Difference of the Results of Two Visits in Down Syndrome Screening Test / 임상검사와정도관리

INTRODUCTION: Estimation of the risk of Down syndrome pregnancy by the triple marker test is performed on women once at anytime during the 15-21 weeks of gestational age. The triple marker test is based on the distribution of the alpha-fetoprotein (AFP), chorionic gonadotropin (CG) and unconjugated estriol (uE3) of the different pregnancy. In spite of the logical excellencies, various factors can affect the result of the test in practical field. We compared differences of the risk of Down syndrome pregnancy based on the specimen obtained from two visits during the 15-21 weeks of gestational age. METHOD: We measured the AFP, CG and uE3 with Access (Beckman Coulter, USA) from the sera of 104 pregnant women who visited two times about 2 weeks of interval during 15-21 weeks of gestational age. We calculated log (MoM) of AFP, CG and uE3 of each marker between two visits, and compared differences of each biochemical marker and difference of risk of Down syndrome pregnancy between two visits. RESULT: Mean+/-SD of log (MoM) of AFP, CG, uE3 of the 1st visit were 0.019+/-0.156, -0.016+/-0.224, 0.002+/-0.138, respectively, and those of AFP, CG, uE3 of the 2nd visit were 0.010+/-0.140, -0.076+/-0.205, 0.057+/-0.138, respectively. CG and uE3 showed statistically significant difference (P<0.001, P<0.001, respectively) but AFP did not (P=0.328). Risk of Down syndrome pregnancy of the 1st visit was 8.017x10(-4)+/-1.6241x10(-3), and that of the 2nd visit was 5.667x10(-4)+/-1.6241x10(-3), with no significant difference statistically (P=0.094). CONCLUSION: The risk of Down syndrome based on the sera of woman who visited two times about 2 weeks of interval between 15-21 weeks of gestational age did not show significant difference. It is resonable that triple marker test is performed on women once at anytime during the 15-21 weeks of gestational age in practical base.

A Method for Measuring Uric Acid Accurately in Refrigerated Urine Specimens / 대한진단검사의학회지

BACKGROUND: There have been many reports about the decrease in uric acid concentration in refrigerated urine specimens as compared to fresh urine. In an effort to correct this problem, pre-treatment steps such as the pre-alkalinization of sample tubes or the pre-dilution of urine were recommended before the refrigeration. The authors sought to find a way to correct the decreased measurement of uric acid concentrations in the refrigerated urine samples. METHODS: The uric acid concentrations of 53 fresh urine samples were measured and all were refrigerated. After 24 hours of refrigeration, the samples were measured for their uric acid concentrations (the refrigerated samples). All samples were then mixed well with 1 M NaOH 20 microL/mL (the refrigerated-alkalinized samples) and they were again measured for their uric acid concentrations. The differences of uric acid concentrations between the fresh urine samples and the refrigerated samples and also between the fresh urine samples and the refrigerated-alkalinized samples were noted. RESULTS: In a precipitated group of 14 urine samples, the compared results between the fresh urine and the refrigerated urine showed a statistically significant difference (P<0.05). However, there were no significant differences between the fresh urine and the refrigerated-alkalinized urine (P=0.49). In a non-precipitated group, there were no significant differences between the fresh urine and the refrigerated urine, or between the fresh urine and the refrigerated-alkalinized urine (P=0.47, P=0.18). CONCLUSIONS: For 24 hour refrigerated urine samples, the addition of 1 M NaOH 20 microL/mL to the urine samples after refrigeration was recommended for accurate measurement of uric acid concentration.

Is the Widal Test Still Useful? / 대한임상병리학회지

BACKGROUND: Widal test has been one of the most important diagnostic tests for typhoid and is still widely used. Widal test has been useful diagnostic tool for typhoid in endemic areas, while it has been largely abandoned in developed countries. Since 1990, occurrance of typhoid has been markedly decreased in Korea, we studied diagnostic usefulness and criteria of Widal test from 1990 to 1997. METHODS: Using rapid slide titration method (Stained Salmonella suspensions, Murex Biotech Ltd., Dartford, England), the Widal test was done in 116 nontyphoid salmonellosis patients, 75 patients with proven typhoid fever, and 173 cases of clinically suspected typhoid fever patients. Stastical analysis was done with discriminant analysis in culture proven salmonellosis. RESULTS: Fifty-four culture proven cases of Salmonella paratyphi (S. paratyphi) A and S. paratyphi B showed no significant cutoff value in O antibodies. Salmonella typhi (S. typhi) O titer at the 1:160 and above showed lower sensitivity (37.3% vs. 69.3%) and specificity (91.4% vs. 93.1%) compared to S. typhi H titer at the 1:320 and above in diagnosis of culture proven cases of typhoid. We applied D (0.01xH titer+0.001xO titer-1.635) score which result from discriminant analysis. Positive D score (> or =0.21) showed sensitivity of 72% and specificity of 92.2% in culture proven cases of typhoid. In clinically suspected patients, positive D score showed 39.3% of sensitivity. CONCLUSIONS: We concluded that the Widal test for O antibodies of S. paratyphi A and S. paratyphi B is not useful for diagnosis of paratyphoid fever. In the present study S. typhi H antibodies are more diagnostic than S. typhi O antibodies. We appled D score and positive D score showed increased sensitivity of Widal test than application of O antibody titer.

Evaluation of Frozen Antibiotics for Antimicrobial Susceptibility Testing of Helicobacter Pylori / 대한임상미생물학회지

BACKGROUND: Antimicrobial susceptibility testing of Helicobacter pylori(H. pylori) is not yet standardized but broth dilution or agar dilution are considered as standard methods. In the broth microdilution method, antibiotic dilutions of different concentrations are made each time, but most of it is discarded because only small volumes of dilutions are used. To improve this tedious procedure and the waste of reagents, antibiotic solutions in 96-well microplates were frozen at -20 degrees C to evaluate their useful storage periods. METHODS: Various concentrations of metronidazole(MTZ) and clarithromycin(CLR) solutions were divided into ten plates of 96-well microplates, sealed and stored at -20 degrees C. The broth microdilution susceptibility test was done with fresh and preserved antibiotic dilutions each month on 5 occasions for 4 strains(initial minimum inhibitory concentration(MIC) for MTZ 1, 4, 16, 64 ug/mL, initial MIC for CLR <0.125, <0.125, <0.125, 32 ug/mL) of H. pylori. The difference of MIC values of more than +/-2 log2 diluti on was considered significant. RESULTS: For both MTZ and CLR, the difference of MIC values of fresh and frozen antibiotic solutions was within +/-1 log2 dilution and the results of susceptibility test were the same for 7 months. CONCLUSIONS: Various concentrations of frozen MTZ and CLR solutions could be used for at least 7 months for the antimicrobial susceptibility testing of H. pylori.

Trends in Rotavirus Gastroenteritis in Korea from 1989 through 1998 and comparison of Slidex Rota-kit 2 and VIDAS Rotavirus / 대한임상미생물학회지

BACKGROUND: Rotavirus activity in Korea has been reported beginning in October, peak in November, continuing in winter and ending in spring. But the peak month and the incidence of rotavirus seems to be changed recently. So we investigated the trends of rotavirus activity for the last 10 years in Hanyang University Hospital (HUH). Also latex agglutination test was compared with automated enzyme-linked fluorescent immunoassay for the detection of rotavirus in stool specimens. METHODS: Stool specimens (3,636 from HUH, 1989-1998; 1,171 from Hanyang University Kuri hospital, HUKH, 1996-1998) from pediatric patients with acute diarrhea were tested for rotavirus,. Sixty specimens were tested by latex agglutination test (Sliders Rota-kit 2, bioMerieux Vitek, France) and enzyme-linked fluorescent immunoassay (VIDAS Rotavirus, bioMerieux Vitek, France) according to the instructions from the manufacturer. RESULTS: The annual incidence of rotavirus diarrhea from 1989 to 1998 was 47%, 32%, 33%, 25%, 26%, 24%, 24%, 17%, 17%, 14%, respectively. Positive rate of rotavirus was 25% for the 10year period in HUH, 20% for the recent 3 years in HUKH. Peak month was November (46%) in the first 5 year, but November incidence decreased to 17% in the last 5 year, and the peak moved to January, February, and March (34%, 35%, 33%, respectively). Epidemic period was from October to February during the first 5 year, but from December to April during the last 5 year period. The agreement rate of the two methods was 90% and VIDAS Rotavirus showed significantly higher sensitivity compared to Sliders Rota-kit 2. CONCLUSIONS: The incidence of rotavirus diarrhea decreased gradually for the last 10 years and the peak month of rotavirus activity was changed from November to January, February, and March. The VIDAS Rotavirus was more sensitive than the Sliders Rota-kit 2 for the detection of rotavirus in stool.

Diagnostic Utility of a Rapid ICT Tuberculosis Assay for the Diagnosis of Pulmonary Tuberculosis / 대한임상미생물학회지

BACKGROUND: Diagnosis of tuberculosis is more complicated because of low sensitivity and time consuming procedures of the conventional diagnostic methods as well as nonspecific clinical features. Recently the serologic diagnosis of tuberculosis has been reported as one of rapid sensitive and specific methods. We evaluated the ability of a rapid ICT Tuberculosis assay(AMRAD/ICT Diagnostics, Syndey, Australia) to detect pulmonary tuberculosis. METHODS: ICT Tuberculosis assay was performed to the sera from 50 patients with pulmonary tuberculosis (24 patients with smear positive, 26 patients with smear negative) and 105 controls (48 patients without tuberculosis, 57 healthy controls). RESULTS: Antibodies were detected in 22 of 24 (92%) smear positive patients and 22 of 26 (85%) smear negative patients who had been clinically diagnosed as having active pulmonary tuberculosis. Two (4.2%) out of 48 patients without tuberculosis and 1 (1.8%) out of 57 healthy controls had a positive antibody response. The overall sensitivity, specificity, and positive and negative predictive value of the ICT Tuberculosis assay were 88%, 97%, 94%, and 94%, respectively. CONCLUSIONS: The ICT Tuberculosis assay was not only sensitive and specific but also rapid and simple. This assay will be useful as a diagnostic method of pulmonary tuberculosis in combination with sputum smear and X-ray.

Serodiagnosis of Chlamydia trachomatis infections by the micro-immunofluorescence test / 대한임상병리학회지

BACKGROUND: Chlamydia trachomatis (C. trachomatis) is an obligatory intracellular parasite which causes trachoma, inclusion conjunctivitis, pneumonia in infants, nongonococcal urethritis, epididymitis, cervicitis, and salpingitis. Salpingitis frequently produces tubal damage and infertility. The micro-immunofluorecence (MIF) test is the standard method for chlamydial serology and is highly sensitive and specific. This study aimed to evaluate the prevalence of C. trachomatis antibodies in healthy individuals and patients with various diseases as well as the clinical value of chlamydial serology by MIF testing. METHODS: A total of 692 serum samples were collected. Of these, 388 samples were obtained from healthy individuals (male 209, female 179). Cord blood samples were collected from 38 healthy babies. Serum samples of 53 female patients with infertility due to PID (group 1), 107 patients with respiratory diseases (group 2; pneumonia, bronchitis, etc.), and 106 patients with cardiovascular diseases (group 3; angina pectoris, acute myocardial infarction, etc.) who were admitted to Hanyang University Hospital from March 1995 to June 1998 were enrolled in this study. Serological diagnosis of a previous infection was made when IgG antibody titers to C. trachomatis were 1:32 or higher. A single titer of antibody of > or =1:512 for IgG or > or =1:16 for IgM was considered to indicate a recent infection. RESULTS: The IgG antibody detection rate in healthy individuals was 27%, broken down by age as follows: or =61 years old, 24%. For cord blood, the antibody was detected in 29% of the samples. There were 1 case (0.3%) of recent infection with C. trachomatis by IgG, and 6 cases (1.5%) for IgM. The incidence of IgG antibodies to C. trachomatis in the disease group was 70%, 28%, and 19% for group 1, group 2, and group 3, respectively. There were 3 cases of recent infection detected by IgG and 4 cases by IgM in group 1. Recent infection with C. trachomatis was detected by IgG in 1 case of group 2 and by IgM in another case of group 3. CONCLUSIONS: In healthy individuals, the prevalence of antibodies to C. trachomatis was highest in those between the ages of 21-40 years. Patients with infertility due to PID showed a significantly higher positive rate (P=0.000 by Chi-square test) and more cases of recent infection to C. trachomatis than others. The results suggest that a positive chlamydial serology indicates a higher risk for infertility due to PID.

Usefulness of Anti-beta2-Glycoprotein I Antibody Test for the Diagnosis of Antiphospholipid Syndrome / 대한임상병리학회지

BACKGROUND: The conventional anticardiolipin antibody (aCL)-ELISA test that has been widely used to diagnose antiphospholipid syndrome (APS) has drawbacks in that false-positive reactions can occur. There have been considerable controversy as to the exact nature of the epitopes to which antiphosholipid antibodies (a PL) are directed. Almost all investigators now agree that the actual antigen to which aPL derived from patient with APS is directed, is beta2-glycoprotein I (beta2GPI). Therefore, we thought that anti-beta2GPI antibodies (abeta2GPI) might be a more specific marker for APS, and attempted to evaluate the usefulness of abeta2GPI test. METHODS: ELISA tests for a CL-IgG and abeta2GPI-IgG were performed simultaneously using the sera from 70 patients with clinically suspected APS and 10 healthy volunteers. The results of abeta2GPI were compared with those of aCL and evaluated clinically by reviewing the medical records. RESULTS: The correlation coefficient between the two was 0.54 (p<0.005). Twelve of 70 patients were abeta2GPI-positive and they were also positive for aCL (mean 45GPL). Forty of 58 abeta2GPI- negative patients were aCL-positive, and many of them were diagnosed to have APS clinically. There was no case showing aCL-negative but abeta2GPI-positive result. CONCLUSIONS: According to our results, abeta2GPI test seems specific but too insensitive to differentiate APS by itself, so it has no additional diagnostic value superior to aCL test. We believe that a study which includes more cases and various test methods will be needed for the precise assessment of abeta2GPI test.

Two Cases of Diarrheal Disease Caused by Plesiomonas shigelloides / 대한임상병리학회지

Plesiomonas shigelloides is known to cause diarrhea in human. It is a facultatively anaerobic gram-negative rod belonging to the family Vibrionaceae. We isolated P. shigelloides from two patients with diarrhea, a 62-year-old woman with steroid therapy and a 4-year-old boy with no predisposing factor. The organisms were isolated on enteric agars as a nonlactose fermenter and were identified by oxidase, indole, and other biochemical characteristics. The isolates were susceptible to commonly used antimicrobial agents with the exception of ampicillin. P. shigelloides infection is rarely reported in our country, but appears to be a significant cause of diarrhea that responds to antimicrobial therapy. Therefore we suggest the need for correctly identifying P. shigelloides.