Background: Screening for Chlamydia trachomatis specific antibodies is valuable in diagnosing asymptomatic pelvic inflammatory disease (PID) and tubal damage following repeated episodes of PID. The assays in current use are unsuitable for screening large numbers of samples so there is a need to develop more suitable assays. Aims: To compare the performance of several commercial C trachomatis enzyme immunoassays (EIAs) (SeroCT, C tracho pep , Medac p-EIA, Vircell and Labsystems C trachomatis IgG EIAs) using major outer membrane protein (MOMP), an inactivated organism EIA (Genzyme Virotech EIA), and a genus specific EIA (Platelia Chlamydia IgG) with the whole cell inclusion immunofluorescence (WIF) assay. In addition, to adapt, using time resolved fluorescence technology, the assay showing the highest correlation with WIF. Methods: Ninety sera from patients presenting with ectopic pregnancies, 187 sera from those with a variety of types of infertility, 33 sera from cases of PID where a fourfold rise in WIF titre occurred, and 90 sera from antenatal clinic attenders were tested. A panel of 36 sera from laboratory diagnosed cases of Chlamydia psittaci/Chlamydia pneumoniae infection was also tested. Results: The Genzyme Virotech EIA showed the highest rank correlation coefficient (0.82) with WIF, particularly at high WIF titres. The MOMP specific assays varied in their correlation with WIF, with rank correlation coefficients ranging from 0.70 (Medac p-EIA) to 0.80 (Vircell EIA). The Genzyme Virotech assay showed poor specificity (5.6%; 95% confidence interval (CI), 0.68% to 18.7%)-it was reactive with 34 of the panel of 36 C psittaci/ C pneumoniae positive sera. The MOMP based EIAs showed high specificity, particularly the Medac p-ELISA (97.2%; 95% CI, 85.5% to 99.9%)-only one serum was reactive. In view of the good correlation between WIF and the Genzyme Virotech EIA, a time resolved fluorescence immunoassay (TRFIA) was developed using the Genzyme Virotech antigen. Using an appropriate cut off the TRFIA assay showed excellent correlation with WIF. Conclusions: The TRFIA assay may be useful as a screening assay, possibly in conjunction with one of the highly specific EIAs studied (for example, Medac p-EIA) to confirm the antibody specificity of sera selected by the screening assay.
A time resolved fluorometric immunoassay (TRFIA) has been developed and compared with an in house enzyme linked immunosorbent assay (ELISA) and commercial ELISA (Bindazyme) for the detection of tetanus antitoxin in human sera. A panel of 132 sera submitted for routine testing was used. Scatterplots showed a high degree of correlation between all three assays, although some divergence of results was apparent for low titre sera when comparing in house ELISA results with Bindazyme ELISA and TRFIA results. The TRFIA appeared to be more sensitive than the in house ELISA, and the Bindazyme assay compared well with the TRFIA. The intra-assay precision of all three assays, in terms of percentage coefficient of variation (%CV), was between 2.0% and 4.0%. The interassay precision ranged from 5% to 8% for the in house ELISA, 13% to 19% for the Bindazyme assay, and 11% to 13% for TRFIA. Both Bindazyme and TRFIA assays were simple to perform, accurate, reproducible, and amenable to automation. A particular benefit of the TRFIA was its large dynamic range, enabling tetanus antitoxin values of 0.01 IU/ml to 50 IU/ml to be measured with just one dilution of serum. TRFIA appears to be a useful serological technique worthy of further development. (J Clin Pathol 2001;54:812-815) Keywords: tetanus antitoxin; fluorometric immunoassay; enzyme linked immunoassay Fluorometric immunoassays are used infrequently in microbiology laboratories in the UK, although they have found wide application in other areas of pathology, where the sensitive and specific detection of antibodies is important (personal communication, 2001, Perkin Elmer Wallac, Cambridge, UK). In theoretical terms, a fluorometric detection system is capable of achieving sensitivities at least an order of magnitude below colorimetric assays using the same enzymes, because fluorescent compounds can repeatedly produce a signal in a short space of time. Background fluorescence by some of the components in serum (such as proteins and bilirubin) has been a major limitation preventing the widespread use of conventional fluorescence based immunoassays; however, the use of lanthanide chelates (for example, europium) and time resolved detection systems eliminates background interference, because europium decays over a much longer time period than natural fluorescence, and time resolution enables specific europium related fluorescence to be measured. A previous study, 1 in which a time resolved fluorometric immunoassay (TRFIA) was developed and evaluated for the detection of tetanus antitoxin in human sera, has described this methodology to be simple to perform, accurate, reproducible, and to be amenable to automation. Our laboratory tests a large number of sera for routine and serosurveillance purposes and, although the in house enzyme linked immunosorbent assay (ELISA) used at present is satisfactory, we wished to determine whether the claims made for TRFIA were justified. Using the Wallac DELFIA (dissociation enhanced lanthanide fluorescence immunoassay) system, a time re...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.