Detection of endocervical anti-Chlamydia trachomatis immunoglobulin A in pregnant women by a rapid, 6-minute enzyme-linked immunosorbent assay: comparison with PCR and chlamydial antigen detection methods.
There is a need for a rapid, uncomplicated, and inexpensive test for Chlamydia trachomatis infection in women. We evaluated the ability of a 6-min enzyme-linked immunosorbent assay (ELISA) that requires no laboratory equipment (IgA Rapid SeroTest; Savyon Diagnostics) to detect C. trachomatis immunoglobulin A (IgA) in the endocervices of 167 inner-city pregnant women and compared the results with DNA amplification (Amplicor PCR; Roche Diagnostics) and antigen detection (Chlamydiazyme; Abbott Laboratories) performed on the same women. Anti-C. trachomatis IgA was detected in the cervices of 32 women (19.2%). Samples from 23 women (13.8%) were PCR positive, while chlamydial antigen was present in 20 women (12.0%). There was only 1 sample (4.3%) that was positive by PCR but negative by ELISA; 10 samples were ELISA positive and PCR negative. In contrast, seven samples (30.4%) were PCR positive but Chlamydiazyme negative and four were Chlamydiazyme positive and PCR negative. Compared to PCR, the IgA ELISA had a sensitivity of 95.7%, a specificity of 93.1%, a positive predictive value of 68.8%, and a negative predictive value of 99.3%. The antigen assay had a sensitivity of only 69.6%, a specificity of 97.2%, a positive predictive value of 80.0%, and a negative predictive value of 95.2%. In high-risk groups where laboratory testing is not available, or where the patient might not return to obtain her testing result and be treated, the Rapid IgA SeroTest is a viable alternative for detection of cervical C. trachomatis in pregnant women.
Witkin
S S
SS
Division of Immunology and Infectious Diseases, Cornell University Medical College, New York, New York 10021, USA. switkin@mail.med.cornell.edu
Bongiovanni
A M
AM
Inglis
S R
SR
D000907:Antibodies, Bacterial / Q000032:analysis / Q000276:immunology*; D000942:Antigens, Bacterial / Q000032:analysis*; D002584:Cervix Uteri / Q000276:immunology / Q000382:microbiology; D002690:Chlamydia Infections / Q000175:diagnosis* / Q000276:immunology; D002692:Chlamydia trachomatis / Q000276:immunology / Q000302:isolation & purification*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000276:immunology*; D016133:Polymerase Chain Reaction / Q000379:methods; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000175:diagnosis / Q000276:immunology / Q000382:microbiology*
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D007070:Immunoglobulin A