Abstract: Objectives To determine the prevalences of genital C.trachomatis and serum chlamydial antibodies in pregnant women,PID patients and the patients attending STD clinic,and to compare the chlamydial serology with control subjects.Methods Genital C.trachomatis was detected by cell culture,and serum chlamydial antibodies were measured by EIA and MIF.Results Genital C.trachomatis was found in 3.3% of pregnant women,6.7% of PID patients,20.4% or 15.6% of male or female patients attending STD clinic,respectively.Prevalence of chlamydial EIA-IgG/MIF-IgG antibodies was 46.7%/11.9% in pregnant women,70.2%/39.9% in PID patients,73.5%/52.4% and 75.4%/63.1% in male and female STD patients,which were statistically higher than those of controls (except pregnant women).Women,rather than men,with genital C.trachomatis were more likely to have serum chlamydial antibodies than those without infection.Eight subjects were measured with acute antibodies to C.trachomatis.Conclusions There is strong relation between cervical C.trachomatis and serum chlamydial antibodies.Serum antibodies to C.trachomatis are of no help for the diagnosis of genital C.trachoamtis infections.Routine screening of C.trachomatis is needed for patients with PID but not for pregnant women.

Key words: Chlamydia trachomatis, Cells,cultured, Serology