Performance Evaluation of a New Automated Chemiluminescent Immunoanalyzer-Based Interferon-Gamma Releasing Assay AdvanSure I3 in Comparison With the QuantiFERON-TB Gold In-Tube Assay

BACKGROUND: The interferon-gamma (IFN-γ) releasing assay (IGRA) is widely used for latent tuberculosis infection (LTBI) diagnosis. We evaluated the analytical performance of a new automated chemiluminescent immunoanalyzer-based IGRA (CLIA-IGRA), AdvanSure I3 (LG Life Sciences, Seoul, Korea) and compared it with that of the QuantiFERON-TB Gold In-Tube (QFT-GIT) assay. METHODS: Repeatability and reproducibility were evaluated at four levels. Detection capability, including limit of blank (LoB), limit of detection (LoD), and limit of quantification (LoQ), was evaluated using IFN-γ standard material (National Institute for Biological Standards and Control code: 87/586). Agreement between the results of two assays was evaluated using 341 blood samples from healthcare workers and patients at a tertiary care hospital. To determine the cut-off value of CLIA-IGRA for diagnosing LTBI, the ROC curve was analyzed. RESULTS: Repeatability and reproducibility were 4.86–7.00% and 6.36–7.88% CV, respectively. LoB, LoD, and LoQ were 0.022, 0.077, and 0.249 IU/mL, respectively. IFN-γ values between CLIA-IGRA and QFT-GIT showed a strong correlation within the analytical measurable range of both assays, especially when the value was low. Qualitative comparison of the two assays yielded a 99.1% overall agreement (kappa coefficient=0.98). A cut-off value of 0.35 IU/mL was appropriate for diagnosing LTBI. CONCLUSIONS: CLIA-IGRA is a reliable assay for LTBI diagnosis, with performance similar to that of QFT-GIT.

Detection of Anti-Extractable Nuclear Antigens in Patients with Systemic Rheumatic Disease via Fluorescence Enzyme Immunoassay and Its Clinical Utility

Development of Statistical Software for the Korean Laboratory Accreditation Program Using R Language: LaboStats

BACKGROUND: In Korea, the Korean Laboratory Accreditation Program (KLAP) has set minimum standards for verification of clinical test performance. This verification process is time-consuming and labor-intensive when performed manually. We developed a free, statistical software program for KLAP, using the R language (R Foundation for Statistical Computing, Vienna, Austria). METHODS: We used CLSI guidelines for the algorithm. We built graphic user interfaces, including data input, with Embarcadero Delphi EX4 (Embarcadero Technologies, Inc., Texas, USA). The R Base Package and MCR Package for Method Comparison Regression were used to implement statistical and graphical procedures. RESULTS: Our program LaboStats has six modules: parallel test, linearity, method comparison, precision, reference interval, and cutoff. Data can be entered into the field either manually or by copying and pasting from an MS Excel worksheet. Users can print out precise reports. CONCLUSIONS: LaboStats can be useful for evaluating clinical test performance characteristics and preparing documents requested by KLAP.

Diagnostic Performance and Comparative Evaluation of the Architect, Liaison, and Platelia Epstein-Barr Virus Antibody Assays

BACKGROUND: Epstein-Barr Virus (EBV) is one of the most prevalent causes of viral infection in humans. EBV infection stage (acute, past, or absent infection) is typically determined using a combination of assays that detect EBV-specific markers, such as IgG and IgM antibodies against the EBV viral capsid antigen (VCA) and IgG antibodies against the EBV nuclear antigen (EBNA). We compared the diagnostic performance and agreement of results between three commercial EBV antibody assays using an EBV performance panel (SeraCare Life Science, Milford, MA, USA) as a reference. METHODS: EBV antibody tests of EBV VCA IgM, VCA IgG, and EBNA IgG antibodies were performed by the Architect (Abbott Diagnostics, Wiesbaden, Germany), Liaison (DiaSorin, Saluggia, Italy), and Platelia (Bio-Rad, Marnes-la-Coquette, France) assays. Agreement between the three assays was evaluated using 279 clinical samples, and EBV DNA and antibody test results were compared. RESULTS: The three EBV antibody assays showed good diagnostic performance with good and excellent agreement with the performance panel (kappa coefficient, >0.6). The overall VCA IgM positivity rate was higher in EBV DNA-positive samples than in EBV DNA-negative samples for all three EBV antibody assays (P=0.02). The three EBV antibody assays exhibited good agreement in results for the clinical samples. CONCLUSIONS: The diagnostic performance of the three EBV antibody assays was acceptable, and they showed comparable agreement in results for the clinical samples.

The Korean guideline for colorectal cancer screening

Colorectal cancer is the third most common cancer in Korea; it is the second most common cancer in men and the third most common in women. The incidence rate in Korea has continuously increased since 1999 when the National Cancer Registry statistics began. Currently; there are several screening modalities; that have been recommended by expert societies, including fecal occult blood test, colonoscopy, computed tomographic colonography The annual fecal immunochemical test (FIT) has been used in adults aged 50 and older as part of the National Cancer Screening Program in Korea since 2004. Although several study results from regional or national colorectal cancer screening programs in other countries have been reported, the National Cancer Screening Program in Korea has not yet been evaluated with evidence-based methods. Herein report the consensus statements on the National Screening Guideline for colorectal cancer developed by a multi-society expert committee in Korea, as follows: 1) We recommend annual or biennial FIT for screening for colorectal cancer in asymptomatic adults, beginning at 45 years of age and continuing until 80 years (recommendation B). 2) There is no evidence for the risks or benefits of FIT in adults older than 80 years (recommendation I). 3) Selective use of colonoscopy for colorectal cancer screening is recommended, taking into consideration individual preference and the risk of colorectal cancer (recommendation C). 4) There is no evidence for the risks or benefits of double-contrast barium enema for colorectal cancer screening in asymptomatic adults (recommendation I). 5) There is no evidence for the risks or benefits of computed tomographic colonography for colorectal cancer screening in asymptomatic adults (recommendation I).

Epidemiology and Resistance Patterns of Bacterial Pathogens in Urinary Tract Infections in the Northern Gyeonggi-do Area during 2007-2011

BACKGROUND: Bacteria that cause urinary tract infections (UTIs) are found with different frequencies in different regions; moreover, antibiotic susceptibility can also vary by region. We retrospectively studied and compared the species and antimicrobial susceptibility of bacterial pathogens isolated from patients with UTIs in the northern Gyeonggi-do area. METHODS: We analyzed urine specimens collected from patients who visited the Myongji Hospital between 2007 and 2011. The urine specimens were cultured, and bacteria were identified by biochemical examination with an API kit (bioMerieux Inc., USA). Antimicrobial susceptibility was determined by the disc diffusion method and the Vitek II system (bioMerieux Inc., USA). RESULTS: A total of 11,818 (31.4%) urine specimens were culture positive. The most common species identified were Escherichia coli (37.1%), Klebsiella pneumoniae (7.4%), Enterococcus faecium (6.1%), and Candida spp. (5.5%). The proportion of isolates producing extended-spectrum beta-lactamases significantly increased during the study period. CONCLUSIONS: E. coli, K. pneumoniae, and E. faecium were the 3 most common organisms identified. Of note, however, was the increasing frequency of Pseudomonas spp. and Proteus spp. isolated during the more recent years. Further studies are required from other centers in the northern Gyeonggi-do area.

Comparison of COBAS AmpliPrep/COBAS TaqMan HCV Qualitative Test v2.0 with COBAS AMPLICOR Hepatitis C Virus Test v2.0 for the Qualitative Detection of Hepatitis C Virus RNA in Korean Clinical Samples / 임상검사와정도관리

BACKGROUND: We comparatively evaluated the performance of the conventional COBAS Amplicor HCV test v2.0 (CAM; Roche Molecular Systems, USA) and the newly developed COBAS AmpliPrep/COBAS TaqMan HCV test v2.0 (CAP/CTM; Roche Molecular Systems) for qualitative detection of hepatitis C virus (HCV) RNA in clinical samples. METHODS: Six hundred serum samples (100 HCV-positive, 500 HCV-negative, as determined by CAM) were selected and analysed using the new qualitative HCV RNA test, CAP/CTM qualitative test. Results were compared by confirmatory CAP/CTM quantitative test, which is a quantitative HCV RNA real-time polymerase chain reaction by Roche Molecular Systems, and anti-HCV test (Roche Diagnostics GmbH, Germany). Twenty-two additional serum samples, which gave a gray zone result by CAM, were selected for comparison. RESULTS: The two qualitative HCV RNA assays yielded concordant results for 586 of 600 tested samples (concordance rate, 97.7%; kappa coefficient, 0.92; 95% confidence interval [CI], 0.87 to 0.96; P<0.001). Upon re-testing by CAM, we found that the concordance rate increased to 98.2% (kappa coefficient, 0.93; 95% CI, 0.89 to 0.97; P<0.001). The additional 22 samples showing gray zone results for CAM were retested and were also tested by CAP/CTM. The results for 13 of these samples changed to negative and were now concordant with the CAP/CTM and confirmatory CAP/CTM quantitative results. For the remaining samples, the results were variable. For all the 22 samples, the results of the new CAP/CTM were in agreement with those obtained by confirmatory CAP/CTM quantitative test. CONCLUSIONS: The results of the two assays were in good agreement, with 97.7% concordance rate. However, CAP/CTM is more sensitive than CAM and showed no gray zone results. Therefore, it can be a more efficient and useful test for the qualitative detection of HCV RNA in clinical samples.

Evaluation of the UniCel(TM) DxI 800 Immunoassay Analyzer in Measuring Five Tumor Markers

PURPOSE: Tumor marker concentrations in a given specimen measured by different analyzers vary according to assay methods, epitopes for antibodies used, and reagent specificities. Although great effort in quality assessment has been instituted, discrepancies among results from different analyzers are still present. We evaluated the assay performance of the UniCel(TM) DxI 800 automated analyzer in measuring the alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), carbohydrate antigen (CA) 125, CA 15-3 and CA 19-9 tumor markers. MATERIALS AND METHODS: The linearity and precision performance of the five tumor marker assays were evaluated, and concentrations of the respective markers as measured by DxI were compared to those measured by other conventional analyzers (ADVIA Centaur(TM) and Vitros(TM) ECi) using 200 specimens collected from 100 healthy persons and 100 patients with respective cancers. RESULTS: The linear fits for all five tumor markers were statistically acceptable (F=4648 for AFP, F=15846 for CEA, F=6445 for CA 125, F=2285 for CA 15-3, F=7459 for CA 19-9; p<0.0001 for all). The imprecision of each tumor marker assay was less than 5% coefficient of variation, except for low and high concentrations of AFP. The results from UniCel(TM) DxI 800 were highly correlated with those from other analyzers. CONCLUSION: Our results demonstrate that UniCel(TM) DxI 800 has good linearity and precision performance for the tumor markers assayed in this study. However, there were discrepancies between assaying methods. Efforts to standardize tumor marker assays should be undertaken, and the redetermination of cut-off levels is necessary when developing methods of analyzing tumor markers.

Identification of Bacterial and Fungal Isolates by Sequence Analysis of 16S rRNA and Internal Transcribed Spacer / 대한임상미생물학회지

BACKGROUND: Accurate and rapid identification of pathogens is one of the most important tasks of the clinical microbiology laboratory, and, in cases of rare pathogens, the identification is difficult and time-consuming upon the use of conventional methods alone. Herein, we will report our molecular work involving the identification of bacteria and fungi. METHODS: Sixty bacterial isolates had been collected from November 2004 to May 2007, and 15 fungal isolates had been collected from September 2005 to May 2007. Species identifications were performed using sequence analyses of the 16S rRNA region of bacteria and the internal transcribed spacer (ITS) region of fungi. The data were compared with those of GenBank (http://www.ncbi.nlm.nih.gov/) or EMBL (http://www.ebi.ac.uk/embl/). RESULTS: Sixty bacterial isolates included: 23 isolates with genus information (group 1), 17 isolates (group 2) that were too fastidious for genus or species identification, 16 isolates (group 3) with results from identification kits having low confidence, and 4 isolates (group 4) with odd antibiograms according to the species. In 58 of 60 isolates, identification of the genus or species could be obtained using molecular genetic methods. Thirty-eight isolates (63%) and 20 (33%) of 58 isolates could be identified at the species and genus levels, repectively. Among the total of 15 fungal isolates, 11 (73%) and 4 (27%) isolates were identified at the species and genus levels, respectively. CONCLUSION: 16S rRNA and ITS sequencing analyses are very useful for identifying the species or genus of a pathogenic microorganism in the clinical microbiology laboratory.

A Transfusion Experience for a Patient with Cis-A2B3 Phenotype / 대한수혈학회지

We report the case of a 64-year-old man presenting to the hospital for treatment of his anemia. Exact ABO blood typing is an essential step to prevent transfusion reactions. The selection of the wrong blood component for transfusion can be a clinical problem and in this case the patient had a cis-AB blood type that could have caused an ABO discrepancy. In this case neither autologous or directed blood transfusion was possible and O+ red blood cell was transfused without a transfusion reaction.

Comparison of Sensitivity of Tests for Detecting Bacterial Contamination in Platelet Concentrates / 대한수혈학회지

BACKGROUND: The demand for platelet concentrates has increased for patients with hemato-oncologic diseases as well as for patients with chronic diseases. As platelet concentrates are preserved at 22~24degrees C, the chance of bacterial contamination exposure is increased, which can cause fatal outcomes. We evaluated various methods for detecting bacterial contamination in platelet concentrates. METHODS: 0.5 MacFarland standard solutions were prepared using the Staphylococcus aureus ATCC 25923 & Escherichia coli ATCC25922 strains. The platelet concentrates were inoculated with various concentrations (10(1)~10(5) CFU/mL) of bacteria and then gram staining, plate culture, broth culture and 16s RNA were used to detect bacteria. RESULTS: The gram stain method was unable to detect bacteria concentrations less than 10(4) CFU/mL. The plate culture method detected bacterial growth concentrations up to 10(3) CFU/mL, but only 1 specimen of S. aureus was detected at the lowest concentration of 10(1) CFU/mL. The broth culture method detected 10(2) CFU/mL concentrations except for samples from S. aureus and E. coli strains. Among the 10(1) CFU/mL lowest concentrations, bacterial growth detected 3 samples from S. aureus and 2 samples from E. coli. For the broth culture method, detection of bacterial growth up to 10(1) CFU/mL took 58.9 hours, it took 57.5 hours for S. aureus and E. coli respectively, and it took 43.9 hours and 49.0 hours for 10(2) CFU/mL concentrations of S. aureus and E. coli, respectively. The PCR method showed all positive results except for 1 specimen of E. coli. CONCLUSION: The broth culture method showed similar sensitivity to PCR except for the 43.9~58.9 hours of an incubation period to show positive RESULTS. Overall, the PCR method was most sensitive and rapid method for detecting bacterial contamination in platelet concentrates.

Comparison of Two Commercial Real-time Nucleic Acid Amplification Methods for Detecting the Viral Load of Human Immunodeficiency Virus Type 1 / 대한수혈학회지

BACKGROUND: Detection of the viral load of Human Immunodeficiency Virus type 1 (HIV-1) RNA is important for clinical decision making and for determining the prognosis of HIV-infected patients. The aim of the study is to compare the performance of real-time RT-PCR (COBAS AmpliPrep/COBAS TaqMan HIV-1, CAP/CTM, Roche Diagnostics) and the Nucleic Acid Sequence Based Amplification (NucliSens EasyQ HIV-1, NucliSens, BioMerieux) methods for testing Korean HIV-infected patients. METHODS: Among the specimens that were requested to undergo HIV-1 RNA viral load detection from 2005 to 2006, 153 specimens were selected based on the status of the specimens. The CAP/CTM and NucliSens tests were performed according to the manufacturer's instruction. RESULTS: HIV-1 RNA was detected by both tests in 93 specimens. Among the remainder, CAP/CTM detected HIV-1 RNA in 10 specimens, while the same specimens showed results lower than the detection limit with using the NucliSens. Though the results were appropriately correlated (r=0.85, P<0.0001), the mean differences between the two test results were -0.1321 log(10) IU/mL on the Bland-Altman test. CONCLUSION: The methodologic difference or the presence of a HIV subtype may affect the agreement between the two tests. The standardization of methods and the establishment of a linear range for the individual laboratory results may be helpful to obtain accurate test results.

Evaluation of Multiplex PCR Assay Using Dual Priming Oligonucleotide System for Detection Mutation in the Duchenne Muscular Dystrophy Gene / 대한진단검사의학회지

BACKGROUND: Exon deletions of Duchenne muscular dystrophy (DMD) gene account for most of the alterations found in DMD and Becker muscular dystrophy (BMD). This study was to evaluate the usefulness of dual priming oligonucleotide multiplex PCR (DPO PCR) in detection of exon deletions of DMD gene. METHODS: Thirty-seven DMD or BMD patients who had known exon deletions detected by conventional multiplex PCR (conventional PCR) and nine control subjects were enrolled in this study. When a discrepancy was shown between the results of conventional PCR and DPO PCR, the multiplex ligation-dependent probe amplification (MLPA) technique was performed as a confirmation test. RESULTS: The same deletions previously identified by conventional PCR in 32 out of 37 subjects were also detected by DPO PCR. For the five subjects (13.5%) showing discrepant results between the conventional PCR and DPO PCR, MLPA was performed and its results were found to correlate better with those of DPO PCR. The discrepancies were due to false positive or false negative results of the conventional PCR. CONCLUSIONS: DPO PCR shows a high agreement of results with the conventional PCR and is considered an adequate method to be used as a primary genetic test for the diagnosis of DMD. Because of an improved accuracy, especially for determining the boundaries of DMD gene deletions, DPO PCR can be very useful as a supplement to the conventional PCR.

Evaluating the Appropriateness of a Single Unit Transfusion / 대한수혈학회지

BACKGROUND: The domestic quantity of blood components consumed has been decreasing since 2002, but the rate of a single unit RBC transfusion (SUT) has been on the increase. In the past, a SUT was regarded as an uncesssary procedure, but currently is considered as an effective method to maintain a minimal hemoglobin concentration for physiological needs. We investigated the actual conditions of a SUT. METHODS: We analyzed 800 cases of SUTs performed at a tertiary care university hospital between March 2006 March and February 2007. The subjects of the study were divided into a surgical group (n=561) and medical group (n=239) for the purpose of RBC unit usage and were analyzed by groups and ordering departments, with an analysis of the pre and post-transfusion hemoglobin concentration and hematocrit values. The distribution according to the pre and post-transfusion hemoglobin ranges were calculated. RESULTS: The mean hemoglobin concentration increment of the surgical group was significantly lower than that of the medical group (P<0.0001) and the mean pre and post-transfusion hemoglobin concentrations of the medical group were lower than that of the surgical group (P<0.0001). Approximately 26% cases of the SUTs performed in the surgical group were appropriate, based on a post-transfusion hemoglobin concentration below 10 g/dL. In the medical group, about 75% of the SUTs were appropriate based on a pre-transfusion hemoglobin concentration below 9 g/dL. CONCLUSION: Most transfusions are decided based on various clinical situations and opinions of the clinicians. Therefore, continuous evaluation of the appropriateness of transfusion is necessary. In our study, the appropriateness of a SUT was estimated indirectly based on the pre and post-transfusion hemoglobin concentration. Consequently, policies and strategies for performing asingle unit RBC transfusion are required.

Evaluation of the Abbott Cell-Dyn Sapphire Hematology Analyzer / 대한진단검사의학회지

BACKGROUND: The performance of Cell-Dyn Sapphire (Abbott Diagnostic, USA) was compared to the Bayer Advia 2120 (Bayer Diagnostics, USA), Sysmex XE-2100 (Sysmex Corporation, Japan), and reference microscopy. METHODS: Three hundred samples for routine CBC and WBC differentials were randomly chosen for a comparison analysis. The Cell-Dyn Sapphire system was evaluated according to the linearity, imprecision, inter-instrument correlations, and white blood cell differential. RESULTS: The CBC parameters (WBC, RBC, hemoglobin and platelet) showed a significant linearity with correlation coefficients greater than 0.99 (P<0.0001). Coefficients of variation (CV) for withinrun and differential count of WBC were less than 5% except for Total CV for monocytes, eosinophils, and basophils and within-run CV for low valued eosinophils. The correlation coefficients with manual count were lower in monocytes, eosinophils, and basophils than in neutrophils and lymphocytes. The correlation with other hematology anlayzers was significant exclusive of basophils. CONCLUSIONS: These results demonstrate that the Cell-Dyn Sapphire has a good linearity, an acceptable reproducibility, a minimal carryover, and a comparable performance with the sysmex XE-2100 and Advia 2120.