Chlamydia trachomatis

Causative Agents

Chlamydia trachomatis is one of three Chlamydia species (Chlamydia pneumoniae and Chlamydia psittaci) which are human pathogens. The bacteria mainly cause sexually transmitted disease (STDs) and trachoma. While the genovars A, B, Ba and C result trachoma; LGV-I,-II and –III result lymphogranuloma (LGV) and genovars D and K result oculogenital disease. Chlamydia trachomatis’ genome is 1,042,519 base pairs long with 894 predicted protein-coding sequences. (1, 2)


Chlamydia is the most frequent sexually transmitted disease (STD) in the U.S. with an estimated 3 million cases emerging every year and 250,000 to 500,000 cases of pelvic inflammatory disease (PID) and 250,000 cases of epididymitis are caused by Chlamydia trachomatis. In addition, the infection facilitates HIV transmission. The disease is generally unrecognized or inadequately treated, and by ascending infection to reproductive tract; infertility, ectopic pregnancy, or chronic pelvic pain can develop. (1, 3)

Modes of Transmission

Chlamydia trachomatis infection could be transmitted via unprotected vaginal, anal or oral sex. The infection can be passed from an infected mother to the newborn during vaginal delivery. Besides, the risk of transmission increases by the increase of the number of sexual partners. (3, 4)


Diagnosis and monitoring of Chlamydia infections can be performed with ELISA (Enzyme-Linked Immunosorbent Assay), fluorescent monoclonal antibody tests (detects the major outer membrane protein or the LPS), rapid tests (antibodies against the chlamydial lipopolysaccharide-LPS), leukocyte esterase tests and DNA probes. In addition the infection can be diagnosed via nucleic acid amplification tests (NAATs) which comprise PCR and Real-Time PCR methods. NAATs are more sensitive, reliable and rapid compared to previous methods. (1, 2, 5)

Annotated Bibliography

  1. Current Methods of Laboratory Diagnosis of Chlamydia trachomatis Infections, Black C.M., Clin Microbiol Rev. 1997 Jan ;10 (1):160-84 C M Black
  2. Screening Tests To Detect Chlamydia trachomatis and Neisseria gonorrhoeae Infections, Johnson R.E., Newhall W.J., Papp J.R., Knapp J.S., Black C.M., Gift T.L., Steece R., Markowitz L.E., Devine O.J.,
    Walsh C.M., Wang S., Gunter D.C., Irwin K.L., DeLisle S., Berman S.M., MMWR, Recommendations and Reports, 2002, 51(RR15);1-27
  3. Rapid Detection of Chlamydia trachomatis and Typing of the Lymphogranuloma venereum associated L-Serovars by TaqMan PCR, Schaeffer A., Henrich B., BMC Infectious Diseases, 2008, 8:56
  4. Chlamydia trachomatis ompA Variants in Trachoma: What Do They Tell Us?, Andreasen AA, Burton MJ, Holland MJ, Polley S, Faal N, 2008, PLoS Negl Trop Dis 2(9): e306.
  5. Development of Real-Time PCR Assays for Genotyping of Chlamydia trachomatis, Jalal H., Stephen H., Alexander S., Carne C., Sonnex C., Journal of Clinical Microbiology, Aug. 2007, p. 2649–2653

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