(P102) FEASIBILITY OF A 10-MINUTE POINT-OF-CARE TREPONEMAL IGM ANTIBODY DIAGNOSTIC FOR CONGENITAL SYPHILIS TESTING OF NEWBORNS FROM HEEL STICK BLOOD

Tuesday, September 17, 2024

4:15 PM - 5:15 PM EST

Primary Author(s)

Irene Stafford, MD, MS (she/her/hers)

Associate Professor
University of Texas Health Science Center Houston – McGovern Medical School
Houston, Texas, United States

Co-Author(s)(s)

Jeffrey D. Klausner, MD (he/him/his)

Clinical Professor
Department of Population and Public Health Sciences, University of Southern California
Los Angeles, California, United States
GL

Gary Lehnus, PhD

Diagnostics Direct
NP

Norman Proulx, BSc

Diagnostics Direct

Background:
Congenital syphilis rates in the U.S. have increased drastically over the past decade. Diagnosis of congenital syphilis can be difficult due to the wide range of clinical presentations and the transfer of maternal treponemal and nontreponemal IgG antibodies to the fetus through the placenta. This study describes Diagnostics Direct’s work to determine the feasibility of a rapid congenital syphilis test based on detection solely of IgM antibody to Treponema pallidum in newborn capillary blood.

Methods:
Syphilis IgM Health Check: A 10-minute POC immunochromatographic test from capillary blood that detects IgM antibody to Treponema pallidum. The test input is 20 uL of capillary whole blood and has a visual readout.

Feasibility Studies: Two studies were performed using residual, de-identified clinical samples to assess the preliminary performance of the Syphilis IgM Health Check.

Results:
In the first study, 18 syphilis IgM sera samples were tested with the Syphilis IgM Health Check and the Viramed ViraBlot IgM test and were positive by both tests. The Viramed test showed IgM reactions with 3 - 5 VDRL antigens and the early recombinant lipoprotein markers of 47 and 44.5 kDa. Minimal reactions to IgM were observed with the later stage markers of 17 and 15 kDa, indicating early syphilis infection. In the second study, Syphilis IgM Health Check was used to test 20 negative sera and 30 positive sera from late secondary, latent, and tertiary infections where only IgG is detectable. IgM was not detected in any sample, indicating the test design has the desired specificity to virtually eliminate the risk of false positive results.

Conclusion:
The Syphilis IgM Health Check prototype provides robust detection of IgM antibody to Treponema pallidum in early syphilis infection and once complete, will provide clinicians a rapid test to support diagnosis of congenital syphilis providing for more rapid initiation of treatment.