (ECG) for the diagnosis of AMI at hospital admission were 39.1%, 59.4%, 64.1%, 68.7%, 70.3%, and 54.7%, respectively. Specificities of cTnT, CK-MB, myoglobin, H-FABP (by ELISA), H-FABP (by LTIA), and ECG were 98.1%, 71.7%, 81.1%, 77.4%, 90.6%, and 92.5%, respectively. The automated H-FABP (by LTIA) is superior to cTnT, CK-MB, myoglobin, and H-FABP (by ELISA) tests for the diagnosis of AMI in patients admitted within 4 hours from the onset of chest pain.

C3435T polymorphism of MDR1 gene with warfarin resistance

BACKGROUND Some patients show warfarin resistance needing more than 70 mg of warfarin per week. In this study, we examined if C3435T polymorphism of MDR1 gene could be a factor of warfarin resistance. METHODS We examined 196 blood specimens from the patients who took warfarin more than 42 mg/week for at least 1 year. The subjects consisted of 74 European Americans, 59 African Americans, 42 Hispanic Americans and 21 Asian Americans. Genotype of C3435T polymorphism was determined by using real-time polymerase chain reaction (PCR). RESULTS Ninety (45.9%) of the 196 patients had C3435T genotype and the remaining patients had C3435C genotype (35.7%) and T3435T genotype (18.4%). Mean dose of warfarin of patients with C3435C, C3435T and T3435T genotypes were 59.5mg/week, 56.9 mg/week and 55.6 mg/week, respectively. There was no statistical difference in the dose of warfarin between the 3 genotypes within each race. CONCLUSION Our results suggest that C3435T polymorphism of MDR1 gene is not associated with warfarin resistance.

Three Cases Showing False Results in the Detection of Monoclonal Components Using Capillary Electrophoresis

In the detection of monoclonal proteins using capillary electrophoresis (CE), several problems have been described, especially for small amounts of paraprotein, light chain (LC) disease, and cases associated with contrast interference. In this report, we describe 3 unusual cases that showed false-positive peaks due to radiologic contrast interference and the escape of monoclonal LC in CE. In these cases questionable for monoclonal components, conventional gel tests and free LC assays could be helpful to confirm monoclonal gammopathy. Therefore, multiple methodological modalities should be combined for diagnosing and monitoring plasma cell neoplasms and related disorders. * CE : capillary electrophoresis LC : light chain IS : immunosubtraction IT : immunotyping CT : computed tomography Ig : immunoglobulin FLC : free light chain rFLC : ratio of free light chain EP : electrophoresis IFE : immunofixation electrophoresis UV : ultraviolet

Usefulness of total IgE in predicting positive allergen specific IgE Tests in Korean subjects

BACKGROUND Total IgE levels in allergic patients tend to be higher than those in healthy individuals. We evaluated the usefulness of total IgE levels in predicting positive results of allergen specific IgEs in multiple allergen simultaneous tests. METHODS A total of 133 patients with allergic symptoms were evaluated. Allergen specific IgEs were detected using 3 different kits: Allergy screen (R-biopharm, Germany), AdvanSure Allergy Screen (LG Life Science, Korea) and Polycheck allergy (Biocheck Co., Germany). Total IgE was measured by turbidoimmunometric assay (LX-2200, Eiken Chemical Co., Japan). The patients were divided into high (≥ 170 IU/mL) and low (<170 IU/mL) groups of total IgE level, and the positive rates and number of positive allergen specific IgEs were evaluated in each group. Positive concordance rates among different kits were also evaluated. RESULTS High total IgE group showed significantly higher positive rates and number of positive allergen specific IgEs in all of the 3 test kits used compared to low total IgE group. Only two of the allergens, Dermatophagoides farinae and Dermatophagoides pteronyssinus had positive concordance rates of ≥ 50%. Allergen specific IgEs to these two allergens showed good correlation with total IgE (correlation coefficients >0.5). CONCLUSIONS Total IgE appears to be useful in predicting positive results in allergen specific IgE tests to common allergens. The specific IgEs to D. farinae and D. pteronyssinus showed good correlation with total IgE. However, for other allergens, significant differences were observed among different test kits, and the standardization of allergens in multiple allergen simultaneous tests is needed.

Comparison of Nine Different Qualitative HBsAg Assay Kits

BACKGROUND Qualitative hepatitis B surface antigen (HBsAg) assay kits are still commonly used in Korea where hepatitis B virus (HBV) infection is endemic. The accurate determination of HBsAg plays a crucial role in the diagnosis and prevention of HBV infection, especially in endemic areas. The aim of this study was to compare the detection sensitivities of 9 qualitative HBsAg assay kits. METHODS Seven pooled sera with HBsAg concentration ranging from 0.14 IU/mL to 29.96 IU/mL were prepared. The HBsAg concentration of each pooled serum was determined by a quantitative HBsAg assay, Architect HBsAg (Abbott Laboratories, Ireland). The fully automated immunoassay kits included Elecsys HBsAg (Roche Diagnostics, Germany) and Immulite 2000 HBsAg (DPC, USA) and the rapid tests included 5 immunochromatographic assay (ICA) kits and 2 reverse passive hemagglutination assay (RPHA) kits. RESULTS Elecsys HBsAg (Roche Diagnostics) showed positive result in pooled serum with HBsAg concentration of 0.14 IU/mL, but Immulite 2000 HBsAg (DPC) showed negative result in the same concentration. Although ICA kits showed variable results among different assay kits, all of them showed negative results in pooled sera with HBsAg concentration of < or = 1.89 IU/mL. Two RPHA kits showed negative results in pooled sera with HBsAg concentration of < or = 7.98 IU/mL. CONCLUSIONS Although ICAs were more sensitive than RPHAs, they had variable sensitivities for HBsAg and were less sensitive than the automated immunoassay kits. Therefore, ICAs and RPHAs should be used with caution in the screening tests for HBsAg and their sensitivities need to be improved.

Usefulness of biological variation in the establishment of delta check limits.

BACKGROUND Biological variation is used in the calculation of reference change values (RCVs) for a delta check. In this study, we examined the correlation between intra-individual biological coefficients of variation (CVI) and delta check limits according to population distribution. METHODS A total of 1,533,359 paired test results of nine routine chemistry tests were used to make the population distributions of delta percent changes. Their 0.5th, 2.5th, 97.5th, and 99.5th percentiles were then used for delta check limits. RESULTS A large difference was observed between the chemistry tests in the percentage exceeding the delta check limits according to the RCVs. The mean percentage of test results of each test item exceeding the delta check limits of RCV95% ranged from 12.3% to 40.6%. Delta percent changes of protein, albumin, sodium (Na), potassium (K) and chloride (Cl) showed a symmetric distribution. However, an asymmetric distribution was observed in the delta percent changes of glucose, aspartate transaminase (AST), alanine aminotransferase (ALT) and creatinine. A good correlation was observed between CVI and the delta check limits according to population distribution and a closer correlation was observed when using the test items with CVI of <5.0%. CONCLUSIONS Intra-individual biological coefficients of variation (CVI) would be useful for the establishment of delta check limits.

Evaluation of enzymatic BM Test HbA1c on the JCA-BM6010/C and comparison with Bio-Rad Variant II Turbo, Tosoh HLC 723 G8, and AutoLab immunoturbidimetry assay.

Abstract Background: A novel enzymatic HbA1c assay was introduced for use in an automated chemistry analyzer. With this unique method, HbA1c and plasma glucose can be measured from the same EDTA tube. We evaluated the analytical performance of this enzymatic HbA1c assay in a JCA-BM6010/C analyzer and compared the HbA1c values with the results from other widely used methodological instruments. Methods: The imprecision, linearity, carry-over and concordance rate of the enzymatic HbA1c test (BM Test HbA1c) using the JCA-BM6010/C analyzer were evaluated. Three hundred and seventy-seven specimens with HbA1c concentrations from 16 to 133 mmol/mol were used for a comparison study with two high performance liquid chromatography methods: Variant II Turbo and Tosoh HLC 723 G8 and the AutoLab Hemoglobin A1c immunoturbidimetry reagent using a Hitachi 7600-110. Forty specimens were used for the glucose method comparison. Results: The HbA1c coefficients of variation of the within-run imprecision for low and high levels were 0.6% and 0.4%, respectively. The linearity of the BM Test HbA1c using the JCA-BM6010/C analyzer was excellent in the range between 31 mmol/mol and 143 mmol/mol. The carry-over rate was 0.2%. The relationships between the BM test and the other three methods were 0.916×Tosoh G8+3.644, r=0.986; 0.887×Bio-Rad Variant II+1.896, r=0.972; and 0.941×AutoLab+4.532, r=0.977. The concordance rates using a cut-off of 48 mmol/mol were 91.5% with Tosoh G8, 82.8% with Bio-Rad Variant II, and 91.0% with AutoLab. The simultaneously assayed plasma glucose with HbA1c was 1.002×Routine plasma glucose+0.625, r=1.000 Conclusions: The enzymatic BM Test HbA1c in the JCA-BM6010/C analyzer showed excellent precision and linearity, and a minimal carry-over rate. The simultaneously assayed plasma glucose analysis showed good performance.

Intactness of Medical Nonsterile Gloves on Use of Alcohol Disinfectants

Dear Editor, Phlebotomists wear gloves for their own protection and for patient safety; they wash hands (or apply alcohol disinfectants when pressed for time) and change gloves between patients [13]. Blood collection is delayed when gloves are changed after washing and drying hands. Moreover, latex glove disposal might increase environmental pollution. Cleansing gloved hands to prolong the use of gloves results in considerable savings of disposable examination gloves. However, the current regulation prohibits alcohol disinfection when gloves are worn, because of the concern that sanitary intactness of gloves may be compromised by alcohol; it also prohibits examination gloves to be reprocessed because of their composition, thinness, and inelasticity [1]. We evaluated the intactness of 50 medical nonsterile gloves after using alcohol disinfectants, by testing five pairs of gloves from different brands: four brands of powder-free non-sterile latex medical examination gloves and one brand of nitrile gloves. Latex glove of brands Top glove (Top Glove, Klang, Malaysia) and HandyCare (Latexx Manufacturing, Kamunting, Malaysia) were sanitized with 62% ethanol Clesis hand sanitizer gel (Liebecos, Cheonan, Korea), and Dowoo (Siam Sempermed Corp., Bangkok, Thailand) brand, with 62% ethanol 3M Hand Instant Sanitizer (3M Korea, Seoul, Korea). Gloves were sanitized by rubbing and drying the gloves 30 times. DERMAGRIP Nitrile extended cuff examination gloves (WRP Asian Pacific, Sepang, Malaysia) were sanitized in the same way, using 62% ethanol 3M Hand Instant Sanitizer. After sanitation, the gloves were filled with water and checked for leakage. All the gloves were intact after the sanitization procedure. Latex gloves of the brand Maxter (Maxter Glove Manufacturing, Klang, Malaysia) were still intact after performing the rub-and-dry action 100 times with 83% ethanol skin cleaner, New Clean Swab A (Meditop, Yongin, Korea). The distribution of major contaminated regions on the hands of phlebotomists was studied to check for decontamination after venipuncture. Fig. 1 shows the contact points of the five phlebotomists’ hands with the forearm of the patient. Bacterial suspensions of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii were prepared to match 0.5 McFarland turbidity standards. Glass slides were smeared with each inoculum and dried for 30 minutes at room temperature. Gloved fingertips were placed on the smeared surface for 1 minute; then, they were pressed onto blood agar plate, and the plate was incubated at 35°C for 18 hours to allow for bacterial growth. Subsequently, we rubbed the gloved fingertips with alcohol disinfectant and dried them; the

Comparison of Four Automated Carcinoembryonic Antigen Immunoassays: ADVIA Centaur XP, ARCHITECT I2000sr, Elecsys E170, and Unicel Dxi800

Background Carcinoembryonic antigen (CEA) is one of the tumor markers available for evaluating disease progression status after initial therapy and monitoring subsequent treatment modalities in colorectal, gastrointestinal, lung, and breast carcinoma. We evaluated the correlations and differences between widely used, automated CEA immunoassays at four different medical laboratories. Methods In total, 393 serum samples with CEA ranging from 3.0 to 1,000 ng/mL were analyzed on ADVIA Centaur XP (Siemens Diagnostics, Tarrytown, NY, USA), ARCHITECT i2000sr (Abbott Diagnostics, Abbott Park, IL, USA), Elecsys E170 (Roche Diagnostics, Indianapolis, IN, USA), and Unicel DxI800 (Beckman Coulter, Fullerton, CA, USA), and the results were compared. Deming regression, Passing-Bablok regression, and Bland-Altman analyses were performed to evaluate the data correlation and % differences among these assays. Results Deming regression analysis of data from Elecsys E170 and UniCel DxI800 showed good correlation (y=3.1615+0.8970x). According to Bland-Altman plot, no statistically significant bias (−1.78 ng/mL [95% confidence interval: −4.02 to 0.46]) was observed between Elecsys E170 and UniCel DxI800. However, the relative differences of CEA concentrations between assays exceeded the acceptable limit of 30%. Regarding the agreement of positivity with cut-off value 5.0 ng/mL, ARCHITECT i2000sr and Elecsys E170 showed the highest agreement (95.2%), whereas ADVIA Centaur XP and ARCHITECT i2000sr showed the lowest agreement (70.7%). Conclusions Agreements between automated CEA immunoassays are variable, and individual CEA concentrations may differ significantly between assays. Standardization of serum CEA concentrations and further harmonization are needed.