NDM-5 and OXA-48 Co-producing Uropathogenic Escherichia coli Isolate: First Case in Korea

No abstract available.

First Case of Pasteurella multocida Pneumonic Bacteremia in Korea

No abstract available.

Globicatella sanguinis Bacteremia in a Korean Patient / 대한임상미생물학회지

Globicatella sanguinis is an unusual pathogen causing bacteremia, meningitis, and urinary tract infection, and can be misidentified as Streptococcus pneumoniae or viridans streptococci due to its colonial morphology. A 76-year-old female patient with hypertension and degenerative arthritis was admitted to the hospital complaining of knee joint pain. Blood culture revealed the presence of Gram-positive cocci, and the isolated organism was equally identified as S. pneumoniae using the MicroScan identification system (Beckman Coulter, USA) and Vitek 2 identification system (bioMérieux, USA). However, the isolate showed optochin resistance based on the optochin disk susceptibility test. The organism was finally confirmed to be G. sanguinis based on 16S rRNA sequencing and hydrogen sulfide production testing. Accurate identification of G. sanguinis isolated from aseptic body fluids including blood is important for appropriate antibiotic selection based on accurate application of interpretative criteria of antimicrobial susceptibility test.

Vancomycin Resistance due to vanA Gene Expression in an Aerococcus viridans Isolate: First Case in Korea

No abstract available.

A Case of Streptococcus gallolyticus subsp. gallolyticus Bacteremia in Liver Cirrhosis

Streptococcus bovis bacteremia in humans has been traditionally associated with infective endocarditis, colorectal cancer, and liver cirrhosis. S. bovis strains were previously categorized by biotype, but since the 2000s, they have been reclassified by DNA homology. We report a case of S. gallolyticus subsp. gallolyticus bacteremia, identified by 16S rRNA sequencing, in a patient diagnosed with liver cirrhosis. A 61-yr-old man with a history of liver cirrhosis presented to the hospital with a complaint of fever. Blood culture revealed the presence of gram-positive cocci, and the isolated organism was identified as S. bovis by the MicroScan identification kit (Beckman Coulter, USA), but as Enterococcus saccharolyticus by the Vitek 2 identification kit (bioMérieux, USA). The organism was finally confirmed as S. gallolyticus subsp. gallolyticus by 16S rRNA sequencing.

Algorithm for Differential Diagnosis of in Vitro and in Vivo Hemolysis in Anticoagulated Blood Specimens

BACKGROUND: Hemolytic specimens contain components that interfere with clinical laboratory results. We evaluated previously published hemolysis indices (HI) and developed an algorithm for differentiating between mechanical hemolysis and immune-mediated hemolysis based on complete blood count (CBC). METHODS: Sixty-three residual EDTA (ethylenediamine tetraacetic acid)-anticoagulated blood specimens were obtained during regular health check-ups, and each specimen was divided into 3 aliquots (A control, B, and C group). Aliquots B and C were mechanically hemolysed by 2 and 5 aspirations, respectively, using a 25-gauge needle before testing; aliquot A was analysed immediately without hemolysis. Additionally, we collected 36 specimens from patients suspected of having immune-mediated hemolysis after thorough reviewing their various laboratory results including direct antiglobulin test. We compared CBC parameters between the groups (A, B, C, D [B+C], and E [immune-mediated hemolysis group]). RESULTS: Our HI scoring system using the sum of red blood cell ghosts, measured hemoglobin-calculated hemoglobin, mean corpuscular hemoglobin concentration-corpuscular hemoglobin concentration mean, and mean platelet volume rather than mean corpuscular hemoglobin, effectively identified mechanical hemolysis; the results were similar to those of previous studies. Furthermore, the HI score using the sum of mean corpuscular volume, red cell distribution width, hemoglobin distribution width, polymorphonuclear %, and neutrophil % differentiated mechanical hemolysis from immune-mediated hemolysis (cut-off, 9; sensitivity, 91.7%; specificity, 92.9%; area under the receiver operating characteristic curve, 0.965 [95% confidence interval, 0.924–0.988]). CONCLUSIONS: The newly developed algorithm may provide effective screening for detecting hemolysis and differential diagnosis of mechanical hemolysis and immune-mediated hemolysis based on CBC results.

FIB-4 Score as a Useful Screening Test for Diagnosing Liver Fibrosis

BACKGROUND: Liver biopsy is the gold standard for assessing liver fibrosis; however, it has a relatively high risk of resulting in complications. Although a non-invasive method (i.e., transient elastography—fibroscan) was introduced, it is expensive and is dependent on the patient's status. Thus, the FIB-4 score, a non-invasive formula, has been used to predict the degree of liver fibrosis. The aim of this study was to evaluate the usefulness of the FIB-4 score in predicting stages of liver fibrosis. METHODS: We analysed the age, diagnosis, and liver stiffness of 282 patients by measuring the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) as well as their platelet count. Liver elasticity was evaluated by two classification criteria (Foucher et al. and Mueller et al.). The FIB-4 score was calculated using the formula: age×AST/(platelet count×ALT½). The cut-off value of the FIB-4 score was determined according to the area under the relative operating characteristic curve (AUC) based on liver elasticity. RESULTS: The FIB-4 cut-off values, as determined using two different criteria, have the highest AUC, thereby indicating a robust ability to distinguish between healthy liver tissue and the presence of any liver fibrosis. The FIB-4 score with a cut-off value of 2.07, as determined by Mueller et al., had the highest AUC (0.837) and odds ratio (2.741) with a sensitivity of 78.3% and a specificity of 76.5%. CONCLUSIONS: An FIB-4 score of 2.07 is a cut-off value that is useful in detecting fibrotic progression in chronic liver disease in our laboratory. Each laboratory should determine an appropriate FIB-4 cut-off value that is relative to the particular characteristics of their patient population.

Detection of Bacterial and Viral Pathogens in Stool Specimens Using Multiplex PCR

BACKGROUND: The rapid and accurate detection of diarrheal pathogens is essential to prevent the spread of diarrheal diseases. Recently, a multiplex PCR assay was developed to simultaneously detect various bacterial and viral diarrheal pathogens. In this study, we investigated the frequency of detection of various potential pathogens causing diarrhea by using multiplex PCR and compared the results to the results of stool culture tests for bacteria and enzyme immunoassays (EIAs) for rotaviruses and Clostridium difficile toxin B (CDTB). METHODS: We retrospectively analysed the results for multiplex PCR, culture tests, and EIA obtained from stool specimens submitted to the laboratory from May 2013 to September 2014. Multiplex PCR was performed using the Seeplex diarrhea ACE detection kit (Seegene, Korea), which detects five viruses and eight bacteria. RESULTS: Among 890 stool specimens, 408 (45.8%) were found to be positive by PCR. The PCR positivity rate for bacteria and viruses was 31.1% (277/890) and 18.9% (161/890), respectively. The relative frequencies of microorganisms or toxins detected by PCR were, in decreasing order, CDTB 24.0%, Clostridium perfringens 20.6%, norovirus-GII 15.8%, rotavirus 11.3%, Campylobacter spp. 7.5%, enteric adenovirus 5.7%, and Salmonella spp. 5.1%. The concordance rate of the results obtained using the PCR and culture tests was 99.2% for Salmonella spp., 95.7% for Campylobacter spp., and. 79.8% for C. difficile . The concordance rates for rotaviruses and CDTB were 99.7% and 83.6%, respectively. CONCLUSIONS: The multiplex PCR method showed a high detection rate and is useful for the simultaneous detection of various diarrheal pathogens.

Scoring System for Detecting Spurious Hemolysis in Anticoagulated Blood Specimens

BACKGROUND: The identification of in vitro hemolysis (IVH) using a hematology analyzer is challenging because centrifugation of the specimens cannot be performed for cell counts. In the present study, we aimed to develop a scoring system to help identify the presence of hemolysis in anticoagulated blood specimens. METHODS: Thirty-seven potassium EDTA anticoagulated blood specimens were obtained, and each specimen was divided into 3 aliquots (A, B, and C). Aliquots B and C were mechanically hemolyzed by aspirating 2 and 5 times, respectively, using a 27-gauge needle and then tested; aliquot A was analyzed immediately without any hemolysis. After the cells were counted, aliquots B and C were centrifuged and the supernatants were tested for the hemolytic index and lactate dehydrogenase levels. RESULTS: The 4 hematologic parameters were selected and scored from 0 to 3 as follows: or =38.5 for mean cell hemoglobin concentration (MCHC, g/dL); or =0.04 for red blood cell ghosts (10(12)/L); or =1.31 for difference value (g/dL) of measured hemoglobin and calculated hemoglobin; and or =3.35 for difference value (g/dL) of MCHC and cell hemoglobin concentration mean. The hemolysis score was calculated by adding all the scores from the 4 parameters. At the cutoff hemolysis score of 3, the IVH of aliquots B and C were detected as 64.9% and 91.9%, respectively. CONCLUSIONS: The scoring system might provide effective screening for detecting spurious IVH.

Microbiological Characteristics according to Transudative and Exudative Effusion in Pleural Fluid Culture / 대한임상미생물학회지

A total of 1,132 pleural fluid culture results obtained from October 2012 to July 2014 were analyzed to elucidate the microbiological characteristics according to transudative and exudative pleural fluid. The pleural fluid cultures were performed using aerobic and anaerobic blood culture bottles. The blood and pleural fluid for total protein, lactate dehydrogenase, and glucose measurement were submitted to laboratory at the same time with pleural fluid cultures. The rates for culture positivity, anaerobes isolation, and polymicrobials between transudative and exudative pleural fluid were 5.2% vs. 10.4%, 14.8% vs. 7.8%, and 14.8% vs. 10.9%.

Factors Influencing the False Positive Signals of Continuous Monitoring Blood Culture System / 대한임상미생물학회지

BACKGROUND: The false positive signals of a continuous monitoring blood culture system (CMBCS) increase the reporting time and laboratory cost. This study aimed to determine the highly relevant variables that discriminate false positive signals from true positive signals in a CMBCS. METHODS: Among 184,363 blood culture sets (aerobic and anaerobic), the signal-positive samples according to a BACTEC FX system (Plus Aerobic/F, BDA; Plus Anaerobic/F, BDN) and BacT/Alert 3D system (Standard Aerobic, BSA; Standard Anaerobic, BSN) between April 2010 and November 2013 were classified into two groups: false positive or true positive signals. The data of 15 parameters between the two groups were then statistically compared. RESULTS: Among total blood cultures, the positive rates of CMBCS signals according to BDA, BDN, BSA, and BSN were 4.9%, 2.8%, 3.8%, and 3.2%, respectively. The false positive rates of CMBCS signals according to BDA, BDN, BSA, and BSN were 0.6%, 0.1%, 0.1%, and 0.1%, respectively. The blood volume, detection time, time interval between admission and test, C-reactive protein concentration, leukocyte count, delta neutrophil index, and mean peroxidase index showed statistically significant differences between the two groups. CONCLUSION: There were no variables with diagnostic sensitivity and specificity for discriminating the two groups. Therefore, analysis of bacterial growth curves produced by CMBCS is needed for early and effective detection of false positive signals.

Development of an Integrated Reporting System for Verifying Hemolysis, Icterus, and Lipemia in Clinical Chemistry Results

BACKGROUND: Hemolysis, icterus, and lipemia (HIL) cause preanalytical interference and vary unpredictably with different analytical equipments and measurement methods. We developed an integrated reporting system for verifying HIL status in order to identify the extent of interference by HIL on clinical chemistry results. METHODS: HIL interference data from 30 chemical analytes were provided by the manufacturers and were used to generate a table of clinically relevant interference values that indicated the extent of bias at specific index values (alert index values). The HIL results generated by the Vista 1500 system (Siemens Healthcare Diagnostics, USA), Advia 2400 system (Siemens Healthcare Diagnostics), and Modular DPE system (Roche Diagnostics, Switzerland) were analyzed and displayed on physicians' personal computers. RESULTS: Analytes 11 and 29 among the 30 chemical analytes were affected by interference due to hemolysis, when measured using the Vista and Modular systems, respectively. The hemolysis alert indices for the Vista and Modular systems were 0.1-25.8% and 0.1-64.7%, respectively. The alert indices for icterus and lipemia were <1.4% and 0.7% in the Vista system and 0.7% and 1.0% in the Modular system, respectively. CONCLUSIONS: The HIL alert index values for chemical analytes varied depending on the chemistry analyzer. This integrated HIL reporting system provides an effective screening tool for verifying specimen quality with regard to HIL and simplifies the laboratory workflow.

A Complex Chromosomal Rearrangement Involving 46,XX,t(1;7;16)(p32.1;q22;q13) in a Female with Recurrent Miscarriages After in vitro Fertilization

Balanced complex chromosomal rearrangements involving three or more chromosomes are often detected in phenotypically normal female patients with an adverse obstetric history. Here, we report a 32-yr-old phenotypically normal female with a history of multiple in vitro fertilization (IVF) failures and carrying a balanced complex chromosomal rearrangement involving chromosomes 1, 7, and 16. Cytogenetic analysis revealed the following complex karyotype: 46,XX,t(1;7;16)(p32.1;q22;q13). The patient achieved a twin pregnancy after IVF, although no heartbeat was detected during the sixth gestational week checkup. Tissues from intrauterine fetal demise were tested for chromosomal analysis and revealed 46,XX,t(1;7;16)(p32.1;q22;q13)mat and 46,XY,der(1)t(1;16)(p32.1;q13),der(7)t(1;7) (p32.1;q22)mat. This case illustrates the importance of chromosomal analysis in infertile females or infertile females with multiple IVF failures. Therefore, it would be beneficial for patients visiting infertility clinics to undergo cytogenetic screening for complex chromosome rearrangements before further counseling and prenatal investigations.

Two Cases of Mycoplasma pneumoniae Pneumonia with A2063G Mutation in the 23S rRNA Gene in Siblings

We describe 2 cases of pneumonia caused by the same macrolide-resistant Mycoplasma pneumoniae in siblings. M. pneumoniae was identified using real-time PCR. Direct sequence analysis of the 23S rRNA gene revealed a point mutation in V domain (A2063G) of the 23S rRNA gene.

Artifactual Hyperbilirubinemia due to Paraprotein Interference in a Case of Multiple Myeloma / 임상검사와정도관리

When analyzing samples containing paraproteins, various interference effects are encountered in the clinical laboratory. Precipitation of paraproteins mostly interferes with the assays that use photometric detection. Herein, we present a case of a patient with multiple myeloma who had paraproteins and spuriously elevated total bilirubin levels (31.1 mg/dL), which were measured by using Roche total bilirubin assay on the Modular DPE (Roche Diagnostics, Switzerland) chemical analyzer. The total bilirubin concentration reduced from 31.1 mg/dL to 1.5 mg/dL, when tested after three fold dilution of the sample on Modular DPE chemical analyzer.

Macrolide Resistance of Mycoplasma pneumoniae and Its Detection Rate by Real-Time PCR in Primary and Tertiary Care Hospitals

BACKGROUND: This study aimed to evaluate the prevalence of Mycoplasma pneumoniae in primary and tertiary care hospitals and its macrolide resistance rate. METHODS: Nasopharyngeal swabs were collected from 195 pediatric patients in primary and tertiary care hospitals from October to November 2010. The AccuPower MP real-time PCR kit (Bioneer, Korea) was used for the detection of M. pneumoniae. Direct amplicon sequencing was performed to detect point mutations conferring resistance to macrolides in the 23S rRNA gene. RESULTS: Among the 195 specimens, 17 (8.7%) were M. pneumoniae positive, and 3 of the strains (17.6%) obtained from these 17 specimens displayed the A2063G mutation in 23S rRNA. Three macrolide-resistant M. pneumoniae isolates were isolated from patients hospitalized at the primary care hospital. The positive rates of M. pneumoniae for the primary and tertiary care hospitals were 12.1% (15/124) and 2.8% (2/71), respectively (P=0.033). CONCLUSIONS: The positive rate of M. pneumoniae in the primary care hospital was higher than that in the tertiary care hospital. Simultaneous detection of M. pneumoniae and macrolide-resistant mutation genes in the 23S rRNA by real-time PCR is needed for rapid diagnosis and therapy of M. pneumoniae infections.

Evaluation of the Dimension Vista 1500 Chemical Autoanalyzer / 임상검사와정도관리

BACKGROUND: Laboratory tasks involve the analysis of a large number of specimens and generation of accurate results in a short period of time. The Dimension Vista 1500 (Siemens, Germany), an automated chemistry analyzer, has been introduced in our hospital to improve the efficiency of laboratory analysis. In order to assess the performance and usability of the analyzer, we evaluated its analytical performance and clinical usefulness, and compared these factors to those of the formerly used Modular DP analyzer (Roche Diagnostics, USA), Vitros 5.1 FS analyzer (Ortho Clinical Diagnostics, USA), and ADVIA Centaur analyzer (Siemens). METHODS: The accuracy, linearity, recovery factor, and sample carryover of the Dimension Vista 1500 analyzer were determined for 19 routine, immunochemistry, and cardiac marker tests (blood urea nitrogen, creatinine, glucose, calcium, phosphorus, total protein, albumin, AST, ALT, gamma-glutamyl transferase, creatine kinase [CK], lactate dehydrogenase, alkaline phosphatase, total bilirubin, high-sensitivity C-reactive protein, CK-MB, cardiac troponin I [cTnI], myoglobin, B-type natriuretic peptide), and values obtained for Modular DP, ADVIA centaur, and Vitros 5.1 FS analyzers were used to make comparisons. RESULTS: The coefficient of variation (CV) showed excellent values of or =0.996 with excellent linearity between 0.99 and 1.02. In addition, the recovery factor values of the tests were 88-107%, and percentage sample carryover values of the tests were or =0.96, except for cTnI (0.935), and showed good correlation (P<0.001). CONCLUSIONS: The Dimension Vista 1500 analyzer showed good analytical performance (linearity, precision, and accuracy) for 15 routine chemistry and 4 cardiac marker tests. Furthermore, results from the tests performed on the Dimension Vista 1500 analyzer correlated well with those obtained from similar tests performed on the Modular DP, ADVIA centaur, and Vitros 5.1 FS analyzers. Therefore, the Dimension Vista 1500 analyzer is appropriate for a tertiary care hospital where large volumes of tests have to be processed within a short period of time.

Comparison of Six Clinical Chemistry Test Results According to the Treatment of EDTA Anticoagulant in Body Fluid Specimens / 임상검사와정도관리

BACKGROUND: Specimen requirements such as type of anticoagulant and number of tube for body fluid analysis vary with specimen type and requested laboratory tests. We compared the results of six clinical chemistry tests between EDTA anticoagulated and anticoagulant-free body fluids. METHODS: A total of 191 body fluids (45 pleural, 28 bronchoalveolar lavage, 35 peritoneal, 45 peritosol, and 38 synovial fluids) were aliquoted into EDTA tubes and anticoagulant-free tubes, and were simultaneously tested for total protein, albumin, glucose, lactate dehydrogenase, adenosine deaminase, and amylase. RESULTS: The coefficient of determination (R2) for all six clinical chemistry test results between EDTA anticoagulated and anticoagulant-free body fluids are more than 0.95 with the exception of glucose in bronchoalveolar lavage fluid (R2= 0.78). CONCLUSIONS: EDTA anticoagulated specimen could be used for testing routinely requested clinical chemistry tests in body fluid analysis, that only one tube of specimen is necessary to perform cell count, differential count, and clinical chemistry tests.

The Value of Serum Procalcitonin Level for Differentiation between Contaminants and Pathogens in Bacteremia / 대한임상미생물학회지

BACKGROUND: Bacteremia is a life-threatening infection, and prognosis is highly dependent on early recognition and treatment with appropriate antimicrobial agents. We investigated the diagnostic performance of serum procalcitonin (PCT) for differentiation between contaminants and true pathogens in blood cultures. METHODS: Serum PCT, C-reactive protein (CRP) and blood culture were performed for 473 patients between February 2008 and October 2008. We retrospectively reviewed the patients' clinical characteristics and laboratory results based on medical records. RESULTS: The mean concentration of PCT was significantly different between the two negative and positive blood culture groups (6.45 ng/mL vs 28.77 ng/mL, P<0.001). Procalcitonin levels were found to be markedly higher in those with Gram-negative bacilli (mean+/-SD; 59.58+/-67.00 ng/mL) bacteremia than in those with Gram-positive cocci (mean+/-SD; 17.75+/-42.88 ng/mL) bacteremia (P<0.001). The areas under the receiver operating characteristic curves (95% confidence interval) for PCT and CRP were 0.880 (0.820~0.940) and 0.637 (0.538~0.736), respectively. The use of a PCT level of 2 ng/mL as a cutoff value yielded an 83.6% positive predictive value and a 77.4% negative predictive value for the detection of bacteremia pathogens. CONCLUSION: Serum PCT is a helpful diagnostic marker for rapidly and accurately distinguishing between contaminants and pathogens in blood cultures.

Evaluation of the Diagnostic Performance of the AdvanSure TB/NTM Real-Time PCR Kit for Detection of Mycobacteria / 대한임상미생물학회지

BACKGROUND: The AdvanSure TB/NTM real-time PCR kit (AdvanSure) was newly developed in Korea to detect Mycobacterium tuberculosis and nontuberculous mycobacteria (NTM) utilizing a specific primer and TaqMan probe targeting the IS6110 and rpoB genes which are unique to these species. The purpose of the present study was to evaluate the clinical utility of AdvanSure by comparing the results of acid-fast staining, mycobacteria culture, COBAS Amplicor MTB PCR (Amplicor), and AdvanSure. METHODS: A total of 182 specimens (105 respiratory and 77 nonrespiratory specimens) were obtained from 165 patients, and acid fast bacilli (AFB) staining, mycobacteria culture, and Amplicor were performed on all specimens. AdvanSure was also performed on the above specimens using the SLAN real-time PCR detection system. The sensitivity and specificity of AdvanSure were analyzed using AFB staining and culture. RESULTS: Of the 182 specimens, M. tuberculosis was detected in 43 specimens and NTM was detected in 12 specimens according to PCR and/or culture. The sensitivity and specificity of the AdvanSure based on AFB culture were 97.3% (36/37) and 95.5% (127/133) in M. tuberculosis and 75.0% (9/12) and 100% (0/133) in NTM, respectively. CONCLUSION: AdvanSure could be useful for detecting M. tuberculosis and NTM in the clinical laboratory with high sensitivity and specificity.