title: Chlamydia antibody testing in screening for tubal factor subfertility: the significance of IgG antibody decline over time.
abstract: BACKGROUND
  Chlamydia (C.) trachomatis antibody testing in screening for tubal factor subfertility is limited by false negative results, i.e. negative Chlamydia antibody tests in patients with tubal pathology at laparoscopy. The present study was performed to determine whether decline in C. trachomatis IgG antibodies over time is responsible for those false negative results.
  
  
  METHODS
  A total of 39 women with an initial titre of > or =64 were re-studied after 4-7 years. A new serum sample was collected from each patient. The initial and the second serum sample were tested for C. trachomatis IgG antibodies using a micro-immunofluorescence assay (MIF). A species-specific enzyme-linked immunosorbent assay (ELISA) was used to validate the MIF test results. All patients filled out a questionnaire to determine risk factors for renewed C. trachomatis infection between the initial and second serum sample.
  
  
  RESULTS
  Seven of the 39 patients (18.0%) showed a decline (>2 titre steps) in IgG antibodies by MIF over a period of 4-7 years, but IgG antibodies never became undetectable. In the 7/39 patients who showed a decline by MIF, signal/cut-off values by ELISA did not change.
  
  
  CONCLUSIONS
  A decline in IgG antibody titre is not a significant cause of false negative Chlamydia antibody test results.
authors.affiliation: Research Institute Growth and Development (GROW), Department of Obstetrics and Gynaecology, 6202 AZ Maastricht, The Netherlands. agij@sgyn.azn.nl
authors.forename: Anna P
authors.initials: AP
authors.lastname: Gijsen
authors.forename: Jolande A
authors.initials: JA
authors.lastname: Land
authors.forename: Valère J
authors.initials: VJ
authors.lastname: Goossens
authors.forename: Marlea E P
authors.initials: ME
authors.lastname: Slobbe
authors.forename: Cathrien A
authors.initials: CA
authors.lastname: Bruggeman
mesh_terms: D000328:Adult; D000907:Antibodies, Bacterial / Q000032:analysis*; D002690:Chlamydia Infections / Q000209:etiology; D002692:Chlamydia trachomatis / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005184:Fallopian Tube Diseases / Q000150:complications* / Q000382:microbiology*; D005188:False Negative Reactions; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007247:Infertility, Female / Q000209:etiology*; D008875:Middle Aged; D012307:Risk Factors; D013997:Time Factors
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G