Congenital syphilis: detection of Treponema pallidum in stillborns.

Paraffin-embedded tissue from all 17 autopsies performed following 56 stillbirths associated with maternal syphilis during a 3-year period (1987-1989) was reexamined to compare immunofluorescent antigen (IFA) testing with silver staining for the detection of Treponema pallidum. Congenital syphilis (CS) originally was diagnosed in 9 of the 17 cases of stillbirth, on the basis of positive silver stains (7 cases) or morphological findings alone (2). Upon review, silver staining revealed T. pallidum in 10 of 17 cases and IFA testing revealed the pathogen in 15 of 17 cases, enabling diagnosis of CS in 16 of 17 cases of stillbirth associated with a reactive maternal rapid plasma reagin (RPR) card test. Most stillbirths associated with a reactive maternal RPR test during this time period involved CS, and IFA testing for T. pallidum is superior to silver staining for the identification of treponemes.