Correlation of Treponemal Immunoassay Signal Strength Values with Reactivity of Confirmatory Treponemal Testing

Yetunde F Fakile; Heather Jost; Karen W Hoover; Kathleen J Gustafson; Susan M Novak-Weekley; Jeff M Schapiro; Anthony Tran; Joan M Chow; Ina U Park

doi:10.1128/JCM.01165-17

Correlation of Treponemal Immunoassay Signal Strength Values with Reactivity of Confirmatory Treponemal Testing

J Clin Microbiol. 2017 Dec 26;56(1):e01165-17. doi: 10.1128/JCM.01165-17. Print 2018 Jan.

Authors

Yetunde F Fakile¹, Heather Jost², Karen W Hoover², Kathleen J Gustafson³, Susan M Novak-Weekley⁴, Jeff M Schapiro⁵, Anthony Tran⁶, Joan M Chow⁴, Ina U Park^{4

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Affiliations

¹ Centers for Disease Control and Prevention, Atlanta, Georgia, USA yfakile@cdc.gov.
² Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
³ Sexually Transmitted Disease Control Branch, Division of Communicable Disease Control, Center for Infectious Diseases, California Department of Public Health, Richmond, California, USA.
⁴ Southern California Permanente Medical Group Regional Reference Laboratories, North Hollywood, California, USA.
⁵ Kaiser Permanente Northern California Regional Laboratory, Berkeley, California, USA.
⁶ San Francisco Department of Public Health, San Francisco, California, USA.
⁷ Department of Family and Community Medicine, School of Medicine, University of California-San Francisco, San Francisco, California, USA.

Abstract

Automated treponemal immunoassays are used for syphilis screening with the reverse-sequence algorithm; discordant results (e.g., enzyme immunoassay [EIA] reactive and reactive plasma reagin [RPR] nonreactive) are resolved with a second treponemal test. We conducted a study to determine automated immunoassay signal strength values consistently correlating with reactive confirmatory treponemal testing. We conducted a cross-sectional analysis of four automated immunoassays (BioPlex 2200 microbead immunoassay [MBIA], Liaison chemiluminescence immunoassay [CIA], Advia-Centaur CIA, and Trep-Sure EIA) and three manual assays (Treponema pallidum particle agglutination [TP-PA], fluorescent treponemal antibody absorption [FTA-ABS] test, and Inno-LIA line immunoassay). We compared signal strength values of automated immunoassays and positive and negative agreement. Among 1,995 specimens, 908 (45.5%) were true positives (≥4/7 tests reactive) and 1,087 (54.5%) were true negatives (≥4/7 tests nonreactive). Positive agreement ranged from 86.1% (83.7 to 88.2%) for FTA-ABS to 99.7% (99.0 to 99.9%) for Advia-Centaur CIA; negative agreement ranged from 86.3% (84.1 to 88.2%) for Trep-Sure EIA to 100% for TP-PA (99.6 to 100%). Increasing signal strength values correlated with increasing reactivity of confirmatory testing (P < 0.0001 for all automated immunoassays by Cochran-Armitage test for trend). All automated immunoassays had signal strength cutoffs corresponding to ≥4/7 reactive treponemal tests. BioPlex MBIA and Liaison CIA had signal strength cutoffs correlating with ≥99% and 100% TP-PA reactivity, respectively. The Advia-Centaur CIA and Trep-Sure EIA had signal strength cutoffs correlating with at least 95% TP-PA reactivity. All automated immunoassays had signal strength cutoffs correlating with at least 95% FTA-ABS reactivity. Assuming that a 95% level of confirmation is adequate, these signal strength values can be used in lieu of confirmatory testing with TP-PA and FTA-ABS.

Keywords: algorithim; automated; immunoassays; syphilis; treponemal.

Publication types

Comparative Study

MeSH terms

Algorithms
Antibodies, Bacterial / blood
Cross-Sectional Studies
Humans
Immunoassay*
Mass Screening / methods*
Predictive Value of Tests
Reproducibility of Results
Syphilis / blood
Syphilis / diagnosis*
Syphilis / immunology
Syphilis Serodiagnosis / methods*
Treponema pallidum / immunology

Substances

Antibodies, Bacterial