title: [The importance of using a test to detect Chlamydia trachomatis infection in patients undergoing counseling and testing for sexually transmitted diseases at a public health center].
abstract: OBJECTIVE
  Serum levels of antibody against Chlamydia trachomatis are used routinely to diagnose chlamydial infection among patients undergoing counseling and testing for sexually transmitted disease at public health centers in Japan, whereas tests for pathogen detection are conducted at most clinics. The objective of the present study was to evaluate the usefulness of a test for detecting C. trachomatis and to compare it with that of screening for serum chlamydia antibodies at a public health center.
  
  
  METHODS
  Serum chlamydia antibody titers were estimated using an ELISA, while C. trachomatis was detected in the urine using the nucleic acid amplification assay that included strand displacement amplification (SDA). We compared the results of 120 patients (64 men and 56 women), because the sensitivity of the method using urine samples from women has been reported to be as high as that using cervical samples. The serum antibody test results were considered to be positive when either one or both of the IgA and IgG antibodies were positive.
  
  
  RESULTS
  The overall prevalence of positive results for the antibody test was 24.2% (14.1% for men and 35.7% for women), and that for the SDA method was 7.5% (3.1% for men and 12.5% for women). The concordance rate of the 2 tests was 81.7%, with a kappa statistic of 0.35 (95% CI, 0.10-0.59). Of the 9 subjects who were positive for C. trachomatis using the SDA assay, 1 had serum chlamydia IgA antibodies, 6 had IgG antibodies, 1 had both the antibodies, and 1 had no antibodies. On the other hand, of the 111 subjects who were negative for C. trachomatis, only 8 had chlamydia IgA antibodies, 5 had IgG antibodies, and 8 had both the antibodies. These results indicated there was no association between serum IgA antibodies and the presence of C. trachomatis. The presence of serum chlamydia antibodies was significantly higher in subjects with a past history of genital chlamydial infection than in those without a past history of infection (P<0.01). However, there was no difference in the results of the SDA assay between subjects with or without a previous infection.
  
  
  CONCLUSIONS
  Thus, although serum chlamydia antibodies are generally measured at public health centers, tests for detecting C. trachomatis should also be used.
authors.affiliation: Maebashi municipal public health center.
authors.forename: Toru
authors.initials: T
authors.lastname: Hatori
authors.forename: Tamiko
authors.initials: T
authors.lastname: Nakamura
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tsukui
mesh_terms: D000328:Adult; D000907:Antibodies, Bacterial / Q000032:analysis*; D002690:Chlamydia Infections / Q000175:diagnosis*; D002692:Chlamydia trachomatis / Q000276:immunology* / Q000302:isolation & purification*; D003151:Community Health Centers; D003376:Counseling; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D012749:Sexually Transmitted Diseases / Q000175:diagnosis*
chemical_list: D000907:Antibodies, Bacterial