Chlamydial serology in genital infections: ImmunoComb versus Ipazyme

The ImmunoComb Chlamydia trachomatis IgG/IgA (Orgenics, Israel) is a new serologic test using C. trachomatis L2 elementary bodies (Washington Research Foundation, Seattle) as antigen. The Ipazyme IgG/IgA test (Savyon, Israel) employs whole cells with C. trachomatis L2 inclusions, i.e. elementary and reticulate bodies. Theoretically, the ImmunoComb is expected to be less cross-reactive (LPS) with Chlamydia pneumoniae than the Ipazyme (LPS and reticulate body group specific antigens). Compared with the Ipazyme, the ImmunoComb IgA showed both a higher positive predictive value (36% versus 25%) and sensitivity (67% versus 33%) for antigen detection in a control group of 100 post partum women with a 6% prevalence of C. trachomatis positive cervical smears. In sterility patients (45 cases with occluded and 53 with open fallopian tubes) the tube status was predicted by the ImmunoComb (Ipazyme) with 74% (72%) positive predictive value, 87% (80%) sensitivity, and 87% (81%) negative predictive value. IgG/IgA prevalence in 118 patients with C. trachomatis positive cervical smears was 85%/55% for the ImmunoComb and 84%/49% for the Ipazyme. The ImmunoComb is considerably faster and easier in handling and less subjective in reading than the Ipazyme.