Evaluation of a Treponema pallidum-Specific IgM Enzyme Immunoassay and Treponema pallidum Western Blot Antibody Detection in the Diagnosis of Maternal and Congenital Syphilis

BACKGROUND: Congenital syphilis (CS) is a result of untreated or inadequately treated maternal syphilis. CS is more likely with early stages of maternal syphilis, but most mothers lack signs or symptoms and the risk of CS is unclear. GOAL: The goal of this study was to evaluate Treponema pallidum IgM Western blot (TP IgM WB) and a T. pallidum IgM enzyme immunoassay (TP IgM ELISA) in mothers with syphilis to determine if positive tests better indicate a risk of CS than a rapid plasma reagin titer >/=1:16. STUDY DESIGN: Ninety-seven mother-baby pairs with reactive syphilis serology were evaluated. RESULTS: TP IgM WB tests were positive in 18 pregnancies (7 of 18 babies had CS) and negative in 79 pregnancies (7 of 82 babies had CS). Thirty-two mothers had titers >/=1:16 (6 babies with CS) and 65 mothers had titers </=1:8 (8 babies with CS). CONCLUSION: TP IgM tests better identify mothers at risk of delivering babies with CS than maternal titer >/=1:16.