Chlamydia trachomatis Infection
Common Sexually Transmitted Bacterial Infection
Chlamydia is the most commonly reported bacterial sexually transmitted infection (STI) in North America. More than 2,000,000 people in the U.S. have Chlamydia infection.
Chlamydia is a common sexually transmitted infection caused by Chlamydia trachomatis, and is easily cured with antibiotics. Infection does not prevent against reinfection, and there is no vaccine to prevent infection.
Chlamydia Transmission
Chlamydia trachomatis (chlamydia) is transmitted during unprotected vaginal, anal or oral sex, and can be passed from an infected mother to the newborn during vaginal delivery. As the number of sexual partners increases, so does the risk of transmission.
Developmental Cycle of Chlamydia trachomatis
C. trachomatis infectious particles (elementary bodies) gain entry to host cells by attaching to a receptor on the surface of epithelial cells. The infectious form of C. trachomatis is the elementary body. The elementary bodies are ingested by host cells by a process similar to endocytosis. Following entry into the host cell, the elementary body completes its growth cycle within the endosome through which it entered the cell.
Inside the host cell, the elementary bodies reorganize to an active replicating form known as a reticulate body. The reticulate body is larger than the elementary body (0.5-1 um and 0.25-0.35 um, respectively). Once formed, the reticulate body begins dividing by binary fission. After about 24 hours, the reticulate bodies again become elementary bodies, and are released by the cell to infect new cells.
Although elementary bodies are adapted for survival outside the host cell, the metabolically active or vegetative reticulate body is not stable outside the host cell. The elementary body is the infectious particle responsible for cell to cell and host to host transmission. The reticulate body is non-infective and does not survive outside the host cell.
Cervicitis and Urethritis: Lower Genital Tract Infection
Chlamydia trachomatis infects epithelial cells in the urethra and cervix resulting in inflammation of the urethra (urethritis) and/or cervix (cervicitis).
Symptoms of Chlamydia Infection
Chlamydia infection is often asymptomatic: therefore infection may not be diagnosed and infection may progress undetected to involve the upper genital tract resulting in permanent damage. Symptoms, when present, often mild and appear 1-3 weeks after exposure.
In men and women with urethritis, pain and burning may be present, especially during urination. In men, a discharge from the penis may also be noted.
In women with cervicitis, abdominal pain, vaginal discharge, bleeding between menstrual cycles and/or pain during intercourse may be present.
Complications of Chlamydia Infection
It is estimated that approximately 40% of women infected with Chlamydia will develop pelvic inflammatory disease that may result in permanent damage to the fallopian tubes, uterus and other tissues. Damage to the fallopian tubes or uterus may lead to infertility. Ectopic pregnancy can also result due to damage to fallopian tubes. Ectopic pregnancy occurs when an egg is fertilized outside the uterus in the abdomen.
Men rarely develop complications from chlamydia urethritis; however, when infection does progress to the upper genital tract, the epididymis (tubes that carry sperm from the testes) can be affected causing fever, pain and possibly infertility.
Women with genital Chlamydia infection have a five times greater risk of contracting HIV infection, if exposed through an infected sexual partner.
Chlamydia Screening Recommendations
Because Chlamydia trachomatis is the most common sexually transmitted infection in young women, and infection is often symptomatic, it is recommended that sexually active women under the age of 26 have annual screening tests for Chlamydia infection. Screening is recommended in older women when risk factors such as new or multiple sexual partners exist.
Read more about Chlamydia and other sexually transmitted infections (STIs):
Bacteria: Sexually Transmitted Infections (STI), Pneumonia and Zoonoses
Sexually transmitted infection
PID: Risk factors and prevention
Sources:
Sexually Transmitted Diseases - Chlamydia (Centres for Disease Control and Prevention)
Schachter J. Biology of Chlamydia trachomatis (Chapter 28) in Sexually Transmitted Diseases, Third Edition. McGraw-Hill, New York 1999.
Schachter J and WE Stamm. Chlamydia (Chapter 55). In Manual of Clinical Microbiology, Sixth Edition. American Society of Microbiology Press, Washington, 1995.
