This is an archived article.

December 18, 1996

Promising research on gel to prevent most common STD

A University of Washington study may point the way to development of a contraceptive gel to prevent transmission of Chlamydia trachomatis, the most common cause of sexually transmitted disease.

The findings, reported in the mid-December Journal of Clinical Investigation, identify the structure by which chlamydia bacteria attach to and infect cells.

Chlamydia acts like a virus since it must enter a cell to multiply and survive. UW researchers identified the carbohydrate structure which Chlamydia trachomatis uses to connect to and infect host cells as a sugar chain containing 8 or 9 mannose (simple sugar) residues. The research was led by Dr. Cho-chou Kuo and colleague Dr. Sen-itiroh Hakomori, of the UW School of Public Health and Community Medicine.

The discovery was made by using two-dimensional sugar mapping techniques developed by research collaborators in Japan.

With the binding molecule for Chlamydia trachomatis identified, researchers were able to prevent chlamydial infection of cell cultures using similar carbohydrates from known sources. Kuo explains that when cell receptors are saturated with these compounds, molecules carrying chlamydia infection have no point to attach to and, thus, cannot infect the cell.

With these important findings, researchers can now begin work to synthesize a similar carbohydrate to develop anti-adhesive therapies for the prevention of chlamydia, such as contraceptive gels or eye ointments. Chlamydia is also the leading cause of preventable blindness worldwide. Kuo explains such products could be used at times people may be at risk of contracting chlamydia.

The National Institutes of Health estimates that approximately 4 million new cases of sexually transmitted Chlamydia trachomatis infection occur each year in the United States. Symptoms in men and women may be minor and often disappear without treatment. However, the disease will continue to do damage internally. In women, the bacteria damage cells in the reproductive tract, causing inflammation and scarring, leading to infertility and ectopic pregnancy.

Men infected with Chlamydia trachomatis can continue to infect their sexual partners if not treated.

Chlamydial infection can be treated with antibiotics. However, this type of therapy often fails to prevent blindness and infertility due to tissue destruction and can be too costly, or even unavailable, in Third World locations. Kuo explains that a preventive agent included in contraceptive devices could provide an affordable, effective way to reduce the number of chlamydial infections, and subsequent health problems, throughout the world.