Diagnosis of Chlamydia trachomatis infection--culture versus serology

Current methods of laboratory diagnosis of Chlamydia trachomatis infections

Infections caused by Chlamydia trachomatis are probably the most common sexually transmitted diseases in the United States. Commonly unrecognized and often inadequately treated, chlamydial infections can ascend the reproductive tract and cause pelvic inflammatory disease, which often results in the devastating consequences of infertility, ectopic pregnancy, or chronic pelvic pain. C. trachomatis infections are also known to increase the risk for human immunodeficiency virus infection. The obligate intracellular life cycle of C. trachomatis has traditionally required laboratory diagnostic tests that are technically demanding, labor-intensive, expensive, and difficult to access. In spite of these historical challenges, however, laboratory diagnosis of C. trachomatis has been a rapidly advancing area in which there is presently a wide array of commercial diagnostic technologies, costs, manufacturers. This review describes and compares the diagnostic methods for C. trachomatis infection that are currently approved for use in the United States, including the newest DNA amplification technologies which are yet to be licensed for commercial use. Issues to consider in selecting a test for purposes of screening versus diagnosis based on prevalence, performance, legal, social, and cost issues are also discussed.

Chlamydia trachomatis antibody testing is more accurate than hysterosalpingography in predicting tubal factor infertility

OBJECTIVE

To compare the likelihood of abnormal Chlamydia trachomatis antibody test results with that of abnormal hysterosalpingography (HSG) test results in patients with tubal factor infertility.

DESIGN

Anti-C. trachomatis immunoglobulin G antibodies were determined prospectively in 211 consecutive infertility patients by means of an indirect fluorescent antibody technique. The results were compared with the results of HSG with respect to their predictive value of tubal factor infertility. Likelihood ratio calculations were used.

SETTING

University hospital-based, tertiary care infertility clinic.

PATIENTS

A series of 211 consecutive infertility patients.

INTERVENTIONS

C. trachomatis antibody testing, HSG, laparoscopy.

MAIN OUTCOME MEASURES

Likelihood ratios for abnormal C. trachomatis antibody test results and abnormal HSG results in infertility patients, as assessed by laparoscopy.

RESULTS

The positive likelihood ratio for C. trachomatis antibody testing was 9.1, indicating a patient with tubal factor infertility to be 9.1 times more likely to have abnormal serology results than a patient without tubal factor infertility. This was superior to HSG, which had a positive likelihood ratio of 2.6 in our study and of 1.6 to 6.1 in the literature. The odds ratio of C. trachomatis antibody testing was 31.5 in our study. Its 90% confidence interval (8.3 to 138.5) did not overlap that of HSG as calculated from a meta-analysis of literature reports (5.3 to 7.9).

CONCLUSIONS

C. trachomatis antibody testing is simple, inexpensive, and causes minimal inconvenience to the patient. It is more likely than HSG to be abnormal in patients with tubal factor infertility. C. trachomatis antibody testing deserves to become an integral component of the initial fertility work-up.

Detection of IgG, IgM and IgA antibodies in patients with uncomplicated Chlamydia trachomatis infection: a comparison between enzyme linked immunofluorescent assay and isolation in cell culture

The diagnostic value of serum IgG, IgM and IgA in patients with uncomplicated urogenital Chlamydia trachomatis infection was compared with isolation in cell culture. C. trachomatis specific antibodies were determined with an enzyme linked immunofluorescent assay using elementary bodies from C. trachomatis serotypes E,F,H,I,J and LGV2 as antigens. At least two sera from each patient were tested and cultures were also established on the same day. Excluding the IgM titres in men, significantly more IgG, IgA and IgM and combinations of these antibodies were observed in culture positive patients. The sensitivity with which IgG titres in men or IgG and/or IgM titres in men and women could be determined, was significantly lower using C. trachomatis LGV2 as the only antigen than when all 6 antigens were used. The presence of 10 or more leucocytes in the urine sediment of men correlated positively with an IgG or an IgG and/or IgM titre.

Evaluation of two ELISA's for detecting Chlamydia trachomatis from endocervical swabs

Two enzyme immunoassays (EIAs) detecting Chlamydia trachomatis from endocervical swabs, Syva MicroTrak (MT) and Abbott Chlamydiazyme (CZ), were compared with a tissue culture (TC) standard. Initially, 8% (100 of 1250) of specimens were TC positive, yielding sensitivities of 94% (94 of 100) for MT and 79% (79 of 100) for CZ with identical 98% specificities (1129 of 1150 for MT and 1130 of 1150 for CZ). Discrepant specimens were retested by both EIAs and assayed for elementary bodies (EBs) by a fluorescent antibody test. After discrepancy analysis, 9.5% (118) of 1240 patients were either TC or EB positive, yielding sensitivities of 94.1% for MT (111 of 118) and 79.7% for CZ (94 of 118) with identical specificities of 100% (1122 of 1122). These results indicate that the MT is significantly more sensitive (p less than 0.05, McNemar test) than CZ in detecting C. trachomatis from endocervical swabs.

Comparison of different methods for the detection of antibodies to Chlamydia trachomatis in human sera

Different methods for the detection of IgG antibodies to Chlamydia trachomatis were compared as to their specificity, sensitivity and efficacy. A modified microimmunofluorescence test (MIF) was used as a reference method. Two commercial ELISA tests kits (Chlamyset-antibody EIA, Orion, Finland and Chlamydelisa, Whittacker M.A. Bioproducts, USA), the complement fixation test (CFT) and five self-made ELISA tests with CFT antigens were compared with the reference method and with each other. In comparison to the reference method, the Chlamyset was found to be the most useful method. Three of the ELISA tests with CFT antigens were statistically comparable with the Chlamyset and the CFT, but the two others showed statistically significant differences. The Chlamydelisa and the MIF showed great differences from all other methods. The Chlamydelisa was very sensitive but apparently unspecific. Possible reasons for the different results are discussed.

Laboratory diagnosis of human chlamydial infections

Chlamydia trachomatis is a human pathogen that causes ocular disease (trachoma and inclusion conjunctivitis), genital disease (cervicitis, urethritis, salpingitis, and lymphogranuloma venereum), and respiratory disease (infant pneumonitis). Respiratory chlamydioses also occur with infection by avian strains of C. psittaci or infection by the newly described TWAR agent. Diagnosis of most acute C. trachomatis infections relies on detection of the infecting agent by cell culture, fluorescent antibody, immunoassay, cytopathologic, or nucleic acid hybridization methods. Individual non-culture tests for C. trachomatis are less sensitive and specific than the best chlamydial cell culture system but offer the advantages of reduced technology and simple transport of clinical specimens. Currently available nonculture tests for C. trachomatis perform adequately as screening tests in populations in which the prevalence of infection is greater than 10%. A negative culture or nonculture test for C. trachomatis does not, however, exclude infection. The predictive value of a positive nonculture test may be unsatisfactory when populations of low infection prevalence are tested. Tests that detect antibody responses to chlamydial infection have limited utility in diagnosis of acute chlamydial infection because of the high prevalence of persistent antibody in healthy adults and the cross-reactivity due to infection by the highly prevalent C. trachomatis and TWAR agents. Assays for changes in antibody titer to the chlamydial genus antigen are used for the diagnosis of respiratory chlamydioses. A single serum sample that is negative for chlamydial antibody excludes the diagnosis of lymphogranuloma venereum.