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.
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
Martina
M
Herremans
Daan W
DW
Notermans
Mart
M
Mommers
Laetitia M
LM
Kortbeek
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