The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Charlotte A Gaydos - One of the best experts on this subject based on the ideXlab platform.
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a case control study evaluating rt pcr esi ms technology compared to Direct Fluorescent Antibody and xtag rvp pcr
Diagnostic Microbiology and Infectious Disease, 2014Co-Authors: Justin Hardick, Sufyan Sadiq, Elizabeth Perelstein, Stephen Peterson, Richard E Rothman, Charlotte A GaydosAbstract:Waste nasopharyngeal swabs (N = 244) were evaluated by the reverse-transcriptase polymerase chain reaction/electrospray ionization mass spectrometry PLEX-ID Broad Respiratory Virus Surveillance Kit version 2.5 compared to Direct Fluorescent Antibody and xTAG Respiratory Virus Panel for percent agreement, sensitivity, and specificity. Sensitivity and specificity were 91% (111/122) and 95.1% (116/122), respectively. Sensitivity by virus, except parainfluenza, was 92.9–100%, and specificity was 99–100%.
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influence of endocervical specimen adequacy on pcr and Direct Fluorescent Antibody staining for detection of chlamydia trachomatis infections
Journal of Clinical Microbiology, 1997Co-Authors: Laura E Welsh, Thomas C Quinn, Charlotte A GaydosAbstract:The cellular quality of the endocervical swab specimen used for the detection of Chlamydia trachomatis may dramatically impact the sensitivity of the diagnostic assay used. An evaluation of the adequacy of 319 endocervical swab specimens from women attending two inner-city sexually transmitted disease and family planning clinics, as well as five high school-based family planning clinics, was performed, and the resulting data were compared with the diagnostic results obtained by both Amplicor PCR and Microtrak Direct Fluorescent-Antibody (DFA) staining. The swab from each patient was rolled across the open circular area of a DFA slide and then used to inoculate a transport tube for PCR (Roche), after which the swab was discarded. The slides were stained and examined by epifluorescence microscopy for the presence of C. trachomatis elementary bodies and for the presence and number of cell types to determine specimen adequacy. Cellular adequacy for a cervical swab specimen was defined as the presence of one or more columnar epithelial or metaplastic epithelial cells or the presence of more than 100 erythrocytes per high-power microscopic field. Of the 319 specimens read by DFA, 204 (63.9%) were determined to be adequate. There were 34 (10.7%) positive specimens by DFA and/or PCR. Twenty-nine (9.1%) specimens were positive by PCR, 20 (6.3%) specimens were DFA positive, and 15 (4.7%) were concordantly positive by both tests. The prevalence of chlamydia among adequate specimens was 14.2% (29/204), compared to 4.3% (5/115) for inadequate specimens (P < 0.0001). Variations in specimen quality and the sensitivity of the diagnostic assay used have a significant impact on determining the prevalence of C. trachomatis in a population.
Greg B Horsman - One of the best experts on this subject based on the ideXlab platform.
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comparison of chemicon simulfluor Direct Fluorescent Antibody staining with cell culture and shell vial Direct immunoperoxidase staining for detection of herpes simplex virus and with cytospin Direct immunofluorescence staining for detection of varic
Clinical and Vaccine Immunology, 2001Co-Authors: Edward L Chan, Ken Brandt, Greg B HorsmanAbstract:A new rapid Direct immunofluorescence assay, the SimulFluor Direct Fluorescent-Antibody (DFA) assay, which can simultaneously detect herpes simplex virus types 1 and 2 (HSV-1 and -2) and varicella-zoster virus (VZV), was evaluated in comparison with our current standard procedures of (i) shell vial Direct immunoperoxidase (shell vial IP) staining and cell culture for detection of HSV and (ii) cytospin DFA staining for VZV detection. A total of 517 vesicular, oral, genital, and skin lesion specimens were tested by all three procedures. For HSV detection, the SimulFluor DFA assay had an overall sensitivity, specificity, positive predictive value, and negative predictive value of 80.0, 98.3, 92.3, and 95.1%, respectively, when compared to culture. Shell vial IP staining had a sensitivity, specificity, positive predictive value, and negative predictive value of 87.6, 100, 100, and 96.9%, respectively, when compared with cell culture. The SimulFluor DFA assay, however, offers same-day, 1.5-hours results versus a 1- to 2-day wait for shell vial IP staining results and a 1- to 6-day wait for culture results for HSV. For VZV detection SimulFluor DFA staining detected 27 positive specimens as compared to 31 by our standard cytospin DFA technique—a correlation of 87.1%. A positive SimulFluor reaction for VZV is indicated by yellow-gold fluorescence compared to the bright apple-green fluorescence observed by cytospin DFA staining. There is no difference in turnaround time between the two assays. The SimulFluor DFA assay is a rapid immunofluorescence assay that can detect 80% of the HSV-positive specimens and 87% of the VZV-positive specimens with a 1.5-h turnaround time.
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a 1 year evaluation of syva microtrak chlamydia enzyme immunoassay with selective confirmation by Direct Fluorescent Antibody assay in a high volume laboratory
Journal of Clinical Microbiology, 1994Co-Authors: E L Chan, Ken Brandt, Greg B HorsmanAbstract: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.
J S Knapp - One of the best experts on this subject based on the ideXlab platform.
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incidence of neisseria gonorrhoeae isolates negative by syva Direct Fluorescent Antibody test but positive by gen probe accuprobe test in a sexually transmitted disease clinic population
Journal of Clinical Microbiology, 1993Co-Authors: J L Beebe, M P Rau, S Flageolle, B Calhoon, J S KnappAbstract:To determine the accuracy of the Syva (Palo Alto, Calif.) Direct Fluorescent-Antibody (DFA) test in comparison with the Gen-Probe (San Diego, Calif.) Accuprobe culture confirmation test, we tested 395 isolates of Neisseria gonorrhoeae from cultures obtained from patients attending a sexually transmitted disease clinic from 1 July 1991 through 30 June 1992. All isolates were tested for DFA reactivity with a polyclonal reagent (Difco Laboratories, Detroit, Mich.) and a monoclonal reagent (Syva, Inc., Direct specimen test) and for specific molecular probe reactivity by the Gen-Probe Accuprobe culture confirmation test for N. gonorrhoeae. The 395 isolates gave positive results for the Gen-Probe culture confirmation test and the Difco polyclonal Direct specimen test. However, 18 (4.6%) of the isolates were negative for N. gonorrhoeae by the Syva DFA test. With the exception of six beta-lactamase-positive isolates, all isolates that were negative by Syva DFA were sensitive to penicillin, tetracycline, spectinomycin, and ceftriaxone by disk-diffusion susceptibility testing. Auxotyping and serotyping studies indicated that strains negative by Syva DFA consisted of several variants. The frequency of N. gonorrhoeae isolates showing negative results by Syva DFA in this patient population ranged from 0 to 11.5%/month. Laboratories using only the Syva DFA test for confirmation of N. gonorrhoeae may incur a significant risk of misidentification.
James L. Beebe - One of the best experts on this subject based on the ideXlab platform.
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Confirmation of the Syva MicroTrak enzyme immunoassay for chlamydia trachomatis by Syva Direct Fluorescent Antibody Test.
Sexually Transmitted Diseases, 1996Co-Authors: James L. Beebe, Helen Masters, Donald Jungkind, David M. Heltzel, Adriana WeinbergAbstract:BACKGROUND AND OBJECTIVES: The Syva Micro Trak enzyme immunoassay (EIA) is used widely for screening women infected with Chlamydia trachomatis. Confirmatory tests used in conjunction with EIA screening have shown that false-positive results are common. GOALS: To evaluate the specificity of the Syva MicroTrak EIA by confirmation of positive specimens with the Syva Direct Fluorescent Specimen Test. STUDY DESIGN: Of 6,039 endocervical specimens collected from women attending Colorado family planning clinics, 328 positive EIA results (5.4%) were obtained by Syva MicroTrak EIA. A random subset of 136 positive specimens was tested by Syva Direct Specimen Test. Twenty of 136 specimens (14.7%) negative by Syva Direct Specimen testing were also tested by Syva blocking Antibody tests (9 of 20 positive, 45%) and Roche Amplicor polymerase chain reaction (PCR; 6 of 20 positive, 30%). Of 20 specimens positive by Syva MicroTrak EIA and negative by Syva Direct Specimen Test, 11 (55%) were also negative by blocking Antibody and PCR, including three specimens with initial EIA sample-to-cutoff ratios greater than 2. CONCLUSIONS: Confirmatory testing of Syva MicroTrak EIA positive specimens with Syva Direct Specimen Test showed that 14.7% were false positive. Coupling the Syva Direct Specimen test with either blocking Antibody or PCR reduces the rate of false-positive results to 8%.
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confirmatory testing of chlamydia trachomatis syva enzyme immunoassay gray zone specimens by syva Direct Fluorescent Antibody test
Sexually Transmitted Diseases, 1993Co-Authors: James L. Beebe, Michael P Rau, Kurt D AlbrechtAbstract:A series of gray zone specimens with sample to cutoff ratio of 0.7 to 0.99 encountered in routine use of the Syva Microtrak (Syva, Inc.) Chlamydia trachomatis enzyme immunoassay (EIA) test for urogenital specimens were subjected to repeat testing in duplicate and high-speed centrifugation with Direct Fluorescent Antibody testing of the centrifugate. ImmunoFluorescent C. trachomatis elementary bodies were observed in high-speed centrifugates in more than 40% of two series of gray zone specimens examined indicating that a C. trachomatis gray zone result would require confirmatory testing.
Adriana Weinberg - One of the best experts on this subject based on the ideXlab platform.
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Confirmation of the Syva MicroTrak enzyme immunoassay for chlamydia trachomatis by Syva Direct Fluorescent Antibody Test.
Sexually Transmitted Diseases, 1996Co-Authors: James L. Beebe, Helen Masters, Donald Jungkind, David M. Heltzel, Adriana WeinbergAbstract:BACKGROUND AND OBJECTIVES: The Syva Micro Trak enzyme immunoassay (EIA) is used widely for screening women infected with Chlamydia trachomatis. Confirmatory tests used in conjunction with EIA screening have shown that false-positive results are common. GOALS: To evaluate the specificity of the Syva MicroTrak EIA by confirmation of positive specimens with the Syva Direct Fluorescent Specimen Test. STUDY DESIGN: Of 6,039 endocervical specimens collected from women attending Colorado family planning clinics, 328 positive EIA results (5.4%) were obtained by Syva MicroTrak EIA. A random subset of 136 positive specimens was tested by Syva Direct Specimen Test. Twenty of 136 specimens (14.7%) negative by Syva Direct Specimen testing were also tested by Syva blocking Antibody tests (9 of 20 positive, 45%) and Roche Amplicor polymerase chain reaction (PCR; 6 of 20 positive, 30%). Of 20 specimens positive by Syva MicroTrak EIA and negative by Syva Direct Specimen Test, 11 (55%) were also negative by blocking Antibody and PCR, including three specimens with initial EIA sample-to-cutoff ratios greater than 2. CONCLUSIONS: Confirmatory testing of Syva MicroTrak EIA positive specimens with Syva Direct Specimen Test showed that 14.7% were false positive. Coupling the Syva Direct Specimen test with either blocking Antibody or PCR reduces the rate of false-positive results to 8%.