TThe Syva MicroTrak Chlamydia enzyme immunoassay (EIA; Syva Company, San Jose, Calif.) with cytospin and direct fluorescent-antibody assay (DFA) confirmation was evaluated on 43,630 urogenital specimens over a 1-year period in the Provincial Laboratory in Regina, Saskatchewan, Canada. This was a two-phase study intended to define a testing algorithm for Chlamydia trachomatis that would be both highly accurate and cost-effective in our high-volume (> 3,000 tests per month) laboratory. The prevalence of C. trachomatis infection in our population is moderate (8 to 9%). In phase 1, we tested 6,022 male and female urogenital specimens by EIA. All specimens with optical densities above the cutoff value and those within 30% below the cutoff value were retested by DFA. This was 648 specimens (10.8% of the total). A total of 100% (211 of 211) of the specimens with optical densities equal to or greater than 1.00 absorbance unit (AU) above the cutoff value, 98.2% (175 of 178) of the specimens with optical densities of between 0.500 and 0.999 AU above the cutoff value, and 83% (167 of 201) of the specimens with optical densities within 0.499 AU above the cutoff value were confirmed to be positive. A total of 12% (7 of 58) of the specimens with optical densities within 30% below the cutoff value were positive by DFA. In phase 2, we tested 37,608 specimens (32,495 from females; 5,113 from males) by EIA. Only those specimens with optical densities of between 0.499 AU above and 30% below the cutoff value required confirmation on the basis of data from phase 1 of the study. This was 4.5% of all specimens tested. This decrease in the proportion of specimens requiring confirmation provides a significant cost savings to the laboratory. The testing algorithm gives us a 1-day turnaround time to the final confirmed test results. The MicroTrak EIA performed very well in both phases of the study, with a sensitivity, specificity, positive predictive value, and negative predictive value of 96.1, 99.1, 90.3, and 99.7%, respectively, in phase 2. We suggest that for laboratories that use EIA for Chlamydia testing, a study such as this one will identify an appropriate optical density range for confirmatory testing for samples from that particular population.
The aim of the study was to assess the feasibility of and possible selection to attend in colorectal cancer screening.
During the years 1979-1980, 1 785 men and women (born in 1917-1929) were invited to a pilot screening project for colorectal cancer. The screening method used was a guaiac-based faecal occult blood test repeated once if the initial test was positive.
Compliance was 69% and the test was positive in 19% of those attending. In a record linkage with the Finnish Cancer Registry, 47 colorectal cancer cases and 24 deaths from colorectal cancer were observed by the end of 2004. In all, the particular test method was not regarded specific enough for population screening. There was, however, no difference in cancer incidence between those who complied and those who did not when compared to the general population of same age and gender.
Compliance was found high enough to make screening feasible and there was no self selection of persons with low cancer risk to attend screening.
BACKGROUND: Despite its unsatisfactory specificity, rheumatoid factor (RF) is the only serologic marker included in the diagnostic criteria of the American College of Rheumatology (ACR) for rheumatoid arthritis. Recently, the diagnostic value of anti-cyclic citrullinated peptide (CCP) antibodies has been emphasized in rheumatoid arthritis (RA) due to its high specificity. To evaluate the second generation of anti-CCP antibodies as a diagnostic marker, we evaluated anti-CCP test in 163 individuals. METHODS: The study population was divided into the following four groups: RA group (n=18), other disease group with arthritic symptoms (n=44), other disease group without arthritic symptoms (n=45), and healthy group (n=56). Anti-CCP was measured by an ELISA analyzer (Coda, Bio-Rad, USA) with Immunoscan RA (Euro-Diagnostica, Malmo, Sweden) and RF was measured by an automated chemistry analyzer (Toshiba, Japan) with RF-LATEX X1 (Denka Seiken, Japan). RESULTS: The sensitivity of anti-CCP and RF was 72.2% and 100%, respectively, and the respective figures for the specificity were 96.6% and 73%. On each ROC curve, the area under the curve was 0.867 for anti-CCP and 0.959 for RF. In other disease groups, most of the false positive cases of RF were found in the patients with hyperlipidemia or HBV carriage. However, anti-CCP was not detected in any of the patients with these two conditions. False positive rates of RF in the three control groups were 34.1% in other disease group with arthritic symptoms, 48.9% in the other disease group without arthritic symptoms, and 3.6% in healthy group. The respective figures for anti-CCP were 6.8%, 2.2%, and 1.8%. CONCLUSIONS: The specificity of anti-CCP antibodies was higher than that of RF for discriminating RA from other diseases, especially in the patients with hyperlipidemia or HBV carriage. With its high specificity, anti-CCP antibodies can play an additive role in establishing the diagnosis of RA in patients with RF positivity.
Measurement of plasminogen, the key component of fibrinolysis system, is one of the basic methods for estimation of fibrinolysis. Methods based on the use of chromogenic substrates are often used in diagnosis. Plasminogen measurements are important for laboratory diagnosis of thrombophilia caused by deficiency or abnormalities of this fiber, for detection and evaluation of the DIC syndrome, and for monitoring the treatment by fibrinolytic preparations (streptokinase, t-PA, urokinase, etc.). An original chromogenic substrate having no foreign analogs has been created at Institute of Genetics and Selection of Industrial Microorganisms and Research Center of Hematology (Moscow). Unlike previously described plasmin substrates, pNa has been obtained by microbiological methods with Russian commercial enzymes subtilisine 72 and megaterine. This paper presents the results of plasminogen measurements in patients with DIC with the use of the original chromogenic substrate. The results were compared with those of tests with Berihrom-Plasminogen diagnostic kit (Behringwerke AG).
HIV-1 viral load quantitation is now recognized as a useful tool to monitor the efficiency of antiviral treatment and a powerful predictor of disease outcome. Three HIV-1 viral load quantitation methods have been currently available as commercial kits in Canada since 1996.
To evaluate the ability to quantify HIV-1 RNA in plasma of the Amplicor HIV Monitor Test, the NASBA HIV-1 RNA QT Assay and the Quantiplex HIV RNA Assay, version 2.0, at comparable lower detection limits.
Blood was collected from 50 HIV-1-infected patients at various stages of infection and therapy. CD4+ cell count were estimated by flow cytometry. Plasma was isolated and tested in duplicate on four occasions using viral load kits from a single lot. HIV RNA data, performance, sensitivity and intra- and inter-assay variability were compared.
RNA could be quantified in 33 patients by each technique. An inverse correlation was observed between viral load level and CD4+ cell counts in patients with counts below 200. Monitor could detect RNA in 94% of patients, but it showed the greatest variability and failure rate. Quantiplex 2.0 could detect HIV-1 RNA in 78%, and NASBA in 88% of the patients at theoretically equivalent lower detection limits, suggesting that the detection limit of Quantiplex 2.0 may be higher than 500 HIV-1 RNA copies per ml. NASBA had the fewest invalid tests and good reproducibility, comparable to that of Quantiplex 2.0. The mean values from NASBA and Monitor were the most similar but the best correlation was observed between Monitor and Quantiplex 2.0 results.
Monitor, NASBA and Quantiplex results were comparable, although those obtained by Quantiplex were significantly lower. Performing this study at comparable detection limits showed that the detection limit of Quantiplex 2.0 may be higher than stated by the manufacturer.
During the early stages of the 2009/2010 swine-origin H1N1 influenza A (S-OIV H1N1 FluA) outbreak, the development and validation of sensitive and specific detection methods were a priority for rapid and accurate diagnosis. Between May and June 2009, 2 real-time reverse transcriptase-polymerase chain reaction (rRT-PCR) assays targeting the hemagglutinin and neuraminidase genes of the S-OIV H1N1 FluA virus were developed. These assays are highly specific, showing no cross-reactivity against a panel of respiratory viruses and can differentiate S-OIV H1N1 from seasonal FluA viruses. Analytical sensitivities of the 2 assays were found to be 10(-1) tissue culture infectious dose, 50%/ml. Clinical testing showed 99.2% sensitivity and 94.6-98.1% specificity. A large prospective analysis showed that 94.8-95.5% of S-OIV positive specimens were negative by seasonal H1/H3 subtyping. The large-scale validation data presented in this report indicate that these novel assays provide an accurate and efficient method for the rapid detection of S-OIV H1N1 FluA viruses.
Anti-proteinase 3 antineutrophil cytoplasmic antibodies (PR3-ANCA) and anti-myeloperoxidase antibodies (MPO-ANCA) are considered important serological markers for several forms of idiopathic systemic vasculitis. The aim of the study was to verify the analytical and clinical performance of a new automated enzyme fluoroimmunoassay, the EliA system, for PR3-ANCA and MPO-ANCA detection. For this purpose the sera of 52 consecutive well-defined patients with a clinical diagnosis of Wegener's granulomatosis (WG) (n=29) or microscopic polyangiitis (MPA) (n=23), and 70 controls suffering from connective tissue disease (25 systemic lupus erythematosus, 25 Sjögren's syndrome and 20 rheumatoid arthritis) were tested for PR3-ANCA and MPO-ANCA with the EliA assay (Pharmacia Diagnostics, Freiburg, Germany). For comparison purposes, the same sera were also tested by indirect immunofluorescence, another direct immunometric assay (Varelisa, Pharmacia Diagnostics) and a capture PR3-ANCA (Wieslab AB, Lund, Sweden) method. Both the EliA PR3-ANCA and MPO-ANCA assays showed between- and within-assay precision of
The age-specific rate of exposure to hepatitis A virus (HAV) was studied in 1015 native Saudi Arabians (504 males, 511 females) from the Riyadh area. The relatively high prevalence of antibody to HAV (anti-HAV) (38.6%) in children between 1 and 4 years of age indicates that infection is acquired early in life in the Saudi Arabian population. The prevalence of anti-HAV was found to increase steadily so that by the age of 30 years 91.0% of Saudi Arabians have anti-HAV. The prevalence in adult Saudi Arabians was compared with that in expatriates from various parts of the world working in Saudi Arabia. It was lowest among Swedish (10.7-12.3%) and highest among Yemeni (94.5%) blood donors while British blood donors were intermediate same among Saudi Arabian, Yemeni, Egyptian and Filipino blood donors (91.0-94.5%). All the donors tested were of the same age group (20-35 years).