Korean Journal of Laboratory Medicine最新文献

Parvovirus B19 infection is known to cause chronic anemia in immunocompromised hosts, including organ transplant recipients. We report the first case of liver transplant recipient with parvovirus B19-induced pure red cell aplasia in Korea. A 57-yr-old female patient with hepatocellular carcinoma due to hepatitis C virus received a liver transplantation. Two months later, anemia developed and she received periodic red blood cell transfusions. However, chronic anemia persisted and bone marrow examination was performed 8 months after transplantation. Bone marrow aspiration smears showed markedly reduced erythroid precursors with atypical giant pronormoblasts and nuclear remnants with viral inclusions, and characteristic lantern cells were observed in biopsy sections. In addition, parvovirus B19 DNA PCR was positive. She was diagnosed as parvovirus B19-induced pure red cell aplasia and her anemia was improved following intravenous immunoglobulin therapy.

Background: The red blood cell (RBC) deformability test is a useful method for measuring the ability of RBCs to adapt their shape to the flow conditions. Using this test, several investigators have shown the relationship between RBC deformability and numerous clinical conditions. For the quality control (QC) of RBC deformability test, we evaluated whether frozen-thawed-deglycerolized RBCs can be used as QC materials.

Methods: Packed RBCs were frozen with 40% (wt/vol) glycerol and stored at -80°C for 3 months. For 10 different frozen RBC panels, RBCs were thawed, deglycerolized and stored at 4°C for 4 weeks. Using microfluidic ektacytometer, we measured RBC deformability of the thawed RBCs. The stability of thawed RBCs was tested once a day for 28 days of storage time and was analyzed by simple regression analysis. The precision of the test using thawed RBCs was analyzed for 7 days of storage time by calculation of CV values of intra-assay (10 measurements/assay) and between-day measurements.

Results: Frozen-thawed-deglycerolized RBCs were stable for 1 week. Within-run and between-day precisions of the RBC deformability test during 7 days of storage of thawed RBCs were 1.4-2.9%, and 1.9-2.8%, respectively.

Conclusions: Frozen-thawed-deglycerolized RBCs used in RBC deformability test showed satisfactory within-run and between-run precisions and stability for one week after thawing, and may be used as QC materials for this test.

Background: Automated blood cell analyzers often read leukemic blasts as normal cells. In this study, we evaluated the 5-part differential patterns of blasts using automated analyzers to determine if they can differentiate among blast types.

Methods: Blood samples containing 10% or more blasts were collected from patients with acute leukemia (N=175). The 5-part differential count was conducted using DxH 800 (Beckman Coulter, USA) and XE-2100 analyzers (Sysmex Co., Japan), and the results were compared with manual differential counts, which was used as a reference method.

Results: The DxH 800 reported the 5-part white blood cell differential count in 98.9% of the cases. The XE-2100 provided an invalid automated differential count in 72% of the cases. Both analyzers counted most lymphoblasts as lymphocytes and most myeloblasts as monocytes. In 11 cases, the DxH 800 reported a 5-part differential count without a blast flag.

Conclusions: Some automated analyzers are able to recognize and count blasts according to their characteristic cell types. Therefore, complete blood counts obtained automatically can provide valuable data for making provisional decisions regarding the lineage of leukemia cells before further investigation.

Background: Molecular methods have enabled rapid diagnosis of aseptic meningitis and have reduced both unnecessary therapeutic interventions and medical costs. In this study, we evaluated the analytical performance of the recently developed Real-Q Enterovirus Quantification kit (BioSewoom Inc., Korea).

Methods: We evaluated the detection limit, precision, linearity, and cross-reactivity of the Real-Q Enterovirus Quantification kit and compared it with the conventional PCR method. From March to September 2009, we tested 91 CSF specimens from patients who visited the pediatrics department of the university hospital with symptoms of aseptic meningitis or infantile sepsis, and we also tested 48 CSF specimens from patients with febrile convulsion for differential diagnosis.

Results: The Real-Q Enterovirus Quantification kit showed good linearity (r=0.997) within a range from 3 × 10(2) to 3 × 10(10) copies/mL, and the detection limit of the kit was 83 copies/mL. The within-run, between-run, and between-day CVs were 5.3-7.6%, 9.5-12.3%, and 11.4-13.4%, respectively. There was no cross reactivity between enteroviruses and various microorganisms. Positive results were obtained for 39.1% (25/64) of the patients suspected of aseptic meningitis and 44.4% (12/27) of the patients suspected of infantile sepsis. However, among the 48 children with febrile conversion, only 4 were positive for enterovirus. Further, the concordance with conventional PCR was high (73/74).

Conclusions: The Real-Q Enterovirus Quantification kit showed excellent linearity and high reliability with a broad reportable range. It showed good detection rate when used with clinical specimens and also showed a high concordance with the conventional method. Therefore, this assay would be clinically useful not only in diagnosis of aseptic meningitis but also in differential diagnosis of infantile sepsis.

Background: Susceptibility testing of Staphylococcus aureus often requires cumbersome supplementary tests. MicroScan Pos Breakpoint Combo Panel Type 28 (PBC28) (Siemens, USA) includes cefoxitin screening to detect methicillin-resistant Staphylococcus aureus (MRSA), inducible clindamycin resistance detection (ICD), and determination of low-range minimum inhibitory concentration of vancomycin (0.5-16 µg/mL). The purpose of this study was to evaluate the performance of PBC28 in comparison with that of Pos Combo Type 1A (PC1A) (Siemens).

Methods: From December 2009 to March 2010, 500 non-duplicate clinical isolates of S. aureus were tested with PC1A and PBC28. Categorical agreements (CA) between the interpretations of the 2 panels were estimated. The presence of the mecA gene was determined by PCR, and double-disk diffusion test (D-test) was performed on the isolates resistant to erythromycin but susceptible or intermediately resistant to clindamycin. Ninety-six isolates representing various vancomycin minimum inhibitory concentrations (MICs) were tested in parallel with repeat PBC28, broth macrodilution, and epsilometer test (E test).

Results: The CA was 99.3% with a very major error (VME) of 0.2%, major error (ME) of 0.1%, and minor error (mE) of 0.4% in total. PBC28 showed 100% CA for 1 isolate with vancomycin MIC of 4 µg/mL and 35 isolates (7.0%) with MIC of 2 µg/mL. However, only 15, 27, and 35 isolates with vancomycin MIC of 2 µg/mL showed 100% CA in repeat PBC28, broth macrodilution, and E test, respectively. PC1A and PBC28 detected all 314 mecA-positive isolates. Among the 63 isolates tested with the D-test, 58 (92.1%) were positive, and the results were 100% concordant with those of ICD.

Conclusions: PBC28 can be appropriate susceptibility testing of S. aureus, including MRSA detection and ICD. However, the lower-range vancomycin MIC test was not reproducible enough to reliably differentiate MIC of 2 µg/mL from MIC ≤ 1 µg/mL.

Background: The aim of this study was to determine the yearly prevalence and genotype distribution of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae collected over a 3-yr period in Gwangju, Korea.

Methods: Clinical isolates of E. coli and K. pneumoniae collected at Chosun University Hospital from September 15, 2005 to September 14, 2008 were evaluated. Antimicrobial susceptibility testing was performed using the Vitek II system (bioMérieux, USA) and agar dilution methods. Screening for ESBL and AmpC β-lactamase genes was performed using PCR amplification of plasmid DNA followed by direct sequencing of the PCR products.

Results: The percentage of ESBL-producing isolates was 12.6% (196/1,550) for E. coli and 26.2% (294/1,121) for K. pneumoniae. The ESBL gene sequencing results showed that the most prevalent ESBL types were CTX-M (93.5%) and SHV (12.9%) in E. coli, and SHV (73.2%) and CTX-M (46.3%) in K. pneumoniae. The most common ESBL in E. coli was CTX-M-15-like, followed by CTX-M-14-like, SHV-2a-like, and SHV-12-like. The most prevalent ESBL type in K. pneumoniae was SHV-12, followed by CTX-M-14-like and CTX-M-15-like. Fifty-one percent (21/41) of ESBL-producing K. pneumoniae with ESBL types verified by sequencing also had DHA-1-like AmpC β-lactamases. However, none of the ESBL-producing E. coli was positive in the AmpC β-lactamase PCR analysis.

Conclusions: In this study, the most common types of class A ESBLs identified were CTX-M-15-like in E. coli and SHV-12-like in K. pneumoniae.

Background: Malignant hyperthermia (MH) is genetically heterogeneous, with mutations in the gene encoding the skeletal muscle ryanodine receptor (RYR1) at 19q13.1 accounting for up to 80% of the cases. However, the search for known and novel mutations in the RYR1 gene is hampered by the fact that the gene contains 106 exons. We aimed to analyze mutations from the entire RYR1 coding region in Korean MH families.

Methods: We investigated seven affected MH individuals and their family members. The entire RYR1 coding region from the genomic DNA was sequenced, and RYR1 haplotyping and mutational analysis were carried out.

Results: We identified nine different RYR1 mutations or variations from seven Korean MH families. Among these, five previously reported mutations (p.Gly248Arg, p.Arg2435His, p.Arg2458His, p.Arg2676Trp, and p.Leu4838Val) and four novel variations of unknown significance (p.Arg2508Cys, p.Met4022Val, p.Glu2669Lys, and p.Ala4295Val) were identified. In two families, two variations (R2676W & M4022V, R2435H & A4295V, respectively) were identified simultaneously. Four of the observed nine mutations or variations were located outside the hotspot region of RYR1 mutations.

Conclusions: These data indicate that RYR1 is a main candidate gene in Korean MH families, and that comprehensive screening of the entire coding sequence of the RYR1 gene is necessary for molecular genetic investigations in MH-susceptible individuals, owing to the presence of RYR1 mutations or variations outside of the hotspot region.

Background: Nationwide external quality assessment (EQA) of the fecal occult blood test (FOBT) in Korea was first introduced in 2007-2009. The EQA results were analyzed to assess the current status of FOBT and to plan the continuation of the EQA program.

Methods: The surveys included 40 hospitals in the preliminary survey conducted in 2007, 249 general hospitals in 2008, and 389 hospitals in 2009. In the surveys, the participating hospitals provided the results of the distributed materials and replies to the questionnaire on the FOBT test procedures and quality controls.

Results: In the surveys conducted between 2007 and 2009, a total of 650 institutes submitted 653 test system results; 3 institutes used 2 kinds of methods. All of the institutes used immunologic methods; 107 institutes (16.5%) used quantitative equipments and 546 institutes (84.0%) used qualitative kits. Most quantitative tests yielded consistent positive or negative results; however, their cut-off and measured values differed according to the equipments used. A low-level material tested in 2007 was negative in the quantitative methods but positive in some qualitative methods because of lower detection limits. The discordance rates among quantitative tests were 3.2% in 2007, 4.4% in 2008, and 0% in 2009 and the rates among qualitative tests were 13.8% in 2008 and 2.6% in 2009. Semi-solid EQA materials showed the ability to evaluate the overall test procedures with acceptable stability.

Conclusions: In the first Korean FOBT EQA, commercially available EQA materials were proven to be stable. Continuation of the EQA program and further education of laboratory personnel are needed to reduce inconsistency in results. Further, the test kit, procedures, and result reports must be standardized.

Background: Hepatitis C virus (HCV) core antigen (Ag) levels are known to be well correlating with HCV RNA levels, and may be used as an alternative marker of HCV replication for monitoring the response to HCV treatment. However, the low sensitivity of HCV core Ag assay has been an obstacle for clinical use. In this study, recently developed ARCHITECT HCV Ag assay (Abbott Laboratories, USA) was evaluated for analytical performance and clinical usefulness.

Methods: A total of 109 sera from HCV infected patients including various genotypes of HCV (1b, 2, 2a/2c, 2b, and 3a) and 20 sera from healthy donors were used for evaluating the sensitivity, precision, and linearity of the HCV core Ag assay. The cross reactivity with HIV, hepatitis B virus and myeloma proteins (N=5, each) and correlation with HCV RNA PCR assay were also evaluated.

Results: The sensitivity of the HCV core Ag assay was 97.2% (106/109) and there were no false positive results and cross reactivity. The within-run, between-run and between-day CVs were 3.0%, 2.5% and 3.0%, respectively. The levels of HCV core antigen showed a good correlation with those of HCV RNA quantification (r=0.940). The HCV Ag assay showed an excellent linearity in the range from 0.63 to 17,114 fmol/L (r=0.999).

Conclusions: The ARCHITECT HCV Ag assay was good in sensitivity, precision, and linearity and its results well correlated with HCV RNA levels. This assay could be used as a good marker of viral replication for monitoring the therapy response in chronically HCV infected patients.

Background: Manual slide review (MSR) is usually triggered by the results of automated hematology analyzers, but each laboratory has different criteria for MSR. This study was carried out to investigate the current status of MSR criteria of automated complete blood cell count (CBC) and white blood cell (WBC) differential results and to propose a basic guideline for MSR.

Methods: Total 111 laboratories were surveyed regarding MSR using questionnaires. The questionnaire asked: kinds of automated hematology analyzers used and the presence of criteria triggering MSR in seven categories: 1) CBC results, 2) 5 differential WBC counts, 3) 3 differential WBC counts, 4) automated reticulocyte counts, 5) delta check, 6) instrument flags (or messages), 7) clinical information (wards or diseases). Based on the survey results, we determined basic and extended criteria for MSR. With these criteria, we consulted nine hematology experts to get a consensus.

Results: All 111 laboratories had their own MSR criteria. Among 111 laboratories, 98 (88.3%) used more than three criteria for MSR including CBC results and 5-part WBC differential count results and 95 (85.6%) had criteria of flags triggering MSR. For MSR criteria with numeric values, the 10th, 50th, and 90th percentiles of upper and lower threshold values were obtained. The basic guideline for MSR was made.

Conclusions: We proposed a basic guideline for MSR. This guideline would be helpful to hematology laboratories for their daily operation and providing more rapid and accurate CBC and WBC differential results.