Am J Perinatol 2020; 37(07): 671-678
DOI: 10.1055/s-0039-3402748
SMFM Fellowship Series Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Syphilis Immunoassay Signal Strength Correlates with Active Infection in Pregnant Women

1  Department of Obstetrics and Gynecology, UT Southwestern Medical Center, Dallas, Texas
,
Angela R. Seasely
1  Department of Obstetrics and Gynecology, UT Southwestern Medical Center, Dallas, Texas
,
Donna Gaffney
2  Microbiology Laboratory, Parkland Health and Hospital System, Dallas, Texas
,
Vanessa L. Rogers
1  Department of Obstetrics and Gynecology, UT Southwestern Medical Center, Dallas, Texas
,
Donald D. Mcintire
1  Department of Obstetrics and Gynecology, UT Southwestern Medical Center, Dallas, Texas
,
Scott W. Roberts
1  Department of Obstetrics and Gynecology, UT Southwestern Medical Center, Dallas, Texas
,
1  Department of Obstetrics and Gynecology, UT Southwestern Medical Center, Dallas, Texas
› Author Affiliations
Funding None.
Further Information

Publication History

19 September 2019

02 December 2019

Publication Date:
07 January 2020 (online)

Abstract

Objective This study aimed to evaluate the association of ARCHITECT chemiluminescent immunoassay (CIA) signal strength (signal-to-cutoff [S/CO] ratio), with maternal syphilis stage, rapid plasma reagin (RPR) reactivity, and congenital syphilis.

Study Design A prospective observational study of reverse syphilis screening was conducted. Pregnant women were screened with CIA. Reactive CIA was reflexed to RPR; particle agglutination test (Treponema pallidum particle agglutination [TPPA]) was performed for CIA+/RPR− results. Clinical staging with history and physical was performed, and disease stage was determined. Prior treatment was confirmed. We compared S/CO ratio and neonatal outcomes among the following groups:

Group 1: CIA+/RPR+/TPPA+ or CIA+/RPR−/TPPA+ with active syphilis;

Group 2: CIA+/RPR−/TPPA+ or CIA+/serofast RPR/TPPA+, previously treated;

Group 3: CIA+/RPR−/TPPA+, no history of treatment or active disease;

Group 4: CIA+/RPR−/TPPA−, false-positive CIA.

Results A total of 144 women delivered with reactive CIA: 38 (26%) in Group 1, 69 (48%) in Group 2, 20 (14%) in Group 3, and 17 (12%) in Group 4. Mean (±standard deviation) S/CO ratio was 18.3 ± 5.4, 12.1 ± 5.3, 9.1 ± 4.6, and 1.9 ± 0.8, respectively (p < 0.001). Neonates with overt congenital syphilis occurred exclusively in Group 1.

Conclusion Women with active syphilis based on treatment history, clinical staging, and laboratory indices have higher CIA S/CO ratio and are more likely to deliver neonates with overt evidence of congenital syphilis.

Note

This study was presented as a poster presentation at the 39th Annual Pregnancy Meeting of the Society for Maternal-Fetal Medicine in Las Vegas, NV (February 11–16, 2019). Abstract #615.