Comparison of a Treponema pallidum IgM immunoblot with a 19S fluorescent treponemal antibody absorption test for the diagnosis of congenital syphilis.
We compared an in-house Treponema pallidum IgM immunoblot (IB) with a 19S fluorescent treponemal antibody absorption (IgM) test during routine use for the diagnosis of congenital syphilis (CS) in a national reference laboratory in a nonendemic setting. The overall agreement between the assays was high (97%), and 19S positive samples had at least 2 reactive bands in the IB. The high agreement is mainly caused by the large number of negative results (95%). If the 19S is taken as the gold standard, the estimate sensitivity of the IB was at least 88% with a specificity of 97.2%. Analysis of the discrepancies revealed that the IB was positive with 1 or 2 specific bands in 2.8% of the cases, whereas 19S was negative, possibly indicating higher sensitivity of the IB. We conclude that the IB is a sensitive method to detect contact with T. pallidum in neonates and can replace the 19S in routine laboratory screening for CS cases.
Herremans
Martina
M
Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Laboratory for Infectious Diseases and Perinatal Screening, PO Box 1, 3720 BA Bilthoven, The Netherlands. tineke.herremans@rivm.nl
Notermans
Daan W
DW
Mommers
Mart
M
Kortbeek
Laetitia M
LM
D005260:Female; D016508:Fluorescent Treponemal Antibody-Absorption Test; D006801:Humans; D015151:Immunoblotting / Q000379:methods*; D007075:Immunoglobulin M / Q000032:analysis; D007223:Infant; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical; D011247:Pregnancy; D012680:Sensitivity and Specificity; D013590:Syphilis, Congenital / Q000175:diagnosis* / Q000276:immunology; D014210:Treponema pallidum / Q000276:immunology*
D007075:Immunoglobulin M