Corrections: Distribution of hepatitis B virus genotypes in Korea / 대한간학회지

No abstract available.

Distribution of hepatitis B virus genotypes in Korea / 대한간학회지

BACKGROUND/AIMS: Considering the incidence of prevailing hepatitis B virus (HBV) genotypes in neighboring nations, the predominance of genotype C in Korea is exceptional and needs to be confirmed by nationwide investigation. METHODS: A total of 510 HBsAg (+) or HBeAg (+) serum samples was collected from subjects in several cities and harbors throughout the Korean peninsula for genotype (A-G)-specific multiplex PCR analysis. Another 40 serum samples from chronic HBV carriers from Iksan city were selected for sequencing of the entire HBV genome. Phylogenetic analysis was performed with 22 whole genomic sequences of Korean HBV strains enrolled in GenBank. RESULTS: An amplicon was found in 377 specimens and genotype C occupied 98.1% (370 cases); none of the other genotypes were found. A mixed pattern of genotypes B and C was seen in seven specimens (1.9%), of which five were tested using PCR targeting the X fragment; no genotype B bands were found. With the exception of 1 case, which was subgenotype A2, whole sequences of Korean HBV strains (n=62) belonged to subgenotype C2. CONCLUSIONS: The prevailing HBV genotype in Korea is C2; the other genotypes occur only rarely. Future studies should include confirmation of the detection of genotypes other than C.

Evaluation of a Quantitative RealArt HBV LC PCR Assay for Hepatitis B Virus by Real-time PCR / 대한임상미생물학회지

BACKGROUND: As oral antiviral treatment for chronic hepatitis B increases, quantitation of viral load has become an essential test for HBV management, and assays using real-time PCR principles have been introduced recently. METHODS: We analysed the analytical performance (precision, linear range, and sensitivity) of RealArt HBV LC PCR Reagents (Artus GmbH, Hamburg, Germany), its correlation with COBAS AMPLICOR HBV MONITOR Test (Roche Diagnostics, Mannheim, Germany), and distribution of viral load in the patients' sera according to antiviral treatment and presence of HBeAg. RESULTS: Variation of intra-assay and inter-assay were 39.7% and 78.1% at 10(3) copies/mL of viral load, 18.1% and 73.2% at 10(4) copies/mL, and below 10% and below 15% between 10(5)~10(9) copies/mL. Linear range was with 5x10(3)~2.3x10(9) copies/mL. Correlation with Amplicor was y=0.9211x+0.607 (R(2)=0.7801, P<0.001) and the median concentration in the patients without any treatment was 6.3x10(7) copies/mL (HBeAg positive) and 3.1x10(3) copies/mL (HBeAg negative). CONCLUSION: RealArt reagent using principles of real-time PCR, would be an appropriate laboratory method for HBV management.

Appropriate Number of Sputum Specimens and Optimal Use of Mycobacterial Tests for the Diagnosis of Pulmonary Tuberculosis / 대한임상미생물학회지

BACKGROUND: We evaluated an appropriate number of sputum specimens and usage of mycoba c-terial tests (AFB stain, culture and direct PCR) for the diagnosis of pulmonary tuberculosis. METHODS: We reviewed retrospectively the results of mycobacterial tests (AFB stain 8,216, culture 4,728, direct PCR 345) for 8,216 sputum specimens from 1,520 patients with pulmonary tuberculosis from September, 2000 to March, 2004. RESULTS: The cumulative detection rates of acid-fast bacilli by AFB stain was 77.6% in the first specimen, 91.9% in the second, 98.0% in the third and 100% in any specimen submitted later than the third. The respective figures were 78.6%, 93.1%, 97.1% and 100% for AFB culture, and 83.6%, 95.9%, 98.6% and 100% for direct PCR. Three consecutive sputum specimens were submitted only in 14.0% for AFB stain and 13.4% for culture. The quality of sputum graded by Gram stain was poor in 72.2% for AFB stain, 73.1% for culture and 80.8% for direct PCR. The quality of sputum was found to affect significantly the positive rates of AFB stain (P = 0.000) and culture (P = 0.038), but not the rate of direct PCR (P = 0.607). CONCLUSION: Three sequential sputum specimens are needed to diagnose pulmonary tuberculosis effectively and the importance of sputum quality and appropriate use of mycobacterial tests should be emphasized.

Effects on Detection Rate and Turnaround Time by Changes in the Mycobacterial Culture and Identification Methods / 대한진단검사의학회지

BACKGROUND: We evaluated the effects of changes in laboratory practices on the detection rates and turnaround time in a clinical mycobacteriology laboratory. METHODS: A total of 27,339 specimens from 9,947 patients were tested during the period from September 2000 to March 2004, which could be divided into the following four periods according the culture and identification methods used: Period I, use of 2% Ogawa medium for culture and niacin for identification; period II, introduction of PCR for identification; period III, introduction of BacT/Alert system (bioMerieux, Durham, USA) for culturing sterile body fluids; period IV, use of Bact/Alert system for CSF and the second of repeated sputum specimens from the same patients. During these periods, two technicians (one for the first half and the other for the second half periods) did all mycobacterial tests except PCR. RESULTS: Mean detection rates were 8.0% by auramine stain, 7.9% by nested PCR, and 6.6% by culture. The detection rates by culture for sputum specimens varied 11.4%, 7.7%, 8.1% and 5.9% in each of the four periods; for body fluids, the detection rate of 4.3% during the period III was the highest. The proportion of stain results reported within 24 hours and the identification of culture isolates within 21 days changed from 80.9% to 72.4% and from 2.3% to 30.8%, respectively. With an introduction of PCR for identification in the period II the time required for the identification of cultures decreased dramatically from 26.5 days to 4.8 days. The TAT of a direct detection by nested PCR changed from 7.2 days to 5.1 days. CONCLUSIONS: New tests should be introduced in the clinical mycobacteriology laboratory. But the cost and workload of the tests should be taken into consideration to make the laboratory service more efficient.

Detection Rate of Allergen-Specific IgE by Multiple Antigen Simultaneous Test-Immunoblot Assay / 대한진단검사의학회지

BACKGROUND: A new multiple antigen simultaneous test (MAST) has recently been introduced that is simple, rapid, and economical, and requires a small amount of serum samples. We evaluated the MAST-immunoblot assay (AllergyScreen; R-Biopharm, Darmstadt, Germany) for its specific antigen detection rate, and the results were interpreted based on the cut-off levels of classes 0.5, 1.0, 2.0, and 3.0 and correlated with clinical information. METHODS: A total of 166 allergic patients were tested by AllergyScreen (AS) for 10 specific allergens and the results were compared with skin prick test (SPT, cut-off=2+) or specific IgE (cut-off=class 1) on Uni-CAP system (uCAP). Thirty-five healthy subjects considered as truly negative for all allergens were also tested by AS to get the best cut-off level using the receiver operating characteristics (ROC) curve analysis and to evaluate its clinical specificity. RESULTS: The sensitivities (AS/uCAP, 73-31% and AS/SPT, 27-63%), specificities (AS/uCAP, 89-100% and AS/SP, 81-97%), and agreements (AS/uCAP 71-82% and AS/SPT 77-80%) varied with the cut-offm levels used and allergens tested. The overall linear regression equation was Y=0.69X+0.10, R=0.81 (P0.5 class and efficiency was 82% (AS/uCAP) and 75% (AS/ SPT). However, 25 (71%) of the healthy subjects showed positive reactions (0.6-4.0 class) to at least one allergen. CONCLUSIONS: Using an appropriate cut-off, AS/uCAP showed the sensitivity, specificity, and agreement at an acceptable level, and similar or better results compared with previous reports on MAST/ SPT. The AS can be an efficient way of testing for specific allergens in the clinical laboratory or at the physician's office. But, in view of the positive reactions in the healthy subjects, a class of less than 4.0 on AS must be integrated with clinical information for an appropriate data interpretation.

Total Hepatitis C Virus Core Antigen Assay for Hepatitis C Virus Viremia and Comparison with RNA Assay / 대한진단검사의학회지

BACKGROUND: Recently, trak - C (Total HCV core antigen test; Ortho Clinical Diagnostics, Raritan, NJ, USA) that is based on the enzyme- linked immnunosorbent assay was developed. So, we tried to compare the performance of the Hepatitis C virus (HCV) total core antigen test (HCVAg) with the qualitative in-house reverse transcription (RT) - polymerase chain reaction (PCR) assay and HCV- RNA Quantitation assay (HCVQn, Amplicor HCV monitor test version 2.0; Roche Diagnostics System, Basel, Switzerland). METHODS: Dilution test was performed to evaluate the reproducibility and detection sensitivity of the methods. 87 sera of 70 Hepatitis C virus antibody (Ab) positive patients were tested to evaluate the diagnostic sensitivity and concordance of three methods, and to discover the quantity relationship of HCVAg and HCVQn. We also contained the results of 100 negative control specimens by HCV Ag to evaluate the specificity. RESULTS: In the dilution test, the coefficient variation values of HCVAg were 41%, 29%, and 21% and HCVQn were 17%, 11%, and 150% of diluted sera respectively at 50, 5(-1), and 5(-2) dilution factor for four days running. The qualitative in - house HCV RT-PCR (5(-5) dilution factor) and HCVQn (5(-5) dilution factor) were more sensitive than the HCVAg (5(-2) dilution factor). And the diagnostic sensitivity was high in order on the qualitative in - house HCV RT-PCR; 97%, HCVQn; 91%, and HCVAg; 85%. The concordance rate between the three methods was 83.9%. The quantity of HCVAg and HCVQn showed a significant correlation (R =0.8, P<0.0001). CONCLUSIONS: HCVAg showed reliable results and a significant correlation with the quantitative RNA level. HCVQn showed a quantitative result but less sensitivity than the qualitative in-house HCV RT-PCR. Even though the HCVAg has slightly lower sensitivity than the two methods, methodologically, it is the most cost-effective, is simple, and gives high throughput. So it should be a simple economic surrogate marker for viremia detection and viral load monitoring.

A Case of Vibrio cholerae non-O1/non-O139 Gastroenteritis / 대한임상미생물학회지

Vibrio cholerae is an autochthonous inhabitant of estuarine and seawater environment and is a facultative pathogen for humans. V. cholerae non-O1/non-O139 strains are associated with gastroenteritis, septicemia and/or extraintestinal infections. But the reported cases of gastroenteritis by non-O1/non-O139 serotype, are rare in Korea. The authors isolated V. cholerae non-O1/non- O139 strain from a stool of a 67 year-old-woman who had suffered from diabetes, hypertension and Alzheimer disease and analyzed presence of toxin genes by multiplex PCR method.

Comparison of Isolation rate of the Pathogenic Microorganisms According to Stool Culture Methods / 대한임상미생물학회지

BACKGROUND: In developed countries, food-born diseases have decreased and hospital laboratory have taken more simple method rather than complex enrichment-selective methods. But detection rate of pathogenic bacteria in stool culture was not so high. METHODS: We mixed 4 pathogenic bacteria (S. typhi, S. flexneri, V. cholerae and Y. enterocolitica) with 3 stool specimens from healthy persons (for Y. enterocolitica, 5 specimens) and innoculated directly or after enrichment (105 bacteria/plate). After proper incubation, we counted suspected colonies and calculated true positive rate after identification of each colonies. RESULTS: For S. typhi, in the case of direct innoculation on the MacConkey, XLD and SS agar, positive rate of selected colonies were below 36.6%. After enrichment in SF broth for 8 hours, the rate were 80.0%, 83.0% and 70.0% respectively. For S. flexneri, the rates were 86.7%, 100%, 93.3% in direct innoculation, and were highest after enrichment in GN broth for two hours (93.3% in MacConkey and 100.0% in both XLD and SS agar). For V. cholerae, inspite of screening by catalase and oxidase tests, positive rate of selected colonies were 0% (0/7 colonies) in direct innoculation on the MacConkey. After enrichment in APW about 1 day and on TCBS agar, the rate were 100%. For Y. enterocolitica, after incubation at room temperature for 2 days, most selected colonies were Y. enterocolitica on CIN media. CONCLUSION: For more efficient detection of pathogenic bacteria in stool culture, combination of direct innoculation on MacConkey agar and on one or two selective media after proper enrichment process, should be considered.

Comparison of Stain Methods with PCR and Culture for the Detection of Mycobacterium Tuberculosis in the Sputum / 대한임상병리학회지

BACKGROUND: Currently, many laboratories have selected several different methods for the detection of M. tuberculosis in the sputum. To select efficient method for clinical laboratories among the various methods, we compared the results of several methods. METHODS: Total 72 sputums were examined by the six combinations of stain methods. The samples were constructed as follows on the result of direct smear ZN stain; negatives (26), traces (3), 1+(9), 2+(12), 3+(12) and 4+(10). The true positives were determined after close evaluation of the clinical, radiological and other laboratory findings. RESULTS: The sensitivities and specificities of each methods were as follows; direct smear ZN stain were 83.6% and 100%, direct smear Auramine stain were 90.9% and 100%, centrifugation ZN stain were 94.6% and 100%, centrifugation Auramine stain were 98.2% and 94.1%, cytocentrifugation ZN stain were 96.4% and 100%, cytocentrifugation Auramine stain were 100% and 64.7%, nested PCR were 80% and 94.1% and culture were 67.3% and 100% respectively. CONCLUSIONS: Concentration method by centrifugation is suitable for routine laboratory if enough centrifugal force were engaged. Auramine stain is more suitable staining method than ZN stain in direct smear but not in concentrated smear because it has the potency of false positivity. The PCR assay is thought to be not only a fast, sensitive method but also a specific method for the direct detection of M. tuberculosis in the sputum. The culture method using Ogawa media is specific but not sensitive.

Use of Korean Letter "Hangul" and Special Characters in a Chromosome Image Analyzer, QuipsTM 3.0 Operable Only in Mac OS 8.0 / 대한임상병리학회지

BACKGROUND: Nowadays, many laboratories use computer and karyotyping software in chromosome analysis on the development of computer and digital imaging technology. And some of these softwares, such as QuipsTM (Vysis, USA; QuipsTM), are those operated in Macintosh operating system (Mac OS) because it had been considered superior to IBM PC in imaging works. However, Korean users have had difficulties in use of Korean letter "Hangul" because many of these hadn't been operated in Korean Macintosh System (KH series). METHODS: We used a karyotyping software of Macintosh QuipsTM 3.0, which is inconvenient to manage patient informations such as name, department, doctor's name and etc. In order to use "Hangul" in QuipsTM 3.0, we incorporated some files (WorldScript II and ScriptSwitcher 8 along with other files such as fonts, "Imrykki" and etc.) from KH 8.0 (Elex, Co; Korean Macintosh system) to Mac OS 8.0 (Apple, Inc; English Macintosh system). RESULTS: After modifing the operating system of Mac OS 8.0, we could use not only "Hangul", but also Chinese letter "Hanja" and special characters (e.g., "alpha", "-->", and etc). CONCLUSIONS: In using "Hangul" in data management and reporting, we became to be familiar with QuipsTM and had good responses from clinicians.